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Markussen FAF, Cázarez-Márquez F, Melum VJ, Hazlerigg DG, Wood SH. c-fos induction in the choroid plexus, tanycytes and pars tuberalis is an early indicator of spontaneous arousal from torpor in a deep hibernator. J Exp Biol 2024; 227:jeb247224. [PMID: 38690647 PMCID: PMC11166454 DOI: 10.1242/jeb.247224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 04/19/2024] [Indexed: 05/02/2024]
Abstract
Hibernation is an extreme state of seasonal energy conservation, reducing metabolic rate to as little as 1% of the active state. During the hibernation season, many species of hibernating mammals cycle repeatedly between the active (aroused) and hibernating (torpid) states (T-A cycling), using brown adipose tissue (BAT) to drive cyclical rewarming. The regulatory mechanisms controlling this process remain undefined but are presumed to involve thermoregulatory centres in the hypothalamus. Here, we used the golden hamster (Mesocricetus auratus), and high-resolution monitoring of BAT, core body temperature and ventilation rate, to sample at precisely defined phases of the T-A cycle. Using c-fos as a marker of cellular activity, we show that although the dorsomedial hypothalamus is active during torpor entry, neither it nor the pre-optic area shows any significant changes during the earliest stages of spontaneous arousal. Contrastingly, in three non-neuronal sites previously linked to control of metabolic physiology over seasonal and daily time scales - the choroid plexus, pars tuberalis and third ventricle tanycytes - peak c-fos expression is seen at arousal initiation. We suggest that through their sensitivity to factors in the blood or cerebrospinal fluid, these sites may mediate metabolic feedback-based initiation of the spontaneous arousal process.
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Affiliation(s)
- Fredrik A. F. Markussen
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology,Department of Arctic and Marine Biology, BFE, UiT – The Arctic University of Norway, Tromsø, NO-9037, Norway
| | - Fernando Cázarez-Márquez
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology,Department of Arctic and Marine Biology, BFE, UiT – The Arctic University of Norway, Tromsø, NO-9037, Norway
| | - Vebjørn J. Melum
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology,Department of Arctic and Marine Biology, BFE, UiT – The Arctic University of Norway, Tromsø, NO-9037, Norway
| | - David G. Hazlerigg
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology,Department of Arctic and Marine Biology, BFE, UiT – The Arctic University of Norway, Tromsø, NO-9037, Norway
| | - Shona H. Wood
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology,Department of Arctic and Marine Biology, BFE, UiT – The Arctic University of Norway, Tromsø, NO-9037, Norway
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2
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Nogueira-de-Sá PG, Bicudo JEPW, Chaui-Berlinck JG. Energy and time optimization during exit from torpor in vertebrate endotherms. J Comp Physiol B 2023:10.1007/s00360-023-01494-5. [PMID: 37171656 DOI: 10.1007/s00360-023-01494-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 04/25/2023] [Indexed: 05/13/2023]
Abstract
Torpor is used in small sized birds and mammals as an energy conservation trait. Considerable effort has been put towards elucidating the mechanisms underlying its entry and maintenance, but little attention has been paid regarding the exit. Firstly, we demonstrate that the arousal phase has a stereotyped dynamic: there is a sharp increase in metabolic rate followed by an increase in body temperature and, then, a damped oscillation in body temperature and metabolism. Moreover, the metabolic peak is around two-fold greater than the corresponding euthermic resting metabolic rate. We then hypothesized that either time or energy could be crucial variables to this event and constructed a model from a collection of first principles of physiology, control engineering and thermodynamics. From the model, we show that the stereotyped pattern of the arousal is a solution to save both time and energy. We extended the analysis to the scaling of the use of torpor by endotherms and show that variables related to the control system of body temperature emerge as relevant to the arousal dynamics. In this sense, the stereotyped dynamics of the arousal phase necessitates a certain profile of these variables which is not maintained as body size increases.
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Affiliation(s)
- Pedro Goes Nogueira-de-Sá
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil
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3
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Hensleigh E, Murtishaw AS, Treat MD, Heaney CF, Bolton MM, Sabbagh JJ, Calvin KN, Kinney JW, Breukelen FV. Torpor does not influence spatial memory in hibernating golden-mantled ground squirrels (Spermophilus [Callospermophilus] lateralis). Physiol Biochem Zool 2022; 95:390-399. [DOI: 10.1086/721185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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4
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Regan MD, Chiang E, Martin SL, Porter WP, Assadi-Porter FM, Carey HV. Shifts in metabolic fuel use coincide with maximal rates of ventilation and body surface rewarming in an arousing hibernator. Am J Physiol Regul Integr Comp Physiol 2019; 316:R764-R775. [PMID: 30969844 DOI: 10.1152/ajpregu.00379.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
It is well established that hibernating mammals rely predominantly on lipid stores to fuel metabolism throughout the hibernation season. However, it is unclear if other endogenous fuels contribute to the rapid, ~400-fold increase in metabolic rate during the early phase of arousal from torpor. To investigate this issue, we used cavity ring-down spectroscopy, a technique that provides a real-time indication of fuel use by measuring the ratio of 13C to 12C in the exhaled CO2 of arousing 13-lined ground squirrels (Ictidomys tridecemlineatus). We used infrared thermography to simultaneously measure ventilation and surface temperature change in various body regions, and we interpreted these data in light of changing plasma metabolite abundances at multiple stages of arousal from torpor. We found that hibernating squirrels use a combination of lipids and, likely, carbohydrates to fuel the initial ~60 min of arousal before switching to predominantly lipid oxidation. This fuel switch coincided with times of maximal rates of ventilation and rewarming of different body surface regions, including brown adipose tissue. Infrared thermography revealed zonal rewarming, whereby the brown adipose tissue region was the first to warm, followed by the thoracic and head regions and, finally, the posterior half of the body. Consistent with the results from cavity ring-down spectroscopy, plasma metabolite dynamics during early arousal suggested a large reliance on fatty acids, with a contribution from carbohydrates and glycerol. Because of their high oxidative flux rates and efficient O2 use, carbohydrates might be an advantageous metabolic fuel during the early phase of arousal, when metabolic demands are high but ventilation rates and, thus, O2 supply are relatively low.
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Affiliation(s)
- Matthew D Regan
- Department of Comparative Biosciences, University of Wisconsin-Madison , Madison, Wisconsin
| | - Edna Chiang
- Department of Comparative Biosciences, University of Wisconsin-Madison , Madison, Wisconsin.,Department of Bacteriology, University of Wisconsin-Madison , Madison, Wisconsin
| | - Sandra L Martin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine , Aurora, Colorado
| | - Warren P Porter
- Deparment of Integrative Biology, University of Wisconsin-Madison , Madison, Wisconsin
| | - Fariba M Assadi-Porter
- Department of Comparative Biosciences, University of Wisconsin-Madison , Madison, Wisconsin.,Deparment of Integrative Biology, University of Wisconsin-Madison , Madison, Wisconsin
| | - Hannah V Carey
- Department of Comparative Biosciences, University of Wisconsin-Madison , Madison, Wisconsin
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5
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Faherty SL, Villanueva‐Cañas JL, Blanco MB, Albà MM, Yoder AD. Transcriptomics in the wild: Hibernation physiology in free‐ranging dwarf lemurs. Mol Ecol 2018; 27:709-722. [DOI: 10.1111/mec.14483] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/13/2017] [Accepted: 12/14/2017] [Indexed: 12/30/2022]
Affiliation(s)
| | - José Luis Villanueva‐Cañas
- Institute of Evolutionary Biology (CSIC‐Universitat Pompeu Fabra) Barcelona Spain
- Evolutionary Genomics Group Research Programme on Biomedical Informatics (GRIB) Hospital del Mar Research Institute (IMIM) Universitat Pompeu Fabra (UPF) Barcelona Spain
| | | | - M. Mar Albà
- Evolutionary Genomics Group Research Programme on Biomedical Informatics (GRIB) Hospital del Mar Research Institute (IMIM) Universitat Pompeu Fabra (UPF) Barcelona Spain
- Catalan Institution for Research and Advanced Studies (ICREA) Barcelona Spain
| | - Anne D. Yoder
- Department of Biology Duke University Durham NC USA
- Duke Lemur Center Durham NC USA
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Treat MD, Scholer L, Barrett B, Khachatryan A, McKenna AJ, Reyes T, Rezazadeh A, Ronkon CF, Samora D, Santamaria JF, Silva Rubio C, Sutherland E, Richardson J, Lighton JRB, van Breukelen F. Extreme physiological plasticity in a hibernating basoendothermic mammal, Tenrec ecaudatus. J Exp Biol 2018; 221:jeb.185900. [DOI: 10.1242/jeb.185900] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/20/2018] [Indexed: 01/13/2023]
Abstract
Physiological plasticity allows organisms to respond to diverse conditions. However, can being too plastic actually be detrimental? Malagasy common tenrecs, Tenrec ecaudatus, have many plesiomorphic traits and may represent a basal placental mammal. We established a laboratory population of T. ecaudatus and found extreme plasticity in thermoregulation and metabolism, a novel hibernation form, variable annual timing, and remarkable growth and reproductive biology. For instance, tenrec body temperature (Tb) may approximate ambient temperature to as low as 12°C even when tenrecs are fully active. Conversely, tenrecs can hibernate with Tbs of 28°C. During the active season, oxygen consumption may vary 25-fold with little or no changes in Tb. During the Austral winter, tenrecs are consistently torpid but the depth of torpor may be variable. A righting assay revealed that Tb contributes to but does not dictate activity status. Homeostatic processes are not always linked e.g. a hibernating tenrec experienced a ∼34% decrease in heart rate while maintaining constant body temperature and oxygen consumption rates. Tenrec growth rates vary but young may grow ∼40-fold in the 5 weeks until weaning and may possess indeterminate growth as adults. Despite all of this profound plasticity, tenrecs are surprisingly intolerant to extremes in ambient temperature (<8 or >34°C). We contend that while plasticity may confer numerous energetic advantages in consistently moderate environments, environmental extremes may have limited the success and distribution of plastic basal mammals.
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Affiliation(s)
- Michael D. Treat
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Lori Scholer
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Brandon Barrett
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Artur Khachatryan
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Austin J. McKenna
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Tabitha Reyes
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Alhan Rezazadeh
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Charles F. Ronkon
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Dan Samora
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Jeremy F. Santamaria
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Claudia Silva Rubio
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | - Evan Sutherland
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
| | | | | | - Frank van Breukelen
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA
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Abstract
Increasing evidence supports a major role for the renin-angiotensin system (RAS) in energy balance physiology. The RAS exists as a circulating system but also as a local paracrine/autocrine signaling mechanism in target tissues including the gastrointestinal tract, the brain, the kidney, and distinct adipose beds. Through activation of various receptors in these target tissues, the RAS contributes to the control of food intake behavior, digestive efficiency, spontaneous physical activity, and aerobic and anaerobic resting metabolism. Although the assortment of methodologies available to assess the various aspects of energy balance can be daunting for an investigator new to this area, a relatively straightforward array of entry-level and advanced methodologies can be employed to comprehensively and quantitatively dissect the effects of experimental manipulations on energy homeostasis. Such methodologies and a simple initial workflow for the use of these methods are described in this chapter, including the use of metabolic caging systems, bomb calorimetry, body composition analyzers, respirometry systems, and direct calorimetry systems. Finally, a brief discussion of the statistical analyses of metabolic data is included.
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Affiliation(s)
- Justin L Grobe
- Department of Pharmacology, Center for Hypertension Research, The Obesity Research and Education Initiative, François M. Abboud Cardiovascular Research Center, The Fraternal Order of Eagles' Diabetes Research Center, University of Iowa, 51 Newton Rd., 2-307 BSB, Iowa City, IA, 52242, USA.
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Schwartz C, Ballinger MA, Andrews MT. Melatonin receptor signaling contributes to neuroprotection upon arousal from torpor in thirteen-lined ground squirrels. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1292-300. [PMID: 26354846 PMCID: PMC4666939 DOI: 10.1152/ajpregu.00292.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/03/2015] [Indexed: 01/13/2023]
Abstract
The brain of mammalian hibernators is naturally protected. Hibernating ground squirrels undergo rapid and extreme changes in body temperature and brain perfusion as they cycle between lengthy torpor bouts and brief periods of euthermia called interbout arousals (IBAs). Arousal from torpor to IBA occurs rapidly, but there is no evidence of brain injury accompanying this extreme physiological transition. Production of the hormone melatonin accompanies arousal, suggesting that it plays a protective role at this time. Here, we investigated mechanisms of melatonin receptor-mediated protection in the brain of the hibernating ground squirrel. We administered the competitive melatonin receptor antagonist luzindole (30 mg/kg ip) to ground squirrels at the predicted end of a torpor bout, triggering an arousal. We found that luzindole-treated animals exhibited caspase-3 activity two times higher than vehicle-treated animals in the hypothalamus at midarousal (P = 0.01), suggesting that melatonin receptor signaling is important for protection in this brain region. We also found a 30% decline in succinate-fueled mitochondrial respiration in luzindole-treated animals compared with vehicle-treated animals (P = 0.019), suggesting that melatonin receptor signaling is important for optimal mitochondrial function during arousal from torpor. The mitochondrial effects of luzindole treatment were seen only during the hibernation season, indicating that this effect is specifically important for arousal from torpor. These data provide evidence for the protective role of melatonin receptor signaling during the extreme physiological transition that occurs when a hibernating mammal arouses from torpor and provide further evidence for regional and seasonal changes in the hibernator brain.
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MESH Headings
- Adaptation, Physiological
- Animals
- Brain/drug effects
- Brain/metabolism
- Caspase 3/genetics
- Caspase 3/metabolism
- Central Nervous System/physiology
- Female
- Gene Expression Regulation, Enzymologic
- Hibernation/drug effects
- Hibernation/physiology
- Male
- Melatonin/metabolism
- Mitochondria/drug effects
- Mitochondria/metabolism
- Receptor, Melatonin, MT1/antagonists & inhibitors
- Receptor, Melatonin, MT1/metabolism
- Receptor, Melatonin, MT2/antagonists & inhibitors
- Receptor, Melatonin, MT2/metabolism
- Sciuridae/physiology
- Seasons
- Signal Transduction/physiology
- Tryptamines/pharmacology
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Affiliation(s)
- Christine Schwartz
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and Department of Biology, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Mallory A Ballinger
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Matthew T Andrews
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
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9
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Measuring subcutaneous temperature and differential rates of rewarming from hibernation and daily torpor in two species of bats. Comp Biochem Physiol A Mol Integr Physiol 2015; 190:26-31. [PMID: 26300411 DOI: 10.1016/j.cbpa.2015.08.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/07/2015] [Accepted: 08/11/2015] [Indexed: 01/11/2023]
Abstract
Prolonged and remote measurement of body temperature (Tb) in undisturbed small hibernators was not possible in the past because of technological limitations. Although passive integrated transponders (PITs) have been used previously to measure subcutaneous temperature (Tsub) during daily torpor in a small marsupial, no study has attempted to use these devices at Tbs below 10°C. Therefore, we investigated whether subcutaneous interscapular PITs can be used as a viable tool for measuring Tb in a small hibernating bat (Nyctophilus gouldi; Ng) and compared it with measurements of Tb during daily torpor in a heterothermic bat (Syconycteris australis; Sa). The precision of transponders was investigated as a function of ambient temperature (Ta) and remote Tsub readings enabled us to quantify Tsub-Tb differentials during steady-state torpor and arousal. Transponders functioned well outside the manufacturer's recommended range, down to ~5°C. At rest, Tsub and rectal Tb (Trec) were strongly correlated for both bat species (Ng r(2)=0.88; Sa r(2)=0.95) and this was also true for N. gouldi in steady-state torpor (r(2)=0.93). During induced rewarming Tsub increased faster than Trec in both species. Our results demonstrate that transponders can be used to provide accurate remote measurement of Tb in two species of bats during different physiological states, both during steady-state conditions and throughout dynamic phases such as rewarming from torpor. We show that, at least during rewarming, regional heterothermy common to larger hibernators and other hibernating bats is also present in bats capable of daily torpor.
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10
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Carter ET, Eads BC, Ravesi MJ, Kingsbury BA. Exotic invasive plants alter thermal regimes: implications for management using a case study of a native ectotherm. Funct Ecol 2014. [DOI: 10.1111/1365-2435.12374] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Evin T. Carter
- Department of Ecology and Evolutionary Biology University of Tennessee Knoxville TN 37996 USA
| | - Bryan C. Eads
- Department of Biology Indiana ‐ Purdue University Fort Wayne IN 46805 USA
| | - Michael J. Ravesi
- Department of Biology Indiana ‐ Purdue University Fort Wayne IN 46805 USA
| | - Bruce A. Kingsbury
- Department of Biology Indiana ‐ Purdue University Fort Wayne IN 46805 USA
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11
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Geiser F, Currie SE, O'Shea KA, Hiebert SM. Torpor and hypothermia: reversed hysteresis of metabolic rate and body temperature. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1324-9. [PMID: 25253085 DOI: 10.1152/ajpregu.00214.2014] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regulated torpor and unregulated hypothermia are both characterized by substantially reduced body temperature (Tb) and metabolic rate (MR), but they differ physiologically. Although the remarkable, medically interesting adaptations accompanying torpor (e.g., tolerance for cold and ischemia, absence of reperfusion injury, and disuse atrophy) often do not apply to hypothermia in homeothermic species such as humans, the terms "torpor" and "hypothermia" are often used interchangeably in the literature. To determine how these states differ functionally and to provide a reliable diagnostic tool for differentiating between these two physiologically distinct states, we examined the interrelations between Tb and MR in a mammal (Sminthopsis macroura) undergoing a bout of torpor with those of the hypothermic response of a similar-sized juvenile rat (Rattus norvegicus). Our data show that under similar thermal conditions, 1) cooling rates differ substantially (approximately fivefold) between the two states; 2) minimum MR is approximately sevenfold higher during hypothermia than during torpor despite a similar Tb; 3) rapid, endogenously fuelled rewarming occurs in torpor but not hypothermia; and 4) the hysteresis between Tb and MR during warming and cooling proceeds in opposite directions in torpor and hypothermia. We thus demonstrate clear diagnostic physiological differences between these two states that can be used experimentally to confirm whether torpor or hypothermia has occurred. Furthermore, the data can clarify the results of studies investigating the ability of physiological or pharmacological agents to induce torpor. Consequently, we recommend using the terms "torpor" and "hypothermia" in ways that are consistent with the underlying regulatory differences between these two physiological states.
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Affiliation(s)
- Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Shannon E Currie
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Kelly A O'Shea
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Sara M Hiebert
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
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12
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Willis CKR, Wilcox A. Hormones and hibernation: possible links between hormone systems, winter energy balance and white-nose syndrome in bats. Horm Behav 2014; 66:66-73. [PMID: 24768718 DOI: 10.1016/j.yhbeh.2014.04.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/11/2014] [Accepted: 04/15/2014] [Indexed: 12/19/2022]
Abstract
This article is part of a Special Issue "Energy Balance". Hibernation allows mammals to survive in cold climates and during times of reduced food availability. Drastic physiological changes are required to maintain the energy savings that characterize hibernation. These changes presumably enable adjustments in endocrine activity that control metabolism and body temperature, and ultimately influence expression of torpor and periodic arousals. Despite challenges that exist when examining hormonal pathways in small-bodied hibernators, bats represent a potential model taxon for comparative neuroendocrinological studies of hibernation due to their diversity of species and the reliance of many species on heterothermy. Understanding physiological mechanisms underlying hibernation in bats is also important from a conservation physiology perspective due to white-nose syndrome, an emerging infectious disease causing catastrophic mortality among hibernating bats in eastern North America. Here we review the potential influence of three key hormonal mechanisms--leptin, melatonin and glucocorticoids--on hibernation in mammals with an emphasis on bats. We propose testable hypotheses about potential effects of WNS on these systems and their evolution.
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Affiliation(s)
- Craig K R Willis
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada.
| | - Alana Wilcox
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada
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