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Keilholz AN, Pathak I, Smith CL, Osman KL, Smith L, Oti G, Golzy M, Ma L, Lever TE, Nichols NL. Tongue exercise ameliorates structural and functional upper airway deficits in a rodent model of hypoglossal motor neuron loss. Front Neurol 2024; 15:1441529. [PMID: 39296960 PMCID: PMC11408480 DOI: 10.3389/fneur.2024.1441529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Accepted: 08/21/2024] [Indexed: 09/21/2024] Open
Abstract
Introduction Tongue weakness and atrophy can lead to deficits in the vital functions of breathing and swallowing in patients with motor neuron diseases (MNDs; e.g., amyotrophic lateral sclerosis (ALS) and pseudobulbar palsy), often resulting in aspiration pneumonia, respiratory failure, and death. Available treatments for patients with MNDs are largely palliative; thus, there is a critical need for therapies targeting preservation of upper airway function and suggesting a role for tongue exercise in patients with MNDs. Here, we leveraged our inducible rodent model of hypoglossal (XII) motor neuron degeneration to investigate the effects of a strength endurance tongue exercise program on upper airway structure and function. Our model was created through intralingual injection of cholera toxin B conjugated to saporin (CTB-SAP) into the genioglossus muscle of the tongue to induce targeted death of XII motor neurons. Methods Rats in this study were allocated to 4 experimental groups that received intralingual injection of either CTB-SAP or unconjugated CTB + SAP (i.e., control) +/- tongue exercise. Following tongue exercise exposure, we evaluated the effect on respiratory function (via plethysmography), macrostructure [via magnetic resonance imaging (MRI) of the upper airway and tongue], and ultrafine structure [via ex vivo magnetic resonance spectroscopy (MRS) of the tongue] with a focus on lipid profiles. Results Results showed that sham exercise-treated CTB-SAP rats have evidence of upper airway restriction (i.e., reduced airflow) and structural changes present in the upper airway (i.e., airway compression) when compared to CTB-SAP + exercise rats and control rats +/- tongue exercise, which was ameliorated with tongue exercise. Additionally, CTB-SAP + sham exercise rats have evidence of increased lipid expression in the tongue consistent with previously observed tongue hypertrophy when compared to CTB-SAP + exercise rats or control rats +/- tongue exercise. Conclusion These findings provide further evidence that a strength endurance tongue exercise program may be a viable therapeutic treatment option in patients with XII motor neuron degeneration in MNDs such as ALS. Future directions will focus on investigating the underlying mechanism responsible for tongue exercise-induced plasticity in the hypoglossal-tongue axis, particularly inflammatory associated factors such as BDNF.
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Affiliation(s)
- Amy N Keilholz
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Ishan Pathak
- Research Division, Biomolecular Imaging Center, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, United States
- Department of Physics and Astronomy, College of Arts and Science, University of Missouri, Columbia, MO, United States
| | - Catherine L Smith
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Kate L Osman
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Lauren Smith
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Grace Oti
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Mojgan Golzy
- Biostatistics Unit, Department of Family and Community Medicine, University of Missouri, Columbia, MO, United States
| | - Lixin Ma
- Research Division, Biomolecular Imaging Center, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, United States
- Department of Physics and Astronomy, College of Arts and Science, University of Missouri, Columbia, MO, United States
- Department of Radiology, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Teresa E Lever
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Nicole L Nichols
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
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Murphy ER, Thompson R, Osman KL, Haxton C, Brothers M, Lee L, Warncke K, Smith CL, Keilholz AN, Hamad A, Golzy M, Bunyak F, Ma L, Nichols NL, Lever TE. A Strength Endurance Exercise Paradigm Mitigates Deficits in Hypoglossal-Tongue Axis Function, Strength, and Structure in a Rodent Model of Hypoglossal Motor Neuron Degeneration. Front Neurosci 2022; 16:869592. [PMID: 35844238 PMCID: PMC9279620 DOI: 10.3389/fnins.2022.869592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 05/23/2022] [Indexed: 11/18/2022] Open
Abstract
The tongue plays a crucial role in the swallowing process, and impairment can lead to dysphagia, particularly in motor neuron diseases (MNDs) resulting in hypoglossal-tongue axis degeneration (e.g., amyotrophic lateral sclerosis and progressive bulbar palsy). This study utilized our previously established inducible rodent model of dysphagia due to targeted degeneration of the hypoglossal-tongue axis. This model was created by injecting cholera toxin B conjugated to saporin (CTB-SAP) into the genioglossus muscle of the tongue base for retrograde transport to the hypoglossal (XII) nucleus via the hypoglossal nerve, which provides the sole motor control of the tongue. Our goal was to investigate the effect of high-repetition/low-resistance tongue exercise on tongue function, strength, and structure in four groups of male rats: (1) control + sham exercise (n = 13); (2) control + exercise (n = 10); (3) CTB-SAP + sham exercise (n = 13); and (4) CTB-SAP + exercise (n = 12). For each group, a custom spout with adjustable lick force requirement for fluid access was placed in the home cage overnight on days 4 and 6 post-tongue injection. For the two sham exercise groups, the lick force requirement was negligible. For the two exercise groups, the lick force requirement was set to ∼40% greater than the maximum voluntary lick force for individual rats. Following exercise exposure, we evaluated the effect on hypoglossal-tongue axis function (via videofluoroscopy), strength (via force-lickometer), and structure [via Magnetic Resonance Imaging (MRI) of the brainstem and tongue in a subset of rats]. Results showed that sham-exercised CTB-SAP rats had significant deficits in lick rate, swallow timing, and lick force. In exercised CTB-SAP rats, lick rate and lick force were preserved; however, swallow timing deficits persisted. MRI revealed corresponding degenerative changes in the hypoglossal-tongue axis that were mitigated by tongue exercise. These collective findings suggest that high-repetition/low-resistance tongue exercise in our model is a safe and effective treatment to prevent/diminish signs of hypoglossal-tongue axis degeneration. The next step is to leverage our rat model to optimize exercise dosing parameters and investigate corresponding treatment mechanisms of action for future translation to MND clinical trials.
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Affiliation(s)
- Erika R. Murphy
- Department of Speech, Language and Hearing Sciences, School of Health Professions, University of Missouri, Columbia, MO, United States
| | - Rebecca Thompson
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Missouri, Columbia, MO, United States
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Kate L. Osman
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Chandler Haxton
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Margaret Brothers
- Department of Speech, Language and Hearing Sciences, School of Health Professions, University of Missouri, Columbia, MO, United States
| | - Li Lee
- Department of Radiology, School of Medicine, University of Missouri, Columbia, MO, United States
- Research Division, Biomolecular Imaging Center, Harry S. Truman Memorial Veterans’ Hospital, Columbia, MO, United States
| | - Kristen Warncke
- Department of Radiology, School of Medicine, University of Missouri, Columbia, MO, United States
- Research Division, Biomolecular Imaging Center, Harry S. Truman Memorial Veterans’ Hospital, Columbia, MO, United States
| | - Catherine L. Smith
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Amy N. Keilholz
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Ali Hamad
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO, United States
| | - Mojgan Golzy
- Biostatistics Unit, Department of Family and Community Medicine, University of Missouri, Columbia, MO, United States
| | - Filiz Bunyak
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO, United States
| | - Lixin Ma
- Department of Radiology, School of Medicine, University of Missouri, Columbia, MO, United States
- Research Division, Biomolecular Imaging Center, Harry S. Truman Memorial Veterans’ Hospital, Columbia, MO, United States
| | - Nicole L. Nichols
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
- *Correspondence: Nicole L. Nichols,
| | - Teresa E. Lever
- Department of Speech, Language and Hearing Sciences, School of Health Professions, University of Missouri, Columbia, MO, United States
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Missouri, Columbia, MO, United States
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
- Teresa E. Lever,
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Saporin as a Commercial Reagent: Its Uses and Unexpected Impacts in the Biological Sciences—Tools from the Plant Kingdom. Toxins (Basel) 2022; 14:toxins14030184. [PMID: 35324681 PMCID: PMC8952126 DOI: 10.3390/toxins14030184] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/23/2022] [Accepted: 02/23/2022] [Indexed: 02/02/2023] Open
Abstract
Saporin is a ribosome-inactivating protein that can cause inhibition of protein synthesis and causes cell death when delivered inside a cell. Development of commercial Saporin results in a technology termed ‘molecular surgery’, with Saporin as the scalpel. Its low toxicity (it has no efficient method of cell entry) and sturdy structure make Saporin a safe and simple molecule for many purposes. The most popular applications use experimental molecules that deliver Saporin via an add-on targeting molecule. These add-ons come in several forms: peptides, protein ligands, antibodies, even DNA fragments that mimic cell-binding ligands. Cells that do not express the targeted cell surface marker will not be affected. This review will highlight some newer efforts and discuss significant and unexpected impacts on science that molecular surgery has yielded over the last almost four decades. There are remarkable changes in fields such as the Neurosciences with models for Alzheimer’s Disease and epilepsy, and game-changing effects in the study of pain and itch. Many other uses are also discussed to record the wide-reaching impact of Saporin in research and drug development.
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Borkowski LF, Smith CL, Keilholz AN, Nichols NL. Divergent receptor utilization is necessary for phrenic long-term facilitation over the course of motor neuron loss following CTB-SAP intrapleural injections. J Neurophysiol 2021; 126:709-722. [PMID: 34288779 DOI: 10.1152/jn.00236.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intrapleural injection of cholera toxin B conjugated to saporin (CTB-SAP) mimics respiratory motor neuron death and respiratory deficits observed in rat models of neuromuscular diseases. Seven-day CTB-SAP rats elicit enhanced phrenic long-term facilitation (pLTF) primarily through TrkB and PI3K/Akt-dependent mechanisms [i.e., Gs-pathway, which can be initiated by adenosine 2A (A2A) receptors in naïve rats], whereas 28-day CTB-SAP rats elicit moderate pLTF though BDNF- and MEK-/ERK-dependent mechanisms [i.e., Gq-pathway, which is typically initiated by serotonin (5-HT) receptors in naïve rats]. Here, we tested the hypothesis that pLTF following CTB-SAP is 1) A2A receptor-dependent at 7 days and 2) 5-HT receptor-dependent at 28 days. Adult Sprague-Dawley male rats were anesthetized, paralyzed, ventilated, and exposed to acute intermittent hypoxia (AIH; 3-, 5-min bouts of 10.5% O2) following bilateral, intrapleural injections at 7 days and 28 days of 1) CTB-SAP (25 µg) or 2) unconjugated CTB and SAP (control). Intrathecal C4 delivery included either the 1) A2A receptor antagonist (MSX-3; 10 µM; 12 µL) or 2) 5-HT receptor antagonist (methysergide; 20 mM; 15 µL). pLTF was abolished with A2A receptor inhibition in 7-day, not 28-day, CTB-SAP rats versus controls (P < 0.05), whereas pLTF was abolished following 5-HT receptor inhibition in 28-day, not 7-day, CTB-SAP rats versus controls (P < 0.05). In addition, 5-HT2A receptor expression was unchanged in CTB-SAP rats versus controls, whereas 5-HT2B receptor expression was decreased in CTB-SAP rats versus controls (P < 0.05). This study furthers our understanding of the contribution of differential receptor activation to pLTF and its implications for breathing following respiratory motor neuron death.NEW & NOTEWORTHY The current study investigates underlying receptor-dependent mechanisms contributing to phrenic long-term facilitation (pLTF) following CTB-SAP-induced respiratory motor neuron death at 7 days and 28 days. We found that A2A receptors are required for enhanced pLTF in 7-day CTB-SAP rats, whereas 5-HT receptors are required for moderate pLTF in 28-day CTB-SAP rats. Targeting these time-dependent mechanisms have implications for breathing maintenance over the course of many neuromuscular diseases.
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Affiliation(s)
- Lauren F Borkowski
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Catherine L Smith
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Amy N Keilholz
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Nicole L Nichols
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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Lind LA, Lever TE, Nichols NL. Tongue and hypoglossal morphology after intralingual cholera toxin B-saporin injection. Muscle Nerve 2020; 63:413-420. [PMID: 33269488 DOI: 10.1002/mus.27131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 11/23/2020] [Accepted: 11/27/2020] [Indexed: 01/23/2023]
Abstract
INTRODUCTION We recently developed an inducible model of dysphagia using intralingual injection of cholera toxin B conjugated to saporin (CTB-SAP) to cause death of hypoglossal neurons. In this study we aimed to evaluate tongue morphology and ultrastructural changes in hypoglossal neurons and nerve fibers in this model. METHODS Tissues were collected from 20 rats (10 control and 10 CTB-SAP animals) on day 9 post-injection. Tongues were weighed, measured, and analyzed for microscopic changes using laminin immunohistochemistry. Hypoglossal neurons and axons were examined using transmission electron microscopy. RESULTS The cross-sectional area of myofibers in the posterior genioglossus was decreased in CTB-SAP-injected rats. Degenerative changes were observed in both the cell bodies and distal axons of hypoglossal neurons. DISCUSSION Preliminary results indicate this model may have translational application to a variety of neurodegenerative diseases resulting in tongue dysfunction and associated dysphagia.
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Affiliation(s)
- Lori A Lind
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Teresa E Lever
- Department of Otolaryngology-Head and Neck Surgery, University of Missouri, Columbia, Missouri, USA
| | - Nicole L Nichols
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
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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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Xiong L, Liu Y, Zhou M, Wang G, Quan D, Shen C, Shuai W, Kong B, Huang C, Huang H. Targeted ablation of cardiac sympathetic neurons improves ventricular electrical remodelling in a canine model of chronic myocardial infarction. Europace 2019; 20:2036-2044. [PMID: 29860489 DOI: 10.1093/europace/euy090] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 04/05/2018] [Indexed: 12/25/2022] Open
Abstract
Aims The purpose of this study was to evaluate the cardiac electrophysiologic effects of targeted ablation of cardiac sympathetic neurons (TACSN) in a canine model of chronic myocardial infarction (MI). Methods and results Thirty-eight anaesthetized dogs were randomly assigned into the sham-operated, MI, and MI-TACSN groups, respectively. Myocardial infarction-targeted ablation of cardiac sympathetic neuron was induced by injecting cholera toxin B subunit-saporin compound in the left stellate ganglion (LSG). Five weeks after surgery, the cardiac function, heart rate variability (HRV), ventricular electrophysiological parameters, LSG function and neural activity, serum norepinephrine (NE), nerve growth factor (NGF), and brain natriuretic peptide (BNP) levels were measured. Cardiac sympathetic innervation was determined with immunofluorescence staining of growth associated protein-43 (GAP43) and tyrosine hydroxylase (TH). Compared with MI group, TACSN significantly improved HRV, attenuated LSG function and activity, prolonged corrected QT interval, decreased Tpeak-Tend interval, prolonged ventricular effective refractory period (ERP), and action potential duration (APD), decreased the slopes of APD restitution curves, suppressed the APD alternans, increased ventricular fibrillation threshold, and reduced serum NE, NGF, and BNP levels. Moreover, the densities of GAP43 and TH-positive nerve fibres in the infarcted border zone in the MI-TACSN group were lower than those in the MI group. Conclusion Targeted ablation of cardiac sympathetic neuron attenuates sympathetic remodelling and improves ventricular electrical remodelling in the chronic phase of MI. These data suggest that TACSN may be a novel approach to treating ventricular arrhythmias.
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Affiliation(s)
- Liang Xiong
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Yu Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Mingmin Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Guangji Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Dajun Quan
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Caijie Shen
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Wei Shuai
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Bin Kong
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
| | - He Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Cardiovascular Research Institute, Wuhan University, No.238 Jiefang Road, Wuchang, Wuhan, China.,Hubei Key Laboratory of Cardiology, No.238 Jiefang Road, Wuchang, Wuhan, China
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8
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Lind LA, Murphy ER, Lever TE, Nichols NL. Hypoglossal Motor Neuron Death Via Intralingual CTB-saporin (CTB-SAP) Injections Mimic Aspects of Amyotrophic Lateral Sclerosis (ALS) Related to Dysphagia. Neuroscience 2018; 390:303-316. [PMID: 30179644 PMCID: PMC6168367 DOI: 10.1016/j.neuroscience.2018.08.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/20/2018] [Accepted: 08/24/2018] [Indexed: 12/13/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating disease leading to degeneration of motor neurons and skeletal muscles, including those required for swallowing. Tongue weakness is one of the earliest signs of bulbar dysfunction in ALS, which is attributed to degeneration of motor neurons in the hypoglossal nucleus in the brainstem, the axons of which directly innervate the tongue. Despite its fundamental importance, dysphagia (difficulty swallowing) and strategies to preserve swallowing function have seldom been studied in ALS models. It is difficult to study dysphagia in ALS models since the amount and rate at which hypoglossal motor neuron death occurs cannot be controlled, and degeneration is not limited to the hypoglossal nucleus. Here, we report a novel experimental model using intralingual injections of cholera toxin B conjugated to saporin (CTB-SAP) to study the impact of only hypoglossal motor neuron death without the many complications that are present in ALS models. Hypoglossal motor neuron survival, swallowing function, and hypoglossal motor output were assessed in Sprague-Dawley rats after intralingual injection of either CTB-SAP (25 g) or unconjugated CTB and SAP (controls) into the genioglossus muscle. CTB-SAP treated rats exhibited significant (p ≤ 0.05) deficits vs. controls in: (1) lick rate (6.0 ± 0.1 vs. 6.6 ± 0.1 Hz; (2) hypoglossal motor output (0.3 ± 0.05 vs. 0.6 ± 0.10 mV); and (3) hypoglossal motor neuron survival (398 ± 34 vs. 1018 ± 41 neurons). Thus, this novel, inducible model of hypoglossal motor neuron death mimics the dysphagia phenotype that is observed in ALS rodent models, and will allow us to study strategies to preserve swallowing function.
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Affiliation(s)
- Lori A Lind
- Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, United States
| | - Erika R Murphy
- Department of Communication Science and Disorders, University of Missouri, Columbia, MO 65211, United States
| | - Teresa E Lever
- Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, United States; Department of Communication Science and Disorders, University of Missouri, Columbia, MO 65211, United States; Department of Otolaryngology-Head and Neck Surgery, University of Missouri, Columbia, MO 65211, United States
| | - Nicole L Nichols
- Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, United States; Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, United States.
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9
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Xiong L, Liu Y, Zhou M, Wang G, Quan D, Shuai W, Shen C, Kong B, Huang C, Huang H. Targeted ablation of cardiac sympathetic neurons attenuates adverse postinfarction remodelling and left ventricular dysfunction. Exp Physiol 2018; 103:1221-1229. [PMID: 29928790 DOI: 10.1113/ep086928] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 06/19/2018] [Indexed: 01/08/2023]
Affiliation(s)
- Liang Xiong
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Yu Liu
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Mingmin Zhou
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Guangji Wang
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Dajun Quan
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Wei Shuai
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Caijie Shen
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Bin Kong
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - Congxin Huang
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
| | - He Huang
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan China
- Cardiovascular Research Institute of Wuhan University; Wuhan China
- Hubei Key Laboratory of Cardiology; Wuhan China
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10
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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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11
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Nichols NL, Craig TA, Tanner MA. Phrenic long-term facilitation following intrapleural CTB-SAP-induced respiratory motor neuron death. Respir Physiol Neurobiol 2017; 256:43-49. [PMID: 28822818 DOI: 10.1016/j.resp.2017.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 07/20/2017] [Accepted: 08/04/2017] [Indexed: 01/26/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating disease leading to progressive motor neuron degeneration and death by ventilatory failure. In a rat model of ALS (SOD1G93A), phrenic long-term facilitation (pLTF) following acute intermittent hypoxia (AIH) is enhanced greater than expected at disease end-stage but the mechanism is unknown. We suggest that one trigger for this enhancement is motor neuron death itself. Intrapleural injections of cholera toxin B fragment conjugated to saporin (CTB-SAP) selectively kill respiratory motor neurons and mimic motor neuron death observed in SOD1G93A rats. This CTB-SAP model allows us to study the impact of respiratory motor neuron death on breathing without many complications attendant to ALS. Here, we tested the hypothesis that phrenic motor neuron death is sufficient to enhance pLTF. pLTF was assessed in anesthetized, paralyzed and ventilated Sprague Dawley rats 7 and 28 days following bilateral intrapleural injections of: 1) CTB-SAP (25 μg), or 2) un-conjugated CTB and SAP (control). CTB-SAP enhanced pLTF at 7 (CTB-SAP: 162 ± 18%, n = 8 vs. Control: 63 ± 3%; n = 8; p < 0.05), but not 28 days post-injection (CTB-SAP: 64 ± 10%, n = 10 vs. Control: 60 ± 13; n = 8; p > 0.05). Thus, pLTF at 7 (not 28) days post-CTB-SAP closely resembles pLTF in end-stage ALS rats, suggesting that processes unique to the early period of motor neuron death enhance pLTF. This project increases our understanding of respiratory plasticity and its implications for breathing in motor neuron disease.
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Affiliation(s)
- Nicole L Nichols
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, United States.
| | - Taylor A Craig
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, United States
| | - Miles A Tanner
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, United States
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12
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Abstract
Spinal cord injury (SCI) results not only in motor and sensory deficits but also in autonomic dysfunctions. The disruption of connections between higher brain centers and the spinal cord, or the impaired autonomic nervous system itself, manifests a broad range of autonomic abnormalities. This includes compromised cardiovascular, respiratory, urinary, gastrointestinal, thermoregulatory, and sexual activities. These disabilities evoke potentially life-threatening symptoms that severely interfere with the daily living of those with SCI. In particular, high thoracic or cervical SCI often causes disordered hemodynamics due to deregulated sympathetic outflow. Episodic hypertension associated with autonomic dysreflexia develops as a result of massive sympathetic discharge often triggered by unpleasant visceral or sensory stimuli below the injury level. In the pelvic floor, bladder and urethral dysfunctions are classified according to upper motor neuron versus lower motor neuron injuries; this is dependent on the level of lesion. Most impairments of the lower urinary tract manifest in two interrelated complications: bladder storage and emptying. Inadequate or excessive detrusor and sphincter functions as well as detrusor-sphincter dyssynergia are examples of micturition abnormalities stemming from SCI. Gastrointestinal motility disorders in spinal cord injured-individuals are comprised of gastric dilation, delayed gastric emptying, and diminished propulsive transit along the entire gastrointestinal tract. As a critical consequence of SCI, neurogenic bowel dysfunction exhibits constipation and/or incontinence. Thus, it is essential to recognize neural mechanisms and pathophysiology underlying various complications of autonomic dysfunctions after SCI. This overview provides both vital information for better understanding these disorders and guides to pursue novel therapeutic approaches to alleviate secondary complications.
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Affiliation(s)
- Shaoping Hou
- Spinal Cord Research Center, Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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13
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Al Dera H, Brock JA. Spinal cord injury increases the reactivity of rat tail artery to angiotensin II. Front Neurosci 2015; 8:435. [PMID: 25610365 PMCID: PMC4285114 DOI: 10.3389/fnins.2014.00435] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 12/10/2014] [Indexed: 12/13/2022] Open
Abstract
Studies in individuals with spinal cord injury (SCI) suggest the vasculature is hyperreactive to angiotensin II (Ang II). In the present study, the effects of SCI on the reactivity of the rat tail and mesenteric arteries to Ang II have been investigated. In addition, the effects of SCI on the facilitatory action of Ang II on nerve-evoked contractions of these vessels were determined. Isometric contractions of artery segments from T11 (tail artery) or T4 (mesenteric arteries) spinal cord-transected rats and sham-operated rats were compared 6–7 weeks postoperatively. In both tail and mesenteric arteries, SCI increased nerve-evoked contractions. In tail arteries, SCI also greatly increased Ang II-evoked contractions and the facilitatory effect of Ang II on nerve-evoked contractions. By contrast, SCI did not detectably change the responses of mesenteric arteries to Ang II. These findings provide the first direct evidence that SCI increases the reactivity of arterial vessels to Ang II. In addition, in tail artery, the findings indicate that Ang II may contribute to modifying their responses following SCI.
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Affiliation(s)
- Hussain Al Dera
- Department of Anatomy and Neuroscience, University of Melbourne Melbourne, VIC, Australia ; Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences Riyadh, Saudi Arabia
| | - James A Brock
- Department of Anatomy and Neuroscience, University of Melbourne Melbourne, VIC, Australia
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14
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Respiratory function after selective respiratory motor neuron death from intrapleural CTB-saporin injections. Exp Neurol 2014; 267:18-29. [PMID: 25476493 DOI: 10.1016/j.expneurol.2014.11.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 09/26/2014] [Accepted: 11/20/2014] [Indexed: 02/06/2023]
Abstract
UNLABELLED Amyotrophic lateral sclerosis (ALS) causes progressive motor neuron degeneration, paralysis and death by ventilatory failure. In rodent ALS models: 1) breathing capacity is preserved until late in disease progression despite major respiratory motor neuron death, suggesting unknown forms of compensatory respiratory plasticity; and 2) spinal microglia become activated in association with motor neuron cell death. Here, we report a novel experimental model to study the impact of respiratory motor neuron death on compensatory responses without many complications attendant to spontaneous motor neuron disease. In specific, we used intrapleural injections of cholera toxin B fragment conjugated to saporin (CTB-SAP) to selectively kill motor neurons with access to the pleural space. Motor neuron survival, CD11b labeling (microglia), ventilatory capacity and phrenic motor output were assessed in rats 3-28days after intrapleural injections of: 1) CTB-SAP (25 and 50μg), or 2) unconjugated CTB and SAP (i.e. control; (CTB+SAP). CTB-SAP elicited dose-dependent phrenic and intercostal motor neuron death; 7days post-25μg CTB-SAP, motor neuron survival approximated that in end-stage ALS rats (phrenic: 36±7%; intercostal: 56±10% of controls; n=9; p<0.05). CTB-SAP caused minimal cell death in other brainstem or spinal cord regions. CTB-SAP 1) increased CD11b fractional area in the phrenic motor nucleus, indicating microglial activation; 2) decreased breathing during maximal chemoreceptor stimulation; and 3) diminished phrenic motor output in anesthetized rats (7days post-25μg, CTB-SAP 0.3±0.07V; CTB+SAP: 1.5±0.3; n=9; p<0.05). Intrapleural CTB-SAP represents a novel, inducible model of respiratory motor neuron death and provides an opportunity to study compensation for respiratory motor neuron loss.
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Ramer LM, van Stolk AP, Inskip JA, Ramer MS, Krassioukov AV. Plasticity of TRPV1-Expressing Sensory Neurons Mediating Autonomic Dysreflexia Following Spinal Cord Injury. Front Physiol 2012; 3:257. [PMID: 22934013 PMCID: PMC3429033 DOI: 10.3389/fphys.2012.00257] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 06/20/2012] [Indexed: 01/22/2023] Open
Abstract
Spinal cord injury (SCI) triggers profound changes in visceral and somatic targets of sensory neurons below the level of injury. Despite this, little is known about the influence of injury to the spinal cord on sensory ganglia. One of the defining characteristics of sensory neurons is the size of their cell body: for example, nociceptors are smaller in size than mechanoreceptors or proprioceptors. In these experiments, we first used a comprehensive immunohistochemical approach to characterize the size distribution of sensory neurons after high- and low-thoracic SCI. Male Wistar rats (300 g) received a spinal cord transection (T3 or T10) or sham-injury. At 30 days post-injury, dorsal root ganglia (DRGs) and spinal cords were harvested and analyzed immunohistochemically. In a wide survey of primary afferents, only those expressing the capsaicin receptor (TRPV1) exhibited somal hypertrophy after T3 SCI. Hypertrophy only occurred caudal to SCI and was pronounced in ganglia far distal to SCI (i.e., in L4-S1 DRGs). Injury-induced hypertrophy was accompanied by a small expansion of central territory in the lumbar spinal dorsal horn and by evidence of TRPV1 upregulation. Importantly, hypertrophy of TRPV1-positive neurons was modest after T10 SCI. Given the specific effects of T3 SCI on TRPV1-positive afferents, we hypothesized that these afferents contribute to autonomic dysreflexia (AD). Rats with T3 SCI received vehicle or capsaicin via intrathecal injection at 2 or 28 days post-SCI; at 30 days, AD was assessed by recording intra-arterial blood pressure during colo-rectal distension (CRD). In both groups of capsaicin-treated animals, the severity of AD was dramatically reduced. While AD is multi-factorial in origin, TRPV1-positive afferents are clearly involved in AD elicited by CRD. These findings implicate TRPV1-positive afferents in the initiation of AD and suggest that TRPV1 may be a therapeutic target for amelioration or prevention of AD after high SCI.
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Affiliation(s)
- Leanne M Ramer
- International Collaboration On Repair Discoveries, University of British Columbia Vancouver, BC, Canada
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