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Santiago HP, Leite LHR, Lima PMA, Fóscolo DRC, Natali AJ, Prímola-Gomes TN, Szawka RE, Coimbra CC. Effects of physical training on hypothalamic neuronal activation and expressions of vasopressin and oxytocin in SHR after running until fatigue. Pflugers Arch 2024; 476:365-377. [PMID: 38308122 DOI: 10.1007/s00424-024-02916-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
To assess the influence of physical training on neuronal activation and hypothalamic expression of vasopressin and oxytocin in spontaneously hypertensive rats (SHR), untrained and trained normotensive rats and SHR were submitted to running until fatigue while internal body and tail temperatures were recorded. Hypothalamic c-Fos expression was evaluated in thermoregulatory centers such as the median preoptic nucleus (MnPO), medial preoptic nucleus (mPOA), paraventricular nucleus of the hypothalamus (PVN), and supraoptic nucleus (SON). The PVN and the SON were also investigated for vasopressin and oxytocin expressions. Although exercise training improved the workload performed by the animals, it was reduced in SHR and followed by increased internal body temperature due to tail vasodilation deficit. Physical training enhanced c-Fos expression in the MnPO, mPOA, and PVN of both strains, and these responses were attenuated in SHR. Vasopressin immunoreactivity in the PVN was also increased by physical training to a lesser extent in SHR. The already-reduced oxytocin expression in the PVN of SHR was increased in response to physical training. Within the SON, neuronal activation and the expressions of vasopressin and oxytocin were reduced by hypertension and unaffected by physical training. The data indicate that physical training counterbalances in part the negative effect of hypertension on hypothalamic neuronal activation elicited by exercise, as well as on the expression of vasopressin and oxytocin. These hypertension features seem to negatively influence the workload performed by SHR due to the hyperthermia derived from the inability of physical training to improve heat dissipation through skin vasodilation.
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Affiliation(s)
- Henrique P Santiago
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Laura H R Leite
- Departamento de Biofísica e Fisiologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Paulo M A Lima
- Núcleo de Pesquisa da Faculdade de Medicina da Universidade de Rio Verde, Universidade de Rio Verde, Campus Goiânia, Goiânia, Brazil
| | - Daniela R C Fóscolo
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Antônio José Natali
- Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | | | - Raphael E Szawka
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Cândido C Coimbra
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil.
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Yang T, Wang Z, Li J, Shan F, Huang QY. Cerebral Lactate Participates in Hypoxia-induced Anapyrexia Through its Receptor G Protein-coupled Receptor 81. Neuroscience 2024; 536:119-130. [PMID: 37979840 DOI: 10.1016/j.neuroscience.2023.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/25/2023] [Accepted: 11/14/2023] [Indexed: 11/20/2023]
Abstract
Hypoxia-induced anapyrexia is thought to be a regulated decrease in body core temperature (Tcore), but the underlying mechanism remains unclear. Recent evidence suggests that lactate, a glycolysis product, could modulate neuronal excitability through the G protein-coupled receptor 81 (GPR81). The present study aims to elucidate the role of central lactate and GPR81 in a rat model of hypoxia-induced anapyrexia. The findings revealed that hypoxia (11.1% O2, 2 h) led to an increase in lactate in cerebrospinal fluid (CSF) and a decrease in Tcore. Injection of dichloroacetate (DCA, 5 mg/kg, 1 μL), a lactate production inhibitor, to the third ventricle (3 V), alleviated the increase in CSF lactate and the decrease in Tcore under hypoxia. Immunofluorescence staining showed GPR81 was expressed in the preoptic area of hypothalamus (PO/AH), the physiological thermoregulation integration center. Under normoxia, injection of GPR81 agonist 3-chloro-5-hydroxybenzoic acid (CHBA, 0.05 mg/kg, 1 μL) to the 3 V, reduced Tcore significantly. In addition, hypoxia led to a dramatic increase in tail skin temperature and a decrease in interscapular brown adipose tissue skin temperature. The number of c-Fos+ cells in the PO/AH increased after exposure to 11.1% O2 for 2 h, but administration of DCA to the 3 V blunted this response. Injection of CHBA to the 3 V also increased the number of c-Fos+ cells in the PO/AH under normoxia. In light of these, our research has uncovered the pivotal role of central lactate-GPR81 signaling in anapyrexia, thereby providing novel insights into the mechanism of hypoxia-induced anapyrexia.
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Affiliation(s)
- Tian Yang
- Department of Frigid Zone Medicine, College of High Altitude Military Medicine, Army Medical University, Chongqing 400038, China; Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China; Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China
| | - Zejun Wang
- Department of Frigid Zone Medicine, College of High Altitude Military Medicine, Army Medical University, Chongqing 400038, China; Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China; Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China
| | - Junxia Li
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Traumatic Shock and Transfusion, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing 400042, China
| | - Fabo Shan
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Army Occupational Disease, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing 400042, China.
| | - Qing-Yuan Huang
- Department of Frigid Zone Medicine, College of High Altitude Military Medicine, Army Medical University, Chongqing 400038, China; Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China; Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China.
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Verduzco-Mendoza A, Mota-Rojas D, Olmos Hernández SA, Gálvez-Rosas A, Aguirre-Pérez A, Cortes-Altamirano JL, Alfaro-Rodríguez A, Parra-Cid C, Avila-Luna A, Bueno-Nava A. Traumatic brain injury extending to the striatum alters autonomic thermoregulation and hypothalamic monoamines in recovering rats. Front Neurosci 2023; 17:1304440. [PMID: 38144211 PMCID: PMC10748590 DOI: 10.3389/fnins.2023.1304440] [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: 09/29/2023] [Accepted: 11/21/2023] [Indexed: 12/26/2023] Open
Abstract
The brain cortex is the structure that is typically injured in traumatic brain injury (TBI) and is anatomically connected with other brain regions, including the striatum and hypothalamus, which are associated in part with motor function and the regulation of body temperature, respectively. We investigated whether a TBI extending to the striatum could affect peripheral and core temperatures as an indicator of autonomic thermoregulatory function. Moreover, it is unknown whether thermal modulation is accompanied by hypothalamic and cortical monoamine changes in rats with motor function recovery. The animals were allocated into three groups: the sham group (sham), a TBI group with a cortical contusion alone (TBI alone), and a TBI group with an injury extending to the dorsal striatum (TBI + striatal injury). Body temperature and motor deficits were evaluated for 20 days post-injury. On the 3rd and 20th days, rats were euthanized to measure the serotonin (5-HT), noradrenaline (NA), and dopamine (DA) levels using high-performance liquid chromatography (HPLC). We observed that TBI with an injury extending to the dorsal striatum increased core and peripheral temperatures. These changes were accompanied by a sustained motor deficit lasting for 14 days. Furthermore, there were notable increases in NA and 5-HT levels in the brain cortex and hypothalamus both 3 and 20 days after injury. In contrast, rats with TBI alone showed no changes in peripheral temperatures and achieved motor function recovery by the 7th day post-injury. In conclusion, our results suggest that TBI with an injury extending to the dorsal striatum elevates both core and peripheral temperatures, causing a delay in functional recovery and increasing hypothalamic monoamine levels. The aftereffects can be attributed to the injury site and changes to the autonomic thermoregulatory functions.
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Affiliation(s)
- Antonio Verduzco-Mendoza
- Programa de Doctorado en Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Ciudad de México, Mexico
| | - Daniel Mota-Rojas
- Neurofisiología, Conducta y Bienestar Animal, DPAA, Universidad Autónoma Metropolitana, Unidad Xochimilco, Ciudad de México, Mexico
| | | | - Arturo Gálvez-Rosas
- Neurociencias Básicas, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (LGII), SSa, Ciudad de México, Mexico
| | - Alexander Aguirre-Pérez
- Neurociencias Básicas, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (LGII), SSa, Ciudad de México, Mexico
| | - José Luis Cortes-Altamirano
- Neurociencias Básicas, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (LGII), SSa, Ciudad de México, Mexico
- Departamento de Quiropráctica, Universidad Estatal del Valle de Ecatepec, Ecatepec de Morelos, Estado de México, Mexico
- Madrid College of Chiropractic, Real Centro Universitario Escorial María Cristina, Madrid, Spain
| | - Alfonso Alfaro-Rodríguez
- Neurociencias Básicas, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (LGII), SSa, Ciudad de México, Mexico
| | - Carmen Parra-Cid
- Unidad de Ingeniería de Tejidos, Instituto Nacional de Rehabilitación LGII, SSa, Ciudad de México, Mexico
| | - Alberto Avila-Luna
- Neurociencias Básicas, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (LGII), SSa, Ciudad de México, Mexico
| | - Antonio Bueno-Nava
- Neurociencias Básicas, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (LGII), SSa, Ciudad de México, Mexico
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Xu J, Gao W, He T, Yao L, Wu H, Chen Z, Lai Y, Chen Y, Zhang J. The hyperthermic response to intra-preoptic area administration of agmatine in male rats. J Therm Biol 2023; 113:103529. [PMID: 37055134 DOI: 10.1016/j.jtherbio.2023.103529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 01/31/2023] [Accepted: 02/22/2023] [Indexed: 03/05/2023]
Abstract
Agmatine is an endogenous biogenic amine that exerts various effects on the central nervous system. The hypothalamic preoptic area (POA, thermoregulatory command center) has high agmatine immunoreactivity. In this study, in conscious and anesthetized male rats, agmatine microinjection into the POA induced hyperthermic responses associated with increased heat production and locomotor activity. Intra-POA administration of agmatine increased the locomotor activity, the brown adipose tissue temperature and rectum temperature, and induced shivering as demonstrated by increased neck muscle electromyographic activity. However, intra-POA administration of agmatine almost had no impact on the tail temperature of anesthetized rats. Furthermore, there were regional differences in the response to agmatine in the POA. The most effective sites for the microinjection of agmatine to elicit hyperthermic responses were localized in the medial preoptic area (MPA). Agmatine microinjection into the median preoptic nucleus (MnPO) and lateral preoptic nucleus (LPO) had a minimal effect on the mean core temperature. Analysis of the in vitro discharge activity of POA neurons in brain slices when perfused with agmatine showed that agmatine inhibited most warm-sensitive but not temperature-insensitive neurons in the MPA. However, regardless of thermosensitivity, the majority of MnPO and LPO neurons were not responsive to agmatine. The results demonstrated that agmatine injection into the POA of male rats, especially the MPA, induced hyperthermic responses, which may be associated with increased BAT thermogenesis, shivering and locomotor activity by inhibiting warm-sensitive neurons.
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Skin Vascular Resistance Decreases during 5-HT-Induced Hypotension in the Rat. Biomedicines 2023; 11:biomedicines11020547. [PMID: 36831083 PMCID: PMC9953042 DOI: 10.3390/biomedicines11020547] [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: 01/25/2023] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
A recognized vasodilator, the infusion of 5-hydroxytryptamine (5-HT, serotonin) decreases blood pressure through the reduction of total peripheral resistance in the rat. It is not clear which vascular beds/tissues are responsible for this fall. We hypothesized that an increase in blood flow within the skin, measured as an elevated temperature (T) in the thermoregulatory tail and paws, enables at least part of 5-HT-induced reduction in blood pressure through active vasodilation. The temperature of thermoregulatory regions of the skin of an anesthetized male, Sprague Dawley rats were measured using a Optris PI640 thermal camera. The blood pressure of the animal and the temperature of each paw and four locations along the tail (TL1-4) were recorded before, during, and after the infusion of 5-HT at a rate of 25 mg/min into a femoral vein. Contrary to our hypothesis, the temperature of the paws and tail was stable before and during 5-HT infusion and actually increased during the 15-min recovery period. This finding suggests that hyperemia of the skin circulation is not necessary for the fall in blood pressure observed with infused 5-HT, but that a reduction in cutaneous vascular resistance plays a part in the fall in total peripheral resistance.
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Bigiarelli KJ. Rodent Thermoregulation: Considerations for Tail-Cuff Blood Pressure Measurements. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2022; 61:406-411. [PMID: 35948400 PMCID: PMC9536829 DOI: 10.30802/aalas-jaalas-22-000006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Noninvasive blood pressure measurement devices have gained popularity in recent years as an alternative to radiotelemetry and other invasive blood pressure measurement techniques. While many factors must be considered when choosing a measurement method, specific variables should be evaluated when using a tail-cuff blood pressure technique. Rodents have complex and dynamic thermal biology processes that involve fluctuating vasomotor tone of the tail. This and other factors that affect vascular tone, such as the autonomic response to stress, significantly affect peripheral blood flow. Awareness and consideration of thermoregulatory states and vasomotor tone can increase success and decrease variability when measuring blood pressure measurements using a tail-cuff measurement technique.
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Affiliation(s)
- Krista J Bigiarelli
- Pre-Clinical Research and Development, Kent Scientific Corporation, Torrington, Connecticut,Corresponding author.
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7
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Voronova IP. 5-HT Receptors and Temperature Homeostasis. Biomolecules 2021; 11:1914. [PMID: 34944557 PMCID: PMC8699715 DOI: 10.3390/biom11121914] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/11/2021] [Accepted: 12/16/2021] [Indexed: 12/28/2022] Open
Abstract
The present review summarizes the data concerning the influence of serotonin (5-HT) receptors on body temperature in warm-blooded animals and on processes associated with its maintenance. This review includes the most important part of investigations from the first studies to the latest ones. The established results on the pharmacological activation of 5-HT1A, 5-HT3, 5-HT7 and 5-HT2 receptor types are discussed. Such activation of the first 3 type of receptors causes a decrease in body temperature, whereas the 5-HT2 activation causes its increase. Physiological mechanisms leading to changes in body temperature as a result of 5-HT receptors' activation are discussed. In case of 5-HT1A receptor, they include an inhibition of shivering and non-shivering thermogenesis, as well simultaneous increase of peripheral blood flow, i.e., the processes of heat production and heat loss. The physiological processes mediated by 5-HT2 receptor are opposite to those of the 5-HT1A receptor. Mechanisms of 5-HT3 and 5-HT7 receptor participation in these processes are yet to be studied in more detail. Some facts indicating that in natural conditions, without pharmacological impact, these 5-HT receptors are important links in the system of temperature homeostasis, are also discussed.
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Affiliation(s)
- Irina P. Voronova
- Department of Thermophysiology, Scientific Research Institute of Neurosciences and Medicine, 630117 Novosibirsk, Russia
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8
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Verduzco-Mendoza A, Bueno-Nava A, Wang D, Martínez-Burnes J, Olmos-Hernández A, Casas A, Domínguez A, Mota-Rojas D. Experimental Applications and Factors Involved in Validating Thermal Windows Using Infrared Thermography to Assess the Health and Thermostability of Laboratory Animals. Animals (Basel) 2021; 11:3448. [PMID: 34944225 PMCID: PMC8698170 DOI: 10.3390/ani11123448] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/25/2021] [Accepted: 12/01/2021] [Indexed: 12/12/2022] Open
Abstract
Evaluating laboratory animals' health and thermostability are fundamental components of all experimental designs. Alterations in either one of these parameters have been shown to trigger physiological changes that can compromise the welfare of the species and the replicability and robustness of the results obtained. Due to the nature and complexity of evaluating and managing the species involved in research protocols, non-invasive tools such as infrared thermography (IRT) have been adopted to quantify these parameters without altering them or inducing stress responses in the animals. IRT technology makes it possible to quantify changes in surface temperatures that are derived from alterations in blood flow that can result from inflammatory, stressful, or pathological processes; changes can be measured in diverse regions, called thermal windows, according to their specific characteristics. The principal body regions that were employed for this purpose in laboratory animals were the orbital zone (regio orbitalis), auricular pavilion (regio auricularis), tail (cauda), and the interscapular area (regio scapularis). However, depending on the species and certain external factors, the sensitivity and specificity of these windows are still subject to controversy due to contradictory results published in the available literature. For these reasons, the objectives of the present review are to discuss the neurophysiological mechanisms involved in vasomotor responses and thermogenesis via BAT in laboratory animals and to evaluate the scientific usefulness of IRT and the thermal windows that are currently used in research involving laboratory animals.
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Affiliation(s)
- Antonio Verduzco-Mendoza
- PhD Program in Biological and Health Sciences [Doctorado en Ciencias Biológicas y de la Salud], Universidad Autónoma Metropolitana, Mexico City 04960, Mexico;
| | - Antonio Bueno-Nava
- División of Neurosciences, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra, (INR-LGII), Mexico City 14389, Mexico;
| | - Dehua Wang
- School of Life Sciences, Shandong University, Qingdao 266237, China;
| | - Julio Martínez-Burnes
- Animal Health Group, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas, Victoria City 87000, Mexico;
| | - Adriana Olmos-Hernández
- Division of Biotechnology—Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City 14389, Mexico;
| | - Alejandro Casas
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Xochimilco Campus, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.C.); (A.D.)
| | - Adriana Domínguez
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Xochimilco Campus, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.C.); (A.D.)
| | - Daniel Mota-Rojas
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Xochimilco Campus, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.C.); (A.D.)
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Mota-Rojas D, Olmos-Hernández A, Verduzco-Mendoza A, Lecona-Butrón H, Martínez-Burnes J, Mora-Medina P, Gómez-Prado J, Orihuela A. Infrared thermal imaging associated with pain in laboratory animals. Exp Anim 2020; 70:1-12. [PMID: 32848100 PMCID: PMC7887630 DOI: 10.1538/expanim.20-0052] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The science of animal welfare has evolved over the years, and recent scientific advances
have enhanced our comprehension of the neurological, physiological, and ethological
mechanisms of diverse animal species. Currently, the study of the affective states
(emotions) of nonhuman animals is attracting great scientific interest focused primarily
on negative experiences such as pain, fear, and suffering, which animals experience in
different stages of their lives or during scientific research. Studies underway today seek
to establish methods of evaluation that can accurately measure pain and then develop
effective treatments for it, because the techniques available up to now are not
sufficiently precise. One innovative technology that has recently been incorporated into
veterinary medicine for the specific purpose of studying pain in animals is called
infrared thermography (IRT), a technique that works by detecting and measuring levels of
thermal radiation at different points on the body’s surface with high sensitivity. Changes
in IRT images are associated mainly with blood perfusion, which is modulated by the
mechanisms of vasodilatation and vasoconstriction. IRT is an efficient, noninvasive method
for evaluating and controlling pain, two critical aspects of animal welfare in biomedical
research. The aim of the present review is to compile and analyze studies of infrared
thermographic changes associated with pain in laboratory research involving animals.
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Affiliation(s)
- Daniel Mota-Rojas
- Neurophysiology, Behaviour and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana, Xochimilco, Mexico City, C.P. 04960 Mexico
| | - Adriana Olmos-Hernández
- Division of Biotechnology, Department Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City, C.P. 14389, Mexico
| | - Antonio Verduzco-Mendoza
- Division of Biotechnology, Department Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City, C.P. 14389, Mexico
| | - Hugo Lecona-Butrón
- Division of Biotechnology, Department Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City, C.P. 14389, Mexico
| | - Julio Martínez-Burnes
- Graduate and Research Department, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas, C.P. Victoria City, Tamaulipas, C.P. 87000, Mexico
| | - Patricia Mora-Medina
- Livestock Science Department, Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México (UNAM), State of Mexico, C.P. 54740, Mexico
| | - Jocelyn Gómez-Prado
- Neurophysiology, Behaviour and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana, Xochimilco, Mexico City, C.P. 04960 Mexico
| | - Agustín Orihuela
- Facultad de Ciencias Agropecuarias, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, C.P. 62209, México
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Bittencourt MA, Wanner SP, Kunstetter AC, Barbosa NHS, Walker PCL, Andrade PVR, Turnes T, Guglielmo LGA. Comparative effects of two heat acclimation protocols consisting of high-intensity interval training in the heat on aerobic performance and thermoregulatory responses in exercising rats. PLoS One 2020; 15:e0229335. [PMID: 32084208 PMCID: PMC7034902 DOI: 10.1371/journal.pone.0229335] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 02/04/2020] [Indexed: 01/15/2023] Open
Abstract
Acclimation resulting from low- to moderate-intensity physical exertion in the heat induces several thermoregulatory adaptations, including slower exercise-induced increases in core body temperature. However, few studies have investigated the thermoregulatory adaptations induced by high-intensity interval training (HIIT) protocols. Thus, the present study aimed to compare the adaptations in rats’ thermoregulatory parameters and aerobic performance observed after two different heat acclimation regimens consisting of HIIT protocols performed in a hot environment. Twenty-three adult male Wistar rats were initially subjected to an incremental-speed exercise at 32°C until they were fatigued and then randomly assigned to one of the following three heat acclimation strategies: passive heat exposure without any exercise (untrained controls–UN; n = 7), HIIT performed at the maximal aerobic speed (HIIT100%; n = 8) and HIIT performed at a high but submaximal speed (HIIT85%; n = 8). Following the two weeks of interventions, the rats were again subjected to a fatiguing incremental exercise at 32°C, while their colonic temperature (TCOL) was recorded. The workload performed by the rats and their thermoregulatory efficiency were calculated. After the intervention period, rats subjected to both HIIT protocols attained greater workloads (HIIT100%: 313.7 ± 21.9 J vs. HIIT85%: 318.1 ± 32.6 J vs. UN: 250.8 ± 32.4 J; p < 0.01) and presented a lower ratio between the change in TCOL and the distance travelled (HIIT100%: 4.95 ± 0.42°C/km vs. HIIT85%: 4.33 ± 0.59°C/km vs. UN: 6.14 ± 1.03°C/km; p < 0.001) when compared to UN rats. The latter finding indicates better thermoregulatory efficiency in trained animals. No differences were observed between rats subjected to the two HIIT regimens. In conclusion, the two HIIT protocols induce greater thermoregulatory adaptations and performance improvements than passive heat exposure. These adaptations do not differ between the two training protocols investigated in the present study.
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Affiliation(s)
- Myla Aguiar Bittencourt
- Physical Effort Laboratory, Graduate Program in Physical Education, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
- Exercise Physiology Laboratory, Graduate Program in Sport Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Samuel Penna Wanner
- Exercise Physiology Laboratory, Graduate Program in Sport Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- * E-mail:
| | - Ana Cançado Kunstetter
- Exercise Physiology Laboratory, Graduate Program in Sport Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Nicolas Henrique Santos Barbosa
- Exercise Physiology Laboratory, Graduate Program in Sport Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Paula Carolina Leite Walker
- Exercise Physiology Laboratory, Graduate Program in Sport Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Pedro Victor Ribeiro Andrade
- Exercise Physiology Laboratory, Graduate Program in Sport Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Tiago Turnes
- Physical Effort Laboratory, Graduate Program in Physical Education, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Luiz Guilherme Antonacci Guglielmo
- Physical Effort Laboratory, Graduate Program in Physical Education, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
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11
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Nakamura M, Shintani-Ishida K, Ikegaya H. 5-HT 2A Receptor Agonist-Induced Hyperthermia Is Induced via Vasoconstriction by Peripheral 5-HT 2A Receptors and Brown Adipose Tissue Thermogenesis by Peripheral Serotonin Loss at a High Ambient Temperature. J Pharmacol Exp Ther 2018; 367:356-362. [PMID: 30206108 DOI: 10.1124/jpet.118.250217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 09/06/2018] [Indexed: 12/19/2022] Open
Abstract
Recreational drugs such as 3,4-methylenedioxymethamphetamine and cocaine induce hyperthermia, which is affected by ambient temperature. 2-(4-Bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine (25B-NBOMe), a selective agonist of 5-HT2A receptor used as a recreational drug, reportedly induces hyperthermia. This study aimed to verify whether 25B-NBOMe induces ambient temperature-dependent hyperthermia and to clarify its mechanism. Eight-week-old male Sprague-Dawley rats were administered intraperitoneal injection of 25B-NBOMe at an ambient temperature of 23°C or 29°C. 25B-NBOMe administration at 23°C did not change the core body temperature of the rats, whereas administration at 29°C induced significant hyperthermia 30-120 minutes postadministration. Tail surface temperature temporarily decreased 30 minutes postadministration, indicating heat storage by peripheral vasoconstriction despite a high ambient temperature. Because 25B-NBOMe-induced-hyperthermia was suppressed by sarpogrelate, but not by destruction of central noradrenaline or serotonin neurons, peripheral 5-HT2A receptors were considered contributors to the development of hyperthermia at a high ambient temperature, independently from central neurons. The temperature of brown adipose tissue (BAT) increased 60-120 minutes postadministration of 25B-NBOMe at 29°C, indicating thermogenesis. Previous studies have reported that peripheral serotonin contributes to the inhibition of BAT thermogenesis. Decreased plasma serotonin levels were observed at 29°C, and serotonin administration partially suppressed 25B-NBOMe-induced hyperthermia at a high ambient temperature, suggesting that decreased levels of peripheral serotonin induced BAT thermogenesis. Our findings indicate that 25B-NBOMe induces hyperthermia at a high ambient temperature via vasoconstriction regulated by 5-HT2A receptors and BAT thermogenesis mediated by decreased levels of plasma serotonin. Thus, peripheral serotonin plays a partial but important role in thermoregulation.
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Affiliation(s)
- Mami Nakamura
- Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kaori Shintani-Ishida
- Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hiroshi Ikegaya
- Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
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12
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Mei J, Riedel N, Grittner U, Endres M, Banneke S, Emmrich JV. Body temperature measurement in mice during acute illness: implantable temperature transponder versus surface infrared thermometry. Sci Rep 2018; 8:3526. [PMID: 29476115 PMCID: PMC5824949 DOI: 10.1038/s41598-018-22020-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 02/15/2018] [Indexed: 12/14/2022] Open
Abstract
Body temperature is a valuable parameter in determining the wellbeing of laboratory animals. However, using body temperature to refine humane endpoints during acute illness generally lacks comprehensiveness and exposes to inter-observer bias. Here we compared two methods to assess body temperature in mice, namely implanted radio frequency identification (RFID) temperature transponders (method 1) to non-contact infrared thermometry (method 2) in 435 mice for up to 7 days during normothermia and lipopolysaccharide (LPS) endotoxin-induced hypothermia. There was excellent agreement between core and surface temperature as determined by method 1 and 2, respectively, whereas the intra- and inter-subject variation was higher for method 2. Nevertheless, using machine learning algorithms to determine temperature-based endpoints both methods had excellent accuracy in predicting death as an outcome event. Therefore, less expensive and cumbersome non-contact infrared thermometry can serve as a reliable alternative for implantable transponder-based systems for hypothermic responses, although requiring standardization between experimenters.
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Affiliation(s)
- Jie Mei
- Department of Neurology and Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Nico Riedel
- QUEST - Center for Transforming Biomedical Research, Berlin Institute of Health (BIH), Berlin, Germany
| | - Ulrike Grittner
- Center for Stroke Research, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Biostatistics and Clinical Epidemiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Matthias Endres
- Department of Neurology and Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Center for Stroke Research, Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,German Center for Cardiovascular Research (DZHK), Berlin, Germany
| | - Stefanie Banneke
- German Federal Institute for Risk Assessment, German Center for the Protection of Laboratory Animals (Bf3R), Berlin, Germany
| | - Julius Valentin Emmrich
- Department of Neurology and Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
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13
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El Bitar N, Pollin B, Karroum E, Pincedé I, Le Bars D. Entanglement between thermoregulation and nociception in the rat: the case of morphine. J Neurophysiol 2016; 116:2473-2496. [PMID: 27605533 PMCID: PMC5133307 DOI: 10.1152/jn.00482.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/03/2016] [Indexed: 11/22/2022] Open
Abstract
In thermoneutral conditions, rats display cyclic variations of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Systemic morphine elicits their vasoconstriction followed by hyperthermia in a naloxone-reversible and dose-dependent fashion. The dose-response curves were steep with ED50 in the 0.5-1 mg/kg range. Given the pivotal functional role of the rostral ventromedial medulla (RVM) in nociception and the rostral medullary raphe (rMR) in thermoregulation, two largely overlapping brain regions, the RVM/rMR was blocked by muscimol: it suppressed the effects of morphine. "On-" and "off-" neurons recorded in the RVM/rMR are activated and inhibited by thermal nociceptive stimuli, respectively. They are also implicated in regulating the cyclic variations of the vasomotion of the tail and paws seen in thermoneutral conditions. Morphine elicited abrupt inhibition and activation of the firing of on- and off-cells recorded in the RVM/rMR. By using a model that takes into account the power of the radiant heat source, initial skin temperature, core body temperature, and peripheral nerve conduction distance, one can argue that the morphine-induced increase of reaction time is mainly related to the morphine-induced vasoconstriction. This statement was confirmed by analyzing in psychophysical terms the tail-flick response to random variations of noxious radiant heat. Although the increase of a reaction time to radiant heat is generally interpreted in terms of analgesia, the present data question the validity of using such an approach to build a pain index.
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Affiliation(s)
- Nabil El Bitar
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; and
- Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
| | - Bernard Pollin
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; and
- Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
| | - Elias Karroum
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; and
- Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
| | - Ivanne Pincedé
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; and
- Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
| | - Daniel Le Bars
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; and
- Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
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14
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Al-Noori S, Ramsay DS, Cimpan A, Maltzer Z, Zou J, Kaiyala KJ. Brown adipose tissue thermogenesis does not explain the intra-administration hyperthermic sign-reversal induced by serial administrations of 60% nitrous oxide to rats. J Therm Biol 2016; 60:195-203. [PMID: 27503733 DOI: 10.1016/j.jtherbio.2016.07.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 07/15/2016] [Accepted: 07/18/2016] [Indexed: 02/07/2023]
Abstract
Initial administration of ≥60% nitrous oxide (N2O) to rats promotes hypothermia primarily by increasing whole-body heat loss. We hypothesized that the drug promotes heat loss via the tail and might initially inhibit thermogenesis via brown adipose tissue (BAT), major organs of thermoregulation in rodents. Following repeated administrations, N2O inhalation evokes hyperthermia underlain by increased whole-body heat production. We hypothesized that elevated BAT thermogenesis plays a role in this thermoregulatory sign reversal. Using dual probe telemetric temperature implants and infrared (IR) thermography, we assessed the effects of nine repeated 60% N2O administrations compared to control (con) administrations on core temperature, BAT temperature, lumbar back temperature and tail temperature. Telemetric core temperature, telemetric BAT temperature, and IR BAT temperature were reduced significantly during initial 60% N2O inhalation (p≤0.001 compared to con). IR thermography revealed that acute N2O administration unexpectedly reduced tail temperature (p=0.0001) and also inhibited IR lumbar temperature (p<0.0001). In the 9th session, N2O inhalation significantly increased telemetric core temperature (p=0.007) indicative of a hyperthermic sign reversal, yet compared to control administrations, telemetric BAT temperature (p=0.86), IR BAT temperature (p=0.85) and tail temperature (p=0.47) did not differ significantly. Thus, an initial administration of 60% N2O at 21°C may promote hypothermia via reduced BAT thermogenesis accompanied by tail vasoconstriction as a compensatory mechanism to limit body heat loss. Following repeated N2O administrations rats exhibit a hyperthermic core temperature but a normalized BAT temperature, suggesting induction of a hyperthermia-promoting thermogenic adaptation of unknown origin.
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Affiliation(s)
- Salwa Al-Noori
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA; Division of Biological Sciences, School of STEM, University of Washington, Bothell, WA, USA
| | - Douglas S Ramsay
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA
| | - Andreas Cimpan
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA; Division of Biological Sciences, School of STEM, University of Washington, Bothell, WA, USA
| | - Zoe Maltzer
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA
| | - Jessie Zou
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA
| | - Karl J Kaiyala
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA.
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15
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Tékus V, Horváth Á, Hajna Z, Borbély É, Bölcskei K, Boros M, Pintér E, Helyes Z, Pethő G, Szolcsányi J. Noxious heat threshold temperature and pronociceptive effects of allyl isothiocyanate (mustard oil) in TRPV1 or TRPA1 gene-deleted mice. Life Sci 2016; 154:66-74. [DOI: 10.1016/j.lfs.2016.04.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/05/2016] [Accepted: 04/23/2016] [Indexed: 01/18/2023]
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16
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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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17
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El Bitar N, Pollin B, Huang G, Mouraux A, Le Bars D. The rostral ventromedial medulla control of cutaneous vasomotion of paws and tail in the rat: implication for pain studies. J Neurophysiol 2015; 115:773-89. [PMID: 26581872 DOI: 10.1152/jn.00695.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/13/2015] [Indexed: 11/22/2022] Open
Abstract
Thermal neutrality in rodents is achieved by large cyclic variations of the sympathetic drive of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Given the pivotal functional role of rostral ventromedial medulla (RVM) in nociception and rostral medullary raphe (rMR) in thermoregulation, two largely overlapping brain regions, we aimed at circumscribing the brainstem regions that are the source of premotor afferents to sympathetic preganglionic neurons that control the vasomotor tone of the tail and hind paws. A thermometric infrared camera recorded indirectly the vasomotor tone of the tail and hind paws. During the control period, the rat was maintained in vasoconstriction by preserving a stable, homogeneous, and constant surrounding temperature, slightly below the core temperature. The functional blockade of the RVM/rMR by the GABAA receptor agonist muscimol (0.5 nmol, 50 nl) elicited an extensive increase of the temperature of the paws and tail, associated with a slight decrease of blood pressure and heart rate. Both the increased heat loss through vasodilatation and the decrease heart-induced heat production elicited a remarkable reduction of the central temperature. The effective zones were circumscribed to the parts of the RVM/rMR facing the facial nucleus. They match very exactly the brain regions often described as specifically devoted to the control of nociception. Our data support and urge on the highest cautiousness regarding the interpretation of results aimed at studying the effects of any pharmacological manipulations of RVM/rMR with the usual tests of pain.
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Affiliation(s)
- Nabil El Bitar
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and
| | - Bernard Pollin
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and
| | - Gan Huang
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - André Mouraux
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Daniel Le Bars
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and
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18
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El Bitar N, Pollin B, Le Bars D. "On-" and "off-" cells in the rostral ventromedial medulla of rats held in thermoneutral conditions: are they involved in thermoregulation? J Neurophysiol 2014; 112:2199-217. [PMID: 25008415 DOI: 10.1152/jn.00722.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In thermal neutral condition, rats display cyclic variations of the vasomotion of the tail and paws, synchronized with fluctuations of blood pressure, heart rate, and core body temperature. "On-" and "off-" cells located in the rostral ventromedial medulla, a cerebral structure implicated in somatic sympathetic drive, 1) exhibit similar spontaneous cyclic activities in antiphase and 2) are activated and inhibited by thermal nociceptive stimuli, respectively. We aimed at evaluating the implication of such neurons in autonomic regulation by establishing correlations between their firing and blood pressure, heart rate, and skin and core body temperature variations. When, during a cycle, a relative high core body temperature was reached, the on-cells were activated and within half a minute, the off-cells and blood pressure were depressed, followed by heart rate depression within a further minute; vasodilatation of the tail followed invariably within ∼3 min, often completed with vasodilatation of hind paws. The outcome was an increased heat loss that lessened the core body temperature. When the decrease of core body temperature achieved a few tenths of degrees, sympathetic activation switches off and converse variations occurred, providing cycles of three to seven periods/h. On- and off-cell activities were correlated with inhibition and activation of the sympathetic system, respectively. The temporal sequence of events was as follows: core body temperature → on-cell → off-cell ∼ blood pressure → heart rate → skin temperature → core body temperature. The function of on- and off-cells in nociception should be reexamined, taking into account their correlation with autonomic regulations.
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Affiliation(s)
- Nabil El Bitar
- Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 06, Faculté de Médecine, Paris, France; and Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
| | - Bernard Pollin
- Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 06, Faculté de Médecine, Paris, France; and Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
| | - Daniel Le Bars
- Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 06, Faculté de Médecine, Paris, France; and Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France
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