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Borkowski LF, Nichols NL. Differential mechanisms are required for phrenic long-term facilitation over the course of motor neuron loss following CTB-SAP intrapleural injections. Exp Neurol 2020; 334:113460. [PMID: 32916172 PMCID: PMC10823911 DOI: 10.1016/j.expneurol.2020.113460] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/28/2020] [Accepted: 09/01/2020] [Indexed: 01/25/2023]
Abstract
Selective elimination of respiratory motor neurons using intrapleural injections of cholera toxin B fragment conjugated to saporin (CTB-SAP) mimics motor neuron death and respiratory deficits observed in rat models of neuromuscular diseases. This CTB-SAP model allows us to study the impact of motor neuron death on the output of surviving phrenic motor neurons. After 7(d) days of CTB-SAP, phrenic long-term facilitation (pLTF, a form of respiratory plasticity) is enhanced, but returns towards control levels at 28d. However, the mechanism responsible for this difference in magnitude of pLTF is unknown. In naïve rats, pLTF predominately requires 5-HT2 receptors, the new synthesis of BDNF, and MEK/ERK signaling; however, pLTF can alternatively be induced via A2A receptors, the new synthesis of TrkB, and PI3K/Akt signaling. Since A2A receptor-dependent pLTF is enhanced in naïve rats, we suggest that 7d CTB-SAP treated rats utilize the alternative mechanism for pLTF. Here, we tested the hypothesis that pLTF following CTB-SAP is: 1) TrkB and PI3K/Akt, not BDNF and MEK/ERK, dependent at 7d; and 2) BDNF and MEK/ERK, not TrkB and PI3K/Akt, dependent at 28d. Adult Sprague Dawley male rats were anesthetized, paralyzed, ventilated, and were exposed to acute intermittent hypoxia (AIH; 3, 5 min bouts of 10.5% O2) following bilateral, intrapleural injections at 7d and 28d of: 1) CTB-SAP (25 μg), or 2) un-conjugated CTB and SAP (control). Intrathecal C4 delivery included either: 1) small interfering RNA that targeted BDNF or TrkB mRNA; 2) UO126 (MEK/ERK inhibitor); or 3) PI828 (PI3K/Akt inhibitor). Our data suggest that pLTF in 7d CTB-SAP treated rats is elicited primarily through TrkB and PI3K/Akt-dependent mechanisms, whereas BDNF and MEK/ERK-dependent mechanisms induce pLTF in 28d CTB-SAP treated rats. This project increases our understanding of respiratory plasticity and its implications for breathing following motor neuron death.
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Affiliation(s)
- Lauren F Borkowski
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, United States of America
| | - Nicole L Nichols
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, United States of America.
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Ichiba T, Miyagawa T, Kera T, Tsuda T. Effect of manual chest wall compression in participants with chronic obstructive pulmonary disease. J Phys Ther Sci 2018; 30:1349-1354. [PMID: 30464362 PMCID: PMC6220100 DOI: 10.1589/jpts.30.1349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/02/2018] [Indexed: 11/24/2022] Open
Abstract
[Purpose] Pulmonary rehabilitation is appropriate for most individuals with chronic
obstructive pulmonary disease (COPD). Pulmonary rehabilitation consists of conditioning
and exercise therapy. Conditioning includes relaxation, breathing exercises, and manual
chest wall compression during expiration (CWC). CWC improves the symptoms in individuals
with respiratory disease who have undergone mechanical ventilation. However, evidence
supporting the effectiveness of CWC for COPD has been insufficient. This study aimed to
determine physiological responses to CWC in participants with COPD. [Participants and
Methods] Twenty-nine participants with COPD were included in the study. Manual CWC
techniques were performed in a comfortable position chosen by the participants (sitting,
forward-leaning (sitting), or semi-Fowler’s). Ventilatory parameters, occlusion airway
pressure (P0.1), and dyspnea were assessed using a visual analog scale and were
compared before and during CWC. [Results] During manual CWC, oxygen consumption, carbon
dioxide production, end-tidal carbon dioxide concentration, and dyspnea were significantly
decreased; however, P0.1 was not affected. [Conclusion] Manual CWC for COPD had
an immediate physiological effect, including a decrease in dyspnea that may have been
facilitated by a reduced workload of the respiratory muscles. Thus, manual CWC may be
effective for dyspnea by reducing oxygen consumption in the respiratory muscles.
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Affiliation(s)
- Tomomi Ichiba
- Department of Physical Therapy, School of Health Sciences, Kyorin University: 5-4-1 Shimorenjyaku, Mitaka-shi, Tokyo 181-8612, Japan.,Division of Respiratory Care, Showa University Graduate School of Nursing and Rehabilitation Sciences, Japan
| | - Tetsuo Miyagawa
- Division of Respiratory Care, Showa University Graduate School of Nursing and Rehabilitation Sciences, Japan
| | - Takeshi Kera
- Department of Physical Therapy, Takasaki University of Health and Welfare, Japan.,Department for Research Team for Human Care, Tokyo Metropolitan Institute of Gerontology, Japan
| | - Tohru Tsuda
- Department of Respiratory Medicine, Kirigaoka Tsuda Hospital, Japan
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Bartman ME, Johnson SM. Isolated adult turtle brainstems exhibit central hypoxic chemosensitivity. Comp Biochem Physiol A Mol Integr Physiol 2018; 225:65-73. [PMID: 30003967 DOI: 10.1016/j.cbpa.2018.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/27/2018] [Accepted: 07/03/2018] [Indexed: 10/28/2022]
Abstract
During hypoxia, red-eared slider turtles increase ventilation and decrease episodic breathing, but whether these responses are due to central mechanisms is not known. To test this question, isolated adult turtle brainstems were exposed to 240 min of hypoxic solution (bath PO2 = 32.6 ± 1.2 mmHg) and spontaneous respiratory-related motor bursts (respiratory event) were recorded on hypoglossal nerve roots. During hypoxia, burst frequency increased during the first 15 min, and then decreased during the remaining 35-240 min of hypoxia. Burst amplitude was maintained for 120 min, but then decreased during the last 120 min. The number of bursts/respiratory event decreased within 30 min and remained decreased. Pretreatment with either prazosin (α1-adrenergic antagonist) or MDL7222 (5-HT3 antagonist) blocked the hypoxia-induced short-term increase and the longer duration decrease in burst frequency. MDL7222, but not prazosin, blocked the hypoxia-induced decrease in bursts/respiratory event. Thus, during bath hypoxia, isolated turtle brainstems continued to produce respiratory motor output, but the frequency and pattern were altered in a manner that required endogenous α1-adrenergic and serotonin 5-HT3 receptor activation. This is the first example of isolated reptile brainstems exhibiting central hypoxic chemosensitivity similar to other vertebrate species.
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Affiliation(s)
- Michelle E Bartman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA
| | - Stephen M Johnson
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Poliacek I, Simera M, Veternik M, Kotmanova Z, Bolser DC, Machac P, Jakus J. Role of the dorsomedial medulla in suppression of cough by codeine in cats. Respir Physiol Neurobiol 2017; 246:59-66. [PMID: 28778649 DOI: 10.1016/j.resp.2017.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/23/2017] [Accepted: 07/28/2017] [Indexed: 12/24/2022]
Abstract
The modulation of cough by microinjections of codeine in 3 medullary regions, the solitary tract nucleus rostral to the obex (rNTS), caudal to the obex (cNTS) and the lateral tegmental field (FTL) was studied. Experiments were performed on 27 anesthetized spontaneously breathing cats. Electromyograms (EMG) were recorded from the sternal diaphragm and expiratory muscles (transversus abdominis and/or obliquus externus; ABD). Repetitive coughing was elicited by mechanical stimulation of the intrathoracic airways. Bilateral microinjections of codeine (3.3 or 33mM, 54±16nl per injection) in the cNTS had no effect on cough, while those in the rNTS and in the FTL reduced coughing. Bilateral microinjections into the rNTS (3.3mM codeine, 34±1 nl per injection) reduced the number of cough responses by 24% (P<0.05), amplitudes of diaphragm EMG by 19% (P<0.01), of ABD EMG by 49% (P<0.001) and of expiratory esophageal pressure by 56% (P<0.001). Bilateral microinjections into the FTL (33mM codeine, 33±3 nl per injection) induced reductions in cough expiratory as well as inspiratory EMG amplitudes (ABD by 60% and diaphragm by 34%; P<0.01) and esophageal pressure amplitudes (expiratory by 55% and inspiratory by 26%; P<0.001 and 0.01, respectively). Microinjections of vehicle did not significantly alter coughing. Breathing was not affected by microinjections of codeine. These results suggest that: 1) codeine acts within the rNTS and the FTL to reduce cough in the cat, 2) the neuronal circuits in these target areas have unequal sensitivity to codeine and/or they have differential effects on spatiotemporal control of cough, 3) the cNTS has a limited role in the cough suppression induced by codeine in cats.
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Affiliation(s)
- Ivan Poliacek
- Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Mala Hora 4, 036 01, Martin, Slovakia
| | - Michal Simera
- Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Mala Hora 4, 036 01, Martin, Slovakia.
| | - Marcel Veternik
- Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Mala Hora 4, 036 01, Martin, Slovakia
| | - Zuzana Kotmanova
- Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Mala Hora 4, 036 01, Martin, Slovakia
| | - Donald C Bolser
- Dept. of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Peter Machac
- Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Mala Hora 4, 036 01, Martin, Slovakia
| | - Jan Jakus
- Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Mala Hora 4, 036 01, Martin, Slovakia
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Nichols NL, Mitchell GS. Quantitative assessment of integrated phrenic nerve activity. Respir Physiol Neurobiol 2015; 226:81-6. [PMID: 26724605 DOI: 10.1016/j.resp.2015.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/07/2015] [Accepted: 12/14/2015] [Indexed: 12/30/2022]
Abstract
Integrated electrical activity in the phrenic nerve is commonly used to assess within-animal changes in phrenic motor output. Because of concerns regarding the consistency of nerve recordings, activity is most often expressed as a percent change from baseline values. However, absolute values of nerve activity are necessary to assess the impact of neural injury or disease on phrenic motor output. To date, no systematic evaluations of the repeatability/reliability have been made among animals when phrenic recordings are performed by an experienced investigator using standardized methods. We performed a meta-analysis of studies reporting integrated phrenic nerve activity in many rat groups by the same experienced investigator; comparisons were made during baseline and maximal chemoreceptor stimulation in 14 wild-type Harlan and 14 Taconic Sprague Dawley groups, and in 3 pre-symptomatic and 11 end-stage SOD1(G93A) Taconic rat groups (an ALS model). Meta-analysis results indicate: (1) consistent measurements of integrated phrenic activity in each sub-strain of wild-type rats; (2) with bilateral nerve recordings, left-to-right integrated phrenic activity ratios are ∼1.0; and (3) consistently reduced activity in end-stage SOD1(G93A) rats. Thus, with appropriate precautions, integrated phrenic nerve activity enables robust, quantitative comparisons among nerves or experimental groups, including differences caused by neuromuscular disease.
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Affiliation(s)
- Nicole L Nichols
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, United States; Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, United States.
| | - Gordon S Mitchell
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, United States; Department of Physical Therapy, McKnight Brain Institute and Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL 32611-0154, United States
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