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Barrett MS, Hegarty DM, Habecker BA, Aicher SA. Distinct morphology of cardiac- and brown adipose tissue-projecting neurons in the stellate ganglia of mice. Physiol Rep 2022; 10:e15334. [PMID: 35621038 PMCID: PMC9136702 DOI: 10.14814/phy2.15334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/02/2022] [Accepted: 05/07/2022] [Indexed: 11/24/2022] Open
Abstract
Sympathetic neurons that innervate the heart are located primarily in the stellate ganglia (SG), which also contains neurons that project to brown adipose tissue (BAT). These studies were designed to examine the morphology of these two populations (cardiac- and BAT-projecting) and their target connectivity. We examined SG neurons in C57BL/6J mice following injections of the retrograde tracer cholera toxin B (CTb) conjugated to Alexa Fluor 488 and Alexa Fluor 555, into cardiac tissue and intrascapular BAT. BAT-projecting SG neurons were widely dispersed in SG, while cardiac-projecting SG neurons were localized primarily near the inferior cardiac nerve base. SG neurons were not dual-labeled, suggesting that sympathetic innervation is specific to the heart and BAT, supporting the idea of "labeled lines" of efferents. Morphologically, cardiac-projecting SG somata had more volume and were less abundant than BAT-projecting neurons using our tracer-labeling paradigm. We found a positive correlation between the number of primary dendrites per neuron and soma volume in cardiac-projecting SG neurons, though not in BAT-projecting neurons. In both SG subpopulations, the number of cholinergic inputs marked with vesicular acetylcholine transporter (VAChT) puncta contacting the soma was positively correlated to soma volume, suggesting scaling of inputs across a range of neuronal sizes. In separate studies using dual tracing from left and right BAT, we found that BAT-projecting SG neurons were located predominately ipsilateral to the injection, but a small subset of SG neurons project bilaterally to BAT. This tracing approach will allow the assessment of cell-specific mechanisms of plasticity within subpopulations of SG neurons.
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Affiliation(s)
- Madeleine S Barrett
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, Oregon, USA
| | - Deborah M Hegarty
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, Oregon, USA
| | - Beth A Habecker
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, Oregon, USA
| | - Sue A Aicher
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, Oregon, USA
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Effects of Resistance Training on Oxidative Stress Markers and Muscle Damage in Spinal Cord Injured Rats. BIOLOGY 2021; 11:biology11010032. [PMID: 35053030 PMCID: PMC8772953 DOI: 10.3390/biology11010032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/15/2021] [Accepted: 12/18/2021] [Indexed: 01/24/2023]
Abstract
Simple Summary Spinal Cord Injury is a devastating condition that compromises the individual’s health, quality of life and functional independence. Rats submitted to Spinal Cord Injury were evaluated after four weeks of resistance training. Analyses of levels of muscle damage and oxidative stress surgery were performed. Resistance training demonstrated increase antioxidative activity while decreased oxidative damage in injured rats, in addition to having presented changes in the levels of muscle damage in that same group. The results highlight that resistance training promoted a decrease in oxidative stress and a significant response in muscle damage markers. Abstract Background: Spinal cord injury (SCI) is a condition that affects the central nervous system, is characterized by motor and sensory impairments, and impacts individuals’ lives. The objective of this study was to evaluate the effects of resistance training on oxidative stress and muscle damage in spinal cord injured rats. Methodology: Forty Wistar rats were selected and divided equally into five groups: Healthy Control (CON), Sham (SHAM) SCI Untrained group (SCI-U), SCI Trained group (SCI- T), SCI Active Trained group (SCI- AT). Animals in the trained groups were submitted to an incomplete SCI at T9. Thereafter, they performed a protocol of resistance training for four weeks. Results: Significant differences in muscle damage markers and oxidative stress in the trained groups, mainly in SCI- AT, were found. On the other hand, SCI- U group presented higher levels of oxidative stress and biomarkers of LDH and AST. Conclusion: The results highlight that resistance training promoted a decrease in oxidative stress and a significative response in muscle damage markers.
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The Preventive Effect of Cardiac Sympathetic Denervation Induced by 6-OHDA on Myocardial Ischemia-Reperfusion Injury: The Changes of lncRNA/circRNAs-miRNA-mRNA Network of the Upper Thoracic Spinal Cord in Rats. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:2492286. [PMID: 34880964 PMCID: PMC8648479 DOI: 10.1155/2021/2492286] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 09/13/2021] [Indexed: 02/07/2023]
Abstract
In this study, we investigated whether chemical 6-hydroxydopamine (6-OHDA) stimuli caused cardiac sympathetic denervation (SD), and we analyzed gene expression profiles to determine the changes in the lncRNA/circRNAs-miRNA-mRNA network in the affected spinal cord segments to identify putative target genes and molecular pathways in rats with myocardial ischemia–reperfusion injury (MIRI). Our results showed that cardiac sympathetic denervation induced by 6-OHDA alleviated MIRI. Compared with the ischemia reperfusion (IR, MIRI model) group, there were 148 upregulated and 51 downregulated mRNAs, 165 upregulated and 168 downregulated lncRNAs, 70 upregulated and 52 downregulated circRNAs, and 12 upregulated and 11 downregulated miRNAs in the upper thoracic spinal cord of the SD-IR group. Furthermore, we found that the differential genes related to cellular components were mainly enriched in extracellular and cortical cytoskeleton, and molecular functions were mainly enriched in chemokine activity. Pathway analysis showed that the differentially expressed genes were mainly related to the interaction of cytokines and cytokine receptors, sodium ion reabsorption, cysteine and methionine metabolism, mucoglycan biosynthesis, cGMP-PKG signaling pathway, and MAPK signaling pathway. In conclusion, the lncRNA/circRNAs-miRNA-mRNA networks in the upper thoracic spinal cord play an important role in the preventive effect of cardiac sympathetic denervation induced by 6-OHDA on MIRI, which offers new insights into the pathogenesis of MIRI and provides new targets for MIRI.
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Getsy PM, Coffee GA, Hsieh YH, Lewis SJ. Loss of Cervical Sympathetic Chain Input to the Superior Cervical Ganglia Affects the Ventilatory Responses to Hypoxic Challenge in Freely-Moving C57BL6 Mice. Front Physiol 2021; 12:619688. [PMID: 33967819 PMCID: PMC8100345 DOI: 10.3389/fphys.2021.619688] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/30/2021] [Indexed: 11/13/2022] Open
Abstract
The cervical sympathetic chain (CSC) innervates post-ganglionic sympathetic neurons within the ipsilateral superior cervical ganglion (SCG) of all mammalian species studied to date. The post-ganglionic neurons within the SCG project to a wide variety of structures, including the brain (parenchyma and cerebral arteries), upper airway (e.g., nasopharynx and tongue) and submandibular glands. The SCG also sends post-ganglionic fibers to the carotid body (e.g., chemosensitive glomus cells and microcirculation), however, the function of these connections are not established in the mouse. In addition, nothing is known about the functional importance of the CSC-SCG complex (including input to the carotid body) in the mouse. The objective of this study was to determine the effects of bilateral transection of the CSC on the ventilatory responses [e.g., increases in frequency of breathing (Freq), tidal volume (TV) and minute ventilation (MV)] that occur during and following exposure to a hypoxic gas challenge (10% O2 and 90% N2) in freely-moving sham-operated (SHAM) adult male C57BL6 mice, and in mice in which both CSC were transected (CSCX). Resting ventilatory parameters (19 directly recorded or calculated parameters) were similar in the SHAM and CSCX mice. There were numerous important differences in the responses of CSCX and SHAM mice to the hypoxic challenge. For example, the increases in Freq (and associated decreases in inspiratory and expiratory times, end expiratory pause, and relaxation time), and the increases in MV, expiratory drive, and expiratory flow at 50% exhaled TV (EF50) occurred more quickly in the CSCX mice than in the SHAM mice, although the overall responses were similar in both groups. Moreover, the initial and total increases in peak inspiratory flow were higher in the CSCX mice. Additionally, the overall increases in TV during the latter half of the hypoxic challenge were greater in the CSCX mice. The ventilatory responses that occurred upon return to room-air were essentially similar in the SHAM and CSCX mice. Overall, this novel data suggest that the CSC may normally provide inhibitory input to peripheral (e.g., carotid bodies) and central (e.g., brainstem) structures that are involved in the ventilatory responses to hypoxic gas challenge in C57BL6 mice.
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Affiliation(s)
- Paulina M Getsy
- Department of Pediatrics, Division of Pulmonology, Allergy and Immunology, Case Western Reserve University, Cleveland, OH, United States.,The Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, United States
| | - Gregory A Coffee
- Department of Pediatrics, Division of Pulmonology, Allergy and Immunology, Case Western Reserve University, Cleveland, OH, United States
| | - Yee-Hsee Hsieh
- Division of Pulmonary, Critical Care and Sleep Medicine, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, United States
| | - Stephen J Lewis
- Department of Pediatrics, Division of Pulmonology, Allergy and Immunology, Case Western Reserve University, Cleveland, OH, United States.,Department of Pharmacology, Case Western Reserve University, Cleveland, OH, United States
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5
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Thoracic sympathetic nuclei ischemia: Effects on lower heart rates following experimentally induced spinal subarachnoid hemorrhage. Neurochirurgie 2020; 66:155-161. [PMID: 32387429 DOI: 10.1016/j.neuchi.2019.12.016] [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: 08/22/2019] [Revised: 12/09/2019] [Accepted: 12/26/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND The neuropathological mechanism of heart rhythm disorders, following spinal cord pathologies, to our knowledge, has not yet been adequately investigated. In this study, the effect of the ischemic neurodegeneration of the thoracic sympathetic nuclei (TSN) on the heart rate (HR) was examined following a spinal subarachnoid hemorrhage (SSAH). METHODS This study was conducted on 22 rabbits. Five rabbits were used as a control group, five as SHAM, and twelve as a study group. The animals' HRs were recorded via monitoring devices on the first day, and those results were accepted as baseline values. The HRs were remeasured after injecting 0.5 cc of isotonic saline for SHAM and 0.5 cc of autolog arterial blood into the thoracic spinal subarachnoid space at T4-T5 for the study group. After a three-week follow-up with continuous monitoring of their HRs, the rabbit's thoracic spinal cords and stellate ganglia were extracted. The specimens were evaluated by histopathological methods. The densities of degenerated neurons in the TSN and stellate ganglia were compared with the HRs. RESULTS The mean HRs and mean degenerated neuron density of the TSN and stellate ganglia in control group were 251±18/min, 5±2/mm3, and 3±1/mm3, respectively. The mean HRs and the mean degenerated neuron density of the TSN and stellate ganglia were detected as 242±13/min, 6±2/mm3, and 4±2/mm3 in SHAM (P>0.05 vs. control); 176±19/min, 94±12/mm3, and 28±6/mm3 in the study group (P<0.0001 vs. control and P<0.005 vs. SHAM), respectively. CONCLUSIONS SAH induced TSN neurodegeneration may have been responsible for low HRs following SSAH. To date this has not been mentioned in the literature.
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Lujan HL, DiCarlo SE. Direct comparison of cervical and high thoracic spinal cord injury reveals distinct autonomic and cardiovascular consequences. J Appl Physiol (1985) 2020; 128:554-564. [PMID: 31999525 DOI: 10.1152/japplphysiol.00721.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A wide range of spinal cord levels (cervical 8-thoracic 6) project to the stellate ganglia (which provides >90% of sympathetic supply to the heart), with a peak at the thoracic 2 (T2) level. We hypothesize that despite the proximity of the lesions, high thoracic spinal cord injuries (i.e., T2-3 SCI) do not closely mimic the hemodynamic responses recorded with cervical SCI (i.e., C6-7 SCI). To test this hypothesis, rats were instrumented with an intra-arterial telemetry device (Data Sciences International PA-C40) for recording arterial pressure, heart rate, and locomotor activity as well as a catheter within the intraperitoneal space. After recovery, rats were subjected to complete C6-7 spinal cord transection (n = 8), sham transection (n = 4), or T2-3 spinal cord transection (n = 7). After the spinal cord transection or sham transection, arterial pressure, heart rate, and activity counts were recorded in conscious animals, in a thermoneutral environment, for 20 s every minute, 24 h/day for 12 consecutive weeks. After 12 wk, chronic reflex- and stress-induced cardiovascular and hormonal responses were compared in all groups. C6-7 rats had hypotension, bradycardia, and reduced physical activity. In contrast, T2-3 rats were tachycardic. C6-7 rats compared with T2-3 and spinal intact rats also had reduced cardiac sympathetic tonus, reduced reflex- and stress induced cardiovascular responses, and reduced sympathetic support of blood pressure as well as enhanced reliance on angiotensin to maintain arterial blood pressure. Thus injuries above and below the peak level (T2) of spinal cord projections to the stellate ganglia have remarkably different outcomes.NEW & NOTEWORTHY Twelve consecutive weeks of resting hemodynamic data as well as chronic reflex- and stress-induced cardiovascular, autonomic, and hormonal responses were compared in spinal intact and C6-7 and T2-3 spinal cord-transected rats. C6-7 rats compared with T2-3 and spinal intact rats had reduced cardiac sympathetic tonus, reduced reflex- and stress-induced cardiovascular responses, and reduced sympathetic support of blood pressure as well as enhanced reliance on angiotensin to maintain arterial blood pressure. Thus injuries above and below the peak level (T2) of spinal cord projections to the stellate ganglia have remarkably different outcomes.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan
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Sangsiri S, Xu H, Fernandes R, Fink GD, Lujan HL, DiCarlo SE, Galligan JJ. Spinal cord injury alters purinergic neurotransmission to mesenteric arteries in rats. Am J Physiol Heart Circ Physiol 2019; 318:H223-H237. [PMID: 31774690 DOI: 10.1152/ajpheart.00525.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Complications associated with spinal cord injury (SCI) result from unregulated reflexes below the lesion level. Understanding neurotransmission distal to the SCI could improve quality of life by mitigating complications. The long-term impact of SCI on neurovascular transmission is poorly understood, but reduced sympathetic activity below the site of SCI enhances arterial neurotransmission (1). We studied sympathetic neurovascular transmission using a rat model of long-term paraplegia (T2-3) and tetraplegia (C6-7). Sixteen weeks after SCI, T2-3 and C6-7 rats had lower blood pressure (BP) than sham rats (103 ± 2 and 97 ± 4 vs. 117 ± 6 mmHg, P < 0.05). T2-3 rats had tachycardia (410 ± 6 beats/min), and C6-7 rats had bradycardia (299 ± 10 beats/min) compared with intact rats (321 ± 4 beats/min, P < 0.05). Purinergic excitatory junction potentials (EJPs) were measured in mesenteric arteries (MA) using microlectrodes, and norepinephrine (NE) release was measured using amperometry. NE release was similar in all groups, while EJP frequency-response curves from T2-3 and C6-7 rats were left-shifted vs. sham rats. EJPs in T2-3 and C6-7 rats showed facilitation followed by run-down during stimulation trains (10 Hz, 50 stimuli). MA reactivity to exogenous NE and ATP was similar in all rats. In T2-3 and C6-7 rats, NE content was increased in left cardiac ventricles compared with intact rats, but was not changed in MA, kidney, or spleen. Our data indicate that peripheral purinergic, but not adrenergic, neurotransmission increases following SCI via enhanced ATP release from periarterial nerves. Sympathetic BP support is reduced after SCI, but improving neurotransmitter release might maintain cardiovascular stability in individuals living with SCI.NEW & NOTEWORTHY This study revealed increased purinergic, but not noradrenergic, neurotransmission to mesenteric arteries in rats with spinal cord injury (SCI). An increased releasable pool of ATP in periarterial sympathetic nerves may contribute to autonomic dysreflexia following SCI, suggesting that purinergic neurotransmission may be a therapeutic target for maintaining stable blood pressure in individuals living with SCI. The selective increase in ATP release suggests that ATP and norepinephrine may be stored in separate synaptic vesicles in periarterial sympathetic varicosities.
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Affiliation(s)
- Sutheera Sangsiri
- Department of Preclinical Science, Thammasat University, Pathumthani, Thailand.,Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Hui Xu
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan.,Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Roxanne Fernandes
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Greg D Fink
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan.,Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Heidi L Lujan
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - James J Galligan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan.,Neuroscience Program, Michigan State University, East Lansing, Michigan
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Lujan HL, Tonson A, Wiseman RW, DiCarlo SE. Chronic, complete cervical 6-7 cord transection: distinct autonomic and cardiac deficits. J Appl Physiol (1985) 2018; 124:1471-1482. [PMID: 29470149 DOI: 10.1152/japplphysiol.01104.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Spinal cord injury (SCI) resulting in tetraplegia is a devastating, life-changing insult causing paralysis and sensory impairment as well as distinct autonomic dysfunction that triggers compromised cardiovascular, bowel, bladder, and sexual activity. Life becomes a battle for independence as even routine bodily functions and the smallest activity of daily living become major challenges. Accordingly, there is a critical need for a chronic preclinical model of tetraplegia. This report addresses this critical need by comparing, for the first time, resting-, reflex-, and stress-induced cardiovascular, autonomic, and hormonal responses each week for 4 wk in 12 sham-operated intact rats and 12 rats with chronic, complete C6-7 spinal cord transection. Loss of supraspinal control to all sympathetic preganglionic neurons projecting to the heart and vasculature resulted in a profound bradycardia and hypotension, reduced cardiac sympathetic and parasympathetic tonus, reduced reflex- and stress-induced sympathetic responses, and reduced sympathetic support of blood pressure as well as enhanced reliance on angiotensin to maintain arterial blood pressure. Histological examination of the nucleus ambiguus and stellate ganglia supports the profound and distinct autonomic and cardiac deficits and reliance on angiotensin to maintain cardiovascular stability following chronic, complete cervical6-7 cord transection. NEW & NOTEWORTHY For the first time, resting-, reflex-, and stress-induced cardiovascular, autonomic, and hormonal responses were studied in rats with chronic, complete C6-7 cord transection. Loss of supraspinal control of all sympathetic preganglionic neurons reduced cardiac sympathetic and parasympathetic tonus, reflex and stress-induced sympathetic responses, and sympathetic support of blood pressure as well as enhanced reliance on angiotensin to maintain arterial blood pressure. Histological examination supports the distinct deficits associated with cervical cord injury.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Michigan State University College of Osteopathic Medicine , East Lansing, Michigan
| | - Anne Tonson
- Department of Physiology, Michigan State University College of Osteopathic Medicine , East Lansing, Michigan
| | - Robert W Wiseman
- Department of Physiology, Michigan State University College of Osteopathic Medicine , East Lansing, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Michigan State University College of Osteopathic Medicine , East Lansing, Michigan
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Squair JW, DeVeau KM, Harman KA, Poormasjedi-Meibod MS, Hayes B, Liu J, Magnuson DS, Krassioukov AV, West CR. Spinal Cord Injury Causes Systolic Dysfunction and Cardiomyocyte Atrophy. J Neurotrauma 2018; 35:424-434. [PMID: 28599602 PMCID: PMC9836687 DOI: 10.1089/neu.2017.4984] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Individuals with spinal cord injury (SCI) have been shown to exhibit systolic, and to a lesser extent, diastolic cardiac dysfunction. However, previous reports of cardiac dysfunction in this population are confounded by the changing loading conditions after SCI and as such, whether cardiac dysfunction per se is present is still unknown. Therefore, our aim was to establish if load-independent cardiac dysfunction is present after SCI, to understand the functional cardiac response to SCI, and to explore the changes within the cellular milieu of the myocardium. Here, we applied in vivo echocardiography and left-ventricular (LV) pressure-volume catheterization with dobutamine infusions to our Wistar rodent model of cardiac dysfunction 5 weeks following high (T2) thoracic contusion SCI, while also examining the morphological and transcriptional alterations of cardiomyocytes. We found that SCI significantly impairs systolic function independent of loading conditions (end-systolic elastance in control: 1.35 ± 0.15; SCI: 0.65 ± 0.19 mm Hg/μL). The reduction in contractile indices is accompanied by a reduction in width and length of cardiomyocytes as well as alterations in the LV extracellular matrix. Importantly, we demonstrate that the reduction in the rate (dP/dtmax) of LV pressure rise can be offset with beta-adrenergic stimulation, thereby experimentally implicating the loss of descending sympatho-excitatory control of the heart as a principle cause of LV dysfunction in SCI. Our data provide evidence that SCI induces systolic cardiac dysfunction independent of loading conditions and concomitant cardiomyocyte atrophy that may be underpinned by changes in the genes regulating the cardiac extracellular matrix.
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Affiliation(s)
- Jordan W. Squair
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- MD/PhD Training Program, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kathryn M. DeVeau
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
| | - Kathryn A. Harman
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
| | - Malihe-Sadat Poormasjedi-Meibod
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Brian Hayes
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jie Liu
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
| | - David S.K. Magnuson
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
| | - Andrei V. Krassioukov
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, British Columbia, Canada
- GF Strong Rehabilitation Centre, Vancouver Health Authority, Vancouver, British Columbia, Canada
| | - Christopher R. West
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
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10
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Squair JW, Liu J, Tetzlaff W, Krassioukov AV, West CR. Spinal cord injury-induced cardiomyocyte atrophy and impaired cardiac function are severity dependent. Exp Physiol 2018; 103:179-189. [PMID: 29235182 DOI: 10.1113/ep086549] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 11/13/2017] [Indexed: 12/30/2022]
Abstract
NEW FINDINGS What is the central question of this study? How does the severity of spinal cord injury affect left ventricular mechanics, function and the underlying cardiomyocyte morphology? What is the main finding and its importance? Here, we show that severe, but not moderate, spinal cord injury causes cardiomyocyte atrophy, altered left ventricular mechanics and impaired cardiac function. The principal aim of the present study was to assess how the severity of spinal cord injury (SCI) affects left ventricular (LV) mechanics, function and underlying cardiomyocyte morphology. Here, we used different severities of T3 spinal cord contusions (MODERATE, 200 kdyn contusion; SEVERE, 400 kdyn contusion; SHAM) and combined standard echocardiography with speckle tracking analyses to investigate in vivo cardiac function and deformation (contractility) after experimental SCI in the Wistar rat. In addition, we investigated changes in the intrinsic structure of cardiac myocytes ex vivo. We demonstrate that SEVERE SCI induces a characteristic decline in LV chamber size and a reduction in in vivo LV deformation (i.e. radial strain) throughout the entire systolic portion of the cardiac cycle [25.6 ± 3.0 versus 44.5 ± 8.1% (Pre-injury); P = 0.0029]. SEVERE SCI also caused structural changes in cardiomyocytes, including decreased length [115.6 ± 7.63 versus 125.8 ± 6.75 μm (SHAM); P = 0.0458], decreased width [7.78 ± 0.71 versus 10.78 ± 1.08 μm (SHAM); P = 0.0015] and an increase in the length/width ratio [14.88 ± 0.66 versus 11.74 ± 0.89 (SHAM); P = 0.0018], which was significantly correlated with LV flow-generating capacity after SCI (i.e. stroke volume, R2 = 0.659; P = 0.0013). Rats with MODERATE SCI exhibited no changes in any metric versus SHAM. This is the first study to demonstrate that the severity of SCI determines the course of changes in the intrinsic structure of cardiomyocytes, which are directly related to contractile function of the LV.
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Affiliation(s)
- Jordan W Squair
- International Collaboration of Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada.,MD/PhD Training Program, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jie Liu
- International Collaboration of Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Wolfram Tetzlaff
- International Collaboration of Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada.,Department of Zoology, Faculty of Science, University of British Columbia, Vancouver, BC, Canada.,Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Andrei V Krassioukov
- International Collaboration of Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada.,Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, BC, Canada.,GF Strong Rehabilitation Centre, Vancouver Health Authority, University of British Columbia, Vancouver, BC, Canada
| | - Christopher R West
- International Collaboration of Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada.,School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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Biering-Sørensen F, Biering-Sørensen T, Liu N, Malmqvist L, Wecht JM, Krassioukov A. Alterations in cardiac autonomic control in spinal cord injury. Auton Neurosci 2018; 209:4-18. [DOI: 10.1016/j.autneu.2017.02.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 01/30/2017] [Accepted: 02/14/2017] [Indexed: 01/22/2023]
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12
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Wang K, Duan S, Wen X, Wang W, Fang S, Qi D, Huan X, Wang L, He Z. Angiotensin II system in the nucleus tractus solitarii contributes to autonomic dysreflexia in rats with spinal cord injury. PLoS One 2017; 12:e0181495. [PMID: 28742157 PMCID: PMC5524360 DOI: 10.1371/journal.pone.0181495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 07/03/2017] [Indexed: 11/25/2022] Open
Abstract
Background Autonomic dysreflexia (AD) is a potentially life-threating complication after spinal cord injury (SCI), characterized by episodic hypertension induced by colon or bladder distension. The objective of this study was to determine the role of impaired baroreflex regulation by the nucleus tractus solitarii(NTS) in the occurrence of AD in a rat model. Methods T4 spinal cord transection animal model was used in this study, which included 40 Male rats Colorectal distension (CD) was performed to assess AD and compare the changes of BP, HR, and BRS, six weeks after operation. After that, SCI rats with successfully induced AD were selected. Losartan was microinjected into NTS in SCI rats, then 10, 30, 60 minutes later, CD was performed to calculate the changes of BP, HR, and BRS in order to explicit whether Ang II system was involved in the AD occurrence. Ang II was then Intra-cerebroventricular infused in sham operation rats with CD to mimic the activation of Ang II system in AD. Finally, the level of Ang II in NTS and colocalization of AT1R and NMDA receptor within the NTS neurons were also detected in SCI rats. Results Compared with sham operation, SCI significantly aggravated the elevation of blood pressure (BP) and impaired baroreflex sensitivity (BRS) induced by colorectal distension; both of which were significantly improved by microinjection of the angiotensin receptor type I (AT1R) antagonist losartan into the NTS. Level of angiotensin II (Ang II) in the NTS was significantly increased in the SCI rats than sham. Intracerebroventricular infusion of Ang II also mimicked changes in BP and BRS induced by colorectal distension. Blockade of baroreflex by sinoaortic denervation prevented beneficial effect of losartan on AD. Conclusion We concluded that the activation of Ang II system in NTS may impair blood pressure baroreflex, and contribute to AD after SCI.
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Affiliation(s)
- Kai Wang
- Department of Anesthesiology, Central Hospital of Xuzhou, Jiangsu, China
| | - Shaoxia Duan
- Department of Anesthesiology and ICU, South Campus, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xueping Wen
- Department of Orthopedics, Ningxiang People’s Hospital of Hunan Province, Ningxiang, Hunan, China
| | - Weizhong Wang
- Department of Physiology, Second Military Medical University, Shanghai, China
| | - Shangping Fang
- Department of Anesthesiology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Dunyi Qi
- Department of Anesthesiology, Affiliated Hospital of Xuzhou Medical University, Jiangsu, China
| | - Xiang Huan
- Department of Anesthesiology, Central Hospital of Xuzhou, Jiangsu, China
| | - Liwei Wang
- Department of Anesthesiology, Central Hospital of Xuzhou, Jiangsu, China
- * E-mail: (ZH); (LW)
| | - Zhenzhou He
- Department of Anesthesiology and ICU, South Campus, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- * E-mail: (ZH); (LW)
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13
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Popok DW, West CR, McCracken L, Krassioukov AV. Effects of early and delayed initiation of exercise training on cardiac and haemodynamic function after spinal cord injury. Exp Physiol 2017; 102:154-163. [DOI: 10.1113/ep085978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/28/2016] [Indexed: 11/08/2022]
Affiliation(s)
- David W. Popok
- International Collaboration on Repair Discoveries (ICORD); University of British Columbia; Vancouver BC Canada
| | - Christopher R. West
- International Collaboration on Repair Discoveries (ICORD); University of British Columbia; Vancouver BC Canada
- School of Kinesiology; Faculty of Education; University of British Columbia; Vancouver BC Canada
| | - Laura McCracken
- International Collaboration on Repair Discoveries (ICORD); University of British Columbia; Vancouver BC Canada
| | - Andrei V. Krassioukov
- International Collaboration on Repair Discoveries (ICORD); University of British Columbia; Vancouver BC Canada
- Faculty of Medicine; Division of Physical Medicine and Rehabilitation; University of British Columbia; Vancouver BC Canada
- GF Strong Rehabilitation Centre; Vancouver Coastal Health; Vancouver BC Canada
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14
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Gardner RT, Ripplinger CM, Myles RC, Habecker BA. Molecular Mechanisms of Sympathetic Remodeling and Arrhythmias. Circ Arrhythm Electrophysiol 2016; 9:e001359. [PMID: 26810594 DOI: 10.1161/circep.115.001359] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Ryan T Gardner
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.)
| | - Crystal M Ripplinger
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.)
| | - Rachel C Myles
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.)
| | - Beth A Habecker
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.).
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15
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Sharif H, Allison D, O'Leary D, Ditor D. Reproducibility of the QT-variability index in individuals with spinal cord injury. Auton Neurosci 2016; 195:16-9. [DOI: 10.1016/j.autneu.2016.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 12/16/2015] [Accepted: 02/07/2016] [Indexed: 11/28/2022]
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16
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Phillips AA, Matin N, Frias B, Zheng MMZ, Jia M, West C, Dorrance AM, Laher I, Krassioukov AV. Rigid and remodelled: cerebrovascular structure and function after experimental high-thoracic spinal cord transection. J Physiol 2016; 594:1677-88. [PMID: 26634420 DOI: 10.1113/jp270925] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 11/18/2015] [Indexed: 12/25/2022] Open
Abstract
High-thoracic or cervical spinal cord injury (SCI) is associated with several critical clinical conditions related to impaired cerebrovascular health, including: 300-400% increased risk of stroke, cognitive decline and diminished cerebral blood flow regulation. The purpose of this study was to examine the influence of high-thoracic (T3 spinal segment) SCI on cerebrovascular structure and function, as well as molecular markers of profibrosis. Seven weeks after complete T3 spinal cord transection (T3-SCI, n = 15) or sham injury (Sham, n = 10), rats were sacrificed for either middle cerebral artery (MCA) structure and function assessments via ex vivo pressure myography, or immunohistochemical analyses. Myogenic tone was unchanged, but over a range of transmural pressures, inward remodelling occurred after T3-SCI with a 40% reduction in distensibility (both P < 0.05), and a 33% reduction in vasoconstrictive reactivity to 5-HT trending toward significance (P = 0.09). After T3-SCI, the MCA had more collagen I (42%), collagen III (24%), transforming growth factor β (47%) and angiotensin II receptor type 2 (132%), 27% less elastin as well as concurrent increased wall thickness and reduced lumen diameter (all P < 0.05). Sympathetic innervation (tyrosine hydroxylase-positive axon density) and endothelium-dependent dilatation (carbachol) of the MCA were not different between groups. This study demonstrates profibrosis and hypertrophic inward remodelling within the largest cerebral artery after high-thoracic SCI, leading to increased stiffness and possibly impaired reactivity. These deleterious adaptations would substantially undermine the capacity for regulation of cerebral blood flow and probably underlie several cerebrovascular clinical conditions in the SCI population.
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Affiliation(s)
- A A Phillips
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,Centre for Heart, Lung, and Vascular Health, Faculty of Health and Social Development, University of British Columbia, Vancouver, Canada
| | - N Matin
- Pharmacology, Michigan State University, East Lansing, MI, USA
| | - B Frias
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - M M Z Zheng
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - M Jia
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - C West
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - A M Dorrance
- Pharmacology, Michigan State University, East Lansing, MI, USA
| | - I Laher
- Deptartment of Pharmacology and Therapeutic, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - A V Krassioukov
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,GF Strong Rehabilitation Center, Vancouver Coastal Health, Vancouver, Canada.,Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, Vancouver, Canada
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17
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Sankari A, Bascom AT, Riehani A, Badr MS. Tetraplegia is associated with enhanced peripheral chemoreflex sensitivity and ventilatory long-term facilitation. J Appl Physiol (1985) 2015; 119:1183-93. [PMID: 26272316 DOI: 10.1152/japplphysiol.00088.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 08/06/2015] [Indexed: 11/22/2022] Open
Abstract
Cardiorespiratory plasticity induced by acute intermittent hypoxia (AIH) may contribute to recovery following spinal cord injury (SCI). We hypothesized that patients with cervical SCI would demonstrate higher minute ventilation (V̇e) following AIH compared with subjects with thoracic SCI and able-bodied subjects who served as controls. Twenty-four volunteers (8 with cervical SCI, 8 with thoracic SCI, and 8 able-bodied) underwent an AIH protocol during wakefulness. Each subject experienced 15 episodes of isocapnic hypoxia using mixed gases of 100% nitrogen (N2), 8% O2, and 40% CO2 to achieve oxygen saturation ≤90% followed by room air (RA). Measurements were obtained before, during, and 40 min after AIH to obtain ventilation and heart rate variability data [R-R interval (RRI) and low-frequency/high-frequency power (LF/HF)]. AIH results were compared with those of sham studies conducted in RA during the same time period. Individuals with cervical SCI had higher V̇e after AIH compared with able-bodied controls (117.9 ± 23.2% vs. 97.9 ± 11.2%, P < 0.05). RRI decreased during hypoxia in all individuals (those with cervical SCI, from 1,009.3 ± 65.0 ms to 750.2 ± 65.0 ms; those with thoracic SCI, from 945.2 ± 65.0 ms to 674.9 ± 65.0 ms; and those who were able-bodied, from 949 ± 75.0 to 682.2 ± 69.5 ms; P < 0.05). LH/HF increased during recovery in individuals with thoracic SCI and those who were able-bodied (0.54 ± 0.22 vs. 1.34 ± 0.22 and 0.67 ± 0.23 vs. 1.82 ± 0.23, respectively; P < 0.05) but remained unchanged in the group with cervical SCI. Our conclusion is that patients with cervical SCI demonstrate ventilatory long-term facilitation following AIH compared with able-bodied controls. Heart rate responses to hypoxia are acutely present in patients with cervical SCI but are absent during posthypoxic recovery.
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Affiliation(s)
- Abdulghani Sankari
- John D. Dingell VA Medical Center, Detroit, Michigan; Wayne State University, Detroit, Michigan; and
| | - Amy T Bascom
- John D. Dingell VA Medical Center, Detroit, Michigan; Wayne State University, Detroit, Michigan; and
| | | | - M Safwan Badr
- John D. Dingell VA Medical Center, Detroit, Michigan; Wayne State University, Detroit, Michigan; and
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18
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Wecht JM, La Fountaine MF, Handrakis JP, West CR, Phillips A, Ditor DS, Sharif H, Bauman WA, Krassioukov AV. Autonomic Nervous System Dysfunction Following Spinal Cord Injury: Cardiovascular, Cerebrovascular, and Thermoregulatory Effects. CURRENT PHYSICAL MEDICINE AND REHABILITATION REPORTS 2015. [DOI: 10.1007/s40141-015-0093-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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19
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West CR, Popok D, Crawford MA, Krassioukov AV. Characterizing the Temporal Development of Cardiovascular Dysfunction in Response to Spinal Cord Injury. J Neurotrauma 2015; 32:922-30. [DOI: 10.1089/neu.2014.3722] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Christopher R. West
- International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - David Popok
- International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mark A. Crawford
- International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrei V. Krassioukov
- International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, British Columbia, Canada
- GF Strong Rehabilitation Centre, Vancouver Health Authority, Vancouver, British Columbia, Canada
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20
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Lujan HL, Janbaih H, DiCarlo SE. Structural remodeling of the heart and its premotor cardioinhibitory vagal neurons following T(5) spinal cord transection. J Appl Physiol (1985) 2014; 116:1148-55. [PMID: 24610530 PMCID: PMC4097824 DOI: 10.1152/japplphysiol.01285.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 02/28/2014] [Indexed: 12/24/2022] Open
Abstract
Midthoracic spinal cord injury (SCI) is associated with enhanced cardiac sympathetic activity and reduced cardiac parasympathetic activity. The enhanced cardiac sympathetic activity is associated with sympathetic structural plasticity within the stellate ganglia, spinal cord segments T1-T4, and heart. However, changes to cardiac parasympathetic centers rostral to an experimental SCI are relatively unknown. Importantly, reduced vagal activity is a predictor of high mortality. Furthermore, this autonomic dysregulation promotes progressive left ventricular (LV) structural remodeling. Accordingly, we hypothesized that midthoracic spinal cord injury is associated with structural plasticity in premotor (preganglionic parasympathetic neurons) cardioinhibitory vagal neurons located within the nucleus ambiguus as well as LV structural remodeling. To test this hypothesis, dendritic arborization and morphology (cholera toxin B immunohistochemistry and Sholl analysis) of cardiac projecting premotor cardioinhibitory vagal neurons located within the nucleus ambiguus were determined in intact (sham transected) and thoracic level 5 transected (T5X) rats. In addition, LV chamber size, wall thickness, and collagen content (Masson trichrome stain and structural analysis) were determined. Midthoracic SCI was associated with structural changes within the nucleus ambiguus and heart. Specifically, following T5 spinal cord transection, there was a significant increase in cardiac parasympathetic preganglionic neuron dendritic arborization, soma area, maximum dendritic length, and number of intersections/animal. This parasympathetic structural remodeling was associated with a profound LV structural remodeling. Specifically, T5 spinal cord transection increased LV chamber area, reduced LV wall thickness, and increased collagen content. Accordingly, results document a dynamic interaction between the heart and its parasympathetic innervation.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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21
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Zha J, Smith A, Andreansky S, Bracchi-Ricard V, Bethea JR. Chronic thoracic spinal cord injury impairs CD8+ T-cell function by up-regulating programmed cell death-1 expression. J Neuroinflammation 2014; 11:65. [PMID: 24690491 PMCID: PMC4230802 DOI: 10.1186/1742-2094-11-65] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 03/21/2014] [Indexed: 11/10/2022] Open
Abstract
Background Chronic spinal cord injury (SCI) induces immune depression in patients, which contributes to their higher risk of developing infections. While defects in humoral immunity have been reported, complications in T-cell immunity during the chronic phase of SCI have not yet been explored. Methods To assess the impact of chronic SCI on peripheral T-cell number and function we used a mouse model of severe spinal cord contusion at thoracic level T9 and performed flow cytometry analysis on the spleen for T-cell markers along with intracellular cytokine staining. Furthermore we identified alterations in sympathetic activity in the spleen of chronic SCI mice by measuring splenic levels of tyrosine hydroxylase (TH) and norepinephrine (NE). To gain insight into the neurogenic mechanism leading to T-cell dysfunction we performed in vitro NE stimulation of T-cells followed by flow cytometry analysis for T-cell exhaustion marker. Results Chronic SCI impaired both CD4+ and CD8+ T-cell cytokine production. The observed T-cell dysfunction correlated with increased expression of programmed cell death 1 (PD-1) exhaustion marker on these cells. Blocking PD-1 signaling in vitro restored the CD8+ T-cell functional defect. In addition, we showed that chronic SCI mice had higher levels of splenic NE, which contributed to the T-cell exhaustion phenotype, as PD-1 expression on both CD4+ and CD8+ T-cells was up-regulated following sustained exposure to NE in vitro. Conclusions These studies indicate that alteration of sympathetic activity following chronic SCI induces CD8+ T-cell exhaustion, which in turn impairs T-cell function and contributes to immune depression. Inhibition of the exhaustion pathway should be considered as a new therapeutic strategy for chronic SCI-induced immune depression.
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Affiliation(s)
| | | | | | - Valerie Bracchi-Ricard
- The Miami Project to Cure Paralysis, Department of Neurosurgery, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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West CR, Crawford MA, Poormasjedi-Meibod MS, Currie KD, Fallavollita A, Yuen V, McNeill JH, Krassioukov AV. Passive hind-limb cycling improves cardiac function and reduces cardiovascular disease risk in experimental spinal cord injury. J Physiol 2014; 592:1771-83. [PMID: 24535438 DOI: 10.1113/jphysiol.2013.268367] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Spinal cord injury (SCI) causes altered autonomic control and severe physical deconditioning that converge to drive maladaptive cardiac remodelling. We used a clinically relevant experimental model to investigate the cardio-metabolic responses to SCI and to establish whether passive hind-limb cycling elicits a cardio-protective effect. Initially, 21 male Wistar rats were evenly assigned to three groups: uninjured control (CON), T3 complete SCI (SCI) or T3 complete SCI plus passive hind-limb cycling (SCI-EX; 2 × 30 min day(-1), 5 days week(-1) for 4 weeks beginning 6 days post-SCI). On day 32, cardio-metabolic function was assessed using in vivo echocardiography, ex vivo working heart assessments, cardiac histology/molecular biology and blood lipid profiles. Twelve additional rats (n = 6 SCI and n = 6 SCI-EX) underwent in vivo echocardiography and basal haemodynamic assessments pre-SCI and at days 7, 14 and 32 post-SCI to track temporal cardiovascular changes. Compared with CON, SCI exhibited a rapid and sustained reduction in left ventricular dimensions and function that ultimately manifested as reduced contractility, increased myocardial collagen deposition and an up-regulation of transforming growth factor beta-1 (TGFβ1) and mothers against decapentaplegic homolog 3 (Smad3) mRNA. For SCI-EX, the initial reduction in left ventricular dimensions and function at day 7 post-SCI was completely reversed by day 32 post-SCI, and there were no differences in myocardial contractility between SCI-EX and CON. Collagen deposition was similar between SCI-EX and CON. TGFβ1 and Smad3 were down-regulated in SCI-EX. Blood lipid profiles were improved in SCI-EX versus SCI. We provide compelling novel evidence that passive hind-limb cycling prevents cardiac dysfunction and reduces cardiovascular disease risk in experimental SCI.
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Lujan HL, Janbaih H, DiCarlo SE. Dynamic interaction between the heart and its sympathetic innervation following T5 spinal cord transection. J Appl Physiol (1985) 2012; 113:1332-41. [PMID: 22723636 DOI: 10.1152/japplphysiol.00522.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Midthoracic spinal cord injury (SCI) is associated with enhanced sympathetic support of heart rate as well as myocardial damage related to calcium overload. The myocardial damage may elicit an enhanced sympathetic support of contractility to maintain ventricular function. In contrast, the level of inotropic drive may be reduced to match the lower afterload that results from the injury-induced reduction in arterial pressure. Accordingly, the inotropic response to midthoracic SCI may be increased or decreased but has not been investigated and therefore remains unknown. Furthermore, the altered ventricular function may be associated with anatomical changes in cardiac sympathetic innervation. To determine the inotropic drive following midthoracic SCI, a telemetry device was used for repeated measurements of left ventricular (LV) function, with and without beta-adrenergic receptor blockade, in rats before and after midthoracic SCI or sham SCI. In addition, NGF content (ELISA) and dendritic arborization (cholera toxin B immunohistochemistry and Sholl analysis) of cardiac-projecting sympathetic postganglionic neurons in the stellate ganglia were determined. Midthoracic SCI was associated with an enhanced sympathetic support of heart rate, dP/dt(+), and dP/dt(-). Importantly, cardiac function was lower following blockade of the sympathetic nervous system in rats with midthoracic SCI compared with sham-operated rats. Finally, these functional neuroplastic changes were associated with an increased NGF content and structural neuroplasticity within the stellate ganglia. Results document impaired LV function with codirectional changes in chronotropic and inotropic responses following midthoracic SCI. These functional changes were associated with a dynamic interaction between the heart and its sympathetic innervation.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield Ave., Detroit, MI 48201, USA
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Acosta-Rua AJ, Cannon RL, Yezierski RP, Vierck CJ. Sex differences in effects of excitotoxic spinal injury on below-level pain sensitivity. Brain Res 2011; 1419:85-96. [PMID: 21943508 DOI: 10.1016/j.brainres.2011.08.072] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 08/24/2011] [Accepted: 08/30/2011] [Indexed: 11/26/2022]
Abstract
Effects of excitotoxic injury to the thoracic gray matter on sensitivity to below-level nociceptive stimulation were evaluated for female and male Long-Evans rats. Operant escape and lick/guard (L/G) reflex responses to thermal stimulation were evaluated before and for 13-15 weeks after: 1) injections of quisqualic acid (QUIS) into the thoracic gray matter (T8-9), 2) laminectomy and spinal exposure and penetration without injection (sham) or 3) no surgical procedure (control). L/G responding to heat stimulation (44 °C) was unaffected for females and males following thoracic QUIS injections. Similarly, male escape performance was not significantly altered for 44 °C or 10 °C stimulation after QUIS injections or sham surgery. However, escape testing following QUIS and sham injections revealed increased heat sensitivity (44 °C) and decreased cold sensitivity (10 °C) for females. This selective effect is indicative of altered sympathetic activation by the thoracic injections. The effect of sham surgery suggests that female rats are vulnerable to ischemic injury during exposure and manipulation of the spinal cord. Escape from nociceptive heat and cold sensitivity of control males and females was unchanged over 13-15 weeks of testing.
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Affiliation(s)
- Antonio J Acosta-Rua
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, USA
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The correlation between ventricular repolarization and clinical severity of spinal cord injuries. Heart Rhythm 2011; 8:879-84. [PMID: 21277998 DOI: 10.1016/j.hrthm.2011.01.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 01/18/2011] [Indexed: 11/22/2022]
Abstract
BACKGROUND Alteration in ventricular repolarization has been reported in patients with spinal cord injuries (SCIs). However, its clinical impact remains unclear. OBJECTIVE The purpose of this study was to investigate the correlation between SCIs and ventricular repolarization and the associated clinical impact. METHODS One hundred forty-four patients with an SCI were retrospectively reviewed and were divided into two groups (SCI level ≤ T6, n = 110; SCI level >T6, n = 34). The electrocardiograms were reviewed during acute phase (at emergency room) and chronic phase (>1 year). RESULTS There were no differences in the underlying diseases or in ASIA score between the two groups, except there were more patients with tetraplegia among those with an SCI level ≤ T6. For the electrophysiological parameters from the electrocardiograms, the patients with an SCI level ≤ T6 had longer QTc and PR interval than those with an SCI level >T6 during acute phase. In the chronic phase, there were no differences in the electrophysiological parameters between the two groups. Only in patients with an SCI level ≤ T6 did a Kaplan-Meier analysis show that QTc prolongation could predict 30-day mortality after the acute injury. After multivariate Cox regression analysis, only tetraplegia and QTc prolongation were independent predictors of 30-day mortality (odds ratios 7.85 and 34.62, respectively). In patients with an SCI level ≤ T6, the QTc intervals were shorter in the chronic phase than those during the acute phase. CONCLUSION QTc interval was associated with the level of acute SCI and predicted the 30-day mortality.
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Moffitt JA. Editorial Focus: role for neural growth factor in autonomically driven arrhythmogenesis? Focus on: "Structural neuroplasticity following T5 spinal cord transection: increased cardiac sympathetic innervation density and SPN arborization". Am J Physiol Regul Integr Comp Physiol 2010; 299:R983-4. [PMID: 20702797 DOI: 10.1152/ajpregu.00524.2010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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