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Sattgast LH, Wong CP, Branscum AJ, Olson DA, Aguirre-Burk AM, Iwaniec UT, Turner RT. Small changes in thermoregulation influence cancellous bone turnover balance in distal femur metaphysis in growing female mice. Bone Rep 2023; 18:101675. [PMID: 37007217 PMCID: PMC10063413 DOI: 10.1016/j.bonr.2023.101675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 03/30/2023] Open
Abstract
Mice are typically housed at temperatures well below their thermoneutral zone. When individually housed at room temperature (~22 °C) mice experience cold stress which results in cancellous bone loss and has the potential to alter the skeletal response to treatment. It is not clear if there is a threshold temperature for cold stress-induced bone loss. It is also not clear if alternative strategies for attenuating cold stress, such as group housing, influence bone accrual and turnover. This study aimed to determine how small differences in temperature (4 °C) or heat loss (individual versus group housing with nestlets) influence bone in growing female C57BL/6 J mice. Five-week-old mice were randomized by weight to 1 of 4 treatment groups (N = 10/group): 1) baseline, 2) single housed at 22 °C, 3) single housed at 26 °C, or 4) group housed (n = 5/cage) with nestlets at 22 °C. Mice in the baseline group were sacrificed 1 week later, at 6 weeks of age. The other 3 groups of mice were maintained at their respective temperatures and housing conditions for 13 weeks until 18 weeks of age. Compared to baseline, mice single housed at room temperature had increased body weight and femur size, but dramatically decreased cancellous bone volume fraction in distal femur metaphysis. The cancellous bone loss was attenuated but not prevented in mice individually housed at 26 °C or group housed at 22 °C. In conclusion, by impacting thermogenesis or heat loss, modest differences in housing conditions could influence experimental results.
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Affiliation(s)
- Lara H. Sattgast
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Carmen P. Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Dawn A. Olson
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Allan M. Aguirre-Burk
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
| | - Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
- Corresponding author at: Skeletal Biology Laboratory, School of Biological and Population Health Sciences, 127 Milam Hall, Oregon State University, Corvallis, OR 97331, USA.
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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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Long A, Liu Y, Fang X, Jia L, Li Z, Hu J, Wu S, Chen C, Huang P, Wang Y. Famsin, a novel gut-secreted hormone, contributes to metabolic adaptations to fasting via binding to its receptor OLFR796. Cell Res 2023; 33:273-287. [PMID: 36806353 PMCID: PMC10066382 DOI: 10.1038/s41422-023-00782-7] [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: 08/30/2022] [Accepted: 01/19/2023] [Indexed: 02/19/2023] Open
Abstract
The intestine is responsible for nutrient absorption and orchestrates metabolism in different organs during feeding, a process which is partly controlled by intestine-derived hormones. However, it is unclear whether the intestine plays an important role in metabolism during fasting. Here we have identified a novel hormone, famsin, which is secreted from the intestine and promotes metabolic adaptations to fasting. Mechanistically, famsin is shed from a single-pass transmembrane protein, Gm11437, during fasting and then binds OLFR796, an olfactory receptor, to activate intracellular calcium mobilization. This famsin-OLFR796 signaling axis promotes gluconeogenesis and ketogenesis for energy mobilization, and torpor for energy conservation during fasting. In addition, neutralization of famsin by an antibody improves blood glucose profiles in diabetic models, which identifies famsin as a potential therapeutic target for treating diabetes. Therefore, our results demonstrate that communication between the intestine and other organs by a famsin-OLFR796 signaling axis is critical for metabolic adaptations to fasting.
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Affiliation(s)
- Aijun Long
- State Key Laboratory of Membrane Biology, MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yang Liu
- State Key Laboratory of Membrane Biology, MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xinlei Fang
- State Key Laboratory of Membrane Biology, MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Liangjie Jia
- State Key Laboratory of Membrane Biology, MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhiyuan Li
- State Key Laboratory of Membrane Biology, MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jiang Hu
- The Second Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Shuang Wu
- The Second Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Chao Chen
- The First Clinical Medical College of Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Ping Huang
- The Second Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China.
| | - Yiguo Wang
- State Key Laboratory of Membrane Biology, MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
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4
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Bryla A, Zagkle E, Sadowska ET, Cichoń M, Bauchinger U. Measurements of body temperature and oxidative stress reveal differential costs associated with humoral immune function in a passerine bird. J Exp Biol 2022; 225:279339. [PMID: 36314237 DOI: 10.1242/jeb.244897] [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: 08/31/2022] [Accepted: 10/19/2022] [Indexed: 11/05/2022]
Abstract
Eco-immunology considers resistance to antigens a costly trait for an organism, but actual quantification of such costs is not straightforward. Costs of the immune response are visible in impaired coloration and reduced growth or reproductive success. Activation of the humoral immune response is a slow, complex and long-lasting process, which makes the quantification of its energetic cost a potential losing game. We implemented near-continuous measurements of body temperature in zebra finches (Taeniopygia guttata) as a proxy for the energetic cost, with a particular focus during activation of the humoral immune response until the peak of antibody release several days later. At the peak of the antibody release we additionally measured oxygen consumption (open-flow respirometry) and markers of oxidative stress (dROMs, OXY). Birds with an activated immune response maintained a higher night-time body temperature during the first 4 nights after an immune challenge in comparison to controls, implying increased night-time energy use. At peak antibody production, we did not find differences in night-time body temperature and oxygen consumption but observed differentiated results for oxygen consumption during the day. Immune-challenged females had significantly higher oxygen consumption compared with other groups. Moreover, we found that activation of the humoral immune response increases oxidative damage, a potential cost of maintaining the higher night-time body temperature that is crucial at the early stage of the immune response. The costs generated by the immune system appear to consist of two components - energetic and non-energetic - and these appear to be separated in time.
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Affiliation(s)
- Amadeusz Bryla
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Elisavet Zagkle
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Edyta T Sadowska
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Mariusz Cichoń
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Ulf Bauchinger
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland.,Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
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5
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Wang Y, Song Y, Dai Y, Li X, Xie J, Luo J, Yang C, Fan P, Xiao G, Luo Y, Wang Y, Li Y, Cai X. The burst of electrophysiological signals in the suprachiasmatic nucleus of mouse during the arousal detected by microelectrode arrays. Front Bioeng Biotechnol 2022; 10:970726. [PMID: 36110317 PMCID: PMC9468547 DOI: 10.3389/fbioe.2022.970726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/10/2022] [Indexed: 11/13/2022] Open
Abstract
The neural mechanisms of torpor have essential reference significance for medical methods and long-term manned space. Changes in electrophysiology of suprachiasmatic nucleus (SCN) conduce to revealing the neural mechanisms from the torpor to arousal. Due to the lower physiology state during the torpor, it is a challenge to detect neural activities in vivo on freely behaving mice. Here, we introduced a multichannel microelectrode array (MEA) for real-time detection of local field potential (LFP) and action potential (spike) in the SCN in induced torpor mice. Meanwhile, core body temperature and behaviors of mice were recorded for further analysis. Platinum nanoparticles (PtNPs) and Nafion membrane modified MEA has a lower impedance (16.58 ± 3.93 kΩ) and higher signal-to-noise ratio (S/N = 6.1). We found that from torpor to arousal, the proportion of theta frequency bands of LFPs increased, spike firing rates rapidly increased. These results could all be characteristic information of arousal, supported by the microscopic neural activity promoting arousal in mice. MEA displayed real-time dynamic changes of neuronal activities in the SCN, which was more helpful to analyze and understand neural mechanisms of torpor and arousal. Our study provided a factual basis for the neural state in SCN of induced non-hibernating animals, which was helpful for the application of clinics and spaceflight.
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Affiliation(s)
- Yiding Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Yilin Song
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Yuchuan Dai
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Xinrong Li
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Jingyu Xie
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Jinping Luo
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Chao Yang
- China Astronaut Research and Training Center, Beijing, China
| | - Penghui Fan
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Guihua Xiao
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Yan Luo
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ying Wang
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- *Correspondence: Xinxia Cai, ; Yinghui Li, ; Ying Wang,
| | - Yinghui Li
- China Astronaut Research and Training Center, Beijing, China
- *Correspondence: Xinxia Cai, ; Yinghui Li, ; Ying Wang,
| | - Xinxia Cai
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Xinxia Cai, ; Yinghui Li, ; Ying Wang,
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6
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Lyu J, Zhao Y, Zhang N, Xu X, Zheng R, Yu W, Xin W, Yan C, Ji K. Bezafibrate Rescues Mitochondrial Encephalopathy in Mice via Induction of Daily Torpor and Hypometabolic State. Neurotherapeutics 2022; 19:994-1006. [PMID: 35334081 PMCID: PMC9294104 DOI: 10.1007/s13311-022-01216-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2022] [Indexed: 02/07/2023] Open
Abstract
Leigh syndrome (LS) is one of the most common mitochondrial encephalopathy diseases in infants. To date, there is still an absence of effective therapy. Bezafibrate (BEZ), a pan-peroxisome proliferator-activated receptor (PPAR) agonist, ameliorates the phenotype of the mouse model of mitochondrial disease via an unclear mechanism. Here, we applied it to Ndufs4 knockout (KO) mice, a widely used LS animal model, to observe the therapeutic effects and metabolic changes associated with BEZ treatment to explore the therapeutic strategies for mitochondrial diseases. Administration of BEZ significantly enhances survival and attenuates disease progression in Ndufs4 KO mice. Decreased oxidative stress and stunted growth were also observed. As a PPAR agonist, we did not find mitochondrial biogenesis or enhanced metabolism upon BEZ treatment. On the contrary, mice with dietary BEZ showed daily torpor bouts and lower metabolic rates. We speculate that activating energy-saving metabolism in mice may be associated with the therapeutic effects of BEZ, but the exact mechanism of action requires further study.
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Affiliation(s)
- Jingwei Lyu
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, 250012, Shandong, China
| | - Yuying Zhao
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
- Department of Neurology, Qilu Hospital of Shandong University, No.107 West Wenhua Road, Jinan, 250012, Shandong, China
| | - Na Zhang
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
| | - Xuebi Xu
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
- Department of Neurology, First Affiliated Hospital of Wenzhou Medical University, Ouhai District, Nanbaixiang Street, Wenzhou, 325000, China
| | - Rui Zheng
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
- Department of Neurology Qilu Hospital, Qingdao of Shandong University, Qingdao, 266035, Shandong, China
| | - Wenfei Yu
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
| | - Wang Xin
- College of Chemistry, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institutes of Biomedical Sciences, Chemical Engineering and Materials Science, Shandong Normal University, Jinan, 250014, Shandong, China
| | - Chuanzhu Yan
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China
- Department of Neurology, Qilu Hospital of Shandong University, No.107 West Wenhua Road, Jinan, 250012, Shandong, China
- Department of Neurology Qilu Hospital, Qingdao of Shandong University, Qingdao, 266035, Shandong, China
- Brain Science Research Institute, Shandong University, Jinan, 250012, Shandong, China
| | - Kunqian Ji
- Research Institute of Neuromuscular and Neurodegenerative Diseases and Department of Neurology, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China.
- Department of Neurology, Qilu Hospital of Shandong University, No.107 West Wenhua Road, Jinan, 250012, Shandong, China.
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7
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Upton BA, D'Souza SP, Lang RA. QPLOT Neurons-Converging on a Thermoregulatory Preoptic Neuronal Population. Front Neurosci 2021; 15:665762. [PMID: 34017237 PMCID: PMC8130930 DOI: 10.3389/fnins.2021.665762] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/06/2021] [Indexed: 12/12/2022] Open
Abstract
The preoptic area of the hypothalamus is a homeostatic control center. The heterogeneous neurons in this nucleus function to regulate the sleep/wake cycle, reproduction, thirst and hydration, as well as thermogenesis and other metabolic responses. Several recent studies have analyzed preoptic neuronal populations and demonstrated neuronal subtype-specific roles in suppression of thermogenesis. These studies showed similar thermogenesis responses to chemogenetic modulation, and similar synaptic tracing patterns for neurons that were responsive to cold, to inflammatory stimuli, and to violet light. A reanalysis of single-cell/nucleus RNA-sequencing datasets of the preoptic nucleus indicate that these studies have converged on a common neuronal population that when activated, are sufficient to suppress thermogenesis. Expanding on a previous name for these neurons (Q neurons, which reflect their ability to promote quiescence and expression of Qrfp), we propose a new name: QPLOT neurons, to reflect numerous molecular markers of this population and to capture its broader roles in metabolic regulation. Here, we summarize previous findings on this population and present a unified description of QPLOT neurons, the excitatory preoptic neuronal population that integrate a variety of thermal, metabolic, hormonal and environmental stimuli in order to regulate metabolism and thermogenesis.
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Affiliation(s)
- Brian A Upton
- The Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Pediatric Ophthalmology, Center for Chronobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Molecular and Developmental Biology Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States.,Medical Scientist Training Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Shane P D'Souza
- The Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Pediatric Ophthalmology, Center for Chronobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Molecular and Developmental Biology Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Richard A Lang
- The Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Pediatric Ophthalmology, Center for Chronobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
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8
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Reilly SM, Abu-Odeh M, Ameka M, DeLuca JH, Naber MC, Dadpey B, Ebadat N, Gomez AV, Peng X, Poirier B, Walk E, Potthoff MJ, Saltiel AR. FGF21 is required for the metabolic benefits of IKKε/TBK1 inhibition. J Clin Invest 2021; 131:145546. [PMID: 33822771 DOI: 10.1172/jci145546] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 03/23/2021] [Indexed: 12/15/2022] Open
Abstract
The protein kinases IKKε and TBK1 are activated in liver and fat in mouse models of obesity. We have previously demonstrated that treatment with the IKKε/TBK1 inhibitor amlexanox produces weight loss and relieves insulin resistance in obese animals and patients. While amlexanox treatment caused a transient reduction in food intake, long-term weight loss was attributable to increased energy expenditure via FGF21-dependent beiging of white adipose tissue (WAT). Amlexanox increased FGF21 synthesis and secretion in several tissues. Interestingly, although hepatic secretion determined circulating levels, it was dispensable for regulating energy expenditure. In contrast, adipocyte-secreted FGF21 may have acted as an autocrine factor that led to adipose tissue browning and weight loss in obese mice. Moreover, increased energy expenditure was an important determinant of improved insulin sensitivity by amlexanox. Conversely, the immediate reductions in fasting blood glucose observed with acute amlexanox treatment were mediated by the suppression of hepatic glucose production via activation of STAT3 by adipocyte-secreted IL-6. These findings demonstrate that amlexanox improved metabolic health via FGF21 action in adipocytes to increase energy expenditure via WAT beiging and that adipocyte-derived IL-6 has an endocrine role in decreasing gluconeogenesis via hepatic STAT3 activation, thereby producing a coordinated improvement in metabolic parameters.
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Affiliation(s)
- Shannon M Reilly
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Mohammad Abu-Odeh
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA
| | - Magdalene Ameka
- Department of Neuroscience and Pharmacology and.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Julia H DeLuca
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA
| | - Meghan C Naber
- Department of Neuroscience and Pharmacology and.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Benyamin Dadpey
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA
| | - Nima Ebadat
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA
| | - Andrew V Gomez
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA
| | - Xiaoling Peng
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - BreAnne Poirier
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Elyse Walk
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA
| | - Matthew J Potthoff
- Department of Neuroscience and Pharmacology and.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Alan R Saltiel
- Division of Metabolism and Endocrinology, Department of Medicine, UCSD, La Jolla, California, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
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9
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Vincent SG, Fisher JT. In vivo cardiopulmonary impact of skeletal M 3Dq DREADD expression: a pilot study. J Comp Physiol B 2021; 191:1059-1070. [PMID: 34272586 PMCID: PMC8572194 DOI: 10.1007/s00360-021-01387-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/23/2021] [Accepted: 07/06/2021] [Indexed: 01/07/2023]
Abstract
The muscarinic M3 receptor (M3R) is implicated in cardiopulmonary control and many other peripheral physiologic functions. Previous observations report mortality in mice expressing a Gq-linked designer G-protein coupled receptor (Dq) selectively in striated muscle, while M3Dq DREADD (Designer Receptor Exclusively Activated by Designer Drug), selectively expressed in skeletal muscle (SKM) impacts glucose metabolism. We investigated whether activation of SKM M3Dq impacts cardiopulmonary function. Heart rate (HR), body temperature (Tb) and locomotor activity (ACT) were measured in 4 conscious, chronically instrumented M3Dq DREADD mice and 4 wildtype controls. Circadian values of HR, BT and ACT were not different between genotypes (p > 0.05). Activation of the M3Dq DREADD by clozapine N-oxide (CNO; 0.1 mg/kg) resulted in: a significant drop in heart rate, 2 h after injection, compared with a time-matched baseline control period from the same animals (460 ± 28 vs. 532 ± 6, p < 0.05), significantly lower ACT compared to the baseline control (p < 0.05) and reduced pulmonary minute ventilation compared to pre-CNO control (p < 0.05). M3Dq DREADD activation did not cause bronchoconstriction (separate protocol), however, there was a concomitant reduction in HR, Tb and ventilation, accompanied by cardiac arrhythmias. We speculate that reductions in Tb, HR and ventilation reflect a mechanistic link between SKM Gq signaling and the metabolic responses associated with the initiation of torpor. Supported by the Canadian Institutes of Health Research (CIHR MOP-81211).
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Affiliation(s)
- Sandra G. Vincent
- Department of Biomedical and Molecular Sciences and Division of Respirology, Department of Medicine, Queen’s University, Kingston, ON K7L 3N6 Canada
| | - John T. Fisher
- Department of Biomedical and Molecular Sciences and Division of Respirology, Department of Medicine, Queen’s University, Kingston, ON K7L 3N6 Canada
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10
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Shi Z, Qin M, Huang L, Xu T, Chen Y, Hu Q, Peng S, Peng Z, Qu LN, Chen SG, Tuo QH, Liao DF, Wang XP, Wu RR, Yuan TF, Li YH, Liu XM. Human torpor: translating insights from nature into manned deep space expedition. Biol Rev Camb Philos Soc 2020; 96:642-672. [PMID: 33314677 DOI: 10.1111/brv.12671] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/09/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022]
Abstract
During a long-duration manned spaceflight mission, such as flying to Mars and beyond, all crew members will spend a long period in an independent spacecraft with closed-loop bioregenerative life-support systems. Saving resources and reducing medical risks, particularly in mental heath, are key technology gaps hampering human expedition into deep space. In the 1960s, several scientists proposed that an induced state of suppressed metabolism in humans, which mimics 'hibernation', could be an ideal solution to cope with many issues during spaceflight. In recent years, with the introduction of specific methods, it is becoming more feasible to induce an artificial hibernation-like state (synthetic torpor) in non-hibernating species. Natural torpor is a fascinating, yet enigmatic, physiological process in which metabolic rate (MR), body core temperature (Tb ) and behavioural activity are reduced to save energy during harsh seasonal conditions. It employs a complex central neural network to orchestrate a homeostatic state of hypometabolism, hypothermia and hypoactivity in response to environmental challenges. The anatomical and functional connections within the central nervous system (CNS) lie at the heart of controlling synthetic torpor. Although progress has been made, the precise mechanisms underlying the active regulation of the torpor-arousal transition, and their profound influence on neural function and behaviour, which are critical concerns for safe and reversible human torpor, remain poorly understood. In this review, we place particular emphasis on elaborating the central nervous mechanism orchestrating the torpor-arousal transition in both non-flying hibernating mammals and non-hibernating species, and aim to provide translational insights into long-duration manned spaceflight. In addition, identifying difficulties and challenges ahead will underscore important concerns in engineering synthetic torpor in humans. We believe that synthetic torpor may not be the only option for manned long-duration spaceflight, but it is the most achievable solution in the foreseeable future. Translating the available knowledge from natural torpor research will not only benefit manned spaceflight, but also many clinical settings attempting to manipulate energy metabolism and neurobehavioural functions.
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Affiliation(s)
- Zhe Shi
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China.,Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.,State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.,Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200030, China
| | - Meng Qin
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Lu Huang
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou, 510632, China
| | - Tao Xu
- Department of Anesthesiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Ying Chen
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China
| | - Qin Hu
- College of Life Sciences and Bio-Engineering, Beijing University of Technology, Beijing, 100024, China
| | - Sha Peng
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Zhuang Peng
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Li-Na Qu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Shan-Guang Chen
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Qin-Hui Tuo
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Duan-Fang Liao
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Xiao-Ping Wang
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ren-Rong Wu
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ti-Fei Yuan
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226000, China
| | - Ying-Hui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Xin-Min Liu
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.,State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.,Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
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11
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Manaserh IH, Maly E, Jahromi M, Chikkamenahalli L, Park J, Hill J. Insulin sensing by astrocytes is critical for normal thermogenesis and body temperature regulation. J Endocrinol 2020; 247:39-52. [PMID: 32698146 PMCID: PMC7456332 DOI: 10.1530/joe-20-0052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 07/13/2020] [Indexed: 12/23/2022]
Abstract
The important role of astrocytes in the central control of energy balance and glucose homeostasis has recently been recognized. Changes in thermoregulation can lead to metabolic dysregulation, but the role of astrocytes in this process is not yet clear. Therefore, we generated mice congenitally lacking insulin receptors (Ir) in astrocytes (IrKOGFAP mice) to investigate the involvement of astrocyte insulin signaling. IrKOGFAP mice displayed significantly lower energy expenditure and a strikingly lower basal and fasting body temperature. When exposed to cold, however, they were able to mount a thermogenic response. IrKOGFAP mice displayed sex differences in metabolic function and thermogenesis that may contribute to the development of obesity and type II diabetes as early as 2 months of age. While brown adipose tissue exhibited higher adipocyte size in both sexes, more apoptosis was seen in IrKOGFAP males. Less innervation and lower BAR3 expression levels were also observed in IrKOGFAP brown adipose tissue. These effects have not been reported in models of astrocyte Ir deletion in adulthood. In contrast, body weight and glucose regulatory defects phenocopied such models. These findings identify a novel role for astrocyte insulin signaling in the development of normal body temperature control and sympathetic activation of BAT. Targeting insulin signaling in astrocytes has the potential to serve as a novel target for increasing energy expenditure.
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Affiliation(s)
- Iyad H Manaserh
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
- Center for Diabetes and Endocrine Research, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
| | - Emily Maly
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
| | - Marziyeh Jahromi
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
| | - Lakshmikanth Chikkamenahalli
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
| | - Joshua Park
- Department of Neuroscience, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
| | - Jennifer Hill
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
- Center for Diabetes and Endocrine Research, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA
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12
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Northeast RC, Vyazovskiy VV, Bechtold DA. Eat, sleep, repeat: the role of the circadian system in balancing sleep-wake control with metabolic need. CURRENT OPINION IN PHYSIOLOGY 2020; 15:183-191. [PMID: 32617440 PMCID: PMC7323618 DOI: 10.1016/j.cophys.2020.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Feeding and sleep are behaviours fundamental to survival, and as such are subject to powerful homeostatic control. Of course, these are mutually exclusive behaviours, and therefore require coordinated temporal organisation to ensure that both energy demands and sleep need are met. Under optimal conditions, foraging/feeding and sleep can be simply partitioned to appropriate phases of the circadian cycle so that they are in suitable alignment with the external environment. However, under conditions of negative energy balance, increased foraging activity must be balanced against sleep requirements and energy conservation. In mammals and many other species, neural circuits that regulate sleep and energy balance are intimately and reciprocally linked. Here, we examine this circuitry, discuss how homeostatic regulation and temporal patterning of sleep are modulated by altered food availability, and describe the role of circadian system in adaptation to metabolic stress.
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Affiliation(s)
- Rebecca C Northeast
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Vladyslav V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - David A Bechtold
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
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13
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Martin SA, Philbrick KA, Wong CP, Olson DA, Branscum AJ, Jump DB, Marik CK, DenHerder JM, Sargent JL, Turner RT, Iwaniec UT. Thermoneutral housing attenuates premature cancellous bone loss in male C57BL/6J mice. Endocr Connect 2019; 8:1455-1467. [PMID: 31590144 PMCID: PMC6865368 DOI: 10.1530/ec-19-0359] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022]
Abstract
Mice are a commonly used model to investigate aging-related bone loss but, in contrast to humans, mice exhibit cancellous bone loss prior to skeletal maturity. The mechanisms mediating premature bone loss are not well established. However, our previous work in female mice suggests housing temperature is a critical factor. Premature cancellous bone loss was prevented in female C57BL/6J mice by housing the animals at thermoneutral temperature (where basal rate of energy production is at equilibrium with heat loss). In the present study, we determined if the protective effects of thermoneutral housing extend to males. Male C57BL/6J mice were housed at standard room temperature (22°C) or thermoneutral (32°C) conditions from 5 (rapidly growing) to 16 (slowly growing) weeks of age. Mice housed at room temperature exhibited reductions in cancellous bone volume fraction in distal femur metaphysis and fifth lumbar vertebra; these effects were abolished at thermoneutral conditions. Mice housed at thermoneutral temperature had higher levels of bone formation in distal femur (based on histomorphometry) and globally (serum osteocalcin), and lower global levels of bone resorption (serum C-terminal telopeptide of type I collagen) compared to mice housed at room temperature. Thermoneutral housing had no impact on bone marrow adiposity but resulted in higher abdominal white adipose tissue and serum leptin. The overall magnitude of room temperature housing-induced cancellous bone loss did not differ between male (current study) and female (published data) mice. These findings highlight housing temperature as a critical experimental variable in studies using mice of either sex to investigate aging-related changes in bone metabolism.
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Affiliation(s)
- Stephen A Martin
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Kenneth A Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Carmen P Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Dawn A Olson
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Adam J Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Donald B Jump
- Molecular Nutrition and Diabetes Research Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Charles K Marik
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Jonathan M DenHerder
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
| | - Jennifer L Sargent
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
| | - Russell T Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, Oregon, USA
| | - Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, Oregon, USA
- Correspondence should be addressed to U T Iwaniec:
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14
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The origin, significance and plasticity of the thermoeffector thresholds: Extrapolation between humans and laboratory rodents. J Therm Biol 2019; 85:102397. [DOI: 10.1016/j.jtherbio.2019.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 01/07/2023]
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15
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Swoap SJ, Bingaman MJ, Hult EM, Sandstrom NJ. Alternate-day feeding leads to improved glucose regulation on fasting days without significant weight loss in genetically obese mice. Am J Physiol Regul Integr Comp Physiol 2019; 317:R461-R469. [DOI: 10.1152/ajpregu.00140.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Alternate-day fasting (ADF) is effective for weight loss and increases insulin sensitivity in diet-induced obese rodents. However, the efficacy of ADF in genetic models of obesity has not been comprehensively studied. Mice that are deficient in leptin ( ob/ob mice) are obese, diabetic, and prone to deep bouts of torpor when fasted. We tested the hypotheses that an ADF protocol in ob/ob mice would result in 1) induction of torpor on fasted days, 2) minimal body weight loss if the mice experienced torpor, and 3) no improvement in glucose control in the absence of weight loss. Female ob/ob mice and littermate controls were assigned to 1) an ad libitum regimen or 2) an ADF regimen, consisting of fasting every other day with ad libitum feeding between fasts. Over a 19-day period, littermate control mice on the ADF regimen consumed the same amount of food as littermate control mice on the ad libitum regimen, whereas the ADF ob/ob mice consumed 37% less food than ad libitum ob/ob mice. Fasting days, but not fed days, led to torpor in both genotypes. Fasting days, but not fed days, led to weight loss in both genotypes relative to ad libitum controls. Fasting days, but not fed days, produced enhanced insulin sensitivity in both genotypes and normalized circulating glucose in ob/ob mice. These data demonstrate improved glucose control on fasting days with the use of ADF in a genetic model of obesity in the face of minimal weight loss.
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Affiliation(s)
- Steven J. Swoap
- Department of Biology, Williams College, Williamstown, Massachusetts
| | - Mark J. Bingaman
- Department of Biology, Williams College, Williamstown, Massachusetts
| | - Elissa M. Hult
- Department of Biology, Williams College, Williamstown, Massachusetts
| | - Noah J. Sandstrom
- Department of Psychology, Williams College, Williamstown, Massachusetts
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16
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Silvani A, Cerri M, Zoccoli G, Swoap SJ. Is Adenosine Action Common Ground for NREM Sleep, Torpor, and Other Hypometabolic States? Physiology (Bethesda) 2019; 33:182-196. [PMID: 29616880 DOI: 10.1152/physiol.00007.2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This review compares two states that lower energy expenditure: non-rapid eye movement (NREM) sleep and torpor. Knowledge on mechanisms common to these states, and particularly on the role of adenosine in NREM sleep, may ultimately open the possibility of inducing a synthetic torpor-like state in humans for medical applications and long-term space travel. To achieve this goal, it will be important, in perspective, to extend the study to other hypometabolic states, which, unlike torpor, can also be experienced by humans.
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Affiliation(s)
- Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum, University of Bologna , Bologna , Italy
| | - Matteo Cerri
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum, University of Bologna , Bologna , Italy.,National Institute of Nuclear Physics (INFN), Section of Bologna, Bologna , Italy
| | - Giovanna Zoccoli
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum, University of Bologna , Bologna , Italy
| | - Steven J Swoap
- Department of Biology, Williams College , Williamstown, Massachusetts
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17
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Lazzeroni ME, Burbrink FT, Simmons NB. Hibernation in bats (Mammalia: Chiroptera) did not evolve through positive selection of leptin. Ecol Evol 2018; 8:12576-12596. [PMID: 30619566 PMCID: PMC6308895 DOI: 10.1002/ece3.4674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 09/10/2018] [Accepted: 09/14/2018] [Indexed: 01/25/2023] Open
Abstract
Temperature regulation is an indispensable physiological activity critical for animal survival. However, relatively little is known about the origin of thermoregulatory regimes in a phylogenetic context, or the genetic mechanisms driving the evolution of these regimes. Using bats as a study system, we examined the evolution of three thermoregulatory regimes (hibernation, daily heterothermy, and homeothermy) in relation to the evolution of leptin, a protein implicated in regulation of torpor bouts in mammals, including bats. A threshold model was used to test for a correlation between lineages with positively selected lep, the gene encoding leptin, and the thermoregulatory regimes of those lineages. Although evidence for episodic positive selection of lep was found, positive selection was not correlated with lineages of heterothermic bats, a finding that contradicts results from previous studies. Evidence from our ancestral state reconstructions suggests that the most recent common ancestor of bats used daily heterothermy and that the presence of hibernation is highly unlikely at this node. Hibernation likely evolved independently at least four times in bats-once in the common ancestor of Vespertilionidae and Molossidae, once in the clade containing Rhinolophidae and Rhinopomatidae, and again independently in the lineages leading to Taphozous melanopogon and Mystacina tuberculata. Our reconstructions revealed that thermoregulatory regimes never transitioned directly from hibernation to homeothermy, or the reverse, in the evolutionary history of bats. This, in addition to recent evidence that heterothermy is best described along a continuum, suggests that thermoregulatory regimes in mammals are best represented as an ordered continuous trait (homeothermy ← → daily torpor ← → hibernation) rather than as the three discrete regimes that evolve in an unordered fashion. These results have important implications for methodological approaches in future physiological and evolutionary research.
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Affiliation(s)
| | - Frank T. Burbrink
- Division of Vertebrate Zoology, Department of HerpetologyAmerican Museum of Natural HistoryNew YorkNew York
| | - Nancy B. Simmons
- Division of Vertebrate Zoology, Department of MammalogyAmerican Museum of Natural HistoryNew YorkNew York
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18
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Deem JD, Muta K, Ogimoto K, Nelson JT, Velasco KR, Kaiyala KJ, Morton GJ. Leptin regulation of core body temperature involves mechanisms independent of the thyroid axis. Am J Physiol Endocrinol Metab 2018; 315:E552-E564. [PMID: 29944392 PMCID: PMC6230702 DOI: 10.1152/ajpendo.00462.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability to maintain core temperature within a narrow range despite rapid and dramatic changes in environmental temperature is essential for the survival of free-living mammals, and growing evidence implicates an important role for the hormone leptin. Given that thyroid hormone plays a major role in thermogenesis and that circulating thyroid hormone levels are reduced in leptin-deficient states (an effect partially restored by leptin replacement), we sought to determine the extent to which leptin's role in thermogenesis is mediated by raising thyroid hormone levels. To this end, we 1) quantified the effect of physiological leptin replacement on circulating levels of thyroid hormone in leptin-deficient ob/ob mice, and 2) determined if the effect of leptin to prevent the fall in core temperature in these animals during cold exposure is mimicked by administration of a physiological replacement dose of triiodothyronine (T3). We report that, as with leptin, normalization of circulating T3 levels is sufficient both to increase energy expenditure, respiratory quotient, and ambulatory activity and to reduce torpor in ob/ob mice. Yet, unlike leptin, infusing T3 at a dose that normalizes plasma T3 levels fails to prevent the fall of core temperature during mild cold exposure. Because thermal conductance (e.g., heat loss to the environment) was reduced by administration of leptin but not T3, leptin regulation of heat dissipation is implicated as playing a uniquely important role in thermoregulation. Together, these findings identify a key role in thermoregulation for leptin-mediated suppression of thermal conduction via a mechanism that is independent of the thyroid axis.
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Affiliation(s)
- Jennifer D Deem
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington , Seattle, Washington
| | - Kenjiro Muta
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington , Seattle, Washington
| | - Kayoko Ogimoto
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington , Seattle, Washington
| | - Jarrell T Nelson
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington , Seattle, Washington
| | - Kevin R Velasco
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington , Seattle, Washington
| | - Karl J Kaiyala
- Department of Oral Health Sciences, School of Dentistry, University of Washington , Seattle, Washington
| | - Gregory J Morton
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington , Seattle, Washington
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19
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Kato GA, Sakamoto SH, Eto T, Okubo Y, Shinohara A, Morita T, Koshimoto C. Individual differences in torpor expression in adult mice are related to relative birth mass. ACTA ACUST UNITED AC 2018; 221:jeb.171983. [PMID: 29678821 DOI: 10.1242/jeb.171983] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/16/2018] [Indexed: 01/31/2023]
Abstract
Daily torpor is a physiological adaptation in small mammals and birds, characterised by drastic reductions in metabolism and body temperature. Energy-constraining conditions, such as cold and starvation, are known to cause the expression of daily torpor. However, the reason for high degrees of inter- and intra-individual variation in torpor expression (TE) in similar situations is not clear. As littermates of altricial animals are exposed to an uneven allocation of maternal resources from conception to weaning, we tested whether early nutritional experiences have long-term effects on TE in adults. We used full-sibling littermates of laboratory mice that as adults were starved overnight to induce torpor. We measured body mass from birth until adulthood as an indicator of nutritional status, and calculated the relative body mass (RBM) as an indicator of the difference in nutritional status within a litter. After maturation, we subjected mice to five repeated torpor induction trials involving 24 h of fasting and 5 days of recovery. Half of the female mice displayed great individual variation in TE whereas male mice rarely exhibited daily torpor. In females, RBM at birth influenced TE, irrespective of body mass in adulthood; thus, female mice born with low RBMs displayed high TE in adulthood. In conclusion, we provide evidence that TE in mice differs among littermates, and that this variation is linked closely to heterogeneous nutritional experiences during the fetal period.
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Affiliation(s)
- Goro A Kato
- Division of Bio-resources, Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Kihara 5200, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan.,Center of Biomedical Research, Research Center for Human Disease Modeling, Graduate School of Medical Sciences, University of Kyushu, Maidashi 3-1-1, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Shinsuke H Sakamoto
- Department of Animal and Grassland Sciences, Faculty of Agriculture, Kibana Campus, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Takeshi Eto
- Center for Toki and Ecological Restoration, Niigata University, Niigata 952-0103, Japan
| | - Yoshinobu Okubo
- Japan Wildlife Research Center, 3-3-7 Kotobashi, Sumida-ku, Tokyo 130-8606, Japan
| | - Akio Shinohara
- Division of Bio-resources, Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Kihara 5200, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan
| | - Tetsuo Morita
- Department of Animal and Grassland Sciences, Faculty of Agriculture, Kibana Campus, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Chihiro Koshimoto
- Division of Bio-resources, Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Kihara 5200, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan
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20
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Currie SE. No effect of season on the electrocardiogram of long-eared bats (Nyctophilus gouldi) during torpor. J Comp Physiol B 2018; 188:695-705. [PMID: 29623413 DOI: 10.1007/s00360-018-1158-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/27/2018] [Accepted: 04/01/2018] [Indexed: 01/23/2023]
Abstract
Heterothermic animals regularly undergo profound alterations of cardiac function associated with torpor. These animals have specialised tissues capable of withstanding fluctuations in body temperature > 30 °C without adverse effects. In particular, the hearts of heterotherms are able to resist fibrillation and discontinuity of the cardiac conduction system common in homeotherms during hypothermia. To investigate the patterns of cardiac conduction in small insectivorous bats which enter torpor year round, I simultaneously measured ECG and subcutaneous temperature (Tsub) of 21 Nyctophilus gouldi (11 g) during torpor at a range of ambient temperatures (Ta 1-28 °C). During torpor cardiac conduction slowed in a temperature dependent manner, primarily via prolongation along the atrioventricular pathway (PR interval). A close coupling of depolarisation and repolarisation was retained in torpid bats, with no isoelectric ST segment visible until animals reached Tsub <6 °C. There was little change in ventricular repolarisation (JT interval) with decreasing Tsub, or between rest and torpor at mild Ta. Bats retained a more rapid rate of ventricular conduction and repolarisation during torpor relative to other hibernators. Throughout all recordings across seasons (> 2500 h), there was no difference in ECG morphology or heart rate during torpor, and no manifestations of significant conduction blocks or ventricular tachyarrhythmias were observed. My results demonstrate the capacity of bat hearts to withstand extreme fluctuations in rate and temperature throughout the year without detrimental arrhythmogenesis. I suggest that this conduction reserve may be related to flight and the daily extremes in metabolism experienced by these animals, and warrants further investigation of cardiac electrophysiology in other flying hibernators.
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Affiliation(s)
- Shannon E Currie
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia. .,Department of Zoology, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, Tel Aviv, 6997801, Israel.
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21
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Chi QS, Li XJ, Wang DH. 2-Deoxy-D-glucose, not mercaptoacetate, induces a reversible reduction of body temperature in male desert hamsters (Phodopus roborovskii). J Therm Biol 2017; 71:189-194. [PMID: 29301689 DOI: 10.1016/j.jtherbio.2017.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 11/18/2017] [Accepted: 11/20/2017] [Indexed: 11/17/2022]
Abstract
The initiation of torpor is supposed to be related to the availability of metabolic fuels. Studies on metabolic fuel inhibition of glucose by using 2-deoxy-D-glucose (2DG) or fatty acid by mercaptoacetate (MA) in heterothermic mammals produced mixed outcomes. To examine the roles of availability of glucose and fatty acid in the initiation of torpor in desert hamsters (Phodopus roborovskii), we intraperitoneally administrated 2DG and MA to summer-acclimated male hamsters while body temperature (Tb), metabolic rate (MR) and respiratory quotient (RQ) were simultaneously recorded to monitor their thermoregulatory response. 2DG induced a reversible reduction of Tb in desert hamsters both at ambient temperature (Ta) of 23°C and 5°C. At Ta of 23°C, Tb, MR and RQ decreased in a dose-dependent manner with a large Tb-Ta differential (> 6.5°C) and a lowest Tb of 28.0°C which were comparable to those in fasted hamsters. At Ta of 5°C, 2DG-treated hamsters also decreased Tb to the same level as at Ta 23°C, but MR was significantly higher than that at Ta of 23°C at each dose, suggesting doses of 2DG directly affected the hypothalamic Tb set-point. Different from fasted hamsters which maintain normothermic at Ta of 5°C, 2DG-treated hamsters showed a substantial reduction of Tb at Ta 5°C, indicating an overwhelming effect on the thermoregulatory system regardless of Ta. Furthermore, the rapid decrease of Tb and outstretched body posture in 2DG-treated hamsters suggest that the effects of 2DG were not simply mimicking the torpor pathways but that other mechanisms are involved. Interestingly, MA failed to induce a torpor-like state in male desert hamsters. Our results suggest that availability of glucose rather than fatty acid plays an important role for initiation of torpor in desert hamsters.
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Affiliation(s)
- Qing-Sheng Chi
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beichen Xilu, Chaoyang, Beijing 100101, China
| | - Xiu-Juan Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beichen Xilu, Chaoyang, Beijing 100101, China; Institute of Health Sciences, Anhui University, Hefei, Anhui 230601, China
| | - De-Hua Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beichen Xilu, Chaoyang, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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22
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Gordon CJ. The mouse thermoregulatory system: Its impact on translating biomedical data to humans. Physiol Behav 2017; 179:55-66. [PMID: 28533176 PMCID: PMC6196327 DOI: 10.1016/j.physbeh.2017.05.026] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/04/2017] [Accepted: 05/18/2017] [Indexed: 01/01/2023]
Abstract
The laboratory mouse has become the predominant test species in biomedical research. The number of papers that translate or extrapolate data from mouse to human has grown exponentially since the year 2000. There are many physiological and anatomical factors to consider in the process of extrapolating data from one species to another. Body temperature is, of course, a critical determinant in extrapolation because it has a direct impact on metabolism, cardiovascular function, drug efficacy, pharmacokinetics of toxins and drugs, and many other effects. While most would consider the thermoregulatory system of mice to be sufficiently stable and predictable as to not be a cause for concern, the thermal physiology of mice does in fact present unique challenges to the biomedical researcher. A variable and unstable core temperature, high metabolic rate, preference for warm temperatures, large surface area: body mass ratio, and high rate of thermal conductance, are some of the key factors of mice that can affect the interpretation and translation of data to humans. It is the intent of this brief review to enlighten researchers studying interspecies translation of biomedical data on the salient facets of the mouse thermal physiology and show how extrapolation in fields such as physiology, psychology, nutrition, pharmacology, toxicology, and pathology.
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Affiliation(s)
- Christopher J Gordon
- Toxicity Assessment Division, National Health Effects and Environmental Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, United States.
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23
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Meyer CW, Ootsuka Y, Romanovsky AA. Body Temperature Measurements for Metabolic Phenotyping in Mice. Front Physiol 2017; 8:520. [PMID: 28824441 PMCID: PMC5534453 DOI: 10.3389/fphys.2017.00520] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 07/06/2017] [Indexed: 01/01/2023] Open
Abstract
Key Points Rectal probing is subject to procedural bias. This method is suitable for first-line phenotyping, provided probe depth and measurement duration are standardized. It is also useful for detecting individuals with out-of-range body temperatures (during hypothermia, torpor).The colonic temperature attained by inserting the probe >2 cm deep is a measure of deep (core) body temperature.IR imaging of the skin is useful for detecting heat leaks and autonomous thermoregulatory alterations, but it does not measure body temperature.Temperature of the hairy or shaved skin covering the inter-scapular brown adipose tissue can be used as a measure of BAT thermogenesis. However, obtaining such measurements of sufficient quality is very difficult, and interpreting them can be tricky. Temperature differences between the inter-scapular and lumbar areas can be a better measure of the thermogenic activity of inter-scapular brown adipose tissue.Implanted probes for precise determination of BAT temperature (changes) should be fixed close to the Sulzer's vein. For measurement of BAT thermogenesis, core body temperature and BAT temperature should be recorded simultaneously.Tail temperature is suitable to compare the presence or absence of vasoconstriction or vasodilation.Continuous, longitudinal monitoring of core body temperature is preferred over single probing, as the readings are taken in a non-invasive, physiological context.Combining core body temperature measurements with metabolic rate measurements yields insights into the interplay between heat production and heat loss (thermal conductance), potentially revealing novel thermoregulatory phenotypes. Endothermic organisms rely on tightly balanced energy budgets to maintain a regulated body temperature and body mass. Metabolic phenotyping of mice, therefore, often includes the recording of body temperature. Thermometry in mice is conducted at various sites, using various devices and measurement practices, ranging from single-time probing to continuous temperature imaging. Whilst there is broad agreement that body temperature data is of value, procedural considerations of body temperature measurements in the context of metabolic phenotyping are missing. Here, we provide an overview of the various methods currently available for gathering body temperature data from mice. We explore the scope and limitations of thermometry in mice, with the hope of assisting researchers in the selection of appropriate approaches, and conditions, for comprehensive mouse phenotypic analyses.
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Affiliation(s)
- Carola W Meyer
- Department of Pharmacology, Max-Planck Institute for Heart and Lung ResearchBad Nauheim, Germany
| | - Youichirou Ootsuka
- Centre for Neuroscience, School of Medicine, Flinders University of South AustraliaAdelaide, SA, Australia
| | - Andrej A Romanovsky
- FeverLab, St. Joseph's Hospital and Medical CenterPhoenix, AZ, United States
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Carlin JL, Jain S, Gizewski E, Wan TC, Tosh DK, Xiao C, Auchampach JA, Jacobson KA, Gavrilova O, Reitman ML. Hypothermia in mouse is caused by adenosine A 1 and A 3 receptor agonists and AMP via three distinct mechanisms. Neuropharmacology 2017; 114:101-113. [PMID: 27914963 PMCID: PMC5183552 DOI: 10.1016/j.neuropharm.2016.11.026] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/02/2016] [Accepted: 11/28/2016] [Indexed: 10/20/2022]
Abstract
Small mammals have the ability to enter torpor, a hypothermic, hypometabolic state, allowing impressive energy conservation. Administration of adenosine or adenosine 5'-monophosphate (AMP) can trigger a hypothermic, torpor-like state. We investigated the mechanisms for hypothermia using telemetric monitoring of body temperature in wild type and receptor knock out (Adora1-/-, Adora3-/-) mice. Confirming prior data, stimulation of the A3 adenosine receptor (AR) induced hypothermia via peripheral mast cell degranulation, histamine release, and activation of central histamine H1 receptors. In contrast, A1AR agonists and AMP both acted centrally to cause hypothermia. Commonly used, selective A1AR agonists, including N6-cyclopentyladenosine (CPA), N6-cyclohexyladenosine (CHA), and MRS5474, caused hypothermia via both A1AR and A3AR when given intraperitoneally. Intracerebroventricular dosing, low peripheral doses of Cl-ENBA [(±)-5'-chloro-5'-deoxy-N6-endo-norbornyladenosine], or using Adora3-/- mice allowed selective stimulation of A1AR. AMP-stimulated hypothermia can occur independently of A1AR, A3AR, and mast cells. A1AR and A3AR agonists and AMP cause regulated hypothermia that was characterized by a drop in total energy expenditure, physical inactivity, and preference for cooler environmental temperatures, indicating a reduced body temperature set point. Neither A1AR nor A3AR was required for fasting-induced torpor. A1AR and A3AR agonists and AMP trigger regulated hypothermia via three distinct mechanisms.
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Affiliation(s)
- Jesse Lea Carlin
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Shalini Jain
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Elizabeth Gizewski
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Tina C Wan
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Dilip K Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Cuiying Xiao
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - John A Auchampach
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Oksana Gavrilova
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Marc L Reitman
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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25
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Sunagawa GA, Takahashi M. Hypometabolism during Daily Torpor in Mice is Dominated by Reduction in the Sensitivity of the Thermoregulatory System. Sci Rep 2016; 6:37011. [PMID: 27845399 PMCID: PMC5109469 DOI: 10.1038/srep37011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/21/2016] [Indexed: 01/20/2023] Open
Abstract
Some mammals enter a hypometabolic state either daily torpor (minutes to hours in length) or hibernation (days to weeks), when reducing metabolism would benefit survival. Hibernators demonstrate deep torpor by reducing both the sensitivity (H) and the theoretical set-point temperature (TR) of the thermogenesis system, resulting in extreme hypothermia close to ambient temperature. However, these properties during daily torpor remain poorly understood due to the very short steady state of the hypometabolism and the large variation among species and individuals. To overcome these difficulties in observing and evaluating daily torpor, we developed a novel torpor-detection algorithm based on Bayesian estimation of the basal metabolism of individual mice. Applying this robust method, we evaluated fasting induced torpor in various ambient temperatures (TAs) and found that H decreased 91.5% during daily torpor while TR only decreased 3.79 °C in mice. These results indicate that thermogenesis during daily torpor shares a common property of sensitivity reduction with hibernation while it is distinct from hibernation by not lowering TR. Moreover, our findings support that mice are suitable model animals to investigate the regulation of the heat production during active hypometabolism, thus suggesting further study of mice may provide clues to regulating hypometabolism in mammals.
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Affiliation(s)
- Genshiro A Sunagawa
- Laboratory for Retinal Regeneration, RIKEN Center for Developmental Biology, 2-2-3 Minatojimaminami-machi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Masayo Takahashi
- Laboratory for Retinal Regeneration, RIKEN Center for Developmental Biology, 2-2-3 Minatojimaminami-machi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
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26
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Joslin PMN, Bell RK, Swoap SJ. Obese mice on a high-fat alternate-day fasting regimen lose weight and improve glucose tolerance. J Anim Physiol Anim Nutr (Berl) 2016; 101:1036-1045. [PMID: 27273295 DOI: 10.1111/jpn.12546] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 05/13/2016] [Indexed: 12/17/2022]
Abstract
Alternate-day fasting (ADF) causes body weight (BW) loss in humans and rodents. However, it is not clear that ADF while maintaining a high-fat (HF) diet results in weight loss and the accompanying improvement in control of circulating glucose. We tested the hypotheses that a high-fat ADF protocol in obese mice would result in (i) BW loss, (ii) improved glucose control, (iii) fluctuating phenotypes on 'fasted' days when compared to 'fed' days and (iv) induction of torpor on 'fasted days'. We evaluated the physiological effects of ADF in diet-induced obese mice for BW, heart rate (HR), body temperature (Tb ), glucose tolerance, insulin responsiveness, blood parameters (leptin, insulin, free fatty acids) and hepatic gene expression. Diet-induced obese male C57BL/6J mice lost one-third of their pre-diet BW while on an ADF diet for 10 weeks consisting of HF food. The ADF protocol improved glucose tolerance and insulin sensitivity, although mice on a fast day were less glucose tolerant than the same mice on a fed day. ADF mice on a fast day had low circulating insulin, but had an enhanced response to an insulin-assisted glucose tolerance test, suggesting the impaired glucose tolerance may be a result of insufficient insulin production. On fed days, ADF mice were the warmest, had a high HR and displayed hepatic gene expression and circulating leptin that closely mimicked that of mice fed an ad lib HF diet. ADF mice never entered torpor as assessed by HR and Tb . However, on fast days, they were the coolest, had the slowest HR, and displayed hepatic gene expression and circulating leptin that closely mimicked that of Chow-Fed mice. Collectively, the ADF regimen with a HF diet in obese mice results in weight loss, improved blood glucose control, and daily fluctuations in selected physiological and biochemical parameters in the mouse.
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Affiliation(s)
- P M N Joslin
- Department of Biology, Williams College, Williamstown, MA, USA
| | - R K Bell
- Department of Biology, Williams College, Williamstown, MA, USA
| | - S J Swoap
- Department of Biology, Williams College, Williamstown, MA, USA
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27
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Derous D, Mitchell SE, Green CL, Chen L, Han JJ, Wang Y, Promislow DE, Lusseau D, Speakman JR, Douglas A. The effects of graded levels of calorie restriction: VI. Impact of short-term graded calorie restriction on transcriptomic responses of the hypothalamic hunger and circadian signaling pathways. Aging (Albany NY) 2016; 8:642-63. [PMID: 26945906 PMCID: PMC4925820 DOI: 10.18632/aging.100895] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/20/2016] [Indexed: 01/03/2023]
Abstract
Food intake and circadian rhythms are regulated by hypothalamic neuropeptides and circulating hormones, which could mediate the anti-ageing effect of calorie restriction (CR). We tested whether these two signaling pathways mediate CR by quantifying hypothalamic transcripts of male C57BL/6 mice exposed to graded levels of CR (10 % to 40 %) for 3 months. We found that the graded CR manipulation resulted in upregulation of core circadian rhythm genes, which correlated negatively with circulating levels of leptin, insulin-like growth factor 1 (IGF-1), insulin, and tumor necrosis factor alpha (TNF-α). In addition, key components in the hunger signaling pathway were expressed in a manner reflecting elevated hunger at greater levels of restriction, and which also correlated negatively with circulating levels of insulin, TNF-α, leptin and IGF-1. Lastly, phenotypes, such as food anticipatory activity and body temperature, were associated with expression levels of both hunger genes and core clock genes. Our results suggest modulation of the hunger and circadian signaling pathways in response to altered levels of circulating hormones, that are themselves downstream of morphological changes resulting from CR treatment, may be important elements in the response to CR, driving some of the key phenotypic outcomes.
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Affiliation(s)
- Davina Derous
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, AB24 2TZ, UK
- Centre for Genome Enabled Biology and Medicine, University of Aberdeen, Aberdeen, Scotland, AB24 3RL, UK
| | - Sharon E. Mitchell
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, AB24 2TZ, UK
| | - Cara L. Green
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, AB24 2TZ, UK
| | - Luonan Chen
- Key laboratory of Systems Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Jing‐Dong J. Han
- Chinese Academy of Sciences Key Laboratory of Computational Biology, Chinese Academy of Sciences‐Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yingchun Wang
- State Key laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Chaoyang, Beijing, 100101, China
| | - Daniel E.L. Promislow
- Department of Pathology and Department of Biology, University of Washington at Seattle, Seattle, WA 98195, USA
| | - David Lusseau
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, AB24 2TZ, UK
| | - John R. Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, AB24 2TZ, UK
- State Key laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Chaoyang, Beijing, 100101, China
| | - Alex Douglas
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, AB24 2TZ, UK
- Centre for Genome Enabled Biology and Medicine, University of Aberdeen, Aberdeen, Scotland, AB24 3RL, UK
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Voronova IP, Khramova GM, Kulikova EA, Petrovskii DV, Bazovkina DV, Kulikov AV. 5-HT2A receptors control body temperature in mice during LPS-induced inflammation via regulation of NO production. Pharmacol Res 2015; 103:123-31. [PMID: 26621247 DOI: 10.1016/j.phrs.2015.11.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/19/2015] [Accepted: 11/22/2015] [Indexed: 12/12/2022]
Abstract
G protein-coupled 5-HT2A receptors are involved in the regulation of numerous normal and pathological physiological functions. At the same time, its involvement in the regulation of body temperature (Tb) in normal conditions is obscure. Here we study the effect of the 5-HT2A receptor activation or blockade on Tb in sick animals. The experiments were carried out on adult C57BL/6 mouse males. Systemic inflammation and sickness were produced by lipopolysaccharide (LPS, 0.1mg/kg, ip), while the 5-HT2A receptor was stimulated or blocked through the administration of the receptor agonist DOI or antagonist ketanserin (1mg/kg), respectively. LPS, DOI or ketanserin alone produced no effect on Tb. However, administration of LPS together with a peripheral or central ketanserin injection reduced Tb (32.2°C). Ketanserin reversed the LPS-induced expression of inducible NO synthase in the brain. Consequently, an involvement of NO in the mechanism of the hypothermic effect of ketanserin in sick mice was hypothesized. Administration of LPS together with NO synthase inhibitor, l-nitro-arginine methyl ester (60mg/kg, ip) resulted in deep (28.5°C) and prolonged (8h) hypothermia, while administration of l-nitro-arginine methyl ester alone produced no effect on Tb. Thus, 5-HT2A receptors play a key role in Tb control in sick mice. Blockade of this GPCR produces hypothermia in mice with systemic inflammation via attenuation of LPS-induced NO production. These results indicate an unexpected role of 5-HT2A receptors in inflammation and NO production and have a considerable biological impact on understanding the mechanism of animal adaptation to pathogens and parasites. Moreover, adverse side effects of 5-HT2A receptor antagonists in patients with inflammation may be expected.
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Affiliation(s)
- Irina P Voronova
- Institute of Physiology and Fundamental Medicine, Siberian Branch of Russian Academy of Medical Sciences, 630117 Novosibirsk, Russia
| | - Galina M Khramova
- Institute of Physiology and Fundamental Medicine, Siberian Branch of Russian Academy of Medical Sciences, 630117 Novosibirsk, Russia
| | - Elizabeth A Kulikova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Dmitrii V Petrovskii
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Daria V Bazovkina
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Alexander V Kulikov
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia.
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29
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Lu RH, Zhou Y, Yuan XC, Liang XF, Fang L, Bai XL, Wang M, Zhao YH. Effects of glucose, insulin and triiodothyroxine on leptin and leptin receptor expression and the effects of leptin on activities of enzymes related to glucose metabolism in grass carp (Ctenopharyngodon idella) hepatocytes. FISH PHYSIOLOGY AND BIOCHEMISTRY 2015; 41:981-989. [PMID: 25952973 DOI: 10.1007/s10695-015-0063-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 04/25/2015] [Indexed: 06/04/2023]
Abstract
Leptin is an important regulator of appetite and energy expenditure in mammals, but its role in fish metabolism control is poorly understood. Our previous studies demonstrated that leptin has an effect on the regulation of food intake and energy expenditure as well as lipid metabolism (stimulation of lipolysis and inhibition of adipogenesis) in the grass carp Ctenopharyngodon idella. To further investigate the role of leptin in fish, the effects of glucose, insulin and triiodothyroxine (T3) on the expression levels of leptin and leptin receptor (Lepr) and the effects of leptin on the activities of critical glucose metabolism enzymes in grass carp hepatocytes were evaluated in the present study. Our data indicated that leptin gene expression was induced by glucose in a dose-dependent manner, while Lepr gene expression exhibited a biphasic change. A high dose of insulin (100 ng/mL) significantly up-regulated the expression of leptin and Lepr. Leptin expression was markedly up-regulated by a low concentration of T3 but inhibited by a high concentration of T3. T3 up-regulated Lepr expression in a dose-dependent manner. Together, these data suggest that leptin had a close relationship with three factors (glucose, insulin and T3) and might participate in the regulation of glucose metabolism in grass carp. In addition, we also found that leptin affected the activities of key enzymes that are involved in glucose metabolism, which might be mediated by insulin receptor substrate-phosphoinositol 3-kinase signaling.
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Affiliation(s)
- Rong-Hua Lu
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, No. 1 Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
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30
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Gilbert RE, Thai K, Advani SL, Cummins CL, Kepecs DM, Schroer SA, Woo M, Zhang Y. SIRT1 activation ameliorates hyperglycaemia by inducing a torpor-like state in an obese mouse model of type 2 diabetes. Diabetologia 2015; 58:819-27. [PMID: 25563725 DOI: 10.1007/s00125-014-3485-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 12/08/2014] [Indexed: 02/06/2023]
Abstract
AIMS/HYPOTHESIS Nutrient overabundance and diminished physical activity underlie the epidemic of obesity and its consequences of insulin resistance and type 2 diabetes. These same phenomena, obesity and insulin resistance, are also observed in mammals as they ready themselves for the nutrient deprivation of winter, yet their plasma glucose does not rise. Given the role of silent information regulator 2 (Sir2) and its mammalian orthologue, Sirt1, in survival and life extension during energy deprivation, we hypothesised that enhancing its activity may reduce the insensible energy loss engendered by hyperglycaemia and glycosuria. METHODS At 8 weeks of age, db/db and db/m mice were randomised to receive the SIRT1 activator SRT3025 milled in chow (3.18 g/kg) or regular chow and followed for a further 12 weeks. RESULTS When compared with vehicle, SIRT1 activation greatly improved glycaemic control, augmented plasma insulin concentrations, increased pancreatic islet beta cell mass and elevated hepatic expression of the beta cell growth factor, betatrophin in db/db mice. Despite the dramatic reduction in hyperglycaemia, db/db mice displayed worsening insulin resistance, diminished physical activity and further weight gain. These findings along with reduced food intake and reduction in body temperature resembled torpor and hibernation. By contrast, SIRT1 activation conferred only minimal changes in non-diabetic db/m mice. CONCLUSIONS/INTERPRETATION While reducing hyperglycaemia and promoting beta cell expansion, enhancing the activity of SIRT1 facilitates a phenotypic change in a db/db mouse model of diabetes to one that more closely resembles the physiological state of torpor or hibernation.
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Affiliation(s)
- Richard E Gilbert
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St Michael's Hospital, 61 Queen Street East, Toronto, ON, Canada, M5C 2T2,
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31
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Solymár M, Pétervári E, Balaskó M, Szelényi Z. The onset of daily torpor is regulated by the same low body mass in lean mice and in mice with diet-induced obesity. Temperature (Austin) 2015; 2:129-34. [PMID: 27227011 PMCID: PMC4843878 DOI: 10.1080/23328940.2015.1014250] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 01/28/2015] [Accepted: 01/29/2015] [Indexed: 11/17/2022] Open
Abstract
Effects of reducing body mass on body core temperature and locomotor activity of mice originally kept on conventional rodent diet (Group-1) were compared to those made obese by feeding them a high-fat diet (Group-2), both groups being kept at a cool ambient temperature. Based on earlier experience, threshold torpor core temperature of 31° was chosen as the endpoint to decreasing body mass. It was hypothesized that the onset of this hypothermia develops in obese mice only when their body mass approaches a similar low body mass as in lean mice. Mice in Group-1 maintained nocturnal core temperature but developed marked daytime hypothermia of 30–31°C with their body mass approaching 20 g by this time. Mice in Group-2 could maintain normal circadian temperature rhythm for 3 weeks before similar daytime hypothermia started to develop while their body mass dropped also to about 20 g. Mice belonging to Group-1 or Group-2 could regain original body mass after re-feeding with the original diet within 2 days or 5 weeks, respectively. In the course of the development of daily torpor, nighttime normothermia was accompanied by progressive increases in locomotor activity in both groups of mice. It is concluded that in mice a marked fall of daytime body core temperature is only induced when a similar low critical body mass is reached, irrespective of the initial body mass. In other words, in both groups of mice the nutritional state determines the threshold for the thermoregulatory change during torpor.
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Affiliation(s)
- Margit Solymár
- Department of Pathophysiology and Gerontology; Faculty of Medicine; University of Pécs , Hungary
| | - Erika Pétervári
- Department of Pathophysiology and Gerontology; Faculty of Medicine; University of Pécs , Hungary
| | - Márta Balaskó
- Department of Pathophysiology and Gerontology; Faculty of Medicine; University of Pécs , Hungary
| | - Zoltán Szelényi
- Department of Pathophysiology and Gerontology; Faculty of Medicine; University of Pécs , Hungary
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32
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Abstract
Whereas pharmacological responses tend to be fairly rapid in onset and are therefore detectable after a single dose, some diminish on repeated dosing, and others increase in magnitude and therefore can be missed or underestimated in single-dose safety pharmacology studies. Safety pharmacology measurements can be incorporated into repeat-dose toxicity studies, either routinely or on an ad hoc basis. Drivers for this are both scientific (see above) and regulatory (e.g. ICH S6, S7, S9). There are inherent challenges in achieving this: the availability of suitable technical and scientific expertise in the test facility, unsuitable laboratory conditions, use of simultaneous (as opposed to staggered) dosing, requirement for toxicokinetic sampling, unsuitability of certain techniques (e.g. use of anaesthesia, surgical implantation, food restriction), equipment availability at close proximity and sensitivity of the methods to detect small, clinically relevant, changes. Nonetheless, 'fit-for-purpose' data can still be acquired without requiring additional animals. Examples include assessment of behaviour, sensorimotor, visual and autonomic functions, ambulatory ECG and blood pressure, echocardiography, respiratory, gastrointestinal, renal and hepatic function. This is entirely achievable if the safety pharmacology measurements are relatively unobtrusive, both with respect to the animals and to the toxicology study itself. Careful pharmacological validation of any methods used, and establishing their detection sensitivity, is vital to ensure the credibility of generated data.
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Affiliation(s)
- Will S Redfern
- Drug Safety and Metabolism, AstraZeneca R&D, Darwin Building, 310 Cambridge Science Park, Cambridge, CB4 0WG, UK,
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33
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Chong ACN, Greendyk RA, Zeltser LM. Distinct networks of leptin- and insulin-sensing neurons regulate thermogenic responses to nutritional and cold challenges. Diabetes 2015; 64:137-46. [PMID: 25125486 PMCID: PMC4274810 DOI: 10.2337/db14-0567] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Defense of core body temperature (Tc) can be energetically costly; thus, it is critical that thermoregulatory circuits are modulated by signals of energy availability. Hypothalamic leptin and insulin signals relay information about energy status and are reported to promote thermogenesis, raising the possibility that they interact to direct an appropriate response to nutritional and thermal challenges. To test this idea, we used an Nkx2.1-Cre driver to generate conditional knockouts (KOs) in mice of leptin receptor (L(2.1)KO), insulin receptor (I(2.1)KO), and double KOs of both receptors (D(2.1)KO). L(2.1)KOs are hyperphagic and obese, whereas I(2.1)KOs are similar to controls. D(2.1)KOs exhibit higher body weight and adiposity than L(2.1)KOs, solely due to reduced energy expenditure. At 20-22°C, fed L(2.1)KOs maintain a lower baseline Tc than controls, which is further decreased in D(2.1)KOs. After an overnight fast, some L(2.1)KOs dramatically suppress energy expenditure and enter a torpor-like state; this behavior is markedly enhanced in D(2.1)KOs. When fasted mice are exposed to 4°C, L(2.1)KOs and D(2.1)KOs both mount a robust thermogenic response and rapidly increase Tc. These observations support the idea that neuronal populations that integrate information about energy stores to regulate the defense of Tc set points are distinct from those required to respond to a cold challenge.
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Affiliation(s)
- Angie C N Chong
- Institute of Human Nutrition, Columbia University, New York, NY Naomi Berrie Diabetes Center, Columbia University, New York, NY
| | | | - Lori M Zeltser
- Naomi Berrie Diabetes Center, Columbia University, New York, NY Department of Pathology and Cell Biology, Columbia University, New York, NY
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Hetem RS, Maloney SK, Fuller A, Mitchell D. Heterothermy in large mammals: inevitable or implemented? Biol Rev Camb Philos Soc 2014; 91:187-205. [PMID: 25522232 DOI: 10.1111/brv.12166] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 10/24/2014] [Accepted: 11/11/2014] [Indexed: 11/26/2022]
Abstract
Advances in biologging techniques over the past 20 years have allowed for the remote and continuous measurement of body temperatures in free-living mammals. While there is an abundance of literature on heterothermy in small mammals, fewer studies have investigated the daily variability of body core temperature in larger mammals. Here we review measures of heterothermy and the factors that influence heterothermy in large mammals in their natural habitats, focussing on large mammalian herbivores. The mean 24 h body core temperatures for 17 species of large mammalian herbivores (>10 kg) decreased by ∼1.3°C for each 10-fold increase in body mass, a relationship that remained significant following phylogenetic correction. The degree of heterothermy, as measured by the 24 h amplitude of body core temperature rhythm, was independent of body mass and appeared to be driven primarily by energy and water limitations. When faced with the competing demands of osmoregulation, energy acquisition and water or energy use for thermoregulation, large mammalian herbivores appear to relax the precision of thermoregulation thereby conserving body water and energy. Such relaxation may entail a cost in that an animal moves closer to its thermal limits for performance. Maintaining homeostasis requires trade-offs between regulated systems, and homeothermy apparently is not accorded the highest priority; large mammals are able to maintain optimal homeothermy only if they are well nourished, hydrated, and not compromised energetically. We propose that the amplitude of the 24 h rhythm of body core temperature provides a useful index of any compromise experienced by a free-living large mammal and may predict the performance and fitness of an animal.
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Affiliation(s)
- Robyn S Hetem
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa
| | - Shane K Maloney
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa.,School of Anatomy, Physiology, and Human Biology, University of Western Australia, Crawley, 6009, Australia
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa
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Kasza I, Suh Y, Wollny D, Clark RJ, Roopra A, Colman RJ, MacDougald OA, Shedd TA, Nelson DW, Yen MI, Yen CLE, Alexander CM. Syndecan-1 is required to maintain intradermal fat and prevent cold stress. PLoS Genet 2014; 10:e1004514. [PMID: 25101993 PMCID: PMC4125098 DOI: 10.1371/journal.pgen.1004514] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 06/05/2014] [Indexed: 02/07/2023] Open
Abstract
Homeostatic temperature regulation is fundamental to mammalian physiology and is controlled by acute and chronic responses of local, endocrine and nervous regulators. Here, we report that loss of the heparan sulfate proteoglycan, syndecan-1, causes a profoundly depleted intradermal fat layer, which provides crucial thermogenic insulation for mammals. Mice without syndecan-1 enter torpor upon fasting and show multiple indicators of cold stress, including activation of the stress checkpoint p38α in brown adipose tissue, liver and lung. The metabolic phenotype in mutant mice, including reduced liver glycogen, is rescued by housing at thermoneutrality, suggesting that reduced insulation in cool temperatures underlies the observed phenotypes. We find that syndecan-1, which functions as a facultative lipoprotein uptake receptor, is required for adipocyte differentiation in vitro. Intradermal fat shows highly dynamic differentiation, continuously expanding and involuting in response to hair cycle and ambient temperature. This physiology probably confers a unique role for Sdc1 in this adipocyte sub-type. The PPARγ agonist rosiglitazone rescues Sdc1−/− intradermal adipose tissue, placing PPARγ downstream of Sdc1 in triggering adipocyte differentiation. Our study indicates that disruption of intradermal adipose tissue development results in cold stress and complex metabolic pathology. All mammals strive to maintain a fixed body temperature, and do so using a remarkable array of different strategies, which vary depending upon the degree of cold challenge. Physiologists many decades ago observed that a fat layer right underneath the epidermis (and above the dermal muscle layer) thickens in response to colder ambient temperatures. This “intradermal fat” provided insulation within days of climate changes. We have found that syndecan-1, which functions as a facultative lipoprotein uptake receptor, is required for intradermal fat expansion in response to cold exposure. This is a highly specific phenotype not shared by other adipocytes. When intradermal fat is absent, mice do not adapt normally to cold stress, and show altered systemic physiologies, including increased brown adipose tissue thermogenesis and hyper-activation of a stress checkpoint (p38α), designed to protect the body against mutagenic and oxidative stressors. The phenotypes associated with loss of Sdc1 function are reversed when mice are housed in warm temperatures, where defense of body temperature is not required. This study is the first to show that intradermal fat can be genetically regulated, with systemic effects on physiology.
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Affiliation(s)
- Ildiko Kasza
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Yewseok Suh
- Department of Dermatology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Damian Wollny
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Rod J. Clark
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Avtar Roopra
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Ricki J. Colman
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
| | - Ormond A. MacDougald
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Timothy A. Shedd
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - David W. Nelson
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Mei-I Yen
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Chi-Liang Eric Yen
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Caroline M. Alexander
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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Burggren WW. Epigenetics as a source of variation in comparative animal physiology – or – Lamarck is lookin' pretty good these days. J Exp Biol 2014; 217:682-9. [DOI: 10.1242/jeb.086132] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Considerable variation is inherent both within and between comparative physiological data sets. Known sources for such variation include diet, gender, time of day and season of experiment, among many other factors, but a meta-analysis of physiological studies shows that surprisingly few studies report controlling for these factors. In fact, less than 3% of comparative physiological papers mention epigenetics. However, our understanding of epigenetic influences on physiological processes is growing rapidly, and it is highly likely that epigenetic phenomena are an additional ‘hidden’ source of variation, particularly in wild-caught specimens. Recent studies have shown epigenetic inheritance of commonly studied traits such as metabolic rate (water fleas Daphnia magna; emu, Dromaius novaellandiae), hypoxic tolerance, cardiac performance (zebrafish, Danio rerio), as well as numerous morphological effects. The ecological and evolutionary significance of such epigenetic inheritance is discussed in a comparative physiological context. Finally, against this context of epigenetic inheritance of phenotype, this essay also provides a number of caveats and warnings regarding the interpretation of transgenerational phenotype modification as a true epigenetic phenomenon. Parental effects, sperm storage, multiple paternity and direct gamete exposure can all be confounding factors. Epigenetic inheritance may best be studied in animal models that can be maintained in the laboratory over multiple generations, to yield parental stock that themselves are free of epigenetic effects from the historical experiences of their parents.
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Affiliation(s)
- Warren W. Burggren
- Developmental Integrative Biology Research Cluster, Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, TX 76203-5017, USA
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Redfern WS, Ewart LC, Lainée P, Pinches M, Robinson S, Valentin JP. Functional assessments in repeat-dose toxicity studies: the art of the possible. Toxicol Res (Camb) 2013. [DOI: 10.1039/c3tx20093k] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Pietka TA, Sulkin MS, Kuda O, Wang W, Zhou D, Yamada KA, Yang K, Su X, Gross RW, Nerbonne JM, Efimov IR, Abumrad NA. CD36 protein influences myocardial Ca2+ homeostasis and phospholipid metabolism: conduction anomalies in CD36-deficient mice during fasting. J Biol Chem 2012; 287:38901-12. [PMID: 23019328 DOI: 10.1074/jbc.m112.413609] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Sarcolemmal CD36 facilitates myocardial fatty acid (FA) uptake, which is markedly reduced in CD36-deficient rodents and humans. CD36 also mediates signal transduction events involving a number of cellular pathways. In taste cells and macrophages, CD36 signaling was recently shown to regulate store-responsive Ca(2+) flux and activation of Ca(2+)-dependent phospholipases A(2) that cycle polyunsaturated FA into phospholipids. It is unknown whether CD36 deficiency influences myocardial Ca(2+) handling and phospholipid metabolism, which could compromise the heart, typically during stresses. Myocardial function was examined in fed or fasted (18-22 h) CD36(-/-) and WT mice. Echocardiography and telemetry identified conduction anomalies that were associated with the incidence of sudden death in fasted CD36(-/-) mice. No anomalies or death occurred in WT mice during fasting. Optical imaging of perfused hearts from fasted CD36(-/-) mice documented prolongation of Ca(2+) transients. Consistent with this, knockdown of CD36 in cardiomyocytes delayed clearance of cytosolic Ca(2+). Hearts of CD36(-/-) mice (fed or fasted) had 3-fold higher SERCA2a and 40% lower phospholamban levels. Phospholamban phosphorylation by protein kinase A (PKA) was enhanced after fasting reflecting increased PKA activity and cAMP levels in CD36(-/-) hearts. Abnormal Ca(2+) homeostasis in the CD36(-/-) myocardium associated with increased lysophospholipid content and a higher proportion of 22:6 FA in phospholipids suggests altered phospholipase A(2) activity and changes in membrane dynamics. The data support the role of CD36 in coordinating Ca(2+) homeostasis and lipid metabolism and the importance of this role during myocardial adaptation to fasting. Potential relevance of the findings to CD36-deficient humans would need to be determined.
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Affiliation(s)
- Terri A Pietka
- Center for Human Nutrition, Washington University, St. Louis, Missouri 63110, USA
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Yoon JA, Han DH, Noh JY, Kim MH, Son GH, Kim K, Kim CJ, Pak YK, Cho S. Meal time shift disturbs circadian rhythmicity along with metabolic and behavioral alterations in mice. PLoS One 2012; 7:e44053. [PMID: 22952870 PMCID: PMC3428308 DOI: 10.1371/journal.pone.0044053] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 07/30/2012] [Indexed: 11/18/2022] Open
Abstract
In modern society, growing numbers of people are engaged in various forms of shift works or trans-meridian travels. Such circadian misalignment is known to disturb endogenous diurnal rhythms, which may lead to harmful physiological consequences including metabolic syndrome, obesity, cancer, cardiovascular disorders, and gastric disorders as well as other physical and mental disorders. However, the precise mechanism(s) underlying these changes are yet unclear. The present work, therefore examined the effects of 6 h advance or delay of usual meal time on diurnal rhythmicities in home cage activity (HCA), body temperature (BT), blood metabolic markers, glucose homeostasis, and expression of genes that are involved in cholesterol homeostasis by feeding young adult male mice in a time-restrictive manner. Delay of meal time caused locomotive hyperactivity in a significant portion (42%) of subjects, while 6 h advance caused a torpor-like symptom during the late scotophase. Accordingly, daily rhythms of blood glucose and triglyceride were differentially affected by time-restrictive feeding regimen with concurrent metabolic alterations. Along with these physiological changes, time-restrictive feeding also influenced the circadian expression patterns of low density lipoprotein receptor (LDLR) as well as most LDLR regulatory factors. Strikingly, chronic advance of meal time induced insulin resistance, while chronic delay significantly elevated blood glucose levels. Taken together, our findings indicate that persistent shifts in usual meal time impact the diurnal rhythms of carbohydrate and lipid metabolisms in addition to HCA and BT, thereby posing critical implications for the health and diseases of shift workers.
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Affiliation(s)
- Ji-Ae Yoon
- Department of Neuroscience and Neurodegeneration Control Research Center, Kyung Hee University, Seoul, Korea
| | - Dong-Hee Han
- Department of Neuroscience and Neurodegeneration Control Research Center, Kyung Hee University, Seoul, Korea
| | - Jong-Yun Noh
- Department of Neuroscience and Neurodegeneration Control Research Center, Kyung Hee University, Seoul, Korea
| | - Mi-Hee Kim
- Department of Neuroscience and Neurodegeneration Control Research Center, Kyung Hee University, Seoul, Korea
| | - Gi Hoon Son
- Department of Legal Medicine, Korea University College of Medicine, Seoul, Korea
| | - Kyungjin Kim
- Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Chang-Ju Kim
- Department of Physiology, Kyung Hee University School of Medicine, Seoul, Korea
| | - Youngmi Kim Pak
- Department of Neuroscience and Neurodegeneration Control Research Center, Kyung Hee University, Seoul, Korea
- Department of Physiology, Kyung Hee University School of Medicine, Seoul, Korea
| | - Sehyung Cho
- Department of Neuroscience and Neurodegeneration Control Research Center, Kyung Hee University, Seoul, Korea
- Department of Physiology, Kyung Hee University School of Medicine, Seoul, Korea
- * E-mail:
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40
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Kaddis JS, Hanson MS, Cravens J, Qian D, Olack B, Antler M, Papas KK, Iglesias I, Barbaro B, Fernandez L, Powers AC, Niland JC. Standardized transportation of human islets: an islet cell resource center study of more than 2,000 shipments. Cell Transplant 2012; 22:1101-11. [PMID: 22889479 DOI: 10.3727/096368912x653219] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Preservation of cell quality during shipment of human pancreatic islets for use in laboratory research is a crucial, but neglected, topic. Mammalian cells, including islets, have been shown to be adversely affected by temperature changes in vitro and in vivo, yet protocols that control for thermal fluctuations during cell transport are lacking. To evaluate an optimal method of shipping human islets, an initial assessment of transportation conditions was conducted using standardized materials and operating procedures in 48 shipments sent to a central location by eight pancreas-processing laboratories using a single commercial airline transporter. Optimization of preliminary conditions was conducted, and human islet quality was then evaluated in 2,338 shipments pre- and postimplementation of a finalized transportation container and standard operating procedures. The initial assessment revealed that the outside temperature ranged from a mean of -4.6 ± 10.3°C to 20.9 ± 4.8°C. Within-container temperature drops to or below 15°C occurred in 16 shipments (36%), while the temperature was found to be stabilized between 15°C and 29°C in 29 shipments (64%). Implementation of an optimized transportation container and operating procedure reduced the number of within-container temperature drops (≤ 15°C) to 13% (n = 37 of 289 winter shipments), improved the number desirably maintained between 15°C and 29°C to 86% (n = 250), but also increased the number reaching or exceeding 29°C to 1% (n = 2; overall p < 0.0001). Additionally, postreceipt quality ratings of excellent to good improved pre- versus postimplantation of the standardized protocol, adjusting for preshipment purity/viability levels (p < 0.0001). Our results show that extreme temperature fluctuations during transport of human islets, occurring when using a commercial airline transporter for long distance shipping, can be controlled using standardized containers, materials, and operating procedures. This cost-effective and pragmatic standardized protocol for the transportation of human islets can potentially be adapted for use with other mammalian cell systems and is available online at http://iidp.coh.org/sops.aspx.
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Affiliation(s)
- John S Kaddis
- Department of Information Sciences, City of Hope, Duarte, CA 91010-3000, USA
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Abstract
The hypometabolic state of torpor is a widely utilized and well-orchestrated response to food shortage. A new study shows that the melatonin-related orphan receptor GPR50 plays an important function in metabolic regulation for entry into torpor.
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Affiliation(s)
- Steven J Swoap
- Department of Biology, Williams College, Williamstown, MA 01267, USA.
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Ravussin Y, LeDuc CA, Watanabe K, Leibel RL. Effects of ambient temperature on adaptive thermogenesis during maintenance of reduced body weight in mice. Am J Physiol Regul Integr Comp Physiol 2012; 303:R438-48. [PMID: 22761182 DOI: 10.1152/ajpregu.00092.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We showed previously that, at ambient room temperature (22°C), mice maintained at 20% below their initial body weight by calorie restriction expend energy at a rate below that which can be accounted for by the decrease of fat and fat-free mass. Food-restricted rodents may become torpid at subthermoneutral temperatures, a possible confounding factor when using mice as human models in obesity research. We examined the bioenergetic, hormonal, and behavioral responses to maintenance of a 20% body weight reduction in singly housed C57BL/6J +/+ and Lep(ob) mice housed at both 22°C and 30°C. Weight-reduced high-fat-fed diet mice (HFD-WR) showed similar quantitative reductions in energy expenditure-adjusted for body mass and composition-at both 22°C and 30°C: -1.4 kcal/24 h and -1.6 kcal/24 h below predicted, respectively, and neither group entered torpor. In contrast, weight-reduced Lep(ob) mice (OB-WR) housed at 22°C became torpid in the late lights-off period (0200-0500) but did not when housed at 30°C. These studies indicate that mice with an intact leptin axis display similar decreases in "absolute" energy expenditure in response to weight reduction at both 22°C and 30°C ambient temperature. More importantly, the "percent" decrease in total energy expenditure observed in the HFD-WR compared with AL mice is much greater at 30°C (-19%) than at 22°C (-10%). Basal energy expenditure demands are ∼45% lower in mice housed at 30°C vs. 22°C, since the mice housed at thermoneutrality do not allocate extra energy for heat production. The higher total energy expenditure of mice housed at 22°C due to these increased thermogenic demands may mask physiologically relevant changes in energy expenditure showing that ambient temperature must be carefully considered when quantifying energy metabolism in both rodents and humans.
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Affiliation(s)
- Yann Ravussin
- Department of Pediatrics, Division of Molecular Genetics, Columbia University, College of Physicians and Surgeons, New York, New York, USA
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43
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Chu LP, Swoap SJ. Oral bezafibrate induces daily torpor and FGF21 in mice in a PPAR alpha dependent manner. J Therm Biol 2012. [DOI: 10.1016/j.jtherbio.2011.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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44
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Tokizawa K, Onoue Y, Uchida, Y, Nagashima K. Ghrelin Induces Time-Dependent Modulation of Thermoregulation in the Cold. Chronobiol Int 2012; 29:736-46. [DOI: 10.3109/07420528.2012.678452] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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45
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Pincedé I, Pollin B, Meert T, Plaghki L, Le Bars D. Psychophysics of a nociceptive test in the mouse: ambient temperature as a key factor for variation. PLoS One 2012; 7:e36699. [PMID: 22629325 PMCID: PMC3356344 DOI: 10.1371/journal.pone.0036699] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 04/12/2012] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The mouse is increasingly used in biomedical research, notably in behavioral neurosciences for the development of tests or models of pain. Our goal was to provide the scientific community with an outstanding tool that allows the determination of psychophysical descriptors of a nociceptive reaction, which are inaccessible with conventional methods: namely the true threshold, true latency, conduction velocity of the peripheral fibers that trigger the response and latency of the central decision-making process. METHODOLOGY/PRINCIPAL FINDINGS Basically, the procedures involved heating of the tail with a CO(2) laser, recording of tail temperature with an infrared camera and stopping the heating when the animal reacted. The method is based mainly on the measurement of three observable variables, namely the initial temperature, the heating rate and the temperature reached at the actual moment of the reaction following random variations in noxious radiant heat. The initial temperature of the tail, which itself depends on the ambient temperature, very markedly influenced the behavioral threshold, the behavioral latency and the conduction velocity of the peripheral fibers but not the latency of the central decision-making. CONCLUSIONS/SIGNIFICANCE We have validated a psychophysical approach to nociceptive reactions for the mouse, which has already been described for rats and Humans. It enables the determination of four variables, which contribute to the overall latency of the response. The usefulness of such an approach was demonstrated by providing new fundamental findings regarding the influence of ambient temperature on nociceptive processes. We conclude by challenging the validity of using as "pain index" the reaction time of a behavioral response to an increasing heat stimulus and emphasize the need for a very careful control of the ambient temperature, as a prevailing environmental source of variation, during any behavioral testing of mice.
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Affiliation(s)
- Ivanne Pincedé
- Team “Pain", INSERM UMRS 975, CNRS UMR 7225, Paris, France
- Université Pierre et Marie Curie, Faculté de Médecine UPMC, Paris, France
| | - Bernard Pollin
- Team “Pain", INSERM UMRS 975, CNRS UMR 7225, Paris, France
- Université Pierre et Marie Curie, Faculté de Médecine UPMC, Paris, France
| | - Theo Meert
- Department of Psychology, University of Leuven, Leuven, Belgium
| | - Léon Plaghki
- Unité READ, Université Catholique de Louvain, Brussels, Belgium
| | - Daniel Le Bars
- Team “Pain", INSERM UMRS 975, CNRS UMR 7225, Paris, France
- Université Pierre et Marie Curie, Faculté de Médecine UPMC, Paris, France
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Voronova IP, Khramova GM, Kulikov AV, Kozyreva TV. Effect of transfer of the chromosome 13 fragment containing gene il6st on parameters of temperature homeostasis in mice. J EVOL BIOCHEM PHYS+ 2012. [DOI: 10.1134/s0022093012010070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ablation of neurons expressing agouti-related protein, but not melanin concentrating hormone, in leptin-deficient mice restores metabolic functions and fertility. Proc Natl Acad Sci U S A 2012; 109:3155-60. [PMID: 22232663 DOI: 10.1073/pnas.1120501109] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Leptin-deficient (Lep(ob/ob)) mice are obese, diabetic, and infertile. Ablation of neurons that make agouti-related protein (AgRP) in moderately obese adult Lep(ob/ob) mice caused severe anorexia. The mice stopped eating for 2 wk and then gradually recovered. Their body weight fell to within a normal range for WT mice, at which point food intake and glucose tolerance were restored to that of WT mice. Remarkably, both male and female Lep(ob/ob) mice became fertile. Ablation of neurons that express melanin-concentrating hormone (MCH) in adult Lep(ob/ob) mice had no effect on food intake, body weight, or fertility, but resulted in improved glucose tolerance. We conclude that AgRP-expressing neurons play a critical role in mediating the metabolic syndrome and infertility of Lep(ob/ob) mice, whereas MCH-expressing neurons have only a minor role.
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48
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Fisher JT. TRPM8 and dyspnea: from the frigid and fascinating past to the cool future? Curr Opin Pharmacol 2011; 11:218-23. [PMID: 21723782 DOI: 10.1016/j.coph.2011.06.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 05/25/2011] [Accepted: 06/06/2011] [Indexed: 01/01/2023]
Abstract
The transient receptor potential melastatin 8 (TRPM8) ion channel is gated by cool and noxious cold temperatures. The activation threshold is in the range of ≈25-28°C, which aligns well with the discharge of airway afferents. TRPM8 is widely expressed across species and evolutionary changes in the TRPM8 amino acid sequence may tune the temperatures at which it is gated. The discovery of TRPM8 and its molecular/biophysical characterization provides a robust candidate for airway afferents responding to cool/cold temperatures. TRPM8 may provide a mechanistic link for the manipulation of respiratory sensations such as dyspnea or mechanisms leading to cold-induced asthma and cough.
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Affiliation(s)
- John T Fisher
- Department of Physiology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
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Copeland DL, Duff RJ, Liu Q, Prokop J, Londraville RL. Leptin in teleost fishes: an argument for comparative study. Front Physiol 2011; 2:26. [PMID: 21716655 PMCID: PMC3117194 DOI: 10.3389/fphys.2011.00026] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 05/27/2011] [Indexed: 12/13/2022] Open
Abstract
All organisms face tradeoffs with regard to how limited energy resources should be invested. When is it most favorable to grow, to reproduce, how much lipid should be allocated to storage in preparation for a period of limited resources (e.g., winter), instead of being used for growth or maturation? These are a few of the high consequence fitness "decisions" that represent the balance between energy acquisition and allocation. Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand. We make the argument that leptin signaling is a likely candidate for an integrating system. Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologs of mammalian proteins and (we assert), underutilization of the comparative approach.
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Shimizu N, Chikahisa S, Kitaoka K, Nishino S, Séi H. Refeeding after a 24-hour fasting deepens NREM sleep in a time-dependent manner. Physiol Behav 2011; 104:480-7. [PMID: 21605579 DOI: 10.1016/j.physbeh.2011.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 05/06/2011] [Accepted: 05/06/2011] [Indexed: 10/18/2022]
Abstract
Sleep/wake cycle is regulated by a variety of neuropeptides in the hypothalamus, a brain region that also regulates energy homeostasis and feeding behavior. Since circadian rhythms are affected by energy metabolism and feeding condition, we investigated whether changes in feeding regimen would influence sleep/wake parameters and body temperature. We monitored sleep and body temperature across three days of baseline (day 1), fasting (day 2), and refeeding (day 3) conditions under ordinary ambient temperature and employed different refeeding schedules. Refeeding at ZT1 following the 24-h fasting enhanced EEG delta power in NREM sleep. However, when the time of refeeding was set at either ZT7 or ZT12, the enhancement of EEG delta power was attenuated. The amount of NREM sleep was not largely affected by a 24-h fasting started at ZT1, although fasting that started at ZT12 changed the temporal distribution of NREM sleep. Hypothalamic nNOS mRNA level was increased both before and after refeeding at ZT1 compared with control condition, while there was no significant change in mice refed at ZT7. Level of NPY mRNA in the arcuate nucleus was increased before the refeeding only at ZT1. These results suggest that refeeding after a 24-h fasting makes NREM sleep deeper in a time-dependent manner.
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Affiliation(s)
- Noriyuki Shimizu
- Department of Integrative Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
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