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Carlson Z, Drew K. Characterization and Seasonal Modulation of Adenosine A 1 Receptors in the Arctic Ground Squirrel Brain. Int J Mol Sci 2023; 24:ijms24021598. [PMID: 36675112 PMCID: PMC9867220 DOI: 10.3390/ijms24021598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/07/2023] [Accepted: 01/08/2023] [Indexed: 01/15/2023] Open
Abstract
Hibernation is an adaptation that allows animals such as the Arctic ground squirrel (AGS) to survive the absence of food or water during the winter season. Understanding mechanisms of metabolic suppression during hibernation torpor promises new therapies for critical care. The activation of the Adenosine A1 receptor (A1AR) has been shown to be necessary and sufficient for entrance into hibernation with a winter season sensitization to the agonist, but the role of the A1AR in seasonal sensitization is unknown. In the current study, we characterize the A1AR in the forebrain, hippocampus and hypothalamus of summer and torpid AGS. For the first time, we define the pharmacological characteristics of the A1AR agonist, N6-cyclohexyladenosine and the A1AR antagonist dipropylcyclopentylxanthine (DPCPX) in the AGS brain. In addition, we test the hypothesis that increased A1AR agonist efficacy is responsible for sensitization of the A1AR during the torpor season. The resulting 35S-GTPγS binding data indicate an increase in agonist potency during torpor in two out of three brain regions. In addition to 35S-GTPγS binding, [3H]DPCPX saturation and competition assays establish for the first-time pharmacological characteristics for the A1AR agonist, N6-cyclohexyladenosine and the A1AR antagonist dipropylcyclopentylxanthine (DPCPX) in AGS brain.
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Affiliation(s)
- Zachary Carlson
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
| | - Kelly Drew
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
- Center for Transformative Research in Metabolism, University of Alaska, Fairbanks, AK 99775, USA
- Correspondence:
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Granade ME, Hargett SR, Lank DS, Lemke MC, Luse MA, Isakson BE, Bochkis IM, Linden J, Harris TE. Feeding desensitizes A1 adenosine receptors in adipose through FOXO1-mediated transcriptional regulation. Mol Metab 2022; 63:101543. [PMID: 35811051 PMCID: PMC9304768 DOI: 10.1016/j.molmet.2022.101543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/24/2022] [Accepted: 07/04/2022] [Indexed: 12/03/2022] Open
Abstract
OBJECTIVE Adipose tissue is a critical regulator of energy balance that must rapidly shift its metabolism between fasting and feeding to maintain homeostasis. Adenosine has been characterized as an important regulator of adipocyte metabolism primarily through its actions on A1 adenosine receptors (A1R). We sought to understand the role A1R plays specifically in adipocytes during fasting and feeding to regulate glucose and lipid metabolism. METHODS We used Adora1 floxed mice with an inducible, adiponectin-Cre to generate FAdora1-/- mice, where F designates a fat-specific deletion of A1R. We used these FAdora1-/- mice along with specific agonists and antagonists of A1R to investigate changes in adenosine signaling within adipocytes between the fasted and fed state. RESULTS We found that the adipose tissue response to adenosine is not static, but changes dynamically according to nutrient conditions through the insulin-Akt-FOXO1 axis. We show that under fasted conditions, FAdora1-/- mice had impairments in the suppression of lipolysis by insulin on normal chow and impaired glucose tolerance on high-fat diet. FAdora1-/- mice also exhibited a higher lipolytic response to isoproterenol than WT controls when fasted, however this difference was lost after a 4-hour refeeding period. We demonstrate that FOXO1 binds to the A1R promoter, and refeeding leads to a rapid downregulation of A1R transcript and desensitization of adipocytes to A1R agonism. Obesity also desensitizes adipocyte A1R, and this is accompanied by a disruption of cyclical changes in A1R transcription between fasting and refeeding. CONCLUSIONS We propose that FOXO1 drives high A1R expression under fasted conditions to limit excess lipolysis during stress and augment insulin action upon feeding. Subsequent downregulation of A1R under fed conditions leads to desensitization of these receptors in adipose tissue. This regulation of A1R may facilitate reentrance into the catabolic state upon fasting.
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Affiliation(s)
- Mitchell E Granade
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Stefan R Hargett
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Daniel S Lank
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Michael C Lemke
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Melissa A Luse
- Department of Molecular Physiology and Biophysics, University of Virginia, Charlottesville, VA, USA
| | - Brant E Isakson
- Department of Molecular Physiology and Biophysics, University of Virginia, Charlottesville, VA, USA
| | - Irina M Bochkis
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Joel Linden
- Department of Medicine, Center for Immunity, Inflammation and Regenerative Medicine, University of Virginia, Charlottesville, VA, USA
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA.
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Huang YG, Flaherty SJ, Pothecary CA, Foster RG, Peirson SN, Vyazovskiy VV. The relationship between fasting-induced torpor, sleep, and wakefulness in laboratory mice. Sleep 2021; 44:zsab093. [PMID: 33838033 PMCID: PMC8436144 DOI: 10.1093/sleep/zsab093] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 04/03/2021] [Indexed: 11/30/2022] Open
Abstract
STUDY OBJECTIVES Torpor is a regulated and reversible state of metabolic suppression used by many mammalian species to conserve energy. Whereas the relationship between torpor and sleep has been well-studied in seasonal hibernators, less is known about the effects of fasting-induced torpor on states of vigilance and brain activity in laboratory mice. METHODS Continuous monitoring of electroencephalogram (EEG), electromyogram (EMG), and surface body temperature was undertaken in adult, male C57BL/6 mice over consecutive days of scheduled restricted feeding. RESULTS All animals showed bouts of hypothermia that became progressively deeper and longer as fasting progressed. EEG and EMG were markedly affected by hypothermia, although the typical electrophysiological signatures of non-rapid eye movement (NREM) sleep, rapid eye movement (REM) sleep, and wakefulness enabled us to perform vigilance-state classification in all cases. Consistent with previous studies, hypothermic bouts were initiated from a state indistinguishable from NREM sleep, with EEG power decreasing gradually in parallel with decreasing surface body temperature. During deep hypothermia, REM sleep was largely abolished, and we observed shivering-associated intense bursts of muscle activity. CONCLUSIONS Our study highlights important similarities between EEG signatures of fasting-induced torpor in mice, daily torpor in Djungarian hamsters and hibernation in seasonally hibernating species. Future studies are necessary to clarify the effects on fasting-induced torpor on subsequent sleep.
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Affiliation(s)
- Yi-Ge Huang
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT,UK
| | - Sarah J Flaherty
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT,UK
| | - Carina A Pothecary
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE,UK
| | - Russell G Foster
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE,UK
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE,UK
| | - Vladyslav V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT,UK
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Cerri M, Hitrec T, Luppi M, Amici R. Be cool to be far: Exploiting hibernation for space exploration. Neurosci Biobehav Rev 2021; 128:218-232. [PMID: 34144115 DOI: 10.1016/j.neubiorev.2021.03.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 01/08/2023]
Abstract
In mammals, torpor/hibernation is a state that is characterized by an active reduction in metabolic rate followed by a progressive decrease in body temperature. Torpor was successfully mimicked in non-hibernators by inhibiting the activity of neurons within the brainstem region of the Raphe Pallidus, or by activating the adenosine A1 receptors in the brain. This state, called synthetic torpor, may be exploited for many medical applications, and for space exploration, providing many benefits for biological adaptation to the space environment, among which an enhanced protection from cosmic rays. As regards the use of synthetic torpor in space, to fully evaluate the degree of physiological advantage provided by this state, it is strongly advisable to move from Earth-based experiments to 'in the field' tests, possibly on board the International Space Station.
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Affiliation(s)
- Matteo Cerri
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
| | - Timna Hitrec
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
| | - Marco Luppi
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
| | - Roberto Amici
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
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Regan MD, Flynn-Evans EE, Griko YV, Kilduff TS, Rittenberger JC, Ruskin KJ, Buck CL. Shallow metabolic depression and human spaceflight: a feasible first step. J Appl Physiol (1985) 2020; 128:637-647. [PMID: 31999524 DOI: 10.1152/japplphysiol.00725.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Synthetic torpor is an induced state of deep metabolic depression (MD) in an organism that does not naturally employ regulated and reversible MD. If applied to spaceflight crewmembers, this metabolic state may theoretically mitigate numerous biological and logistical challenges of human spaceflight. These benefits have been the focus of numerous recent articles where, invariably, they are discussed in the context of hypothetical deep MD states in which the metabolism of crewmembers is profoundly depressed relative to basal rates. However, inducing these deep MD states in humans, particularly humans aboard spacecraft, is currently impossible. Here, we discuss shallow MD as a feasible first step toward synthetic torpor during spaceflight and summarize perspectives following a recent NASA-hosted workshop. We discuss methods to safely induce shallow MD (e.g., sleep and slow wave enhancement via acoustic and photoperiod stimulation; moderate sedation via dexmedetomidine), which we define as an ~20% depression of metabolic rate relative to basal levels. We also discuss different modes of shallow MD application (e.g., habitual versus targeted, whereby shallow MD is induced routinely throughout a mission or only under certain circumstances, respectively) and different spaceflight scenarios that would benefit from its use. Finally, we propose a multistep development plan toward the application of synthetic torpor to human spaceflight, highlighting shallow MD's role. As space agencies develop missions to send humans further into space than ever before, shallow MD has the potential to confer health benefits for crewmembers, reduce demands on spacecraft capacities, and serve as a testbed for deeper MD technologies.
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Affiliation(s)
- Matthew D Regan
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Erin E Flynn-Evans
- Fatigue Countermeasures Laboratory, Human Systems Integration Division, NASA Ames Research Center, Moffett Field, California
| | - Yuri V Griko
- Countermeasure Development Laboratory, Space Biosciences Division, NASA Ames Research Center, Moffett Field, California
| | - Thomas S Kilduff
- Biosciences Division, Center for Neuroscience, SRI International, Menlo Park, California
| | - Jon C Rittenberger
- Guthrie Robert Packer Hospital Emergency Medicine Program, Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania
| | - Keith J Ruskin
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois
| | - C Loren Buck
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
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Dal Ben D, Lambertucci C, Buccioni M, Martí Navia A, Marucci G, Spinaci A, Volpini R. Non-Nucleoside Agonists of the Adenosine Receptors: An Overview. Pharmaceuticals (Basel) 2019; 12:E150. [PMID: 31597388 PMCID: PMC6958362 DOI: 10.3390/ph12040150] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/03/2019] [Accepted: 10/05/2019] [Indexed: 12/17/2022] Open
Abstract
Potent and selective adenosine receptor (AR) agonists are of pharmacological interest for the treatment of a wide range of diseases and conditions. Among these derivatives, nucleoside-based agonists represent the great majority of molecules developed and reported to date. However, the limited availability of compounds selective for a specific AR subtype (i.e., A2BAR) and a generally long and complex synthetic route for largely substituted nucleosides are the main drawbacks of this category of molecules. Non-nucleoside agonists represent an alternative set of compounds able to stimulate the AR function and based on simplified structures. This review provides an updated overview on the structural classes of non-nucleoside AR agonists and their biological activities, with emphasis on the main derivatives reported in the literature. A focus is also given to the synthetic routes employed to develop these derivatives and on molecular modeling studies simulating their interaction with ARs.
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Affiliation(s)
- Diego Dal Ben
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
| | - Catia Lambertucci
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
| | - Michela Buccioni
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
| | - Aleix Martí Navia
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
| | - Gabriella Marucci
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
| | - Andrea Spinaci
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
| | - Rosaria Volpini
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, 62032 Camerino (MC), Italy.
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Laughlin BW, Bailey IR, Rice SA, Barati Z, Bogren LK, Drew KL. Precise Control of Target Temperature Using N 6-Cyclohexyladenosine and Real-Time Control of Surface Temperature. Ther Hypothermia Temp Manag 2018; 8:108-116. [PMID: 29480748 DOI: 10.1089/ther.2017.0020] [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] [Indexed: 12/21/2022] Open
Abstract
Targeted temperature management is standard of care for cardiac arrest and is in clinical trials for stroke. N6-cyclohexyladenosine (CHA), an A1 adenosine receptor (A1AR) agonist, inhibits thermogenesis and induces onset of hibernation in hibernating species. Despite promising thermolytic efficacy of CHA, prior work has failed to achieve and maintain a prescribed target core body temperature (Tb) between 32°C and 34°C for 24 hours. We instrumented Sprague-Dawley rats (n = 19) with indwelling arterial and venous cannulae and a transmitter for monitoring Tb and ECG, then administered CHA via continuous IV infusion or intraperitoneal (IP) injection. In the first experiment (n = 11), we modulated ambient temperature and increased the dose of CHA in an attempt to manage Tb. In the second experiment (n = 8), we administered CHA (0.25 mg/[kg·h]) via continuous IV infusion and modulated cage surface temperature to control Tb. We rewarmed animals by increasing surface temperature at 1°C h-1 and discontinued CHA after Tb reached 36.5°C. Tb, brain temperature (Tbrain), heart rate, blood gas, and electrolytes were also monitored. Results show that titrating dose to adjust for individual variation in response to CHA led to tolerance and failed to manage a prescribed Tb. Starting with a dose (0.25 mg/[kg·h]) and modulating surface temperature to prevent overcooling proved to be an effective means to achieve and maintain Tb between 32°C and 34°C for 24 hours. Increasing surface temperature to 37°C during CHA administration brought Tb back to normothermic levels. All animals treated in this way rewarmed without incident. During the initiation of cooling, we observed bradycardia within 30 minutes of the start of IV infusion, transient hyperglycemia, and a mild hypercapnia; the latter normalized via metabolic compensation. In conclusion, we describe an intravenous delivery protocol for CHA at 0.25 mg/(kg·h) that, when coupled with conductive cooling, achieves and maintains a prescribed and consistent target Tb between 32°C and 34°C for 24 hours.
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Affiliation(s)
- Bernard W Laughlin
- 1 Institute of Arctic Biology, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska.,2 Department of Chemistry and Biochemistry, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska
| | - Isaac R Bailey
- 1 Institute of Arctic Biology, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska.,2 Department of Chemistry and Biochemistry, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska
| | - Sarah A Rice
- 1 Institute of Arctic Biology, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska.,2 Department of Chemistry and Biochemistry, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska
| | - Zeinab Barati
- 1 Institute of Arctic Biology, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska
| | - Lori K Bogren
- 1 Institute of Arctic Biology, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska
| | - Kelly L Drew
- 1 Institute of Arctic Biology, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska.,2 Department of Chemistry and Biochemistry, University of Alaska Fairbanks College of Natural Science and Mathematics , Fairbanks, Alaska
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