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Bechtel W, Bich L. Situating homeostasis in organisms: maintaining organization through time. J Physiol 2024. [PMID: 39383321 DOI: 10.1113/jp286883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 09/11/2024] [Indexed: 10/11/2024] Open
Abstract
Since it was inspired by Bernard and developed and named by Cannon, the concept of homeostasis has been invoked by many as the central theoretical framework for physiology. It has also been the target of numerous criticisms that have elicited the introduction of a plethora of alternative concepts. We argue that many of the criticisms actually target the more restrictive account of homeostasis advanced by the cyberneticists. What was crucial to Bernard and Cannon was a focus on the maintenance of the organism as the goal of physiological regulation. We analyse how Bernard's and Cannon's broad conception of what was required to maintain the organism was narrowed to negative feedback, characterized in terms of setpoints, by the cyberneticists and demonstrate how many of the alternative concepts challenge the role of setpoints - treating them as variable in light of circumstances or in anticipation of future circumstances, or as dispensable altogether. To support our analysis, we draw on the experimental and theoretical work on thermoregulation, a phenomenon that has been considered as a paradigmatic example of homeostasis and has been a common focus of those advancing alternative concepts. To integrate the insights advanced by the original proponents of homeostasis and the theorists proposing replacement notions we advance a framework in which regulation is viewed from the perspective of maintaining the organism.
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Affiliation(s)
- William Bechtel
- Department of Philosophy, University of California, San Diego, CA, USA
| | - Leonardo Bich
- Department of Philosophy, IAS-Research Centre for Life, Mind and Society, University of the Basque Country (UPV/EHU), Donostia-San Sebastian, Spain
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2
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Tyler MP, Wright BJ, Raison CL, Lowry CA, Evans L, Hale MW. Greater severity of depressive symptoms is associated with changes to perceived sweating, preferred ambient temperature, and warmth-seeking behavior. Temperature (Austin) 2024; 11:266-279. [PMID: 39193043 PMCID: PMC11346520 DOI: 10.1080/23328940.2024.2374097] [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: 03/22/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 08/29/2024] Open
Abstract
The thermosensory system is relevant to both the conceptualization and treatment of depression. There is evidence that depression is associated with changes in thermoregulatory functioning, and that thermosensory pathways can be recruited to influence affect and reduce depressive symptoms. In this study, we investigated the relationship between severity of depressive symptoms and changes to measures of subjective experiences associated with thermoregulatory processes as well as the relationship between severity of depressive symptoms and affective responses to warm stimuli, specifically frequency of warmth-seeking behavior. Participants (N = 529) completed measures of depressive symptoms, subjective experiences associated with thermoregulatory processes (i.e., perceived sweating and preferred ambient temperature) and frequency of warmth-seeking behavior (e.g., long hot baths, saunas, etc.). We demonstrate that, controlling for age and gender, greater severity of depressive symptoms is associated with greater perceived sweating and lower preferred ambient temperature. Furthermore, we demonstrate that greater severity of depressive symptoms is associated with more frequent warmth-seeking behavior, and that something other than thermal preference (i.e., stated preference for warmer temperature) is driving this behavior. These data highlight the importance of incorporating the thermoregulatory system in our conceptualization of the pathophysiology of depression and support the potential to recruit thermosensory pathways to target depressive symptoms.
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Affiliation(s)
- Mark P. Tyler
- School of Psychology and Public Health, La Trobe University, Bundoora, Victoria, Australia
| | - Bradley J. Wright
- School of Psychology and Public Health, La Trobe University, Bundoora, Victoria, Australia
| | - Charles L. Raison
- Department of Psychiatry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Behavioral Health Innovation Center, Vail Health, Edwards, CO, USA
- Department of Spiritual Health, Woodruff Health Sciences Center, Emory University, Atlanta, GA, USA
| | - Christopher A. Lowry
- Department of Integrative Physiology, Center for Neuroscience and Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, USA
| | - Lynette Evans
- School of Psychology and Public Health, La Trobe University, Bundoora, Victoria, Australia
| | - Matthew W. Hale
- School of Psychology and Public Health, La Trobe University, Bundoora, Victoria, Australia
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3
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Nakamura K. Central Mechanisms of Thermoregulation and Fever in Mammals. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1461:141-159. [PMID: 39289279 DOI: 10.1007/978-981-97-4584-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
Thermoregulation is a fundamental homeostatic function in mammals mediated by the central nervous system. The framework of the central circuitry for thermoregulation lies in the hypothalamus and brainstem. The preoptic area (POA) of the hypothalamus integrates cutaneous and central thermosensory information into efferent control signals that regulate excitatory descending pathways through the dorsomedial hypothalamus (DMH) and rostral medullary raphe region (rMR). The cutaneous thermosensory feedforward signals are delivered to the POA by afferent pathways through the lateral parabrachial nucleus, while the central monitoring of body core temperature is primarily mediated by warm-sensitive neurons in the POA for negative feedback regulation. Prostaglandin E2, a pyrogenic mediator produced in response to infection, acts on the POA to trigger fever. Recent studies have revealed that this circuitry also functions for physiological responses to psychological stress and starvation. Master psychological stress signaling from the medial prefrontal cortex to the DMH has been discovered to drive a variety of physiological responses for stress coping, including hyperthermia. During starvation, hunger signaling from the hypothalamus was found to activate medullary reticular neurons, which then suppress thermogenic sympathetic outflows from the rMR for energy saving. This thermoregulatory circuit represents a fundamental mechanism of the central regulation for homeostasis.
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Affiliation(s)
- Kazuhiro Nakamura
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
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4
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O’Brien F, Feetham CH, Staunton CA, Hext K, Barrett-Jolley R. Temperature modulates PVN pre-sympathetic neurones via transient receptor potential ion channels. Front Pharmacol 2023; 14:1256924. [PMID: 37920211 PMCID: PMC10618372 DOI: 10.3389/fphar.2023.1256924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/03/2023] [Indexed: 11/04/2023] Open
Abstract
The paraventricular nucleus (PVN) of the hypothalamus plays a vital role in maintaining homeostasis and modulates cardiovascular function via autonomic pre-sympathetic neurones. We have previously shown that coupling between transient receptor potential cation channel subfamily V Member 4 (Trpv4) and small-conductance calcium-activated potassium channels (SK) in the PVN facilitate osmosensing, but since TRP channels are also thermosensitive, in this report we investigated the temperature sensitivity of these neurones. Methods: TRP channel mRNA was quantified from mouse PVN with RT-PCR and thermosensitivity of Trpv4-like PVN neuronal ion channels characterised with cell-attached patch-clamp electrophysiology. Following recovery of temperature-sensitive single-channel kinetic schema, we constructed a predictive stochastic mathematical model of these neurones and validated this with electrophysiological recordings of action current frequency. Results: 7 thermosensitive TRP channel genes were found in PVN punches. Trpv4 was the most abundant of these and was identified at the single channel level on PVN neurones. We investigated the thermosensitivity of these Trpv4-like channels; open probability (Po) markedly decreased when temperature was decreased, mediated by a decrease in mean open dwell times. Our neuronal model predicted that PVN spontaneous action current frequency (ACf) would increase as temperature is decreased and in our electrophysiological experiments, we found that ACf from PVN neurones was significantly higher at lower temperatures. The broad-spectrum channel blocker gadolinium (100 µM), was used to block the warm-activated, Ca2+-permeable Trpv4 channels. In the presence of gadolinium (100 µM), the temperature effect was largely retained. Using econazole (10 µM), a blocker of Trpm2, we found there were significant increases in overall ACf and the temperature effect was inhibited. Conclusion: Trpv4, the abundantly transcribed thermosensitive TRP channel gene in the PVN appears to contribute to intrinsic thermosensitive properties of PVN neurones. At physiological temperatures (37°C), we observed relatively low ACf primarily due to the activity of Trpm2 channels, whereas at room temperature, where most of the previous characterisation of PVN neuronal activity has been performed, ACf is much higher, and appears to be predominately due to reduced Trpv4 activity. This work gives insight into the fundamental mechanisms by which the body decodes temperature signals and maintains homeostasis.
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Affiliation(s)
| | | | | | | | - Richard Barrett-Jolley
- Department of Musculoskeletal Ageing Science, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
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5
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Metzler-Wilson K, Fang MM, Alibegovic K, Daggett JW, Narra SC, Dazé RP, Miller OG, Wilson TE. Effect of reflex and mechanical decreases in skin perfusion on thermal- and agonist-induced eccrine sweating in humans. Am J Physiol Regul Integr Comp Physiol 2023; 324:R271-R280. [PMID: 36622082 PMCID: PMC9970189 DOI: 10.1152/ajpregu.00066.2022] [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: 04/01/2022] [Revised: 12/07/2022] [Accepted: 01/02/2023] [Indexed: 01/10/2023]
Abstract
In humans, skin blood flux (SkBF) and eccrine sweating are tightly coupled, suggesting common neural control and regulation. This study was designed to separate these two sympathetic nervous system end-organ responses via nonadrenergic SkBF-decreasing mechanical perturbations during heightened sudomotor drive. We induced sweating physiologically via whole body heat stress using a high-density tube-lined suit (protocol 1; 2 women, 4 men), and pharmacologically via forearm intradermal microdialysis of two steady-state doses of a cholinergic agonist, pilocarpine (protocol 2; 4 women, 3 men). During sweating induction, we decreased SkBF via three mechanical perturbations: arm and leg dependency to engage the cutaneous venoarteriolar response (CVAR), limb venous occlusion to engage the CVAR and decrease perfusion pressure, and limb arterial occlusion to cause ischemia. In protocol 1, heat stress increased arm cutaneous vascular conductance and forearm sweat rate (capacitance hygrometry). During heat stress, despite decreases in SkBF during each of the acute (3 min) mechanical perturbations, eccrine sweat rate was unaffected. During heat stress with extended (10 min) ischemia, sweat rate decreased. In protocol 2, both pilocarpine doses (ED50 and EMAX) increased SkBF and sweat rate. Each mechanical perturbation resulted in decreased SkBF but minimal changes in eccrine sweat rate. Taken together, these data indicate that a wide range of acute decreases in SkBF do not appear to proportionally decrease either physiologically- or pharmacologically induced eccrine sweating in peripheral skin. This preservation of evaporative cooling despite acutely decreased SkBF could have consequential impacts for heat storage and balance during changes in body posture, limb position, or blood flow restrictive conditions.
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Affiliation(s)
- Kristen Metzler-Wilson
- Department of Physical Therapy, Indiana University School of Health and Human Sciences, Indianapolis, Indiana
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Milie M Fang
- Division of Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, Indiana
| | - Kenan Alibegovic
- Division of Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, Indiana
| | - James W Daggett
- Division of Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, Indiana
| | - Seetharam C Narra
- Division of Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, Indiana
| | - Robert P Dazé
- Division of Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, Indiana
| | - Olivia G Miller
- Department of Physical Therapy, Indiana University School of Health and Human Sciences, Indianapolis, Indiana
| | - Thad E Wilson
- Division of Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, Indiana
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky
- Saha Cardiovascular Research Center, University of Kentucky College of Medicine, Lexington, Kentucky
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6
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Tan N, Shi J, Xu L, Zheng Y, Wang X, Lai N, Fang Z, Chen J, Wang Y, Chen Z. Lateral Hypothalamus Calcium/Calmodulin-Dependent Protein Kinase II α Neurons Encode Novelty-Seeking Signals to Promote Predatory Eating. Research (Wash D C) 2022; 2022:9802382. [PMID: 36061821 PMCID: PMC9394055 DOI: 10.34133/2022/9802382] [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: 02/15/2022] [Accepted: 06/24/2022] [Indexed: 11/06/2022] Open
Abstract
Predatory hunting is an innate appetite-driven and evolutionarily conserved behavior essential for animal survival, integrating sequential behaviors including searching, pursuit, attack, retrieval, and ultimately consumption. Nevertheless, neural circuits underlying hunting behavior with different features remain largely unexplored. Here, we deciphered a novel function of lateral hypothalamus (LH) calcium/calmodulin-dependent protein kinase II α (CaMKIIα+) neurons in hunting behavior and uncovered upstream/downstream circuit basis. LH CaMKIIα+ neurons bidirectionally modulate novelty-seeking behavior, predatory attack, and eating in hunting behavior. LH CaMKIIα+ neurons integrate hunting-related novelty-seeking information from the medial preoptic area (MPOA) and project to the ventral periaqueductal gray (vPAG) to promote predatory eating. Our results demonstrate that LH CaMKIIα+ neurons are the key hub that integrate MPOA-conveyed novelty-seeking signals and encode predatory eating in hunting behavior, which enriched the neuronal substrate of hunting behavior.
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Affiliation(s)
- Na Tan
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Jiaying Shi
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Lingyu Xu
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yanrong Zheng
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Xia Wang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Nanxi Lai
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Zhuowen Fang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Jialu Chen
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yi Wang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhong Chen
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
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7
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Qian S, Yan S, Pang R, Zhang J, Liu K, Shi Z, Wang Z, Chen P, Zhang Y, Luo T, Hu X, Xiong Y, Zhou Y. A temperature-regulated circuit for feeding behavior. Nat Commun 2022; 13:4229. [PMID: 35869064 PMCID: PMC9307622 DOI: 10.1038/s41467-022-31917-w] [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] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 07/08/2022] [Indexed: 11/08/2022] Open
Abstract
Both rodents and primates have evolved to orchestrate food intake to maintain thermal homeostasis in coping with ambient temperature challenges. However, the mechanisms underlying temperature-coordinated feeding behavior are rarely reported. Here we find that a non-canonical feeding center, the anteroventral and periventricular portions of medial preoptic area (apMPOA) respond to altered dietary states in mice. Two neighboring but distinct neuronal populations in apMPOA mediate feeding behavior by receiving anatomical inputs from external and dorsal subnuclei of lateral parabrachial nucleus. While both populations are glutamatergic, the arcuate nucleus-projecting neurons in apMPOA can sense low temperature and promote food intake. The other type, the paraventricular hypothalamic nucleus (PVH)-projecting neurons in apMPOA are primarily sensitive to high temperature and suppress food intake. Caspase ablation or chemogenetic inhibition of the apMPOA→PVH pathway can eliminate the temperature dependence of feeding. Further projection-specific RNA sequencing and fluorescence in situ hybridization identify that the two neuronal populations are molecularly marked by galanin receptor and apelin receptor. These findings reveal unrecognized cell populations and circuits of apMPOA that orchestrates feeding behavior against thermal challenges.
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Affiliation(s)
- Shaowen Qian
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China.
- Department of Medical Imaging, The 960th Hospital of Joint Logistics Support Force of PLA (Former Jinan Military General Hospital), Jinan, Shandong, China.
| | - Sumei Yan
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Ruiqi Pang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
- Advanced Institute for Brain and Intelligence, School of Medicine, Guangxi University, Nanning, Guangxi, China
| | - Jing Zhang
- Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
| | - Kai Liu
- Department of Medical Imaging, The 960th Hospital of Joint Logistics Support Force of PLA (Former Jinan Military General Hospital), Jinan, Shandong, China
| | - Zhiyue Shi
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Zhaoqun Wang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Penghui Chen
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Yanjie Zhang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Tiantian Luo
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Xianli Hu
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China
| | - Ying Xiong
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China.
| | - Yi Zhou
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, School of Basic Medicine, Army Medical University, Chongqing, China.
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8
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Ambler M, Hitrec T, Pickering A. Turn it off and on again: characteristics and control of torpor. Wellcome Open Res 2022; 6:313. [PMID: 35087956 PMCID: PMC8764563 DOI: 10.12688/wellcomeopenres.17379.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2022] [Indexed: 11/20/2022] Open
Abstract
Torpor is a hypothermic, hypoactive, hypometabolic state entered into by a wide range of animals in response to environmental challenge. This review summarises the current understanding of torpor. We start by describing the characteristics of the wide-ranging physiological adaptations associated with torpor. Next follows a discussion of thermoregulation, control of food intake and energy expenditure, and the interactions of sleep and thermoregulation, with particular emphasis on how those processes pertain to torpor. We move on to review the evidence for the systems that control torpor entry, including both the efferent circulating factors that signal the need for torpor, and the central processes that orchestrate it. Finally, we consider how the putative circuits responsible for torpor induction integrate with the established understanding of thermoregulation under non-torpid conditions and highlight important areas of uncertainty for future studies.
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Affiliation(s)
- Michael Ambler
- School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, Bristol, BS8 1TD, UK
| | - Timna Hitrec
- School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, Bristol, BS8 1TD, UK
| | - Anthony Pickering
- School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, Bristol, BS8 1TD, UK
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9
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Wilson SP, Prescott TJ. Scaffolding layered control architectures through constraint closure: insights into brain evolution and development. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200519. [PMID: 34957842 PMCID: PMC8710877 DOI: 10.1098/rstb.2020.0519] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 10/05/2021] [Indexed: 12/26/2022] Open
Abstract
The functional organization of the mammalian brain can be considered to form a layered control architecture, but how this complex system has emerged through evolution and is constructed during development remains a puzzle. Here we consider brain organization through the framework of constraint closure, viewed as a general characteristic of living systems, that they are composed of multiple sub-systems that constrain each other at different timescales. We do so by developing a new formalism for constraint closure, inspired by a previous model showing how within-lifetime dynamics can constrain between-lifetime dynamics, and we demonstrate how this interaction can be generalized to multi-layered systems. Through this model, we consider brain organization in the context of two major examples of constraint closure-physiological regulation and visual orienting. Our analysis draws attention to the capacity of layered brain architectures to scaffold themselves across multiple timescales, including the ability of cortical processes to constrain the evolution of sub-cortical processes, and of the latter to constrain the space in which cortical systems self-organize and refine themselves. This article is part of the theme issue 'Systems neuroscience through the lens of evolutionary theory'.
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Affiliation(s)
- Stuart P. Wilson
- Department of Psychology, University of Sheffield, Sheffield, UK
| | - Tony J. Prescott
- Department of Computer Science, University of Sheffield, Sheffield, UK
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10
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Liatis T, Gutierrez‐Quintana R, Mari L, Czopowicz M, Polidoro D, Bhatti SFM, Cozzi F, Tirrito F, Brocal J, José‐López R, Kaczmarska A, Cappello R, Harris G, Alves L, Rusbridge C, Rossmeisl JH. Primary orthostatic tremor and orthostatic tremor-plus in dogs: 60 cases (2003-2020). J Vet Intern Med 2022; 36:179-189. [PMID: 34897811 PMCID: PMC8783359 DOI: 10.1111/jvim.16328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 11/15/2021] [Accepted: 11/17/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Orthostatic tremor (OT) is a rare movement disorder characterized by high-frequency (>12 Hz) involuntary, rhythmic, sinusoidal movements affecting predominantly the limbs while standing. OBJECTIVE To describe the signalment, presenting complaints, phenotype, diagnostic findings, treatment, and outcome of a large sample of dogs with OT. ANIMALS Sixty dogs diagnosed with OT based on conscious electromyography. METHODS Multicenter retrospective case series study. Dogs were included if they had a conscious electromyography consistent with muscle discharge frequency >12 Hz while standing. RESULTS Fifty-three cases were diagnosed with primary OT (POT). Giant breed dogs represented most cases (83%; 44/53). Most dogs (79%; 42/53) were younger than 2 years of age at onset of signs, except for Retrievers which were all older than 3.5 years of age. The most common presenting complaints were pelvic limb tremors while standing (85%; 45/53) and difficulty when rising or sitting down (45%; 24/53). Improvement of clinical signs occurred in most dogs (85%; 45/53) treated medically with phenobarbital, primidone, gabapentin, pregabalin or clonazepam, but it was mostly partial rather than complete. Orthostatic tremor-plus was seen in 7 dogs that had concurrent neurological diseases. CONCLUSIONS AND CLINICAL IMPORTANCE Primary OT is a progressive disease of young, purebred, giant/large-breed dogs, which appears to begin later in life in Retrievers. Primary OT apparently responds partially to medications. Orthostatic tremor-plus exists in dogs and can be concomitant or associated with other neurological diseases.
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Affiliation(s)
- Theofanis Liatis
- Small Animal Hospital, School of Veterinary MedicineUniversity of GlasgowGlasgowUnited Kingdom
| | | | - Lorenzo Mari
- Small Animal Referral CentreAnimal Health TrustNewmarketUnited Kingdom
- Wear ReferralsStockton‐on‐TeesUnited Kingdom
| | - Michał Czopowicz
- Division of Veterinary Epidemiology and EconomicsInstitute of Veterinary Medicine, Warsaw University of Life Sciences—SGGWWarsawPoland
| | - Dakir Polidoro
- Small Animal Teaching Hospital, Small Animal Department, Faculty of Veterinary MedicineGhent UniversityGhentBelgium
| | - Sofie F. M. Bhatti
- Small Animal Teaching Hospital, Small Animal Department, Faculty of Veterinary MedicineGhent UniversityGhentBelgium
| | | | | | - Josep Brocal
- Small Animal Hospital, School of Veterinary MedicineUniversity of GlasgowGlasgowUnited Kingdom
- Wear ReferralsStockton‐on‐TeesUnited Kingdom
| | - Roberto José‐López
- Small Animal Hospital, School of Veterinary MedicineUniversity of GlasgowGlasgowUnited Kingdom
| | - Adriana Kaczmarska
- Small Animal Hospital, School of Veterinary MedicineUniversity of GlasgowGlasgowUnited Kingdom
| | | | - Georgina Harris
- The Queen's Veterinary School Hospital, Department of Veterinary MedicineUniversity of CambridgeCambridgeUnited Kingdom
| | - Lisa Alves
- The Queen's Veterinary School Hospital, Department of Veterinary MedicineUniversity of CambridgeCambridgeUnited Kingdom
| | - Clare Rusbridge
- Fitzpatrick Referrals Orthopaedics and NeurologyGodalmingUnited Kingdom
- School of Veterinary MedicineUniversity of SurreyGuilfordUnited Kingdom
| | - John H. Rossmeisl
- Department of Small Animal Clinical Sciences, Virginia‐Maryland College of Veterinary MedicineVirginia Polytechnic Institute and State UniversityBlacksburgVirginiaUSA
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11
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Nakamura K, Morrison SF. Central sympathetic network for thermoregulatory responses to psychological stress. Auton Neurosci 2021; 237:102918. [PMID: 34823147 DOI: 10.1016/j.autneu.2021.102918] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 11/05/2021] [Accepted: 11/13/2021] [Indexed: 11/16/2022]
Abstract
In mammals, many types of psychological stressors elicit a variety of sympathoexcitatory responses paralleling the classic fight-or-flight response to a threat to survival, including increased body temperature via brown adipose tissue thermogenesis and cutaneous vasoconstriction, and increased skeletal muscle blood flow via tachycardia and visceral vasoconstriction. Although these responses are usually supportive for stress coping, aberrant sympathetic responses to stress can lead to clinical issues in psychosomatic medicine. Sympathetic stress responses are mediated mostly by sympathetic premotor drives from the rostral medullary raphe region (rMR) and partly by those from the rostral ventrolateral medulla (RVLM). Hypothalamomedullary descending pathways from the dorsomedial hypothalamus (DMH) to the rMR and RVLM mediate important, stress-driven sympathoexcitatory transmission to the premotor neurons to drive the thermal and cardiovascular responses. The DMH also likely sends an excitatory input to the paraventricular hypothalamic nucleus to stimulate stress hormone release. Neurons in the DMH receive a stress-related excitation from the dorsal peduncular cortex and dorsal tenia tecta (DP/DTT) in the ventromedial prefrontal cortex. By connecting the corticolimbic emotion circuit to the central sympathetic and somatic motor systems, the DP/DTT → DMH pathway plays as the primary mediator of the psychosomatic signaling that drives a variety of sympathetic and behavioral stress responses. These brain regions together with other stress-related regions constitute a central neural network for physiological stress responses. This network model is relevant to understanding the central mechanisms by which stress and emotions affect autonomic regulations of homeostasis and to developing new therapeutic strategies for various stress-related disorders.
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Affiliation(s)
- Kazuhiro Nakamura
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
| | - Shaun F Morrison
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR 97239, USA
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12
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Ambler M, Hitrec T, Pickering A. Turn it off and on again: characteristics and control of torpor. Wellcome Open Res 2021; 6:313. [DOI: 10.12688/wellcomeopenres.17379.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2021] [Indexed: 11/20/2022] Open
Abstract
Torpor is a hypothermic, hypoactive, hypometabolic state entered into by a wide range of animals in response to environmental challenge. This review summarises the current understanding of torpor. We start by describing the characteristics of the wide-ranging physiological adaptations associated with torpor. Next follows a discussion of thermoregulation, control of food intake and energy expenditure, and the interactions of sleep and thermoregulation, with particular emphasis on how those processes pertain to torpor. We move on to take a critical view of the evidence for the systems that control torpor entry, including both the efferent circulating factors that signal the need for torpor, and the central processes that orchestrate it. Finally, we consider how the putative circuits responsible for torpor induction integrate with the established understanding of thermoregulation under non-torpid conditions and highlight important areas of uncertainty for future studies.
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A hypothalamomedullary network for physiological responses to environmental stresses. Nat Rev Neurosci 2021; 23:35-52. [PMID: 34728833 DOI: 10.1038/s41583-021-00532-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2021] [Indexed: 02/07/2023]
Abstract
Various environmental stressors, such as extreme temperatures (hot and cold), pathogens, predators and insufficient food, can threaten life. Remarkable progress has recently been made in understanding the central circuit mechanisms of physiological responses to such stressors. A hypothalamomedullary neural pathway from the dorsomedial hypothalamus (DMH) to the rostral medullary raphe region (rMR) regulates sympathetic outflows to effector organs for homeostasis. Thermal and infection stress inputs to the preoptic area dynamically alter the DMH → rMR transmission to elicit thermoregulatory, febrile and cardiovascular responses. Psychological stress signalling from a ventromedial prefrontal cortical area to the DMH drives sympathetic and behavioural responses for stress coping, representing a psychosomatic connection from the corticolimbic emotion circuit to the autonomic and somatic motor systems. Under starvation stress, medullary reticular neurons activated by hunger signalling from the hypothalamus suppress thermogenic drive from the rMR for energy saving and prime mastication to promote food intake. This Perspective presents a combined neural network for environmental stress responses, providing insights into the central circuit mechanism for the integrative regulation of systemic organs.
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Alberca RW, Gomes E, Moretti EH, Russo M, Steiner AA. Naturally occurring hypothermia promotes survival in severe anaphylaxis. Immunol Lett 2021; 237:27-32. [PMID: 34245741 DOI: 10.1016/j.imlet.2021.07.002] [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: 05/11/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 11/24/2022]
Abstract
Although hypothermia has received substantial attention as an indicator of severity in anaphylaxis, it has been neglected from the perspective of whether it could act as a disease-modifying factor in this condition. Here, the impact of naturally occurring (spontaneous) hypothermia on anaphylaxis was evaluated in a murine model of ovalbumin (OVA)-induced allergy. Nonextreme changes in the ambient temperature (Ta) were used to modulate the magnitude of spontaneous hypothermia. At a Ta of 24°C, challenge with OVA intraperitoneally or intravenously resulted in a rapid, transient fall in body core temperature, which reached its nadir 4-6°C below baseline in 30 min. This hypothermic response was largely attenuated when the mice were kept at a Ta of 34°C. The Ta-dependent attenuation of hypothermia resulted in a survival rate of only 30%, as opposed to survival of 100% in the condition that favored the development of hypothermia. The protective effect of hypothermia did not involve changes in the rate of mast cell degranulation, as assessed by the concentration of mast cell protease-1 in bodily fluids. On the other hand, hypothermia improved oxygenation of the brain and kidneys, as indicated by higher NAD+/NADH ratios. Therefore, it is plausible to propose that naturally occurring hypothermia makes organs more resistant to the anaphylactic insult.
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Affiliation(s)
- Ricardo W Alberca
- Departamento de Imunologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP 05508, Brazil
| | - Eliane Gomes
- Departamento de Imunologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP 05508, Brazil
| | - Eduardo H Moretti
- Departamento de Imunologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP 05508, Brazil
| | - Momtchilo Russo
- Departamento de Imunologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP 05508, Brazil
| | - Alexandre A Steiner
- Departamento de Imunologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP 05508, Brazil.
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15
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Polichnowski AJ, Williamson GA, Blair TE, Hoover DB. Autonomic and cholinergic mechanisms mediating cardiovascular and temperature effects of donepezil in conscious mice. Am J Physiol Regul Integr Comp Physiol 2021; 320:R871-R884. [PMID: 33851543 DOI: 10.1152/ajpregu.00360.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Donepezil is a centrally acting acetylcholinesterase (AChE) inhibitor with therapeutic potential in inflammatory diseases; however, the underlying autonomic and cholinergic mechanisms remain unclear. Here, we assessed effects of donepezil on mean arterial pressure (MAP), heart rate (HR), HR variability, and body temperature in conscious adult male C57BL/6 mice to investigate the autonomic pathways involved. Central versus peripheral cholinergic effects of donepezil were assessed using pharmacological approaches including comparison with the peripherally acting AChE inhibitor, neostigmine. Drug treatments included donepezil (2.5 or 5 mg/kg sc), neostigmine methyl sulfate (80 or 240 μg/kg ip), atropine sulfate (5 mg/kg ip), atropine methyl bromide (5 mg/kg ip), or saline. Donepezil, at 2.5 and 5 mg/kg, decreased HR by 36 ± 4% and 44 ± 3% compared with saline (n = 10, P < 0.001). Donepezil, at 2.5 and 5 mg/kg, decreased temperature by 13 ± 2% and 22 ± 2% compared with saline (n = 6, P < 0.001). Modest (P < 0.001) increases in MAP were observed with donepezil after peak bradycardia occurred. Atropine sulfate and atropine methyl bromide blocked bradycardic responses to donepezil, but only atropine sulfate attenuated hypothermia. The pressor response to donepezil was similar in mice coadministered atropine sulfate; however, coadministration of atropine methyl bromide potentiated the increase in MAP. Neostigmine did not alter HR or temperature, but did result in early increases in MAP. Despite the marked bradycardia, donepezil did not increase normalized high-frequency HR variability. We conclude that donepezil causes marked bradycardia and hypothermia in conscious mice via the activation of muscarinic receptors while concurrently increasing MAP via autonomic and cholinergic pathways that remain to be elucidated.
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Affiliation(s)
- Aaron J Polichnowski
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee.,Center of Excellence in Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, Tennessee
| | - Geoffrey A Williamson
- Department of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, Illinois
| | - Tesha E Blair
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee
| | - Donald B Hoover
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee.,Center of Excellence in Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, Tennessee
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Keramidas ME, Kölegård R, Eiken O. Hypoxia gradually augments metabolic and thermoperceptual responsiveness to repeated whole-body cold stress in humans. Exp Physiol 2020; 105:2123-2140. [PMID: 33140429 PMCID: PMC7756580 DOI: 10.1113/ep089070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 10/30/2020] [Indexed: 12/02/2022]
Abstract
New Findings What is the central question of this study? In male lowlanders, does hypoxia modulate thermoregulatory effector responses during repeated whole‐body cold stress encountered in a single day? What is the main finding and its importance? A ∼10 h sustained exposure to hypoxia appears to mediate a gradual upregulation of endogenous heat production, preventing the progressive hypothermic response prompted by serial cold stimuli. Also, hypoxia progressively degrades mood, and compounds the perceived thermal discomfort, and sensations of fatigue and coldness.
Abstract We examined whether hypoxia would modulate thermoeffector responses during repeated cold stress encountered in a single day. Eleven men completed two ∼10 h sessions, while breathing, in normobaria, either normoxia or hypoxia (PO2: 12 kPa). During each session, subjects underwent sequentially three 120 min immersions to the chest in 20°C water (CWI), interspersed by 120 min rewarming. In normoxia, the final drop in rectal temperature (Trec) was greater in the third (∼1.2°C) than in the first and second (∼0.9°C) CWIs (P < 0.05). The first hypoxic CWI augmented the Trec fall (∼1.2°C; P = 0.002), but the drop in Trec did not vary between the three hypoxic CWIs (P = 0.99). In normoxia, the metabolic heat production (M˙) was greater during the first half of the third CWI than during the corresponding part of the first CWI (P = 0.02); yet the difference was blunted during the second half of the CWIs (P = 0.89). In hypoxia, by contrast, the increase in M˙ was augmented by ∼25% throughout the third CWI (P < 0.01). Regardless of the breathing condition, the cold‐induced elevation in mean arterial pressure was blunted in the second and third CWI (P < 0.05). Hypoxia aggravated the sensation of coldness (P = 0.05) and thermal discomfort (P = 0.04) during the second half of the third CWI. The present findings therefore demonstrate that prolonged hypoxia mediates, in a gradual manner, metabolic and thermoperceptual sensitization to repeated cold stress.
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Affiliation(s)
- Michail E Keramidas
- Division of Environmental Physiology, Swedish Aerospace Physiology Center, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Roger Kölegård
- Division of Environmental Physiology, Swedish Aerospace Physiology Center, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Ola Eiken
- Division of Environmental Physiology, Swedish Aerospace Physiology Center, KTH Royal Institute of Technology, Stockholm, Sweden
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Potter AW, Berglund LG, O'Brien C. A canine thermal model for simulating temperature responses of military working dogs. J Therm Biol 2020; 91:102651. [PMID: 32716889 DOI: 10.1016/j.jtherbio.2020.102651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 11/20/2022]
Abstract
Military working dogs (MWDs) are often required to operate in dangerous or extreme environments, to include hot and humid climate conditions. These scenarios can put MWD at significant risk of heat injury. To address this concern, a two-compartment (core, skin) rational thermophysiological model was developed to predict the temperature of a MWD during rest, exercise, and recovery. The Canine Thermal Model (CTM) uses inputs of MWD mass and length to determine a basal metabolic rate and body surface area. These calculations are used along with time series inputs of environmental conditions (air temperature, relative humidity, solar radiation and wind velocity) and level of metabolic intensity (MET) to predict MWD thermoregulatory responses. Default initial values of core and skin temperatures are set at neutral values representative of an average MWD; however, these can be adjusted to match known or expected individual temperatures. The rational principles of the CTM describe the heat exchange from the metabolic energy of the core compartment to the skin compartment by passive conduction as well as the application of an active control for skin blood flow and to tongue and lingual tissues. The CTM also mathematically describes heat loss directly to the environment via respiration, including panting. Thermal insulation properties of MWD fur are also used to influence heat loss from skin and gain from the environment. This paper describes the CTM in detail, outlining the equations used to calculate avenues of heat transfer (convective, conductive, radiative and evaporative), overall heat storage, and predicted responses of the MWD. Additionally, this paper outlines examples of how the CTM can be used to predict recovery from exertional heat strain, plan work/rest cycles, and estimate work duration to avoid overheating.
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Affiliation(s)
- Adam W Potter
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Bldg 42, Natick, MA, 01760-5007, USA.
| | - Larry G Berglund
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Bldg 42, Natick, MA, 01760-5007, USA.
| | - Catherine O'Brien
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Bldg 42, Natick, MA, 01760-5007, USA.
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Abstract
Animals that lack the hormone leptin become grossly obese, purportedly for 2 reasons: increased food intake and decreased energy expenditure (thermogenesis). This review examines the experimental evidence for the thermogenesis component. Analysis of the data available led us to conclude that the reports indicating hypometabolism in the leptin-deficient ob/ob mice (as well as in the leptin-receptor-deficient db/db mice and fa/fa rats) derive from a misleading calculation artefact resulting from expression of energy expenditure per gram of body weight and not per intact organism. Correspondingly, the body weight-reducing effects of leptin are not augmented by enhanced thermogenesis. Congruent with this, there is no evidence that the ob/ob mouse demonstrates atrophied brown adipose tissue or diminished levels of total UCP1 mRNA or protein when the ob mutation is studied on the inbred C57BL/6 mouse background, but a reduced sympathetic nerve activity is observed. On the outbred "Aston" mouse background, brown adipose tissue atrophy is seen, but whether this is of quantitative significance for the development of obesity has not been demonstrated. We conclude that leptin is not a thermogenic hormone. Rather, leptin has effects on body temperature regulation, by opposing torpor bouts and by shifting thermoregulatory thresholds. The central pathways behind these effects are largely unexplored.
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Affiliation(s)
- Alexander W Fischer
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden.,Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Barbara Cannon
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden
| | - Jan Nedergaard
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden
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19
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Lømo T, Eken T, Bekkestad Rein E, Njå A. Body temperature control in rats by muscle tone during rest or sleep. Acta Physiol (Oxf) 2020; 228:e13348. [PMID: 31342662 DOI: 10.1111/apha.13348] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/17/2019] [Accepted: 07/19/2019] [Indexed: 12/24/2022]
Abstract
AIM To explore the role of tonic motor unit activity in body temperature control. METHODS Motor unit activity in soleus and several other skeletal muscles was recorded electromyographically from adult rats placed in a climate chamber on a load sensitive floor, which, together with video monitoring, allowed detection of every successive period of movement and no movement. RESULTS In the absence of movements during rest or sleep, motor unit activity was exclusively tonic and therefore equivalent to muscle tone as defined here. The amount of tonic activity increased linearly in the soleus as the ambient temperature decreased from 32°C to below 7°C, owing to progressive recruitment and increased firing rate of individual units. Brief movements occurred randomly and frequently during rest or sleep in association with brief facilitation or inhibition of motor neurons that turned tonic motor unit activity on or off, partitioning the tonic activity among the available motor units. Shivering first appeared when a falling ambient temperature reached ≤7°C in several muscles except soleus, which was as active between shivering bursts as during them. CONCLUSION Muscle tone and overt shivering are strikingly different phenomena. Tonic motor unit activity in the absence of movements evokes isometric contractions and, therefore, generates heat. Accordingly, when the amount of tonic activity increases with falling ambient temperature, so must heat production. Consequently, graded muscle tone appears as an important and independent mechanism for thermogenesis during rest or sleep at ambient temperatures ranging from <7°C to at least 32°C.
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Affiliation(s)
- Terje Lømo
- Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Torsten Eken
- Department of Anaesthesiology Oslo University Hospital Oslo Norway
| | | | - Arild Njå
- Institute of Basic Medical Sciences University of Oslo Oslo Norway
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20
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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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21
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Tan CL, Knight ZA. Regulation of Body Temperature by the Nervous System. Neuron 2019; 98:31-48. [PMID: 29621489 DOI: 10.1016/j.neuron.2018.02.022] [Citation(s) in RCA: 306] [Impact Index Per Article: 61.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/19/2018] [Accepted: 02/23/2018] [Indexed: 01/24/2023]
Abstract
The regulation of body temperature is one of the most critical functions of the nervous system. Here we review our current understanding of thermoregulation in mammals. We outline the molecules and cells that measure body temperature in the periphery, the neural pathways that communicate this information to the brain, and the central circuits that coordinate the homeostatic response. We also discuss some of the key unresolved issues in this field, including the following: the role of temperature sensing in the brain, the molecular identity of the warm sensor, the central representation of the labeled line for cold, and the neural substrates of thermoregulatory behavior. We suggest that approaches for molecularly defined circuit analysis will provide new insight into these topics in the near future.
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Affiliation(s)
- Chan Lek Tan
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158
| | - Zachary A Knight
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158; Kavli Center for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158.
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22
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Taylor NA, Nykvist Å, Powers N, Caldwell JN. Thermoeffector threshold plasticity: The impact of thermal pre-conditioning on sudomotor, cutaneous vasomotor and thermogenic thresholds. J Therm Biol 2019; 83:37-46. [DOI: 10.1016/j.jtherbio.2019.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 05/02/2019] [Indexed: 12/16/2022]
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Oral gavage of capsaicin causes TRPV1-dependent acute hypothermia and TRPV1-independent long-lasting increase of locomotor activity in the mouse. Physiol Behav 2019; 206:213-224. [DOI: 10.1016/j.physbeh.2019.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/20/2019] [Accepted: 04/17/2019] [Indexed: 12/18/2022]
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24
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Martinez‐Tellez B, Adelantado‐Renau M, Acosta FM, Sanchez‐Delgado G, Martinez‐Nicolas A, Boon MR, Llamas‐Elvira JM, Martinez‐Vizcaino V, Ruiz JR. The Mediating Role of Brown Fat and Skeletal Muscle Measured by 18 F-Fluorodeoxyglucose in the Thermoregulatory System in Young Adults. Obesity (Silver Spring) 2019; 27:963-970. [PMID: 31006988 PMCID: PMC6594074 DOI: 10.1002/oby.22461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/19/2019] [Indexed: 11/15/2022]
Abstract
OBJECTIVE This study aimed to examine whether brown adipose tissue (BAT) or skeletal muscle activity mediates the relationship between personal level of environmental temperature (Personal-ET) and wrist skin temperature (WT). Moreover, we examined whether BAT and skeletal muscle have a mediating role between Personal-ET and WT (as a proxy of peripheral vasoconstriction/vasodilation). METHODS The levels of BAT were quantified by cold-induced 18 F-fluorodeoxyglucose-positron emission tomography/computed tomography scan and measured the Personal-ET and WT by using iButtons (Maxim Integrated, Dallas, Texas) in 75 participants (74.6% women). RESULTS The study found that BAT volume and metabolic activity played a positive and significant role (up to 25.4%) in the association between Personal-ET and WT. In addition, at the coldest temperatures, the participants with lower levels of WT (inducing higher peripheral vasoconstriction) had higher levels of BAT outcomes, whereas in warm temperatures, participants with higher levels of WT (inducing higher peripheral vasodilation) had lower levels of BAT outcomes. The study did not find any mediating role of skeletal muscle activity. CONCLUSIONS BAT volume and metabolic activity play a role in the relationship between Personal-ET and WT. Moreover, the data suggest that there are two distinct phenotypes: individuals who respond better to the cold, both through nonshivering thermogenesis and peripheral vasoconstriction, and individuals who respond better to the heat.
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Affiliation(s)
- Borja Martinez‐Tellez
- Promoting Fitness & Health Through Physical Activity Research Group, Department of Physical Education and Sports, Faculty of Sport SciencesUniversity of GranadaGranadaSpain
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenthe Netherlands
| | | | - Francisco M. Acosta
- Promoting Fitness & Health Through Physical Activity Research Group, Department of Physical Education and Sports, Faculty of Sport SciencesUniversity of GranadaGranadaSpain
| | - Guillermo Sanchez‐Delgado
- Promoting Fitness & Health Through Physical Activity Research Group, Department of Physical Education and Sports, Faculty of Sport SciencesUniversity of GranadaGranadaSpain
| | - Antonio Martinez‐Nicolas
- Chronobiology Laboratory, Department of Physiology, College of BiologyMare Nostrum Campus, University of Murcia, Instituto Universitario de Investgiación e Envegecimiento (IUIE), Instituto Murciano de Investigación Biosanitaria (IMIB)‐ArrixacaSpain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento SaludableMadridSpain
| | - Mariëtte R. Boon
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenthe Netherlands
| | - Jose M. Llamas‐Elvira
- Nuclear Medicine ServiceVirgen de las Nieves University HospitalGranadaSpain
- Nuclear Medicine DepartmentBiohealth Research Institute in GranadaGranadaSpain
| | - Vicente Martinez‐Vizcaino
- Health and Social Research Center, Castilla‐La Mancha UniversityCuencaSpain
- Faculty of Health SciencesAutonomous University of ChileTalcaChile
| | - Jonatan R. Ruiz
- Promoting Fitness & Health Through Physical Activity Research Group, Department of Physical Education and Sports, Faculty of Sport SciencesUniversity of GranadaGranadaSpain
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McKinley MJ, Martelli D, Pennington GL, Trevaks D, McAllen RM. Integrating Competing Demands of Osmoregulatory and Thermoregulatory Homeostasis. Physiology (Bethesda) 2019; 33:170-181. [PMID: 29616878 DOI: 10.1152/physiol.00037.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mammals are characterized by a stable core body temperature. When maintenance of core temperature is challenged by ambient or internal heat loads, mammals increase blood flow to the skin, sweat and/or pant, or salivate. These thermoregulatory responses enable evaporative cooling at moist surfaces to dissipate body heat. If water losses incurred during evaporative cooling are not replaced, body fluid homeostasis is challenged. This article reviews the way mammals balance thermoregulation and osmoregulation.
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Affiliation(s)
- Michael J McKinley
- Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville , Australia.,Department of Physiology, University of Melbourne , Parkville , Australia
| | - Davide Martelli
- Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville , Australia.,University of Bologna, Bologna , Italy
| | - Glenn L Pennington
- Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville , Australia
| | - David Trevaks
- Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville , Australia
| | - Robin M McAllen
- Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville , Australia
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26
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Abstract
Maintenance of a homeostatic body core temperature is a critical brain function accomplished by a central neural network. This orchestrates a complex behavioral and autonomic repertoire in response to environmental temperature challenges or declining energy homeostasis and in support of immune responses and many behavioral states. This review summarizes the anatomical, neurotransmitter, and functional relationships within the central neural network that controls the principal thermoeffectors: cutaneous vasoconstriction regulating heat loss and shivering and brown adipose tissue for heat production. The core thermoregulatory network regulating these thermoeffectors consists of parallel but distinct central efferent pathways that share a common peripheral thermal sensory input. Delineating the neural circuit mechanism underlying central thermoregulation provides a useful platform for exploring its functional organization, elucidating the molecular underpinnings of its neuronal interactions, and discovering novel therapeutic approaches to modulating body temperature and energy homeostasis.
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Affiliation(s)
- S F Morrison
- Department of Neurological Surgery, Oregon Health and Science University, Portland, Oregon 97239, USA;
| | - K Nakamura
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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27
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Cellular populations and thermosensing mechanisms of the hypothalamic thermoregulatory center. Pflugers Arch 2018; 470:809-822. [DOI: 10.1007/s00424-017-2101-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 12/17/2017] [Accepted: 12/19/2017] [Indexed: 10/18/2022]
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28
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Abstract
Heat exchange processes between the body and the environment are introduced. The definition of the thermoneutral zone as the ambient temperature range within which body temperature (Tb) regulation is achieved only by nonevaporative processes is explained. Thermoreceptors, thermoregulatory effectors (both physiologic and behavioral), and neural pathways and Tb signals that connect receptors and effectors into a thermoregulation system are reviewed. A classification of thermoeffectors is proposed. A consensus concept is presented, according to which the thermoregulation system is organized as a dynamic federation of independent thermoeffector loops. While the activity of each effector is driven by a unique combination of deep (core) and superficial (shell) Tbs, the regulated variable of the system can be viewed as a spatially distributed Tb with a heavily represented core and a lightly represented shell. Core Tb is the main feedback; it is always negative. Shell Tbs (mostly of the hairy skin) represent the auxiliary feedback, which can be negative or positive, and which decreases the system's response time and load error. Signals from the glabrous (nonhairy) skin about the temperature of objects in the environment serve as feedforward signals for various behaviors. Physiologic effectors do not use feedforward signals. The system interacts with other homeostatic systems by "meshing" with their loops. Coordination between different thermoeffectors is achieved through the common controlled variable, Tb. The term balance point (not set point) is used for a regulated level of Tb. The term interthreshold zone is used for a Tb range in which no effectors are activated. Thermoregulatory states are classified, based on whether: Tb is increased (hyperthermia) or decreased (hypothermia); the interthreshold zone is narrow (homeothermic type of regulation) or wide (poikilothermic type); and the balance point is increased (fever) or decreased (anapyrexia). During fever, thermoregulation can be either homeothermic or poikilothermic; anapyrexia is always a poikilothermic state. The biologic significance of poikilothermic states is discussed. As an example of practical applications of the concept presented, thermopharmacology is reviewed. Thermopharmacology uses drugs to modulate specific temperature signals at the level of a thermoreceptor (transient receptor potential channel).
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Abstract
The major symptoms of motion sickness are well known and include facial pallor, nausea and vomiting, and sweating, but it is poorly recognized that they actually reflect severely perturbed thermoregulation. Thus, the purpose of this chapter is to present and discuss existing data related to this subject. While hypothermia during seasickness was first noted nearly 150 years ago, detailed studies of this phenomenon were conducted only during the last two decades. Our own research confirmed that motion sickness-induced hypothermia is quite broadly expressed phylogenetically as, besides humans, it could be provoked in several other animals (rats, musk shrews, and mice). Evidence from human and animal experiments indicates that the physiologic mechanisms responsible for the motion sickness-induced hypothermia include cutaneous vasodilation and sweating (leading to an increase of heat loss) and reduced thermogenesis. Together, these results suggest that motion sickness triggers a highly coordinated physiologic response aiming to reduce body temperature. The chapter is concluded by presenting hypotheses of how and why motion sickness evokes this hypothermic response.
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Affiliation(s)
- Eugene Nalivaiko
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia.
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30
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Blondin DP, Haman F. Shivering and nonshivering thermogenesis in skeletal muscles. HANDBOOK OF CLINICAL NEUROLOGY 2018; 156:153-173. [PMID: 30454588 DOI: 10.1016/b978-0-444-63912-7.00010-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Humans have inherited complex neural circuits which drive behavioral, somatic, and autonomic thermoregulatory responses to defend their body temperature. While they are well adapted to dissipate heat in warm climates, they have a reduced capacity to preserve it in cold environments. Consequently, heat production is critical to defending their core temperature. As in other large mammals, skeletal muscles are the primary source of heat production recruited in cold-exposed humans. This is achieved voluntarily in the form of contractions from exercising muscles or involuntarily in the form of contractions from shivering muscles and the recruitment of nonshivering mechanisms. This review describes our current understanding of shivering and nonshivering thermogenesis in skeletal muscles, from the neural circuitry driving their recruitment to the metabolic substrates that fuel them. The presence of these heat-producing mechanisms can be measured in vivo by combining indirect respiratory calorimetry with electromyography or biomedical imaging modalities. Indeed, much of what is known regarding shivering in humans and other animal models stems from studies performed using these methods combined with in situ and in vivo neurologic techniques. More recent investigations have focused on understanding the metabolic processes that produce the heat from both contracting and noncontracting mechanisms. With the growing interest in the potential therapeutic benefits of shivering and nonshivering skeletal muscle to counter the effects of neuromuscular, cardiovascular, and metabolic diseases, we expect this field to continue its growth in the coming years.
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Affiliation(s)
- Denis P Blondin
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada.
| | - François Haman
- Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
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Morrison SF. Efferent neural pathways for the control of brown adipose tissue thermogenesis and shivering. HANDBOOK OF CLINICAL NEUROLOGY 2018; 156:281-303. [PMID: 30454595 DOI: 10.1016/b978-0-444-63912-7.00017-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The fundamental central neural circuits for thermoregulation orchestrate behavioral and autonomic repertoires that maintain body core temperature during thermal challenges that arise from either the ambient or the internal environment. This review summarizes our understanding of the neural pathways within the fundamental thermoregulatory reflex circuitry that comprise the efferent (i.e., beyond thermosensory) control of brown adipose tissue (BAT) and shivering thermogenesis: the motor neuron systems consisting of the BAT sympathetic preganglionic neurons and BAT sympathetic ganglion cells, and the alpha- and gamma-motoneurons; the premotor neurons in the region of the rostral raphe pallidus, and the thermogenesis-promoting neurons in the dorsomedial hypothalamus/dorsal hypothalamic area. Also included are inputs to, and neurochemical modulators of, these efferent neuronal populations that could influence their activity during thermoregulatory responses. Signals of metabolic status can be particularly significant for the energy-hungry thermoeffectors for heat production.
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Affiliation(s)
- Shaun F Morrison
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR, United States.
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Abstract
Classic lesion and physiology experiments identified the hypothalamic preoptic area as a pivotal region in the regulation of temperature homeostasis. The preoptic area can sense changes in local temperature, receives information about ambient temperature, contributes to fever, and can affect thermoregulation in response to several biologic signals. Electrophysiologic studies indicate that these actions are mediated by a neuronal circuitry that comprises temperature-sensitive as well as temperature-insensitive neurons. Little is known on the molecules that may be required for central thermosensation and much of the efforts towards their identification was done for warm-sensitive neurons. Here we summarize the current knowledge on the subject as well as what the search for these molecules revealed about warm-sensitive neurons.
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Affiliation(s)
- Bruno Conti
- Departments of Molecular Medicine and of Neuroscience, Dorris Neuroscience Center, Scripps Research Institute, La Jolla, CA, United States.
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33
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Loh RKC, Kingwell BA, Carey AL. Human brown adipose tissue as a target for obesity management; beyond cold-induced thermogenesis. Obes Rev 2017; 18:1227-1242. [PMID: 28707455 DOI: 10.1111/obr.12584] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/01/2017] [Accepted: 06/01/2017] [Indexed: 02/01/2023]
Abstract
Elevating energy expenditure via adaptive thermogenesis in brown adipose tissue (BAT) is a potential strategy to reverse obesity. Much early enthusiasm for this approach, based on rodent studies, was tempered by the belief that BAT was relatively inconsequential in healthy adult humans. Interest was reinvigorated a decade ago when a series of studies re-identified BAT, primarily in upper thoracic regions, in adults. Despite the ensuing explosion of pre-clinical investigations and identification of an extensive list of potential target molecules for BAT recruitment, our understanding of human BAT physiology remains limited, particularly regarding interventions which might hold therapeutic promise. Cold-induced BAT thermogenesis (CIT) has been well studied, although is not readily translatable as an anti-obesity approach, whereas little is known regarding the role of BAT in human diet-induced thermogenesis (DIT). Furthermore, human studies dedicated to translating known pharmacological mechanisms of adipose browning from animal models are sparse. Several lines of recent evidence suggest that molecular regulation and physiology of human BAT differ to that of laboratory rodents, which form the majority of our knowledge base. This review will summarize knowledge on CIT and expand upon the current understanding and evidence gaps related to human adaptive thermogenesis via mechanisms other than cold.
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Affiliation(s)
- R K C Loh
- Metabolic and Vascular Physiology Laboratory, Baker Heart and Diabetes Institute, Melbourne, Australia
| | - B A Kingwell
- Metabolic and Vascular Physiology Laboratory, Baker Heart and Diabetes Institute, Melbourne, Australia
| | - A L Carey
- Metabolic and Vascular Physiology Laboratory, Baker Heart and Diabetes Institute, Melbourne, Australia
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Abbott SBG, Saper CB. Median preoptic glutamatergic neurons promote thermoregulatory heat loss and water consumption in mice. J Physiol 2017; 595:6569-6583. [PMID: 28786483 PMCID: PMC5638873 DOI: 10.1113/jp274667] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 07/28/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Glutamatergic neurons in the median preoptic area were stimulated using genetically targeted Channelrhodopsin 2 in transgenic mice. Stimulation of glutamatergic median preoptic area neurons produced a profound hypothermia due to cutaneous vasodilatation. Stimulation also produced drinking behaviour that was inhibited as water was ingested, suggesting pre-systemic feedback gating of drinking. Anatomical mapping of the stimulation sites showed that sites associated with hypothermia were more anteroventral than those associated with drinking, although there was substantial overlap. ABSTRACT The median preoptic nucleus (MnPO) serves an important role in the integration of water/electrolyte homeostasis and thermoregulation, but we have a limited understanding these functions at a cellular level. Using Cre-Lox genetic targeting of Channelrhodospin 2 in VGluT2 transgenic mice, we examined the effect of glutamatergic MnPO neuron stimulation in freely behaving mice while monitoring drinking behaviour and core temperature. Stimulation produced a strong hypothermic response in 62% (13/21) of mice (core temperature: -4.6 ± 0.5°C, P = 0.001 vs. controls) caused by cutaneous vasodilatation. Stimulating glutamatergic MnPO neurons also produced robust drinking behaviour in 82% (18/22) of mice. Mice that drank during stimulation consumed 912 ± 163 μl (n = 8) during a 20 min trial in the dark phase, but markedly less during the light phase (421 ± 83 μl, P = 0.0025). Also, drinking during stimulation was inhibited as water was ingested, suggesting pre-systemic feedback gating of drinking. Both hypothermia and drinking during stimulation occurred in 50% of mice tested. Anatomical mapping of the stimulation sites showed that sites associated with hypothermia were more anteroventral than those associated with drinking, although there was substantial overlap. Thus, activation of separate but overlapping populations of glutamatergic MnPO neurons produces effects on drinking and autonomic thermoregulatory mechanisms, providing a structural basis for their frequently being coordinated (e.g. during hyperthermia).
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Affiliation(s)
- Stephen B. G. Abbott
- Department of NeurologyBeth Israel‐Deaconess Medical Center ‐ Harvard Medical SchoolBostonMAUSA
- The Heart Research InstituteSydneyAustralia
| | - Clifford B. Saper
- Department of NeurologyBeth Israel‐Deaconess Medical Center ‐ Harvard Medical SchoolBostonMAUSA
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Wanner SP, Almeida MC, Shimansky YP, Oliveira DL, Eales JR, Coimbra CC, Romanovsky AA. Cold-Induced Thermogenesis and Inflammation-Associated Cold-Seeking Behavior Are Represented by Different Dorsomedial Hypothalamic Sites: A Three-Dimensional Functional Topography Study in Conscious Rats. J Neurosci 2017; 37:6956-6971. [PMID: 28630253 PMCID: PMC5518423 DOI: 10.1523/jneurosci.0100-17.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 05/12/2017] [Accepted: 06/05/2017] [Indexed: 11/21/2022] Open
Abstract
In the past, we showed that large electrolytic lesions of the dorsomedial hypothalamus (DMH) promoted hypothermia in cold-exposed restrained rats, but attenuated hypothermia in rats challenged with a high dose of bacterial lipopolysaccharide (LPS) in a thermogradient apparatus. The goal of this study was to identify the thermoeffector mechanisms and DMH representation of the two phenomena and thus to understand how the same lesion could produce two opposite effects on body temperature. We found that the permissive effect of large electrolytic DMH lesions on cold-induced hypothermia was due to suppressed thermogenesis. DMH-lesioned rats also could not develop fever autonomically: they did not increase thermogenesis in response to a low, pyrogenic dose of LPS (10 μg/kg, i.v.). In contrast, changes in thermogenesis were uninvolved in the attenuation of the hypothermic response to a high, shock-inducing dose of LPS (5000 μg/kg, i.v.); this attenuation was due to a blockade of cold-seeking behavior. To compile DMH maps for the autonomic cold defense and for the cold-seeking response to LPS, we studied rats with small thermal lesions in different parts of the DMH. Cold thermogenesis had the highest representation in the dorsal hypothalamic area. Cold seeking was represented by a site at the ventral border of the dorsomedial nucleus. Because LPS causes both fever and hypothermia, we originally thought that the DMH contained a single thermoregulatory site that worked as a fever-hypothermia switch. Instead, we have found two separate sites: one that drives thermogenesis and the other, previously unknown, that drives inflammation-associated cold seeking.SIGNIFICANCE STATEMENT Cold-seeking behavior is a life-saving response that occurs in severe systemic inflammation. We studied this behavior in rats with lesions in the dorsomedial hypothalamus (DMH) challenged with a shock-inducing dose of bacterial endotoxin. We built functional maps of the DMH and found the strongest representation of cold-seeking behavior at the ventral border of the dorsomedial nucleus. We also built maps for cold-induced thermogenesis in unanesthetized rats and found the dorsal hypothalamic area to be its main representation site. Our work identifies the neural substrate of cold-seeking behavior in systemic inflammation and expands the functional topography of the DMH, a structure that modulates autonomic, endocrine, and behavioral responses and is a potential therapeutic target in anxiety and panic disorders.
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Affiliation(s)
- Samuel P Wanner
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Federal University of Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - M Camila Almeida
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013
| | - Yury P Shimansky
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013
- Kinesiology Program, Arizona State University, Phoenix, Arizona 85004, and
| | - Daniela L Oliveira
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013
| | - Justin R Eales
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013
| | - Cândido C Coimbra
- Endocrinology and Metabolism Laboratory, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - Andrej A Romanovsky
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013,
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Tupone D, Cano G, Morrison SF. Thermoregulatory inversion: a novel thermoregulatory paradigm. Am J Physiol Regul Integr Comp Physiol 2017; 312:R779-R786. [PMID: 28330964 DOI: 10.1152/ajpregu.00022.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/01/2017] [Accepted: 03/15/2017] [Indexed: 01/06/2023]
Abstract
To maintain core body temperature in mammals, the normal central nervous system (CNS) thermoregulatory reflex networks produce an increase in brown adipose tissue (BAT) thermogenesis in response to skin cooling and an inhibition of the sympathetic outflow to BAT during skin rewarming. In contrast, these normal thermoregulatory reflexes appear to be inverted in hibernation/torpor; thermogenesis is inhibited during exposure to a cold environment, allowing dramatic reductions in core temperature and metabolism, and thermogenesis is activated during skin rewarming, contributing to a return of normal body temperature. Here, we describe two unrelated experimental paradigms in which rats, a nonhibernating/torpid species, exhibit a "thermoregulatory inversion," which is characterized by an inhibition of BAT thermogenesis in response to skin cooling, and a switch in the gain of the skin cooling reflex transfer function from negative to positive values. Either transection of the neuraxis immediately rostral to the dorsomedial hypothalamus in anesthetized rats or activation of A1 adenosine receptors within the CNS of free-behaving rats produces a state of thermoregulatory inversion in which skin cooling inhibits BAT thermogenesis, leading to hypothermia, and skin warming activates BAT, supporting an increase in core temperature. These results reflect the existence of a novel neural circuit that mediates inverted thermoregulatory reflexes and suggests a pharmacological mechanism through which a deeply hypothermic state can be achieved in nonhibernating/torpid mammals, possibly including humans.
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Affiliation(s)
- Domenico Tupone
- Department of Neurological Surgery, Oregon Health and Science University, Portland, Oregon; and
| | - Georgina Cano
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Shaun F Morrison
- Department of Neurological Surgery, Oregon Health and Science University, Portland, Oregon; and
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37
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Abstract
Social interactions are essential for animals to reproduce, defend their territory, and raise their young. The conserved nature of social behaviors across animal species suggests that the neural pathways underlying the motivation for, and the execution of, specific social responses are also maintained. Modern tools of neuroscience have offered new opportunities for dissecting the molecular and neural mechanisms controlling specific social responses. We will review here recent insights into the neural circuits underlying a particularly fascinating and important form of social interaction, that of parental care. We will discuss how these findings open new avenues to deconstruct infant-directed behavioral control in males and females, and to help understand the neural basis of parenting in a variety of animal species, including humans. Please also see the video abstract here.
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Affiliation(s)
- Johannes Kohl
- Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Center for Brain Science, Harvard University, Cambridge, MA, USA
- Sainsbury Wellcome Centre for Neural Circuits and Behaviour, London, UK
| | - Anita E. Autry
- Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Catherine Dulac
- Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Center for Brain Science, Harvard University, Cambridge, MA, USA
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38
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Sajadi MM, Mackowiak PA. Pathogenesis of Fever. Infect Dis (Lond) 2017. [DOI: 10.1016/b978-0-7020-6285-8.00067-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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39
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Histological and Metabolic State of Dams Suckling Small Litter or MSG-Treated Pups. ScientificWorldJournal 2016; 2016:1678541. [PMID: 28004032 PMCID: PMC5149680 DOI: 10.1155/2016/1678541] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/13/2016] [Accepted: 08/16/2016] [Indexed: 11/25/2022] Open
Abstract
Lactation is an important function that is dependent on changes in the maternal homeostasis and sustained by histological maternal adjustments. We evaluated how offspring manipulations during the lactational phase can modulate maternal morphologic aspects in the mammary gland, adipose tissue, and pancreatic islets of lactating dams. Two different models of litter-manipulation-during-lactation were used: litter sizes, small litters (SL) or normal litters (NL) and subcutaneous injections in the puppies of monosodium glutamate (MSG), or saline (CON). SL Dams and MSG Dams presented an increase in WAT content and higher plasma levels of glucose, triglycerides, and insulin, in relation to NL Dams and CON Dams, respectively. The MG of SL Dams and MSG Dams presented a high adipocyte content and reduced alveoli development and the milk of the SL Dams presented a higher calorie and triglyceride content, compared to that of the NL Dams. SL Dams presented a reduction in islet size and greater lipid droplet accumulation in BAT, in relation to NL Dams. SL Dams and MSG Dams present similar responses to offspring manipulation during lactation, resulting in changes in metabolic parameters. These alterations were associated with higher fat accumulation in BAT and changes in milk composition only in SL Dams.
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Abstract
Autonomic thermoregulation is a recently acquired function, as it appears for the first time in mammals and provides the brain with the ability to control energy expenditure. The importance of such control can easily be highlighted by the ability of a heterogeneous group of mammals to actively reduce metabolic rate and enter a condition of regulated hypometabolism known as torpor. The central neural circuits of thermoregulatory cold defense have been recently unraveled and could in theory be exploited to reduce energy expenditure in species that do not normally use torpor, inducing a state called synthetic torpor. This approach may represent the first steps toward the development of a technology to induce a safe and reversible state of hypometabolism in humans, unlocking many applications ranging from new medical procedures to deep space travel.
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Affiliation(s)
- Matteo Cerri
- Department of Biomedical and Neuromotor Sciences, Physiology Division, Alma Mater Studiorum, University of Bologna, 40126 Bologna, Italy;
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41
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Song K, Wang H, Kamm GB, Pohle J, de Castro Reis F, Heppenstall P, Wende H, Siemens J. The TRPM2 channel is a hypothalamic heat sensor that limits fever and can drive hypothermia. Science 2016; 353:1393-1398. [PMID: 27562954 PMCID: PMC7612276 DOI: 10.1126/science.aaf7537] [Citation(s) in RCA: 250] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/27/2016] [Indexed: 07/26/2023]
Abstract
Body temperature homeostasis is critical for survival and requires precise regulation by the nervous system. The hypothalamus serves as the principal thermostat that detects and regulates internal temperature. We demonstrate that the ion channel TRPM2 [of the transient receptor potential (TRP) channel family] is a temperature sensor in a subpopulation of hypothalamic neurons. TRPM2 limits the fever response and may detect increased temperatures to prevent overheating. Furthermore, chemogenetic activation and inhibition of hypothalamic TRPM2-expressing neurons in vivo decreased and increased body temperature, respectively. Such manipulation may allow analysis of the beneficial effects of altered body temperature on diverse disease states. Identification of a functional role for TRP channels in monitoring internal body temperature should promote further analysis of molecular mechanisms governing thermoregulation and foster the genetic dissection of hypothalamic circuits involved with temperature homeostasis.
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Affiliation(s)
- Kun Song
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Hong Wang
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Gretel B. Kamm
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Jörg Pohle
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Fernanda de Castro Reis
- European Molecular Biology Laboratory (EMBL), Adriano Buzzati-Traverso Campus, Via Ramarini 32, 00016 Monterotondo, Italy
| | - Paul Heppenstall
- European Molecular Biology Laboratory (EMBL), Adriano Buzzati-Traverso Campus, Via Ramarini 32, 00016 Monterotondo, Italy
- Molecular Medicine Partnership Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Hagen Wende
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Jan Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
- Molecular Medicine Partnership Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany
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Abstract
Contrary to dogma, much physiological regulation utilizes learning from past experience to make responses that preemptively and effectively neutralize anticipated regulatory challenges. Understanding physiological regulation therefore requires expanding explanatory models beyond homeostasis and allostasis to emphasize the prominence of conditioning.
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Affiliation(s)
- Douglas S Ramsay
- Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA 98195, USA
| | - Stephen C Woods
- Department of Psychiatry and Behavioral Neuroscience, School of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA.
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43
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Tan CL, Cooke EK, Leib DE, Lin YC, Daly GE, Zimmerman CA, Knight ZA. Warm-Sensitive Neurons that Control Body Temperature. Cell 2016; 167:47-59.e15. [PMID: 27616062 DOI: 10.1016/j.cell.2016.08.028] [Citation(s) in RCA: 254] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/22/2016] [Accepted: 08/13/2016] [Indexed: 01/12/2023]
Abstract
Thermoregulation is one of the most vital functions of the brain, but how temperature information is converted into homeostatic responses remains unknown. Here, we use an unbiased approach for activity-dependent RNA sequencing to identify warm-sensitive neurons (WSNs) within the preoptic hypothalamus that orchestrate the homeostatic response to heat. We show that these WSNs are molecularly defined by co-expression of the neuropeptides BDNF and PACAP. Optical recordings in awake, behaving mice reveal that these neurons are selectively activated by environmental warmth. Optogenetic excitation of WSNs triggers rapid hypothermia, mediated by reciprocal changes in heat production and loss, as well as dramatic cold-seeking behavior. Projection-specific manipulations demonstrate that these distinct effectors are controlled by anatomically segregated pathways. These findings reveal a molecularly defined cell type that coordinates the diverse behavioral and autonomic responses to heat. Identification of these warm-sensitive cells provides genetic access to the core neural circuit regulating the body temperature of mammals. PAPERCLIP.
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Affiliation(s)
- Chan Lek Tan
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Elizabeth K Cooke
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David E Leib
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yen-Chu Lin
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Gwendolyn E Daly
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Christopher A Zimmerman
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Zachary A Knight
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.
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Ahnaou A, Raeyemaekers L, Huysmans H, Drinkenburg W. Off-target potential of AMN082 on sleep EEG and related physiological variables: Evidence from mGluR7 (−/−) mice. Behav Brain Res 2016; 311:287-297. [DOI: 10.1016/j.bbr.2016.05.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 04/27/2016] [Accepted: 05/16/2016] [Indexed: 02/08/2023]
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45
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Blessing W, McAllen R, McKinley M. Control of the Cutaneous Circulation by the Central Nervous System. Compr Physiol 2016; 6:1161-97. [PMID: 27347889 DOI: 10.1002/cphy.c150034] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The central nervous system (CNS), via its control of sympathetic outflow, regulates blood flow to the acral cutaneous beds (containing arteriovenous anastomoses) as part of the homeostatic thermoregulatory process, as part of the febrile response, and as part of cognitive-emotional processes associated with purposeful interactions with the external environment, including those initiated by salient or threatening events (we go pale with fright). Inputs to the CNS for the thermoregulatory process include cutaneous sensory neurons, and neurons in the preoptic area sensitive to the temperature of the blood in the internal carotid artery. Inputs for cognitive-emotional control from the exteroceptive sense organs (touch, vision, sound, smell, etc.) are integrated in forebrain centers including the amygdala. Psychoactive drugs have major effects on the acral cutaneous circulation. Interoceptors, chemoreceptors more than baroreceptors, also influence cutaneous sympathetic outflow. A major advance has been the discovery of a lower brainstem control center in the rostral medullary raphé, regulating outflow to both brown adipose tissue (BAT) and to the acral cutaneous beds. Neurons in the medullary raphé, via their descending axonal projections, increase the discharge of spinal sympathetic preganglionic neurons controlling the cutaneous vasculature, utilizing glutamate, and serotonin as neurotransmitters. Present evidence suggests that both thermoregulatory and cognitive-emotional control of the cutaneous beds from preoptic, hypothalamic, and forebrain centers is channeled via the medullary raphé. Future studies will no doubt further unravel the details of neurotransmitter pathways connecting these rostral control centers with the medullary raphé, and those operative within the raphé itself. © 2016 American Physiological Society. Compr Physiol 6:1161-1197, 2016.
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Affiliation(s)
- William Blessing
- Human Physiology, Centre for Neuroscience, Flinders University, Adelaide, S.A., Australia
| | - Robin McAllen
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Vic., Australia
| | - Michael McKinley
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Vic., Australia
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Farrell MJ. Regional brain responses in humans during body heating and cooling. Temperature (Austin) 2016; 3:220-231. [PMID: 27857952 PMCID: PMC4964992 DOI: 10.1080/23328940.2016.1174794] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 10/26/2022] Open
Abstract
Functional brain imaging of responses to thermal challenge in humans provides a viable method to implicate widespread neuroanatomical regions in the processes of thermoregulation. Thus far, functional neuroimaging techniques have been used infrequently in humans to investigate thermoregulation, although preliminary outcomes have been informative and certainly encourage further forays into this field of enquiry. At this juncture, sustained regional brain activations in response to prolonged changes in body temperature are yet to be definitively characterized, but it would appear that thermoregulatory regions are widely distributed throughout the hemispheres of the human brain. Of those autonomic responses to thermal challenge investigated so far, the loci of associated brainstem responses in human are homologous with other species. However, human imaging studies have also implicated a wide range of forebrain regions in thermal sensations and autonomic responses that extend beyond outcomes reported in other species. There is considerable impetus to continue human functional neuroimaging of thermoregulatory responses because of the unique opportunities presented by the method to survey regions across the whole brain in compliant, conscious participants.
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Affiliation(s)
- Michael J Farrell
- Monash Biomedicine Discovery Institute, Department of Medical Imaging and Radiation Sciences, Monash University , Clayton, Australia
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Fonseca MT, Rodrigues AC, Cezar LC, Fujita A, Soriano FG, Steiner AA. Spontaneous hypothermia in human sepsis is a transient, self-limiting, and nonterminal response. J Appl Physiol (1985) 2016; 120:1394-401. [PMID: 26989218 DOI: 10.1152/japplphysiol.00004.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 03/15/2016] [Indexed: 11/22/2022] Open
Abstract
Hypothermia in sepsis is generally perceived as something dysregulated and progressive although there has been no assessment on the natural course of this phenomenon in humans. This was the first study on the dynamics of hypothermia in septic patients not subjected to active rewarming, and the results were surprising. A sample of 50 subjects presenting with spontaneous hypothermia during sepsis was drawn from the 2005-2012 database of an academic hospital. Hypothermia was defined as body temperature below 36.0°C for longer than 2 h, with at least one reading of 35.5°C or less. The patients presented with 138 episodes of hypothermia, 21 at the time of the sepsis diagnosis and 117 with a later onset. However, hypothermia was uncommon in the final 12 h of life of the patients that succumbed. The majority (97.1%) of the hypothermic episodes were transient and self-limited; the median recovery time was 6 h; body temperature rarely fell below 34.0°C. Bidirectional oscillations in body temperature were evident in the course of hypothermia. Nearly half of the hypothermic episodes had onset in the absence of shock or respiratory distress, and the incidence of hypothermia was not increased during either of these conditions. Usage of antipyretic drugs, sedatives, neuroleptics, or other medications did not predict the onset of hypothermia. In conclusion, hypothermia appears to be a predominantly transient, self-limiting, and nonterminal phenomenon that is inherent to human sepsis. These characteristics resemble those of the regulated hypothermia shown to replace fever in animal models of severe systemic inflammation.
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Affiliation(s)
- Monique T Fonseca
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Abner C Rodrigues
- Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil
| | - Luana C Cezar
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Andre Fujita
- Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil
| | | | - Alexandre A Steiner
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil;
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Fischer AW, Hoefig CS, Abreu-Vieira G, de Jong JMA, Petrovic N, Mittag J, Cannon B, Nedergaard J. Leptin Raises Defended Body Temperature without Activating Thermogenesis. Cell Rep 2016; 14:1621-1631. [PMID: 26876182 DOI: 10.1016/j.celrep.2016.01.041] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/08/2015] [Accepted: 01/09/2016] [Indexed: 11/24/2022] Open
Abstract
Leptin has been believed to exert its weight-reducing action not only by inducing hypophagia but also by increasing energy expenditure/thermogenesis. Leptin-deficient ob/ob mice have correspondingly been thought to be thermogenically limited and to show hypothermia, mainly due to atrophied brown adipose tissue (BAT). In contrast to these established views, we found that BAT is fully functional and that leptin treatment did not increase thermogenesis in wild-type or in ob/ob mice. Rather, ob/ob mice showed a decreased but defended body temperature (i.e., were anapyrexic, not hypothermic) that was normalized to wild-type levels after leptin treatment. This was not accompanied by increased energy expenditure or BAT recruitment but, instead, was mediated by decreased tail heat loss. The weight-reducing hypophagic effects of leptin are, therefore, not augmented through a thermogenic effect of leptin; leptin is, however, pyrexic, i.e., it alters centrally regulated thresholds of thermoregulatory mechanisms, in parallel to effects of other cytokines.
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Affiliation(s)
- Alexander W Fischer
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, 10691 Stockholm, Sweden; Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Carolin S Hoefig
- Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Gustavo Abreu-Vieira
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, 10691 Stockholm, Sweden
| | - Jasper M A de Jong
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, 10691 Stockholm, Sweden
| | - Natasa Petrovic
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, 10691 Stockholm, Sweden
| | - Jens Mittag
- Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Barbara Cannon
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, 10691 Stockholm, Sweden
| | - Jan Nedergaard
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, 10691 Stockholm, Sweden.
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Heinricher MM. Pain Modulation and the Transition from Acute to Chronic Pain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 904:105-15. [PMID: 26900066 DOI: 10.1007/978-94-017-7537-3_8] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
There is now increasing evidence that pathological pain states are at least in part driven by changes in the brain itself. Descending modulatory pathways are known to mediate top-down regulation of nociceptive processing, transmitting cortical and limbic influences to the dorsal horn. However, these modulatory pathways are also intimately intertwined with ascending transmission pathways through positive and negative feedback loops. Models of persistent pain that fail to include descending modulatory pathways are thus incomplete. Although teasing out individual links in a recurrent network is never straightforward, it is imperative that understanding of pain modulation be fully integrated into how we think about pain.
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Affiliation(s)
- Mary M Heinricher
- Dept. Neurological Surgery, Oregon Health & Science University, Portland, OR, 97239, USA.
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Santiago HP, Leite LHR, Lima PMA, Rodovalho GV, Szawka RE, Coimbra CC. The improvement of exercise performance by physical training is related to increased hypothalamic neuronal activation. Clin Exp Pharmacol Physiol 2015; 43:116-24. [DOI: 10.1111/1440-1681.12507] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Henrique P Santiago
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Laura HR Leite
- Department of Physiology; Institute of Biological Sciences; Federal University of Juiz de Fora; Juiz de Fora Minas Gerais Brazil
| | - Paulo Marcelo A Lima
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Gisele V Rodovalho
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Raphael E Szawka
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Cândido C Coimbra
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
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