1
|
Vizin RC, Almeida MC, Soriano RN, Romanovsky AA. Selection of preferred thermal environment and cold-avoidance responses in rats rely on signals transduced by the dorsal portion of the lateral funiculus of the spinal cord. Temperature (Austin) 2023; 10:121-135. [PMID: 37187830 PMCID: PMC10177698 DOI: 10.1080/23328940.2023.2191378] [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: 01/30/2023] [Revised: 03/05/2023] [Accepted: 03/09/2023] [Indexed: 05/17/2023] Open
Abstract
Thermoregulatory behaviors are powerful effectors for core body temperature (Tc) regulation. We evaluated the involvement of afferent fibers ascending through the dorsal portion of the lateral funiculus (DLF) of the spinal cord in "spontaneous" thermal preference and thermoregulatory behaviors induced by thermal and pharmacological stimuli in a thermogradient apparatus. In adult Wistar rats, the DLF was surgically severed at the first cervical vertebra bilaterally. The functional effectiveness of funiculotomy was verified by the increased latency of tail-flick responses to noxious cold (-18°C) and heat (50°C). In the thermogradient apparatus, funiculotomized rats showed a higher variability of their preferred ambient temperature (Tpr) and, consequently, increased Tc fluctuations, as compared to sham-operated rats. The cold-avoidance (warmth-seeking) response to moderate cold (whole-body exposure to ~17°C) or epidermal menthol (an agonist of the cold-sensitive TRPM8 channel) was attenuated in funiculotomized rats, as compared to sham-operated rats, and so was the Tc (hyperthermic) response to menthol. In contrast, the warmth-avoidance (cold-seeking) and Tc responses of funiculotomized rats to mild heat (exposure to ~28°C) or intravenous RN-1747 (an agonist of the warmth-sensitive TRPV4; 100 μg/kg) were unaffected. We conclude that DLF-mediated signals contribute to driving spontaneous thermal preference, and that attenuation of these signals is associated with decreased precision of Tc regulation. We further conclude that thermally and pharmacologically induced changes in thermal preference rely on neural, presumably afferent, signals that travel in the spinal cord within the DLF. Signals conveyed by the DLF are important for cold-avoidance behaviors but make little contribution to heat-avoidance responses.
Collapse
Affiliation(s)
- Robson C.L. Vizin
- Thermoregulation and Systemic Inflammation Laboratory (FeverLab), St. Joseph’s Hospital and Medical Center, Dignity Health, Phoenix, AZ, USA
- Center for Natural and Human Sciences, Federal University of ABC, São Bernardo do Campo, SP, Brazil
| | - Maria C. Almeida
- Thermoregulation and Systemic Inflammation Laboratory (FeverLab), St. Joseph’s Hospital and Medical Center, Dignity Health, Phoenix, AZ, USA
- Center for Natural and Human Sciences, Federal University of ABC, São Bernardo do Campo, SP, Brazil
| | - Renato N. Soriano
- Thermoregulation and Systemic Inflammation Laboratory (FeverLab), St. Joseph’s Hospital and Medical Center, Dignity Health, Phoenix, AZ, USA
- Department of Basic Life Sciences, Federal University of Juiz de Fora, Governador Valadares, MG, Brazil
| | - Andrej A. Romanovsky
- Thermoregulation and Systemic Inflammation Laboratory (FeverLab), St. Joseph’s Hospital and Medical Center, Dignity Health, Phoenix, AZ, USA
- School of Molecular Sciences, University of Arizona, Tempe, AZ, USA
- Zharko Pharma, Inc, Olympia, WA, USA
| |
Collapse
|
2
|
Andrade MT, Goulart KNO, Barbosa NHS, Soares DD, Andrade AGP, Gonçalves DAP, Mendes TT, Coimbra CC, Wanner SP. Core body temperatures of rats subjected to treadmill exercise to fatigue or exhaustion: The journal Temperature toolbox. Temperature (Austin) 2022; 10:287-312. [PMID: 37554383 PMCID: PMC10405761 DOI: 10.1080/23328940.2022.2115274] [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: 06/29/2022] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 10/14/2022] Open
Abstract
This study systematically reviewed the literature reporting the changes in rats' core body temperature (TCORE) induced by either incremental- or constant-speed running to fatigue or exhaustion. In addition, multiple linear regression analyses were used to determine the factors contributing to the TCORE values attained when exercise was interrupted. Four databases (EMBASE, PubMed, SPORTDiscus, and Web of Science) were searched in October 2021, and this search was updated in August 2022. Seventy-two studies (n = 1,538 rats) were included in the systematic review. These studies described heterogeneous experimental conditions; for example, the ambient temperature ranged from 5 to 40°C. The rats quit exercising with TCORE values varying more than 8°C among studies, with the lowest and highest values corresponding to 34.9°C and 43.4°C, respectively. Multiple linear regression analyses indicated that the ambient temperature (p < 0.001), initial TCORE (p < 0.001), distance traveled (p < 0.001; only incremental exercises), and running speed and duration (p < 0.001; only constant exercises) contributed significantly to explaining the variance in the TCORE at the end of the exercise. In conclusion, rats subjected to treadmill running exhibit heterogeneous TCORE when fatigued or exhausted. Moreover, it is not possible to determine a narrow range of TCORE associated with exercise cessation in hyperthermic rats. Ambient temperature, initial TCORE, and physical performance-related variables are the best predictors of TCORE at fatigue or exhaustion. From a broader perspective, this systematic review provides relevant information for selecting appropriate methods in future studies designed to investigate exercise thermoregulation in rats.
Collapse
Affiliation(s)
- Marcelo T. Andrade
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Karine N. O. Goulart
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Nicolas H. S. Barbosa
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Danusa D. Soares
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - André G. P. Andrade
- Biomechanics Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Dawit A. P. Gonçalves
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Thiago T. Mendes
- Department of Physical Education, Faculty of Education, Universidade Federal da Bahia, Salvador, Brazil
| | - Cândido C. Coimbra
- Laboratory of Endocrinology and Metabolism, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Samuel P. Wanner
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| |
Collapse
|
3
|
Teixeira-Coelho F, Fonseca CG, Vaz FF, Barbosa NHS, Soares DD, Pires W, Wanner SP. Physical exercise-induced thermoregulatory responses in trained rats: Effects of manipulating the duration and intensity of aerobic training sessions. J Therm Biol 2021; 97:102878. [PMID: 33863441 DOI: 10.1016/j.jtherbio.2021.102878] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/05/2021] [Accepted: 02/13/2021] [Indexed: 11/25/2022]
Abstract
This study investigated the effects of increasing the intensity and/or duration of aerobic training sessions on thermoregulatory responses in rats subjected to exercises in temperate and warm environments. Thirty-two adult male Wistar rats were divided into four groups: a control (CON) group and three groups that were subjected to an 8-week aerobic training, during which the physical overload was achieved by predominantly increasing the exercise intensity (INT), duration (DUR) or by increasing both in an alternate manner (ID). During the last week of training, the rats received an abdominal sensor implant to measure their core body temperature (TCORE) by telemetry. After the training protocol, the 32 rats were subjected to incremental speed-exercises in temperate (23 °C) and warm (32 °C) environments. The rats had their TCORE recorded while running on a treadmill, and the ratio between the increase in TCORE and distance traveled was calculated to estimate thermoregulatory efficiency. All training protocols increased the rats' thermoregulatory efficiency during the incremental-speed exercise at 23 °C; i.e., trained rats attained faster running speeds but unchanged TCORE at fatigue compared to CON rats. However, none of the load components of training sessions - intensity or duration - was more effective than the other in improving this efficiency. At 32 °C, the aerobic training protocols did not influence the exercise-induced thermoregulatory responses. Our data indicate that different progressions in aerobic training performed at temperate conditions improved thermoregulatory efficiency during incremental exercise in the same environment; this training-induced adaptation was not clearly observed when running in warmer conditions.
Collapse
Affiliation(s)
- Francisco Teixeira-Coelho
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Department of Sport Sciences, Institute of Health Science. Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Cletiana Gonçalves Fonseca
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Filipe Ferreira Vaz
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Nicolas Henrique Santos Barbosa
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Danusa Dias Soares
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Washington Pires
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Physical Activity Laboratory, School of Physical Education, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil
| | - Samuel Penna Wanner
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
| |
Collapse
|
4
|
Malheiros-Lima MR, Pires W, Fonseca IAT, Joviano-Santos JV, Ferreira AJ, Coimbra CC, Lima NRV, Wanner SP. Physical Exercise-Induced Cardiovascular and Thermoregulatory Adjustments Are Impaired in Rats Subjected to Cutaneous Artery Denervation. Front Physiol 2018. [PMID: 29515451 PMCID: PMC5826067 DOI: 10.3389/fphys.2018.00074] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
This study aimed to investigate the chronic effects of caudal artery denervation on morphometric parameters of the tail vascular smooth muscle and on physical exercise-induced thermoregulatory and cardiovascular adjustments in rats. Male Wistar rats were subjected to caudal artery denervation or the sham procedure. Approximately 26-28 days after these procedures, their thermoregulatory and cardiovascular parameters were evaluated at rest and during or following a fatiguing treadmill run. At the end of the experiments, the rats were euthanized, and samples of their tails were removed to evaluate morphometric parameters of the vascular smooth muscle surrounding the caudal artery. Denervated rats showed morphological adaptations, including increased arterial wall thickness and wall-to-lumen ratios. In resting rats and following the fatiguing exercise, caudal artery denervation barely affected the thermoregulatory and cardiovascular parameters evaluated. By contrast, caudal artery denervation attenuated the increase in tail skin temperature, decreased the spontaneous baroreflex sensitivity, and exacerbated the increases in mean arterial pressure in exercising rats. The increased wall-to-lumen ratio of denervated rats correlated negatively with the maximum tail skin temperature attained or cutaneous heat loss sensitivity but correlated positively with the maximum diastolic blood pressure attained during exercise. In conclusion, cutaneous denervation induces vascular remodeling characterized by morphological adaptations of the tail vascular smooth muscle. This vascular remodeling likely underlies the impaired tail heat loss and blood pressure adjustments in denervated rats subjected to physical exercise. Therefore, we have highlighted the importance of cutaneous vascular innervation integrity in thermal and cardiovascular control in stress-challenged rats. In this sense, our findings advance the understanding of thermoregulatory and cardiovascular system reactions after a sustained cutaneous vascular innervation injury, which is essential for the treatment of some diseases, such as Parkinson's disease and type 1 and type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Milene R Malheiros-Lima
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Washington Pires
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,Department of Physical Education, Institute of Life Sciences, Universidade Federal de Juiz de Fora, Governador Valadares, Brazil
| | - Ivana A T Fonseca
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Julliane V Joviano-Santos
- Department of Morphology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Anderson J Ferreira
- Department of Morphology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Cândido C Coimbra
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Nilo R V Lima
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Samuel P Wanner
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| |
Collapse
|
5
|
Kunstetter AC, Barbosa NHS, Moraes MM, Pinto VA, Soares DD, Pires W, Wanner SP. Pre-exercise exposure to the treadmill setup changes the cardiovascular and thermoregulatory responses induced by subsequent treadmill running in rats. Temperature (Austin) 2017; 5:109-122. [PMID: 30377632 DOI: 10.1080/23328940.2017.1388343] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022] Open
Abstract
Different methodological approaches have been used to conduct experiments with rats subjected to treadmill running. Some experimenters have exposed rats to the treadmill setup before initiating exercise to minimize the influences of handling and being placed in an anxiety-inducing environment on the physiological responses to subsequent running. Other experimenters have subjected rats to exercise immediately after placing them on the treadmill. Thus, the present study aimed to evaluate the effects of pre-exercise exposure to the treadmill on physical performance and cardiovascular and thermoregulatory responses during subsequent exercise. Male Wistar rats were subjected to fatiguing incremental-speed exercise at 24°C immediately after being placed on the treadmill or after being exposed to the treadmill for 70 min following removal from their home cages. Core body temperature (TCORE), tail-skin temperature (TSKIN), heart rate (HR) and mean arterial pressure (MAP) were recorded throughout the experiments. Rats exposed to the treadmill started exercise with higher TCORE, lower HR and MAP, and unaltered TSKIN. This exposure did not influence performance, but it markedly affected the exercise-induced increases in the four physiological parameters evaluated; for example, the TSKIN increased earlier and at a higher TCORE. Moreover, previous treadmill exposure notably allowed expected exercise-induced changes in cardiovascular parameters to be observed. Collectively, these data indicate that pre-exercise exposure to the treadmill induces important effects on physiological responses during subsequent treadmill running. The present data are particularly relevant for researchers planning experiments involving physical exercise and the recording of physiological parameters in rats.
Collapse
Affiliation(s)
- Ana C Kunstetter
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Nicolas H S Barbosa
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Michele M Moraes
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Valéria A Pinto
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Danusa D Soares
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Washington Pires
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil.,Department of Physical Education, Institute of Life Sciences, Universidade Federal de Juiz de Fora, Governador Valadares (MG), Brazil
| | - Samuel P Wanner
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| |
Collapse
|
6
|
Müller-Ribeiro FC, Wanner SP, Santos WHM, Malheiros-Lima MR, Fonseca IAT, Coimbra CC, Pires W. Changes in systolic arterial pressure variability are associated with the decreased aerobic performance of rats subjected to physical exercise in the heat. J Therm Biol 2016; 63:31-40. [PMID: 28010813 DOI: 10.1016/j.jtherbio.2016.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/03/2016] [Accepted: 11/09/2016] [Indexed: 10/20/2022]
Abstract
Enhanced cardiovascular strain is one of the factors that explains degraded aerobic capacity in hot environments. The cardiovascular system is regulated by the autonomic nervous system, whose activity can be indirectly evaluated by analyzing heart rate variability (HRV) and systolic arterial pressure (SAP) variability. However, no study has addressed whether HRV or SAP variability can predict aerobic performance during a single bout of exercise. Therefore, this study aimed to investigate whether there is an association between cardiovascular variability and performance in rats subjected to treadmill running at two ambient temperatures. In addition, this study investigated whether the heat-induced changes in cardiovascular variability and reductions in performance are associated with each other. Male Wistar rats were implanted with a catheter into their carotid artery for pulsatile blood pressure recordings. After recovery from surgery, the animals were subjected to incremental-speed exercise until they were fatigued under temperate (25°C) and hot (35°C) conditions. Impaired performance and exaggerated cardiovascular responses were observed in the hot relative to the temperate environment. Significant and negative correlations between most of the SAP variability components (standard deviation, variance, very low frequency [VLF], and low frequency [LF]) at the earlier stages of exercise and total exercise time were observed in both environmental conditions. Furthermore, the heat-induced changes in the sympathetic components of SAP variability (VLF and LF) were associated with heat-induced impairments in performance. Overall, the results indicate that SAP variability at the beginning of exercise predicts the acute performance of rats. Our findings also suggest that heat impairments in aerobic performance are associated with changes in cardiovascular autonomic control.
Collapse
Affiliation(s)
- Flávia C Müller-Ribeiro
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Samuel P Wanner
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Weslley H M Santos
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Milene R Malheiros-Lima
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ivana A T Fonseca
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Cândido C Coimbra
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Washington Pires
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Department of Physical Education, Institute of Life Sciences, Universidade Federal de Juiz de Fora, Governador Valadares, MG, Brazil.
| |
Collapse
|
7
|
Wanner SP, Prímola-Gomes TN, Pires W, Guimarães JB, Hudson ASR, Kunstetter AC, Fonseca CG, Drummond LR, Damasceno WC, Teixeira-Coelho F. Thermoregulatory responses in exercising rats: methodological aspects and relevance to human physiology. Temperature (Austin) 2015; 2:457-75. [PMID: 27227066 PMCID: PMC4844073 DOI: 10.1080/23328940.2015.1119615] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 11/02/2015] [Accepted: 11/02/2015] [Indexed: 01/18/2023] Open
Abstract
Rats are used worldwide in experiments that aim to investigate the physiological responses induced by a physical exercise session. Changes in body temperature regulation, which may affect both the performance and the health of exercising rats, are evident among these physiological responses. Despite the universal use of rats in biomedical research involving exercise, investigators often overlook important methodological issues that hamper the accurate measurement of clear thermoregulatory responses. Moreover, much debate exists regarding whether the outcome of rat experiments can be extrapolated to human physiology, including thermal physiology. Herein, we described the impact of different exercise intensities, durations and protocols and environmental conditions on running-induced thermoregulatory changes. We focused on treadmill running because this type of exercise allows for precise control of the exercise intensity and the measurement of autonomic thermoeffectors associated with heat production and loss. Some methodological issues regarding rat experiments, such as the sites for body temperature measurements and the time of day at which experiments are performed, were also discussed. In addition, we analyzed the influence of a high body surface area-to-mass ratio and limited evaporative cooling on the exercise-induced thermoregulatory responses of running rats and then compared these responses in rats to those observed in humans. Collectively, the data presented in this review represent a reference source for investigators interested in studying exercise thermoregulation in rats. In addition, the present data indicate that the thermoregulatory responses of exercising rats can be extrapolated, with some important limitations, to human thermal physiology.
Collapse
Affiliation(s)
- Samuel Penna Wanner
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais ; Belo Horizonte (MG), Brazil
| | - Thales Nicolau Prímola-Gomes
- Laboratório de Biologia do Exercício; Departamento de Educação Física; Universidade Federal de Viçosa ; Viçosa (MG), Brazil
| | - Washington Pires
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais ; Belo Horizonte (MG), Brazil
| | - Juliana Bohnen Guimarães
- Laboratório de Fisiologia do Exercício; Universidade Estadual de Minas Gerais ; Ibirité (MG), Brazil
| | - Alexandre Sérvulo Ribeiro Hudson
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais ; Belo Horizonte (MG), Brazil
| | - Ana Cançado Kunstetter
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais ; Belo Horizonte (MG), Brazil
| | - Cletiana Gonçalves Fonseca
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais ; Belo Horizonte (MG), Brazil
| | - Lucas Rios Drummond
- Laboratório de Biologia do Exercício; Departamento de Educação Física; Universidade Federal de Viçosa ; Viçosa (MG), Brazil
| | - William Coutinho Damasceno
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais ; Belo Horizonte (MG), Brazil
| | - Francisco Teixeira-Coelho
- Laboratório de Fisiologia do Exercício; Departamento de Educação Física; Universidade Federal de Minas Gerais; Belo Horizonte (MG), Brazil; Centro de Formação de Professores; Universidade Federal do Recôncavo da Bahia; Amargosa (BA), Brazil
| |
Collapse
|
8
|
Dietary glutamine prevents the loss of intestinal barrier function and attenuates the increase in core body temperature induced by acute heat exposure. Br J Nutr 2014; 112:1601-10. [PMID: 25322775 DOI: 10.1017/s0007114514002608] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Dietary glutamine (Gln) supplementation improves intestinal function in several stressful conditions. Therefore, in the present study, the effects of dietary Gln supplementation on the core body temperature (T core), bacterial translocation (BT) and intestinal permeability of mice subjected to acute heat stress were evaluated. Male Swiss mice (4 weeks old) were implanted with an abdominal temperature sensor and randomly assigned to one of the following groups fed isoenergetic and isoproteic diets for 7 d before the experimental trials: group fed the standard AIN-93G diet and exposed to a high ambient temperature (39°C) for 2 h (H-NS); group fed the AIN-93G diet supplemented with l-Gln and exposed to a high temperature (H-Gln); group fed the standard AIN-93G diet and not exposed to a high temperature (control, C-NS). Mice were orally administered diethylenetriaminepentaacetic acid radiolabelled with technetium (99mTc) for the assessment of intestinal permeability or 99mTc-Escherichia coli for the assessment of BT. Heat exposure increased T core (approximately 41°C during the experimental trial), intestinal permeability and BT to the blood and liver (3 h after the experimental trial) in mice from the H-NS group relative to those from the C-NS group. Dietary Gln supplementation attenuated hyperthermia and prevented the increases in intestinal permeability and BT induced by heat exposure. No correlations were observed between the improvements in gastrointestinal function and the attenuation of hyperthermia by Gln. Our findings indicate that dietary Gln supplementation preserved the integrity of the intestinal barrier and reduced the severity of hyperthermia during heat exposure. The findings also indicate that these Gln-mediated effects occurred through independent mechanisms.
Collapse
|
9
|
Wanner SP, Costa KA, Soares ADN, Cardoso VN, Coimbra CC. Physical exercise-induced changes in the core body temperature of mice depend more on ambient temperature than on exercise protocol or intensity. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2014; 58:1077-1085. [PMID: 23857354 DOI: 10.1007/s00484-013-0699-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 06/13/2013] [Accepted: 06/14/2013] [Indexed: 06/02/2023]
Abstract
The mechanisms underlying physical exercise-induced hyperthermia may be species specific. Therefore, the present study aimed to investigate the effects of exercise intensity and ambient temperature on the core body temperature (T core) of running mice, which provide an important experimental model for advancing the understanding of thermal physiology. We evaluated the influence of different protocols (constant- or incremental-speed exercises), treadmill speeds and ambient temperatures (T a) on the magnitude of exercise-induced hyperthermia. To measure T core, a telemetric sensor was implanted in the abdominal cavity of male adult Swiss mice under anesthesia. After recovering from the surgery, the animals were familiarized to running on a treadmill and then subjected to the different running protocols and speeds at two T a: 24 °C or 34 °C. All of the experimental trials resulted in marked increases in T core. As expected, the higher-temperature environment increased the magnitude of running-induced hyperthermia. For example, during incremental exercise at 34 °C, the maximal T core achieved was increased by 1.2 °C relative to the value reached at 24 °C. However, at the same T a, neither treadmill speed nor exercise protocol altered the magnitude of exercise-induced hyperthermia. We conclude that T core of running mice is influenced greatly by T a, but not by the exercise protocols or intensities examined in the present report. These findings suggest that the magnitude of hyperthermia in running mice may be regulated centrally, independently of exercise intensity.
Collapse
Affiliation(s)
- Samuel Penna Wanner
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, Minas Gerais, Brazil, 31270-901,
| | | | | | | | | |
Collapse
|
10
|
Kunstetter AC, Wanner SP, Madeira LG, Wilke CF, Rodrigues LOC, Lima NRV. Association between the increase in brain temperature and physical performance at different exercise intensities and protocols in a temperate environment. ACTA ACUST UNITED AC 2014; 47:679-88. [PMID: 25003543 PMCID: PMC4165295 DOI: 10.1590/1414-431x20143561] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 04/16/2014] [Indexed: 12/31/2022]
Abstract
There is evidence that brain temperature (Tbrain) provides a more
sensitive index than other core body temperatures in determining physical
performance. However, no study has addressed whether the association between
performance and increases in Tbrain in a temperate environment is
dependent upon exercise intensity, and this was the primary aim of the present study.
Adult male Wistar rats were subjected to constant exercise at three different speeds
(18, 21, and 24 m/min) until the onset of volitional fatigue. Tbrain was
continuously measured by a thermistor inserted through a brain guide cannula.
Exercise induced a speed-dependent increase in Tbrain, with the fastest
speed associated with a higher rate of Tbrain increase. Rats subjected to
constant exercise had similar Tbrain values at the time of fatigue,
although a pronounced individual variability was observed (38.7-41.7°C). There were
negative correlations between the rate of Tbrain increase and performance
for all speeds that were studied. These results indicate that performance during
constant exercise is negatively associated with the increase in Tbrain,
particularly with its rate of increase. We then investigated how an incremental-speed
protocol affected the association between the increase in Tbrain and
performance. At volitional fatigue, Tbrain was lower during incremental
exercise compared with the Tbrain resulting from constant exercise
(39.3±0.3 vs 40.3±0.1°C; P<0.05), and no association between the
rate of Tbrain increase and performance was observed. These findings
suggest that the influence of Tbrain on performance under temperate
conditions is dependent on exercise protocol.
Collapse
Affiliation(s)
- A C Kunstetter
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - S P Wanner
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - L G Madeira
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - C F Wilke
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - L O C Rodrigues
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - N R V Lima
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| |
Collapse
|
11
|
Costa KA, Soares ADN, Wanner SP, Santos RDGCD, Fernandes SOA, Martins FDS, Nicoli JR, Coimbra CC, Cardoso VN. L-arginine supplementation prevents increases in intestinal permeability and bacterial translocation in male Swiss mice subjected to physical exercise under environmental heat stress. J Nutr 2014; 144:218-23. [PMID: 24259555 DOI: 10.3945/jn.113.183186] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dietary supplementation with l-arginine has been shown to improve the intestinal barrier in many experimental models. This study investigated the effects of arginine supplementation on the intestinal permeability and bacterial translocation (BT) induced by prolonged physical exercise under heat stress. Under anesthesia, male Swiss mice (5-wk-old) were implanted with an abdominal sensor to record their core body temperature (T(core)). After recovering from surgery, the mice were divided into 3 groups: a non-supplemented group that was fed the standard diet formulated by the American Institute of Nutrition (AIN-93G; control), a non-supplemented group that was fed the AIN-93G diet and subjected to exertional hyperthermia (H-NS), and a group supplemented with l-arginine at 2% and subjected to exertional hyperthermia (H-Arg). After 7 d of treatment, the H-NS and H-Arg mice were forced to run on a treadmill (60 min, 8 m/min) in a warm environment (34°C). The control mice remained at 24°C. Thirty min before the exercise or control trials, the mice received a diethylenetriamine pentaacetic acid (DTPA) solution labeled with technetium-99m ((99m)Tc-DTPA) or (99m)Tc-Escherichia coli by gavage to assess intestinal permeability and BT, respectively. The H-NS mice terminated the exercise with T(core) values of ∼40°C, and, 4 h later, presented a 12-fold increase in the blood uptake of (99m)Tc-DTPA and higher bacterial contents in the blood and liver than the control mice. Although supplementation with arginine did not change the exercise-induced increase in T(core), it prevented the increases in intestinal permeability and BT caused by exertional hyperthermia. Our results indicate that dietary l-arginine supplementation preserves the integrity of the intestinal epithelium during exercise under heat stress, acting through mechanisms that are independent of T(core) regulation.
Collapse
|
12
|
Pires W, Wanner SP, Lima MRM, Fonseca IAT, Fumega U, Haibara AS, Coimbra CC, Lima NRV. Physical exercise performance in temperate and warm environments is decreased by an impaired arterial baroreflex. PLoS One 2013; 8:e72005. [PMID: 23951278 PMCID: PMC3737155 DOI: 10.1371/journal.pone.0072005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 07/10/2013] [Indexed: 11/18/2022] Open
Abstract
The present study aimed to investigate whether running performance in different environments is dependent on intact arterial baroreceptor reflexes. We also assessed the exercise-induced cardiovascular and thermoregulatory responses in animals lacking arterial baroafferent signals. To accomplish these goals, male Wistar rats were subjected to sinoaortic denervation (SAD) or sham surgery (SHAM) and had a catheter implanted into the ascending aorta to record arterial pressure and a telemetry sensor implanted in the abdominal cavity to record core temperature. After recovering from these surgeries, the animals were subjected to constant- or incremental-speed exercises performed until the voluntary interruption of effort under temperate (25° C) and warm (35° C) conditions. During the constant-speed exercises, the running time until the rats were fatigued was shorter in SAD rats in both environments. Although the core temperature was not significantly different between the groups, tail skin temperature was higher in SAD rats under temperate conditions. The denervated rats also displayed exaggerated increases in blood pressure and double product compared with the SHAM rats; in particular, in the warm environment, these exaggerated cardiovascular responses in the SAD rats persisted until they were fatigued. These SAD-mediated changes occurred in parallel with increased variability in the very low and low components of the systolic arterial pressure power spectrum. The running performance was also affected by SAD during the incremental-speed exercises, with the maximal speed attained being decreased by approximately 20% in both environments. Furthermore, at the maximal power output tolerated during the incremental exercises, the mean arterial pressure, heart rate and double product were exaggerated in the SAD relative to SHAM rats. In conclusion, the chronic absence of the arterial baroafferents accelerates exercise fatigue in temperate and warm environments. Our findings also suggest that an augmented cardiovascular strain accounted for the early interruption of exercise in the SAD rats.
Collapse
Affiliation(s)
- Washington Pires
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | | | | | | | | | | | | |
Collapse
|