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Falvey A, Palandira SP, Chavan SS, Brines M, Dantzer R, Tracey KJ, Pavlov VA. Electrical stimulation of the dorsal motor nucleus of the vagus in male mice can regulate inflammation without affecting the heart rate. Brain Behav Immun 2024:S0889-1591(24)00376-3. [PMID: 38670240 DOI: 10.1016/j.bbi.2024.04.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/01/2024] [Accepted: 04/22/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND The vagus nerve plays an important role in neuroimmune interactions and in the regulation of inflammation. A major source of efferent vagus nerve fibers that contribute to the regulation of inflammation is the brainstem dorsal motor nucleus of the vagus (DMN) as recently shown using optogenetics. In contrast to optogenetics, electrical neuromodulation has broad therapeutic implications. However, the anti-inflammatory effectiveness of electrical stimulation of the DMN (eDMNS) and the possible heart rate (HR) alterations associated with this approach have not been investigated. Here, we examined the effects of eDMNS on HR and cytokine levels in mice administered with lipopolysaccharide (LPS, endotoxin) and in mice subjected to cecal ligation and puncture (CLP) sepsis. METHODS Anesthetized male 8-10-week-old C57BL/6 mice on a stereotaxic frame were subjected to eDMNS using a concentric bipolar electrode inserted into the left or right DMN or sham stimulation. eDMNS (500, 250 or 50 μA at 30 Hz, for 1 min) was performed and HR recorded. In endotoxemia experiments, sham or eDMNS utilizing 250 μA or 50 μA was performed for 5 mins and was followed by LPS (0.5 mg/kg) i.p. administration. eDMNS was also applied in mice with cervical unilateral vagotomy or sham operation. In CLP experiments sham or left eDMNS was performed immediately post CLP. Cytokines and corticosterone were analyzed 90 mins after LPS administration or 24 h after CLP. CLP survival was monitored for 14 days. RESULTS Either left or right eDMNS at 500 μA and 250 μA decreased HR, compared with baseline pre-stimulation. This effect was not observed at 50 μA. Left side eDMNS at 50 μA, compared with sham stimulation, significantly decreased serum and splenic levels of the pro-inflammatory cytokine TNF and increased serum levels of the anti-inflammatory cytokine IL-10 during endotoxemia. The anti-inflammatory effect of eDMNS was abrogated in mice with unilateral vagotomy and was not associated with serum corticosterone alterations. Right side eDMNS in endotoxemic mice suppressed serum TNF and increased serum IL-10 levels but had no effects on splenic cytokines. In mice with CLP, left side eDMNS suppressed serum IL-6, as well as splenic IL-6 and increased splenic IL-10 and significantly improved the survival rate of CLP mice. CONCLUSIONS For the first time we show that a regimen of eDMNS which does not cause bradycardia alleviates LPS-induced inflammation. These eDMNS anti-inflammatory effects require an intact vagus nerve and are not associated with corticosteroid alterations. eDMNS also decreases inflammation and improves survival in a model of polymicrobial sepsis. These findings are of interest for further studies exploring bioelectronic anti-inflammatory approaches targeting the brainstem DMN.
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Affiliation(s)
- Aidan Falvey
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA
| | - Santhoshi P Palandira
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Elmezzi Graduate School of Molecular Medicine, 350 Community Drive, Manhasset, NY 11030, USA
| | - Sangeeta S Chavan
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra University, Hempstead, NY 11549, USA; Elmezzi Graduate School of Molecular Medicine, 350 Community Drive, Manhasset, NY 11030, USA
| | - Michael Brines
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA
| | - Robert Dantzer
- University of Texas MD Anderson Cancer Center, Department of Symptom Research, Houston, TX 77030, USA
| | - Kevin J Tracey
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra University, Hempstead, NY 11549, USA; Elmezzi Graduate School of Molecular Medicine, 350 Community Drive, Manhasset, NY 11030, USA
| | - Valentin A Pavlov
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra University, Hempstead, NY 11549, USA; Elmezzi Graduate School of Molecular Medicine, 350 Community Drive, Manhasset, NY 11030, USA.
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Gorman RA, Yakobov S, Polidovitch N, Debi R, Sanfrancesco VC, Hood DA, Lakin R, Backx PH. The effects of daily dose of intense exercise on cardiac responses and atrial fibrillation. J Physiol 2024; 602:569-596. [PMID: 38319954 DOI: 10.1113/jp285697] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 12/08/2023] [Indexed: 02/08/2024] Open
Abstract
Atrial fibrillation (AF) is a supraventricular tachyarrhythmia that is strongly associated with cardiovascular (CV) disease and sedentary lifestyles. Despite the benefits of exercise on overall health, AF incidence in high-level endurance athletes rivals that of CV disease patients, suggesting a J-shaped relationship with AF. To investigate the dependence of AF vulnerability on exercise, we varied daily swim durations (120, 180 or 240 min day-1 ) in 7-week-old male CD1 mice. We assessed mice after performing equivalent amounts of cumulative work during swimming (i.e. ∼700 L O2 kg-1 ), as determined from O2 consumption rates (V ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ ). The meanV ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ during exercise increased progressively throughout the training period and was indistinguishable between the swim groups. Consistent with similar improvements in aerobic conditioning induced by swimming, skeletal muscle mitochondria content increased (P = 0.027) indistinguishably between exercise groups. Physiological ventricular remodelling, characterized by mild hypertrophy and left ventricular dilatation, was also similar between exercised mice without evidence of ventricular arrhythmia inducibility. By contrast, prolongation of daily swim durations caused progressive and vagal-dependent heart rate reductions (P = 0.008), as well as increased (P = 0.005) AF vulnerability. As expected, vagal inhibition prolonged (P = 0.013) atrial refractoriness, leading to reduced AF vulnerability, although still inducible in the 180 and 240 min swim groups. Accordingly, daily swim dose progressively increased atrial hypertrophy (P = 0.003), fibrosis (P < 0.001) and macrophage accumulation (P = 0.006) without differentially affecting the ventricular tissue properties. Thus, increasing daily exercise duration drives progressively adverse atrial-specific remodelling and vagal-dependent AF vulnerability despite robust and beneficial aerobic conditioning and physiological remodelling of ventricles and skeletal muscle. KEY POINTS: Previous studies have suggested that a J-shaped dose-response relationship exists between physical activity and cardiovascular health outcomes, with moderate exercise providing protection against many cardiovascular disease conditions, whereas chronic endurance exercise can promote atrial fibrillation (AF). We found that AF vulnerability increased alongside elevated atrial hypertrophy, fibrosis and inflammation as daily swim exercise durations in mice were prolonged (i.e. ≥180 min day-1 for 6 weeks). The MET-h week-1 (based on O2 measurements during swimming) needed to induce increased AF vulnerability mirrored the levels linked to AF in athletes. These adverse atria effects associated with excessive daily exercise occurred despite improved aerobic conditioning, skeletal muscle adaptation and physiological ventricular remodelling. We suggest that atrial-specific changes observed with exercise arise from excessive elevations in venous filling pressures during prolonged exercise bouts, which we argue has implications for all AF patients because elevated atrial pressures occur in most cardiovascular disease conditions as well as ageing which are linked to AF.
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Affiliation(s)
- Renée A Gorman
- Department of Biology, York University, Toronto, ON, Canada
- Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Simona Yakobov
- Department of Biology, York University, Toronto, ON, Canada
- Muscle Health Research Centre, York University, Toronto, ON, Canada
| | | | - Ryan Debi
- Department of Biology, York University, Toronto, ON, Canada
| | - Victoria C Sanfrancesco
- Muscle Health Research Centre, York University, Toronto, ON, Canada
- Department of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - David A Hood
- Muscle Health Research Centre, York University, Toronto, ON, Canada
- Department of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Robert Lakin
- Department of Biology, York University, Toronto, ON, Canada
- Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Peter H Backx
- Department of Biology, York University, Toronto, ON, Canada
- Muscle Health Research Centre, York University, Toronto, ON, Canada
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Bentley RF, Dorian P, Vecchiarelli E, Banks L, Connelly KA, Yan AT, Osman W, Goodman JM. The effect of chronic exercise training and acute exercise on power spectral analysis of heart rate variability. Appl Physiol Nutr Metab 2024; 49:148-156. [PMID: 37751466 DOI: 10.1139/apnm-2023-0007] [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] [Indexed: 09/28/2023]
Abstract
Moderate to vigorous physical activity performed regularly is cardioprotective and reduces all-cause mortality, concomitant with increased resting heart rate variability (HRV). However, there are contradictory reports regarding the effects of chronic and acute exercise on nocturnal HRV in those performing exercise well-beyond physical activity guidelines. Therefore, the purpose of this study was to compare the power spectral analysis components of HRV in middle-aged endurance athletes (EA) and recreationally active individuals (REC) and explore acute exercise effects in EA. A total of 119 EA (52, 49-57 years) and 32 REC (56, 52-60 years) were recruited to complete 24 h Holter monitoring (GE SEER 1000) in the absence of exercise. Fifty one EA (52, 49-57 years) then underwent 24 h Holter monitoring following an intense bout of endurance exercise. Power spectral HRV analysis was completed hourly and averaged to quantify morning (1000-1200 h), evening (1900-2100 h), and nocturnal (0200-0400 h) HRV. EA had greater very low frequency (VLF) and low frequency (LF) (both p < 0.001) compared to REC. LF/high frequency (HF) was greater in EA at 0200-0400 h (p = 0.04). Among all participants, the change in HR and HF from 1000-1200 to 0200-0400 h was negatively correlated (r = -0.47, p < 0.001). Following acute exercise in EA, only nocturnal HRV was assessed. VLF (p < 0.001) and HF (p = 0.008) decreased, while LF/HF increased (p = 0.02). These results suggest that in EA, both long-term and acute exercises increase nocturnal sympathovagal activity through an increase in LF and decrease in HF, respectively. Further work is required to understand the mechanism underlying reduced nocturnal HRV in middle-aged EA and the long-term health implications.
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Affiliation(s)
- Robert F Bentley
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada
| | - Paul Dorian
- Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
- Division of Cardiology, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON M5B 1T8, Canada
- Heart and Stroke/Richard Lewar Centres of Excellence in Cardiovascular Research, University of Toronto
| | - Emily Vecchiarelli
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada
| | - Laura Banks
- University Health Network/Toronto Rehabilitation Institute, Cardiovascular Prevention and Rehabilitation Program, Toronto, ON M5G 2A2, Canada
| | - Kim A Connelly
- Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
- Division of Cardiology, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON M5B 1T8, Canada
- Heart and Stroke/Richard Lewar Centres of Excellence in Cardiovascular Research, University of Toronto
| | - Andrew T Yan
- Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
- Division of Cardiology, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON M5B 1T8, Canada
| | - Wesseem Osman
- Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Jack M Goodman
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada
- University Health Network/Toronto Rehabilitation Institute, Cardiovascular Prevention and Rehabilitation Program, Toronto, ON M5G 2A2, Canada
- Division of Cardiology, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
- Heart and Stroke/Richard Lewar Centres of Excellence in Cardiovascular Research, University of Toronto
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Lakin R, Polidovitch N, Yang S, Parikh M, Liu X, Debi R, Gao X, Chen W, Guzman C, Yakobov S, Izaddoustdar F, Wauchop M, Lei Q, Xu W, Nedospasov SA, Christoffels VM, Backx PH. Cardiomyocyte and endothelial cells play distinct roles in the tumour necrosis factor (TNF)-dependent atrial responses and increased atrial fibrillation vulnerability induced by endurance exercise training in mice. Cardiovasc Res 2023; 119:2607-2622. [PMID: 37713664 PMCID: PMC10730243 DOI: 10.1093/cvr/cvad144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 06/22/2023] [Accepted: 07/18/2023] [Indexed: 09/17/2023] Open
Abstract
AIMS Endurance exercise is associated with an increased risk of atrial fibrillation (AF). We previously established that adverse atrial remodelling and AF susceptibility induced by intense exercise in mice require the mechanosensitive and pro-inflammatory cytokine tumour necrosis factor (TNF). The cellular and mechanistic basis for these TNF-mediated effects is unknown. METHODS AND RESULTS We studied the impact of Tnf excision, in either atrial cardiomyocytes or endothelial cells (using Cre-recombinase expression controlled by Nppa or Tie2 promoters, respectively), on the cardiac responses to six weeks of intense swim exercise training. TNF ablation, in either cell type, had no impact on the changes in heart rate, autonomic tone, or left ventricular structure and function induced by exercise training. Tnf excision in atrial cardiomyocytes did, however, prevent atrial hypertrophy, fibrosis, and macrophage infiltration as well as conduction slowing and increased AF susceptibility arising from exercise training. In contrast, endothelial-specific excision only reduced the training-induced atrial hypertrophy. Consistent with these cell-specific effects of Tnf excision, inducing TNF loss from atrial cardiomyocytes prevented activation of p38MAPKinase, a strain-dependent downstream mediator of TNF signalling, without affecting the atrial stretch as assessed by atrial pressures induced by exercise. Despite TNF's established role in innate immune responses and inflammation, neither acute nor chronic exercise training caused measurable NLRP3 inflammasome activation. CONCLUSIONS Our findings demonstrate that adverse atrial remodelling and AF vulnerability induced by intense exercise require TNF in atrial cardiomyocytes whereas the impact of endothelial-derived TNF is limited to hypertrophy modulation. The implications of the cell autonomous effects of TNF and crosstalk between cells in the atria are discussed.
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Affiliation(s)
- Robert Lakin
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Nazari Polidovitch
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Sibao Yang
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
- Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130022, China
| | - Mihir Parikh
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Xueyan Liu
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
- Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130022, China
| | - Ryan Debi
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Xiaodong Gao
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Wenliang Chen
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Camilo Guzman
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Simona Yakobov
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Farzad Izaddoustdar
- Department of Physiology, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Marianne Wauchop
- Department of Physiology, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Qian Lei
- Department of Anesthesiology, Sichuan Academy of Medical Sciences and Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Weimin Xu
- Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130022, China
| | - Sergei A Nedospasov
- Laboratory of Molecular Mechanisms of Immunity, Engelhardt Institute of Molecular Biology, Moscow 119991, Russia
- Division of Immunobiology and Biomedicine, Sirius University of Science and Technology, Sirius 354349, Russia
| | - Vincent M Christoffels
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, Amsterdam, The Netherlands
| | - Peter H Backx
- Department of Biology, York University, 354 & 357 Farquharson Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
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Orsi JB, Araujo LS, Scariot PPM, Polisel EEC, Cardoso LO, Gobatto CA, Manchado-Gobatto FB. Critical Velocity, Maximal Lactate Steady State, and Muscle MCT1 and MCT4 after Exhaustive Running in Mice. Int J Mol Sci 2023; 24:15753. [PMID: 37958736 PMCID: PMC10648804 DOI: 10.3390/ijms242115753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/30/2023] [Accepted: 10/12/2023] [Indexed: 11/15/2023] Open
Abstract
Although the critical velocity (CV) protocol has been used to determine the aerobic capacity in rodents, there is a lack of studies that compare CV with maximal lactate steady state intensity (iMLSS) in mice. As a consequence, their physiological and molecular responses after exercise until exhaustion at CV intensity remain unclear. Thus, we aimed to compare and correlate CV with iMLSS in running mice, following different mathematical models for CV estimation. We also evaluated their physiological responses and muscle MCT1 and MCT4 after running until exhaustion at CV. Thirty C57BL/6J mice were divided into two groups (exercised-E and control-C). Group E was submitted to a CV protocol (4 days), using linear (lin1 and lin2) and hyperbolic (hyp) mathematical models to determine the distance, velocity, and time to exhaustion (tlim) of each predictive CV trial, followed by an MLSS protocol. After a running effort until exhaustion at CV intensity, the mice were immediately euthanized, while group C was euthanized at rest. No differences were observed between iMLSS (21.1 ± 1.1 m.min-1) and CV estimated by lin1 (21.0 ± 0.9 m.min-1, p = 0.415), lin2 (21.3 ± 0.9 m.min-1, p = 0.209), and hyp (20.6 ± 0.9 m.min-1, p = 0.914). According to the results, CV was significantly correlated with iMLSS. After running until exhaustion at CV (tlim = 28.4 ± 8,29 min), group E showed lower concentrations of hepatic and gluteal glycogen than group C, but no difference in the content of MCT1 (p = 0.933) and MCT4 (p = 0.123) in soleus muscle. Significant correlations were not found between MCT1 and MCT4 and tlim at CV intensity. Our results reinforce that CV is a valid and non-invasive protocol to estimate the maximal aerobic capacity in mice and that the content of MCT1 and MCT4 was not decisive in determining the tlim at CV, at least when measured immediately after the running effort.
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Affiliation(s)
- Juan B Orsi
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
| | - Lara S Araujo
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
| | - Pedro P M Scariot
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
| | - Emanuel E C Polisel
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
| | - Luisa O Cardoso
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
| | - Claudio A Gobatto
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
| | - Fúlvia B Manchado-Gobatto
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Pedro Zaccaria Street, 1.300, Jardim Santa Luíza, Limeira 13484-350, São Paulo, Brazil
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cardiac autonomic control and neural arousal as indexes of fatigue in professional bus drivers. Saf Health Work 2022; 13:148-154. [PMID: 35664913 PMCID: PMC9142350 DOI: 10.1016/j.shaw.2022.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/19/2021] [Accepted: 01/23/2022] [Indexed: 11/22/2022] Open
Abstract
Background Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.
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Barazi N, Polidovitch N, Debi R, Yakobov S, Lakin R, Backx PH. Dissecting the Roles of the Autonomic Nervous System and Physical Activity on Circadian Heart Rate Fluctuations in Mice. Front Physiol 2021; 12:692247. [PMID: 34733171 PMCID: PMC8558381 DOI: 10.3389/fphys.2021.692247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 09/22/2021] [Indexed: 01/02/2023] Open
Abstract
Heart rate (HR) and blood pressure as well as adverse cardiovascular events show clear circadian patterns, which are linked to interdependent daily variations in physical activity and cardiac autonomic nerve system (ANS) activity. We set out to assess the relative contributions of the ANS (alone) and physical activity to circadian HR fluctuations. To do so, we measured HR (beats per minute, bpm) in mice that were either immobilized using isoflurane anesthesia or free-moving. Nonlinear fits of HR data to sine functions revealed that anesthetized mice display brisk circadian HR fluctuations with amplitudes of 47.1±7.4bpm with the highest HRs in middle of the dark (active) period (ZT 18: 589±46bpm) and lowest HRs in the middle of the light (rest) period (ZT 6: 497±54bpm). The circadian HR fluctuations were reduced by ~70% following blockade of cardiac parasympathetic nervous activity (PNA) with atropine while declining by <15% following cardiac sympathetic nerve activity (SNA) blockade with propranolol. Small HR fluctuation amplitudes (11.6±5.9bpm) remained after complete cardiac ANS blockade. Remarkably, circadian HR fluctuation amplitudes in freely moving, telemetrized mice were only ~32% larger than in anesthetized mice. However, after gaining access to running wheels for 1week, circadian HR fluctuations increase to 102.9±12.1bpm and this is linked directly to increased O2 consumption during running. We conclude that, independent of physical activity, the ANS is a major determinant of circadian HR variations with PNA playing a dominant role compared to SNA. The effects of physical activity to the daily HR variations are remarkably small unless mice get access to running wheels.
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Affiliation(s)
- Nour Barazi
- Department of Biology, York University, Toronto, ON, Canada
| | | | - Ryan Debi
- Department of Biology, York University, Toronto, ON, Canada
| | - Simona Yakobov
- Department of Biology, York University, Toronto, ON, Canada
| | - Robert Lakin
- Department of Biology, York University, Toronto, ON, Canada
| | - Peter H Backx
- Department of Biology, York University, Toronto, ON, Canada
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Kassan A, Ait-Aissa K, Kassan M. Hypothalamic miR-204 Induces Alteration of Heart Electrophysiology and Neurogenic Hypertension by Regulating the Sympathetic Nerve Activity: Potential Role of Microbiota. Cureus 2021; 13:e18783. [PMID: 34692262 PMCID: PMC8523185 DOI: 10.7759/cureus.18783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2021] [Indexed: 02/06/2023] Open
Abstract
There is abundant evidence demonstrating the association between gut dysbiosis and neurogenic diseases such as hypertension. A common characteristic of resistant hypertension is the chronic elevation in sympathetic nervous system (SNS) activity accompanied by increased release of norepinephrine (NE), indicating a neurogenic component that contributes to the development of hypertension. Factors that modulate the sympathetic tone to the cardiovascular system in hypertensive patients are still poorly understood. Research has identified an interaction between the brain and the gut, and this interaction plays a possible role in the mechanism of heart damage-induced hypertension. Data, however, remain scarce, and further study is required to define the role of microbiota in sympathetic neural function and its relationship with heart damage and blood pressure (BP) control. Experimental evidence has pointed toward a bidirectional relationship between alterations in the types of bacteria present in the gut and neurogenic diseases, such as hypertension. Our published data showed that miR-204, a microRNA that plays an important role in the CNS function, is affected by gut dysbiosis. Therefore, miR-204 could be a key element that regulates normal sinus rhythm and neuronal hypertension. In this review, we will shed light on the potential mechanism by which microbiota affects hypothalamic miR-204, which in turn, could hinder the sympathetic nerve drive to the cardiovascular system leading to arrhythmia and hypertension.
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Affiliation(s)
- Adam Kassan
- School of Pharmacy, West Coast University, Los Angeles, USA
| | | | - Modar Kassan
- Physiology, The University of Tennessee Health Science Center, Memphis, USA
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Short-term exercise affects cardiac function ex vivo partially via changes in calcium channel levels, without influencing hypoxia sensitivity. J Physiol Biochem 2021; 77:639-651. [PMID: 34449060 PMCID: PMC8605979 DOI: 10.1007/s13105-021-00830-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 07/13/2021] [Indexed: 12/12/2022]
Abstract
Exercise is known to improve cardiac recovery following coronary occlusion. However, whether short-term exercise can improve cardiac function and hypoxia tolerance ex vivo independent of reperfusion injury and the possible role of calcium channels in improved hypoxia tolerance remains unknown. Therefore, in the current study, heart function was measured ex vivo using the Langendorff method at different oxygen levels after a 4-week voluntary wheel-running regimen in trained and untrained male mice (C57Bl/6NCrl). The levels of cardiac Ca2+-channels: L-type Ca2+-channel (CACNA1C), ryanodine receptor (RyR-2), sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2), and sodium-calcium exchanger were measured using western blot. Trained mice displayed lower cardiac afterload pressure generation capacity (rate and amplitude), but unaltered hypoxia tolerance when compared to untrained mice with similar heart rates. The level of CACNA1C positively correlated with the pressure generation rate and amplitude. Furthermore, the CACNA1C-RYR-2 ratio also positively correlated with the pressure generation rate. While the 4-week training period was not enough to alter the intrinsic cardiac hypoxia tolerance, interestingly it decreased pressure generation capacity and slowed pressure decreasing capacity in the mouse hearts ex vivo. This reduction in pressure generation rate could be linked to the level of channel proteins in sarcolemmal Ca2+-cycling in trained mice. However, the Ca2+-channel levels did not differ significantly between the groups, and thus, the level of calcium channels cannot fully explain all the functional alterations, despite the detected correlations. Therefore, additional studies are warranted to reveal further mechanisms that contribute to the reduced intrinsic capacity for pressure production in trained mouse hearts.
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10
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Weiser-Bitoun I, Davoodi M, Rosenberg AA, Alexandrovich A, Yaniv Y. Opening the Schrödinger Box: Short- and Long-Range Mammalian Heart Rate Variability. Front Physiol 2021; 12:665709. [PMID: 34276396 PMCID: PMC8278020 DOI: 10.3389/fphys.2021.665709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/07/2021] [Indexed: 11/14/2022] Open
Abstract
Background The interactions between the autonomic nervous system (ANS), intrinsic systems (e.g., endocrine), and internal pacemaker mechanisms govern short (milliseconds–seconds)- and long (seconds–minutes)-range heart rate variability (HRV). However, there is a debate regarding the identity of the mechanism underlying HRV on each time scale. We aim to design a general method that accurately differentiates between the relative contribution of the ANS and pacemaker mechanisms to HRV in various mammals, without the need for drug perturbations or organ isolation. Additionally, we aim to explore the universality of the relative contribution of the ANS and pacemaker system of different mammals. Methods This work explored short- and long-range HRVs using published ECG data from dogs, rabbits, and mice. To isolate the effects of ANS on HRV, ECG segments recorded before and after ANS-blockade were compared. Results Differentiation of the ANS from extrinsic and intrinsic pacemaker mechanisms was successfully achieved. In dogs, the internal pacemaker mechanisms were the main contributors to long-range and the ANS to short-range HRV. In rabbits and mice, the ANS and the internal pacemaker mechanisms affected both time scales, and anesthesia changed the relative contribution of the pacemaker mechanism to short- and long-range HRVs. In mice, the extrinsic mechanisms affected long-range HRV, while their effect was negligible in rabbits. Conclusion We offer a novel approach to determine the relative contributions of ANS and extrinsic and intrinsic pacemaker mechanisms to HRV and highlight the importance of selecting mammalian research models with HRV mechanisms representative of the target species of interest.
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Affiliation(s)
| | - Moran Davoodi
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | | | | | - Yael Yaniv
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
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11
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Soeda F, Toda A, Masuzaki K, Miki R, Koga T, Fujii Y, Takahama K. Effects of enriched environment on micturition activity in freely moving C57BL/6J mice. Low Urin Tract Symptoms 2021; 13:400-409. [PMID: 33648020 DOI: 10.1111/luts.12376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/27/2022]
Abstract
OBJECTIVES An enriched environment (EE) has been known to promote structural changes in the brain and enhance learning and emotional performance. However, little is known about the effect of an EE on brain stem functions, such as the micturition function. In this study, we examined whether an EE affects micturition activity in mice. METHODS Male C57BL/6J mice were used. We assessed the micturition activity of freely moving mice using a novel system developed in-house. RESULTS During the dark period, but not light, the EE significantly increased voiding frequency, total voided volume, mean voided volume, voiding duration, mean flow rate, and maximum flow rate compared with the control environment. This EE effect on micturition function was associated with habituation to novel environments in the open-field test, but not with amelioration of motor coordination in the rotarod test. Interestingly, even after the mice were withdrawn from the EE, the improvements in micturition function persisted, while other behavioral changes were abolished. The relative value of voiding frequency and total voided volume during the light period, expressed as a percentage of 24 hours, increased with age when mice were reared in a standard environment. However, this age-related change was not observed in mice reared in an EE. CONCLUSIONS These results suggest that an EE may promote micturition activity during the active phase of C57BL/6J mice, and its effects persist even after withdrawal from the EE. Furthermore, an EE may mitigate dysfunctions in micturition activity, such as polyuria, during the resting phase in aged mice.
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Affiliation(s)
- Fumio Soeda
- Department of Pharmaceutics, Daiichi University of Pharmacy, Fukuoka, Japan.,Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Akihisa Toda
- Department of Pharmaceutics, Daiichi University of Pharmacy, Fukuoka, Japan
| | - Kazuya Masuzaki
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Risa Miki
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Takayuki Koga
- Department of Pharmaceutics, Daiichi University of Pharmacy, Fukuoka, Japan
| | - Yukiko Fujii
- Department of Pharmaceutics, Daiichi University of Pharmacy, Fukuoka, Japan
| | - Kazuo Takahama
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
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12
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Kaidonis X, Niu W, Chan AY, Kesteven S, Wu J, Iismaa SE, Vatner S, Feneley M, Graham RM. Adaptation to exercise-induced stress is not dependent on cardiomyocyte α 1A-adrenergic receptors. J Mol Cell Cardiol 2021; 155:78-87. [PMID: 33647309 DOI: 10.1016/j.yjmcc.2021.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 01/20/2021] [Accepted: 02/21/2021] [Indexed: 12/31/2022]
Abstract
The 'fight or flight' response to physiological stress involves sympathetic nervous system activation, catecholamine release and adrenergic receptor stimulation. In the heart, this induces positive inotropy, previously attributed to the β1-adrenergic receptor subtype. However, the role of the α1A-adrenergic receptor, which has been suggested to be protective in cardiac pathology, has not been investigated in the setting of physiological stress. To explore this, we developed a tamoxifen-inducible, cardiomyocyte-specific α1A-adrenergic receptor knock-down mouse model, challenged mice to four weeks of endurance swim training and assessed cardiac outcomes. With 4-OH tamoxifen treatment, expression of the α1A-adrenergic receptor was knocked down by 80-89%, without any compensatory changes in the expression of other adrenergic receptors, or changes to baseline cardiac structure and function. Swim training caused eccentric hypertrophy, regardless of genotype, demonstrated by an increase in heart weight/tibia length ratio (30% and 22% in vehicle- and tamoxifen-treated animals, respectively) and an increase in left ventricular end diastolic volume (30% and 24% in vehicle- and tamoxifen-treated animals, respectively) without any change in the wall thickness/chamber radius ratio. Consistent with physiological hypertrophy, there was no increase in fetal gene program (Myh7, Nppa, Nppb or Acta1) expression. In response to exercise-induced volume overload, stroke volume (39% and 30% in vehicle- and tamoxifen-treated animals, respectively), cardiac output/tibia length ratio (41% in vehicle-treated animals) and stroke work (61% and 33% in vehicle- and tamoxifen-treated animals, respectively) increased, regardless of genotype. These findings demonstrate that cardiomyocyte α1A-adrenergic receptors are not necessary for cardiac adaptation to endurance exercise stress and their acute ablation is not deleterious.
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Affiliation(s)
- Xenia Kaidonis
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St.Vincent's Clinical School, University of NSW, Kensington, NSW 2052, Australia
| | - Wenxing Niu
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Medical Sciences, University of NSW, Kensington, NSW 2052, Australia
| | - Andrea Y Chan
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Scott Kesteven
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St.Vincent's Clinical School, University of NSW, Kensington, NSW 2052, Australia
| | - Jianxin Wu
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Siiri E Iismaa
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St.Vincent's Clinical School, University of NSW, Kensington, NSW 2052, Australia
| | - Stephen Vatner
- Cardiovascular Research Institute, Dept. of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ 07103, USA
| | - Michael Feneley
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St.Vincent's Clinical School, University of NSW, Kensington, NSW 2052, Australia
| | - Robert M Graham
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St.Vincent's Clinical School, University of NSW, Kensington, NSW 2052, Australia.
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13
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Lakin R, Debi R, Yang S, Polidovitch N, Goodman JM, Backx PH. Differential negative effects of acute exhaustive swim exercise on the right ventricle are associated with disproportionate hemodynamic loading. Am J Physiol Heart Circ Physiol 2021; 320:H1261-H1275. [PMID: 33416456 DOI: 10.1152/ajpheart.00603.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acute exhaustive endurance exercise can differentially impact the right ventricle (RV) versus the left ventricle (LV). However, the hemodynamic basis for these differences and its impact on postexercise recovery remain unclear. Therefore, we assessed cardiac structure and function along with hemodynamic properties of mice subjected to single bouts (216 ± 8 min) of exhaustive swimming (ES). One-hour after ES, LVs displayed mild diastolic impairment compared with that in sedentary (SED) mice. Following dobutamine administration to assess functional reserve, diastolic and systolic function were slightly impaired. Twenty-four hours after ES, LV function was largely indistinguishable from that in SED. By contrast, 1-h post swim, RVs showed pronounced impairment of diastolic and systolic function with and without dobutamine, which persisted 24 h later. The degree of RV impairment correlated with the time-to-exhaustion. To identify hemodynamic factors mediating chamber-specific responses to ES, LV pressure was recorded during swimming. Swimming initiated immediate increases in heart rates (HRs), systolic pressure, dP/dtmax and -dP/dtmin, which remained stable for ∼45 min. LV end-diastolic pressures (LVEDP) increased to ≥45 mmHg during the first 10 min and subsequently declined. After 45 min, HR and -dP/dtmin declined, which correlated with gradual elevations in LVEDP (to ∼45 mmHg) as mice approached exhaustion. All parameters rapidly normalized postexercise. Consistent with human studies, our findings demonstrate a disproportionate negative impact of acute exhaustive exercise on RVs that persisted for at least 24 h. We speculate that the differential effects of exhaustive exercise on the ventricles arise from a ∼2-fold greater hemodynamic load in the RV than in LV originating from profound elevations in LVEDPs as mice approach exhaustion.NEW & NOTEWORTHY Acute exhaustive exercise differentially impacts the right ventricle (RV) versus left ventricle (LV), yet the underlying hemodynamic basis remains unclear. Using pressure-volume analyses and pressure-telemetry implantation in mice, we confirmed a marked disproportionate and persistent negative impact of exhaustive exercise on the RV. These differences in responses of the ventricles to exhaustive exercise are of clinical relevance, reflecting ∼2-fold greater hemodynamic RV loads versus LVs arising from massive (∼45 mmHg) increases in LV end-diastolic pressures at exhaustion.
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Affiliation(s)
- Robert Lakin
- Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada.,Department of Biology, York University, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
| | - Ryan Debi
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Sibao Yang
- Department of Biology, York University, Toronto, Ontario, Canada.,Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Nazari Polidovitch
- Department of Biology, York University, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
| | - Jack M Goodman
- Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
| | - Peter H Backx
- Department of Biology, York University, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
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14
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Gaidica M, Dantzer B. Quantifying the Autonomic Response to Stressors-One Way to Expand the Definition of "Stress" in Animals. Integr Comp Biol 2020; 60:113-125. [PMID: 32186720 DOI: 10.1093/icb/icaa009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Quantifying how whole organisms respond to challenges in the external and internal environment ("stressors") is difficult. To date, physiological ecologists have mostly used measures of glucocorticoids (GCs) to assess the impact of stressors on animals. This is of course too simplistic as Hans Seyle himself characterized the response of organisms to "noxious stimuli" using multiple physiological responses. Possible solutions include increasing the number of biomarkers to more accurately characterize the "stress state" of animal or just measuring different biomarkers to more accurately characterize the degree of acute or chronic stressors an animal is experiencing. We focus on the latter and discuss how heart rate (HR) and heart rate variability (HRV) may be better predictors of the degree of activation of the sympathetic-adrenal-medullary system and complement or even replace measures of GCs as indicators of animal health, welfare, fitness, or their level of exposure to stressors. The miniaturization of biological sensor technology ("bio-sensors" or "bio-loggers") presents an opportunity to reassess measures of stress state and develop new approaches. We describe some modern approaches to gathering these HR and HRV data in free-living animals with the aim that heart dynamics will be more integrated with measures of GCs as bio-markers of stress state and predictors of fitness in free-living animals.
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Affiliation(s)
- Matt Gaidica
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA
| | - Ben Dantzer
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
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15
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Maternal Treadmill Exercise Reduces the Neurotoxicity of Prenatal Sevoflurane Exposure in Rats via Activation of p300 Histone Acetyltransferase. Neurochem Res 2020; 45:1626-1635. [DOI: 10.1007/s11064-020-03023-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/28/2020] [Accepted: 04/03/2020] [Indexed: 12/12/2022]
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16
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Adeyemi O, Parker N, Pointon A, Rolf M. A pharmacological characterization of electrocardiogram PR and QRS intervals in conscious telemetered rats. J Pharmacol Toxicol Methods 2020; 102:106679. [PMID: 32014539 DOI: 10.1016/j.vascn.2020.106679] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/20/2019] [Accepted: 01/28/2020] [Indexed: 12/01/2022]
Abstract
INTRODUCTION The conscious telemetered rat is widely used as an early in vivo screening model for assessing the cardiovascular safety of novel pharmacological agents. The current study aimed to identify its utility in assessing electrocardiogram (ECG) PR and QRS interval changes. METHOD Male Han-Wistar rats (~250 g) were implanted with radio-telemetry devices for the recording of ECG and haemodynamic parameters. Animals (n = 4-8) were treated with single doses of calcium (nifedipine, diltiazem or verapamil; CCBs) or sodium channel blockers (quinidine or flecainide; SCBs) or their corresponding vehicles in an ascending dose design. Data was recorded continuously up to 24 h post-dose. Pharmacokinetic analysis of blood samples was performed to allow comparison of effects to published data in other species. RESULTS Of the CCBs, only diltiazem (300 mg/kg) prolonged the PR interval (49 ± 2 versus vehicle: 43 ± 1 ms), although this was not statistically significant (p = .11). QA interval decreased with nifedipine (30 ± 1 versus 24 ± 0 ms) and diltiazem (34 ± 1 versus 27 ± 1 ms) but increased with verapamil (30 ± 0 versus 37 ± 1 ms) demonstrating pharmacological activity of each agent. Both SCBs, caused statistically significant (p < .05) increases in both intervals - quinidine (100 mg/kg; PR: 50 ± 2 versus 43 ± 1 ms; QRS: 22 ± 2 versus 18 ± 1 ms) and flecainide (9 mg/kg; PR: 56 ± 1 versus 46 ± 1 ms; QRS: 27 ± 1 versus 21 ± 1 ms). Drug plasma exposure was confirmed in all animals. DISCUSSION At similar plasma concentrations to other species, the conscious telemetered rat demonstrates limited utility in assessing PR interval prolongation by CCBs, despite significant contractility effects being observed. However, results with SCBs demonstrate a potential application for evaluating drug-induced QRS prolongation.
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Affiliation(s)
- Oladipupo Adeyemi
- AstraZeneca, R&D Biopharmaceuticals, Fleming Building (B623), Babraham Research Park, Babraham, Cambridgeshire CB22 3AT, United Kingdom.
| | - Nicole Parker
- AstraZeneca, R&D Oncology, Fleming Building (B623), Babraham Research Park, Babraham, Cambridgeshire CB22 3AT, United Kingdom
| | - Amy Pointon
- AstraZeneca, R&D Biopharmaceuticals, Darwin Building, Unit 310, Cambridge Science Park, Milton Road, United Kingdom
| | - Mike Rolf
- AstraZeneca, R&D Biopharmaceuticals, Pepparedsleden 1, 431 83 Mölndal, Sweden
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Development of an Exercise Training Protocol to Investigate Arteriogenesis in a Murine Model of Peripheral Artery Disease. Int J Mol Sci 2019; 20:ijms20163956. [PMID: 31416228 PMCID: PMC6720754 DOI: 10.3390/ijms20163956] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 01/19/2023] Open
Abstract
Exercise is a treatment option in peripheral artery disease (PAD) patients to improve their clinical trajectory, at least in part induced by collateral growth. The ligation of the femoral artery (FAL) in mice is an established model to induce arteriogenesis. We intended to develop an animal model to stimulate collateral growth in mice through exercise. The training intensity assessment consisted of comparing two different training regimens in C57BL/6 mice, a treadmill implementing forced exercise and a free-to-access voluntary running wheel. The mice in the latter group covered a much greater distance than the former pre- and postoperatively. C57BL/6 mice and hypercholesterolemic ApoE-deficient (ApoE−/−) mice were subjected to FAL and had either access to a running wheel or were kept in motion-restricting cages (control) and hind limb perfusion was measured pre- and postoperatively at various times. Perfusion recovery in C57BL/6 mice was similar between the groups. In contrast, ApoE−/− mice showed significant differences between training and control 7 d postoperatively with a significant increase in pericollateral macrophages while the collateral diameter did not differ between training and control groups 21 d after surgery. ApoE−/− mice with running wheel training is a suitable model to simulate exercise induced collateral growth in PAD. This experimental set-up may provide a model for investigating molecular training effects.
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18
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Debi R, Lakin R, Spector S. Mid‐life crisis or mid‐life gains: 2 years of high‐intensity exercise is highly beneficial for the middle‐aged heart. J Physiol 2019; 597:1787-1788. [DOI: 10.1113/jp277752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ryan Debi
- Department of BiologyYork University Toronto Ontario M3J 1P3 Canada
| | - Robert Lakin
- Department of BiologyYork University Toronto Ontario M3J 1P3 Canada
| | - Steven Spector
- Department of BiologyYork University Toronto Ontario M3J 1P3 Canada
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