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Li H, Yao S, Xia W, Ma X, Shi L, Ju H, Li Z, Zhong Y, Xie B, Tao Y. Targeted metabolome and transcriptome analyses reveal changes in gibberellin and related cell wall-acting enzyme-encoding genes during stipe elongation in Flammulina filiformis. Front Microbiol 2023; 14:1195709. [PMID: 37799602 PMCID: PMC10548271 DOI: 10.3389/fmicb.2023.1195709] [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: 03/28/2023] [Accepted: 08/08/2023] [Indexed: 10/07/2023] Open
Abstract
Flammulina filiformis, a typical agaric fungus, is a widely cultivated and consumed edible mushroom. Elongation of its stipe (as the main edible part) is closely related to its yield and commercial traits; however, the endogenous hormones during stipe elongation and their regulatory mechanisms are not well understood. Gibberellin (GA) plays an important role in the regulation of plant growth, but little has been reported in macro fungi. In this study, we first treated F. filiformis stipes in the young stage with PBZ (an inhibitor of GA) and found that PBZ significantly inhibited elongation of the stipe. Then, we performed GA-targeted metabolome and transcriptome analyses of the stipe at both the young and elongation stages. A total of 13 types of GAs were detected in F. filiformis; the contents of ten of them, namely, GA3, GA4, GA8, GA14, GA19, GA20, GA24, GA34, GA44, and GA53, were significantly decreased, and the contents of three (GA5, GA9, and GA29) were significantly increased during stipe elongation. Transcriptome analysis showed that the genes in the terpenoid backbone biosynthesis pathway showed varying expression patterns: HMGS, HMGR, GPS, and FPPS were significantly upregulated, while CPS/KS had no significant difference in transcript level during stipe elongation. In total, 37 P450 genes were annotated to be involved in GA biosynthesis; eight of them were upregulated, twelve were downregulated, and the rest were not differentially expressed. In addition, four types of differentially expressed genes involved in stipe elongation were identified, including six signal transduction genes, five cell cycle-controlling genes, twelve cell wall-related enzymes and six transcription factors. The results identified the types and content of GAs and the expression patterns of their synthesis pathways during elongation in F. filiformis and revealed the molecular mechanisms by which GAs may affect the synthesis of cell wall components and the cell cycle of the stipe through the downstream action of cell wall-related enzymes, transcription factors, signal transduction and cell cycle control, thus regulating stipe elongation. This study is helpful for understanding the roles of GAs in stipe development in mushrooms and lays the foundation for the rational regulation of stipe length in agaric mushrooms during production.
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Affiliation(s)
- Hui Li
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, Hebei, China
| | - Sen Yao
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, Hebei, China
| | - Weiwei Xia
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, Hebei, China
| | - Xinbin Ma
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, Hebei, China
| | - Lei Shi
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Huimin Ju
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Ziyan Li
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yingli Zhong
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Baogui Xie
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yongxin Tao
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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Thakre PP, Rana S, Benevides ES, Fuller DD. Targeting drug or gene delivery to the phrenic motoneuron pool. J Neurophysiol 2023; 129:144-158. [PMID: 36416447 PMCID: PMC9829468 DOI: 10.1152/jn.00432.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/19/2022] [Accepted: 11/19/2022] [Indexed: 11/24/2022] Open
Abstract
Phrenic motoneurons (PhrMNs) innervate diaphragm myofibers. Located in the ventral gray matter (lamina IX), PhrMNs form a column extending from approximately the third to sixth cervical spinal segment. Phrenic motor output and diaphragm activation are impaired in many neuromuscular diseases, and targeted delivery of drugs and/or genetic material to PhrMNs may have therapeutic application. Studies of phrenic motor control and/or neuroplasticity mechanisms also typically require targeting of PhrMNs with drugs, viral vectors, or tracers. The location of the phrenic motoneuron pool, however, poses a challenge. Selective PhrMN targeting is possible with molecules that move retrogradely upon uptake into phrenic axons subsequent to diaphragm or phrenic nerve delivery. However, nonspecific approaches that use intrathecal or intravenous delivery have considerably advanced the understanding of PhrMN control. New opportunities for targeted PhrMN gene expression may be possible with intersectional genetic methods. This article provides an overview of methods for targeting the phrenic motoneuron pool for studies of PhrMNs in health and disease.
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Affiliation(s)
- Prajwal P Thakre
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
| | - Ethan S Benevides
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
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Devinney MJ, Mitchell GS. Spinal activation of protein kinase C elicits phrenic motor facilitation. Respir Physiol Neurobiol 2017; 256:36-42. [PMID: 29081358 DOI: 10.1016/j.resp.2017.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 10/16/2017] [Accepted: 10/18/2017] [Indexed: 12/14/2022]
Abstract
The protein kinase C family regulates many cellular functions, including multiple forms of neuroplasticity. The novel PKCθ and atypical PKCζ isoforms have been implicated in distinct forms of spinal, respiratory motor plasticity, including phrenic motor facilitation (pMF) following acute intermittent hypoxia or inactivity, respectively. Although these PKC isoforms are critical in regulating spinal motor plasticity, other isoforms may be important for phrenic motor plasticity. We tested the impact of conventional/novel PKC activator, phorbol 12-myristate 13-acetate (PMA) on pMF. Rats given cervical intrathecal injections of PMA exhibited pMF, which was abolished by pretreatment of broad-spectrum PKC inhibitors bisindolymalemide 1 (BIS) or NPC-15437 (NPC). Because PMA fails to activate atypical PKC isoforms, and NPC does not block PKCθ, this finding demonstrates that classical/novel PKC isoforms besides PKCθ are sufficient to elicit pMF. These results advance our understanding of mechanisms producing respiratory motor plasticity, and may inspire new treatments for disorders that compromise breathing, such as ALS, spinal injury and obstructive sleep apnea.
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Affiliation(s)
- Michael J Devinney
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, 53706, United States
| | - Gordon S Mitchell
- Center for Respiratory Research and Rehabilitation, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, United States.
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Abstract
The cervical spine is the most common site of traumatic vertebral column injuries. Respiratory insufficiency constitutes a significant proportion of the morbidity burden and is the most common cause of mortality in these patients. In seeking to enhance our capacity to treat specifically the respiratory dysfunction following spinal cord injury, investigators have studied the "crossed phrenic phenomenon", wherein contraction of a hemidiaphragm paralyzed by a complete hemisection of the ipsilateral cervical spinal cord above the phrenic nucleus can be induced by respiratory stressors and recovers spontaneously over time. Strengthening of latent contralateral projections to the phrenic nucleus and sprouting of new descending axons have been proposed as mechanisms contributing to the observed recovery. We have recently demonstrated recovery of spontaneous crossed phrenic activity occurring over minutes to hours in C1-hemisected unanesthetized decerebrate rats. The specific neurochemical and molecular pathways underlying crossed phrenic activity following injury require further clarification. A thorough understanding of these is necessary in order to develop targeted therapies for respiratory neurorehabilitation following spinal trauma. Animal studies provide preliminary evidence for the utility of neuropharmacological manipulation of serotonergic and adenosinergic pathways, nerve grafts, olfactory ensheathing cells, intraspinal microstimulation and a possible role for dorsal rhizotomy in recovering phrenic activity following spinal cord injury.
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Transporter Protein-Coupled DPCPX Nanoconjugates Induce Diaphragmatic Recovery after SCI by Blocking Adenosine A1 Receptors. J Neurosci 2016; 36:3441-52. [PMID: 27013674 DOI: 10.1523/jneurosci.2577-15.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 01/08/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Respiratory complications in patients with spinal cord injury (SCI) are common and have a negative impact on the quality of patients' lives. Systemic administration of drugs that improve respiratory function often cause deleterious side effects. The present study examines the applicability of a novel nanotechnology-based drug delivery system, which induces recovery of diaphragm function after SCI in the adult rat model. We developed a protein-coupled nanoconjugate to selectively deliver by transsynaptic transport small therapeutic amounts of an A1 adenosine receptor antagonist to the respiratory centers. A single administration of the nanoconjugate restored 75% of the respiratory drive at 0.1% of the systemic therapeutic drug dose. The reduction of the systemic dose may obviate the side effects. The recovery lasted for 4 weeks (the longest period studied). These findings have translational implications for patients with respiratory dysfunction after SCI. SIGNIFICANCE STATEMENT The leading causes of death in humans following SCI are respiratory complications secondary to paralysis of respiratory muscles. Systemic administration of methylxantines improves respiratory function but also leads to the development of deleterious side effects due to actions of the drug on nonrespiratory sites. The importance of the present study lies in the novel drug delivery approach that uses nanotechnology to selectively deliver recovery-inducing drugs to the respiratory centers exclusively. This strategy allows for a reduction in the therapeutic drug dose, which may reduce harmful side effects and markedly improve the quality of life for SCI patients.
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Ghali MGZ, Marchenko V. Dynamic changes in phrenic motor output following high cervical hemisection in the decerebrate rat. Exp Neurol 2015; 271:379-89. [DOI: 10.1016/j.expneurol.2015.06.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 11/16/2022]
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Hoy KC, Alilain WJ. Acute theophylline exposure modulates breathing activity through a cervical contusion. Exp Neurol 2015; 271:72-6. [PMID: 25979115 DOI: 10.1016/j.expneurol.2015.04.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 04/21/2015] [Accepted: 04/24/2015] [Indexed: 01/25/2023]
Abstract
Cervical spinal contusion injuries are the most common form of spinal cord injury (>50%) observed in humans. These injuries can result in the impaired ability to breathe. In this study we examine the role of theophylline in the rescue of breathing behavior after a cervical spinal contusion. Previous research in the C2 hemisection model has shown that acute administration of theophylline can rescue phrenic nerve activity and diaphragmatic EMG on the side ipsilateral to injury. However, this effect is dependent on intact and uninjured pathways. In this study we utilized a cervical contusion injury model that more closely mimics the human condition. This injury model can determine the effectiveness of therapeutic interventions, in this case theophylline, on the isolated contused pathways of the spinal cord. Three weeks after a 150 kD C3/4 unilateral contusion subjects received a 15 mg/kg dose of theophylline prior to a contralateral C2 hemisection. Subjects that received theophylline were able to effectively utilize damaged pathways to breathe for up to 2 min, while subjects treated with saline were unable to support ventilation. Through these experiments, we demonstrate that theophylline can make injured pathways that mediate breathing more effective and therefore, suggest a potential therapeutic role in the critical time points immediately after injury.
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Affiliation(s)
- Kevin C Hoy
- Department of Neurosciences, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH 44109, USA
| | - Warren J Alilain
- Department of Neurosciences, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH 44109, USA.
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Beth Zimmer M, Grant JS, Ayar AE, Goshgarian HG. Ipsilateral inspiratory intercostal muscle activity after C2 spinal cord hemisection in rats. J Spinal Cord Med 2015; 38:224-30. [PMID: 24969369 PMCID: PMC4397205 DOI: 10.1179/2045772314y.0000000220] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Upper cervical spinal cord hemisection causes paralysis of the ipsilateral hemidiaphragm; however, the effect of C2 hemisection on the function of the intercostal muscles is not clear. We hypothesized that C2 hemisection would eliminate inspiratory intercostal activity ipsilateral to the injury and that some activity would return in a time-dependent manner. METHODS Female Sprague Dawley rats were anesthetized with urethane and inspiratory intercostal electromyogram (EMG) activity was recorded in control rats, acutely injured C2 hemisected rats, and at 1 and 16 weeks post C2 hemisection. RESULTS Bilateral recordings of intercostal EMG activity showed that inspiratory activity was reduced immediately after injury and increased over time. EMG activity was observed first in rostral spaces followed by recovery occurring in caudal spaces. Theophylline increased respiratory drive and increased intercostal activity, inducing activity that was previously absent. CONCLUSION These results suggest that there are crossed, initially latent, respiratory connections to neurons innervating the intercostal muscles similar to those innervating phrenic motor neurons.
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Affiliation(s)
- M. Beth Zimmer
- Department of Biological Sciences, Ferris State University, Big Rapids, MI, USA,Correspondence to: M. Beth Zimmer, Department of Biological Sciences, Ferris State University, 820 Campus Drive, 2120 ASC, Big Rapids, MI 49307, USA;
| | - Joshua S. Grant
- Department of Ophthalmology and Visual Science, University of Michigan Health System, University of Michigan, Ann Arbor, MI, USA
| | - Angelo E. Ayar
- Department of Dermatology, University of Michigan Health System, University of Michigan, Ann Arbor, MI, USA
| | - Harry G. Goshgarian
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI, USA
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Abstract
Three theories of regeneration dominate neuroscience today, all purporting to explain why the adult central nervous system (CNS) cannot regenerate. One theory proposes that Nogo, a molecule expressed by myelin, prevents axonal growth. The second theory emphasizes the role of glial scars. The third theory proposes that chondroitin sulfate proteoglycans (CSPGs) prevent axon growth. Blockade of Nogo, CSPG, and their receptors indeed can stop axon growth in vitro and improve functional recovery in animal spinal cord injury (SCI) models. These therapies also increase sprouting of surviving axons and plasticity. However, many investigators have reported regenerating spinal tracts without eliminating Nogo, glial scar, or CSPG. For example, many motor and sensory axons grow spontaneously in contused spinal cords, crossing gliotic tissue and white matter surrounding the injury site. Sensory axons grow long distances in injured dorsal columns after peripheral nerve lesions. Cell transplants and treatments that increase cAMP and neurotrophins stimulate motor and sensory axons to cross glial scars and to grow long distances in white matter. Genetic studies deleting all members of the Nogo family and even the Nogo receptor do not always improve regeneration in mice. A recent study reported that suppressing the phosphatase and tensin homolog (PTEN) gene promotes prolific corticospinal tract regeneration. These findings cannot be explained by the current theories proposing that Nogo and glial scars prevent regeneration. Spinal axons clearly can and will grow through glial scars and Nogo-expressing tissue under some circumstances. The observation that deleting PTEN allows corticospinal tract regeneration indicates that the PTEN/AKT/mTOR pathway regulates axonal growth. Finally, many other factors stimulate spinal axonal growth, including conditioning lesions, cAMP, glycogen synthetase kinase inhibition, and neurotrophins. To explain these disparate regenerative phenomena, I propose that the spinal cord has evolved regenerative mechanisms that are normally suppressed by multiple extrinsic and intrinsic factors but can be activated by injury, mediated by the PTEN/AKT/mTOR, cAMP, and GSK3b pathways, to stimulate neural growth and proliferation.
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Affiliation(s)
- Wise Young
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, State University of New Jersey, Piscataway, NJ, USA
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Warren PM, Alilain WJ. The challenges of respiratory motor system recovery following cervical spinal cord injury. PROGRESS IN BRAIN RESEARCH 2014; 212:173-220. [DOI: 10.1016/b978-0-444-63488-7.00010-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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The pattern and extent of retrograde transsynaptic transport of WGA-Alexa 488 in the phrenic motor system is dependent upon the site of application. J Neurosci Methods 2013; 222:156-64. [PMID: 24239778 DOI: 10.1016/j.jneumeth.2013.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/28/2013] [Accepted: 11/01/2013] [Indexed: 11/23/2022]
Abstract
The first aim of the study was to determine if WGA-Alexa 488 would undergo retrograde transsynaptic transport in the phrenic motor system as we have shown with WGA-HRP in a previous study. The advantage of using WGA-Alexa 488 is that labeled neurons could be isolated and analyzed for intracellular molecular mechanisms without exposing tissue sections to chemicals for histochemical staining. The second aim of the study was to investigate the pattern and extent of labeling that occurs when WGA-Alexa 488 is applied to the cervical phrenic nerve as compared to intradiaphragmatic injection. After injecting the hemidiaphragm ipsilateral to a C2 spinal cord hemisection, WGA-Alexa 488 presumably diffused to the contralateral hemidiaphragm and labeled the phrenic nuclei bilaterally. In all animals with hemidiaphragmatic injection, the rostral ventral respiratory group (rVRG) was also labeled bilaterally in the medulla. Thus, injection of WGA-Alexa 488 into the diaphragm results in retrograde transsynaptic transport in the phrenic motor system. After applying WGA-Alexa 488 to the ipsilateral intact cervical phrenic nerve in both C2 hemisected rats and rats with a sham hemisection, only ipsilateral phrenic neurons were labeled; there was no labeling of the rVRG or any other center in the medulla. These results suggest that WGA-Alexa 488 must be applied in the vicinity of the phrenic myoneural junction where there is a high concentration of WGA receptors in order for transsynaptic transport to occur. The present study provides investigators with a new tool to study plasticity in the respiratory system after spinal cord injury.
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Awad BI, Warren PM, Steinmetz MP, Alilain WJ. The role of the crossed phrenic pathway after cervical contusion injury and a new model to evaluate therapeutic interventions. Exp Neurol 2013; 248:398-405. [PMID: 23886671 DOI: 10.1016/j.expneurol.2013.07.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/25/2013] [Accepted: 07/16/2013] [Indexed: 11/29/2022]
Abstract
More than 50% of all spinal cord injury (SCI) cases are at the cervical level and usually result in the impaired ability to breathe. This is caused by damage to descending bulbospinal inspiratory tracts and the phrenic motor neurons which innervate the diaphragm. Most investigations have utilized a lateral C2 hemisection model of cervical SCI to study the resulting respiratory motor deficits and potential therapies. However, recent studies have emerged which incorporate experimental contusion injuries at the cervical level of the spinal cord to more closely reflect the type of trauma encountered in humans. Nonetheless, a common deficit observed in these contused animals is the inability to increase diaphragm motor activity in the face of respiratory challenge. In this report we tested the hypothesis that, following cervical contusion, all remaining tracts to the phrenic nucleus are active, including the crossed phrenic pathway (CPP). Additionally, we investigated the potential function these spared tracts might possess after injury. We find that, following a lateral C3/4 contusion injury, not all remaining pathways are actively exciting downstream phrenic motor neurons. However, removing some of these pathways through contralateral hemisection results in a cessation of all activity ipsilateral to the contusion. This suggests an important modulatory role for these pathways. Additionally, we conclude that this dual injury, hemi-contusion and post contra-hemisection, is a more effective and relevant model of cervical SCI as it results in a more direct compromise of diaphragmatic motor activity. This model can thus be used to test potential therapies with greater accuracy and clinical relevance than cervical contusion models currently allow.
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Affiliation(s)
- Basem I Awad
- Department of Neurosciences, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA; Department of Neurological Surgery, Mansoura University School of Medicine, Mansoura, Egypt
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Spinal 5-HT7 receptors and protein kinase A constrain intermittent hypoxia-induced phrenic long-term facilitation. Neuroscience 2013; 250:632-43. [PMID: 23850591 DOI: 10.1016/j.neuroscience.2013.06.068] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/21/2013] [Accepted: 06/29/2013] [Indexed: 01/09/2023]
Abstract
Phrenic long-term facilitation (pLTF) is a form of serotonin-dependent respiratory plasticity induced by acute intermittent hypoxia (AIH). pLTF requires spinal Gq protein-coupled serotonin-2 receptor (5-HT2) activation, new synthesis of brain-derived neurotrophic factor (BDNF) and activation of its high-affinity receptor, TrkB. Intrathecal injections of selective agonists for Gs protein-coupled receptors (adenosine 2A and serotonin-7; 5-HT7) also induce long-lasting phrenic motor facilitation via TrkB "trans-activation." Since serotonin released near phrenic motor neurons may activate multiple serotonin receptor subtypes, we tested the hypothesis that 5-HT7 receptor activation contributes to AIH-induced pLTF. A selective 5-HT7 receptor antagonist (SB-269970, 5mM, 12 μl) was administered intrathecally at C4 to anesthetized, vagotomized and ventilated rats prior to AIH (3, 5-min episodes, 11% O2). Contrary to predictions, pLTF was greater in SB-269970 treated versus control rats (80 ± 11% versus 45 ± 6% 60 min post-AIH; p<0.05). Hypoglossal LTF was unaffected by spinal 5-HT7 receptor inhibition, suggesting that drug effects were localized to the spinal cord. Since 5-HT7 receptors are coupled to protein kinase A (PKA), we tested the hypothesis that PKA inhibits AIH-induced pLTF. Similar to 5-HT7 receptor inhibition, spinal PKA inhibition (KT-5720, 100 μM, 15 μl) enhanced pLTF (99 ± 15% 60 min post-AIH; p<0.05). Conversely, PKA activation (8-br-cAMP, 100 μM, 15 μl) blunted pLTF versus control rats (16 ± 5% versus 45 ± 6% 60 min post-AIH; p<0.05). These findings suggest a novel mechanism whereby spinal Gs protein-coupled 5-HT7 receptors constrain AIH-induced pLTF via PKA activity.
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Burke PGR, Sousa LO, Tallapragada VJ, Goodchild AK. Inhibition of protein kinase A activity depresses phrenic drive and glycinergic signalling, but not rhythmogenesis in anaesthetized rat. Eur J Neurosci 2013; 38:2260-70. [PMID: 23627348 DOI: 10.1111/ejn.12230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/20/2013] [Accepted: 03/25/2013] [Indexed: 11/28/2022]
Abstract
The cAMP-protein kinase A (PKA) pathway plays a critical role in regulating neuronal activity. Yet, how PKA signalling shapes the population activity of neurons that regulate respiratory rhythm and motor patterns in vivo is poorly defined. We determined the respiratory effects of focally inhibiting endogenous PKA activity in defined classes of respiratory neurons in the ventrolateral medulla and spinal cord by microinjection of the membrane-permeable PKA inhibitor Rp-adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS) in urethane-anaesthetized adult Sprague Dawley rats. Phrenic nerve activity, end-tidal CO2 and arterial pressure were recorded. Rp-cAMPS in the preBötzinger complex (preBötC) caused powerful, dose-dependent depression of phrenic burst amplitude and inspiratory period. Rp-cAMPS powerfully depressed burst amplitude in the phrenic premotor nucleus, but had no effect at the phrenic motor nucleus, suggesting a lack of persistent PKA activity here. Surprisingly, inhibition of PKA activity in the preBötC increased phrenic burst frequency, whereas in the Bötzinger complex phrenic frequency decreased. Pretreating the preBötC with strychnine, but not bicuculline, blocked the Rp-cAMPS-evoked increase in frequency, but not the depression of phrenic burst amplitude. We conclude that endogenous PKA activity in excitatory inspiratory preBötzinger neurons and phrenic premotor neurons, but not motor neurons, regulates network inspiratory drive currents that underpin the intensity of phrenic nerve discharge. We show that inhibition of PKA activity reduces tonic glycinergic transmission that normally restrains the frequency of rhythmic respiratory activity. Finally, we suggest that the maintenance of the respiratory rhythm in vivo is not dependent on endogenous cAMP-PKA signalling.
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Affiliation(s)
- P G R Burke
- Australian School of Advanced Medicine, Level 1, 2 Technology Drive, Macquarie University, Sydney, NSW, Australia
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15
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Theophylline regulates inflammatory and neurotrophic factor signals in functional recovery after C2-hemisection in adult rats. Exp Neurol 2012; 238:79-88. [PMID: 22981449 DOI: 10.1016/j.expneurol.2012.08.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 08/09/2012] [Accepted: 08/11/2012] [Indexed: 11/24/2022]
Abstract
Recovery of respiratory activity in an upper cervical hemisection model (C2H) of spinal cord injury (SCI) can be induced by systemic theophylline administration 24-48 h after injury. The objectives in the present study are (1) to identify pro-inflammatory and neurotrophic factors expressed after C2H and (2) molecular signals involved in functional recovery. Four groups of adult female rats classified as (i) sham (SH) controls, (ii) subjected to a left C2 hemisection (C2H) only, (iii) C2H rats administered theophylline for 3 consecutive days 2 days after C2H (C2H-T day 5) and (iv) C2H rats treated with theophylline for 3 consecutive days 2 days after C2H and then weaned for 12 days (C2H-T day 17) prior to assessment of respiratory function and molecular analysis were employed. Corresponding sham controls, C2H untreated (vehicle only controls) and C2H treated (theophylline) rats were sacrificed, C3-C6 spinal cord segments quickly dissected and left (ipsilateral) hemi spinal cord and right (contralateral) hemi spinal cord were separately harvested 2 days post surgery. Sham operated and C2H untreated-controls corresponding to C2H-T day 5 and C2H-T day 17 rats, respectively, were prepared similarly. Messenger RNA levels for pro-inflammatory genes (TXNIP, IL-1β, TNF-α and iNOS) and neurotrophic and survival factors (BDNF, GDNF, and Bcl2) were analyzed by real time quantitative PCR. Gene expression pattern was unaltered in SH rats. TXNIP, iNOS, BDNF, GDNF and Bcl2 mRNA levels were significantly increased in the ipsilateral hemi spinal cord in C2H rats. BDNF, GDNF and Bcl2 levels remained elevated in the ipsilateral hemi spinal cord in C2H-T day 5 rats. In this same group, there was further enhancement in TXNIP and IL-1β while iNOS returned to basal levels. Theophylline increased DNA binding activity of transcription factors - cyclic AMP responsive element (CRE) binding protein (CREB) and pro-inflammatory NF-κB. Messenger RNA levels for all genes returned to basal levels in C2H-T day 17 rats. However, BDNF mRNA levels remained significantly elevated after weaning from the drug. Our results suggest that enhanced resolution of early inflammatory processes and expression of pro-survival factors may underlie theophylline-induced respiratory recovery. The results identify potential targets for gene and drug therapies.
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Chew DJ, Fawcett JW, Andrews MR. The challenges of long-distance axon regeneration in the injured CNS. PROGRESS IN BRAIN RESEARCH 2012. [PMID: 23186719 DOI: 10.1016/b978-0-444-59544-7.00013-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Injury to the central nervous system (CNS) that results in long-tract axonal damage typically leads to permanent functional deficits in areas innervated at, and below, the level of the lesion. The initial ischemia, inflammation, and neurodegeneration are followed by a progressive generation of scar tissue, dieback of transected axons, and demyelination, creating an area inhibitory to regrowth and recovery. Two ways to combat this inhibition is to therapeutically target the extrinsic and intrinsic properties of the axon-scar environment. Scar tissue within and surrounding the lesion site can be broken down using an enzyme known as chondroitinase. Negative regulators of adult neuronal growth, such as Nogo, can be neutralized with antibodies. Both therapies greatly improve functional recovery in animal models. Alternatively, modifying the intrinsic growth properties of CNS neurons through gene therapy or pharmacotherapy has also shown promising axonal regeneration after injury. Despite these promising therapies, the main challenge of long-distance axon regeneration still remains; achieving a level of functional and organized connectivity below the level of the lesion that mimics the intact CNS.
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Affiliation(s)
- Daniel J Chew
- Centre for Brain Repair, University of Cambridge, Forvie Site, Robinson Way, Cambridge, UK
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Treatments to restore respiratory function after spinal cord injury and their implications for regeneration, plasticity and adaptation. Exp Neurol 2011; 235:18-25. [PMID: 22200541 DOI: 10.1016/j.expneurol.2011.12.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 11/18/2011] [Accepted: 12/09/2011] [Indexed: 02/04/2023]
Abstract
Spinal cord injury (SCI) often leads to impaired breathing. In most cases, such severe respiratory complications lead to morbidity and death. However, in the last few years there has been extensive work examining ways to restore this vital function after experimental spinal cord injury. In addition to finding strategies to rescue breathing activity, many of these experiments have also yielded a great deal of information about the innate plasticity and capacity for adaptation in the respiratory system and its associated circuitry in the spinal cord. This review article will highlight experimental SCI resulting in compromised breathing, the various methods of restoring function after such injury, and some recent findings from our own laboratory. Additionally, it will discuss findings about motor and CNS respiratory plasticity and adaptation with potential clinical and translational implications.
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Sandhu M, Dougherty B, Lane M, Bolser D, Kirkwood P, Reier P, Fuller D. Respiratory recovery following high cervical hemisection. Respir Physiol Neurobiol 2009; 169:94-101. [PMID: 19560562 PMCID: PMC2783827 DOI: 10.1016/j.resp.2009.06.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/09/2009] [Accepted: 06/19/2009] [Indexed: 01/16/2023]
Abstract
In this paper we review respiratory recovery following C2 spinal cord hemisection (C2HS) and introduce evidence for ipsilateral (IL) and contralateral (CL) phrenic motor neuron (PhrMN) synchrony post-C2HS. Rats have rapid, shallow breathing after C2HS but ventilation ( logical or (E)) is maintained. logical or (E) deficits occur during hypercapnic challenge reflecting reduced tidal volume (VT), but modest recovery occurs by 12 wks post-injury. IL PhrMN activity recovers in a time-dependent manner after C2HS, and neuroanatomical evidence suggests that this may involve both mono- and polysynaptic pathways. Accordingly, we used cross-correlation to examine IL and CL PhrMN synchrony after C2HS. Uninjured rats showed correlogram peaks consistent with synchronous activity and common synaptic input. Correlogram peaks were absent at 2 wks post-C2HS, but by 12 wks 50% of rats showed peaks occurring with a 1.1+/-0.19ms lag from zero on the abscissa. These data are consistent with prolonged conduction time to IL (vs. CL) PhrMNs and the possibility of polysynaptic inputs to IL PhrMNs after chronic C2HS.
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Affiliation(s)
- M.S. Sandhu
- Department of Physical Therapy College of Public Health and Health Professions McKnight Brain Institute University of Florida P.O. Box 100154, 100 S. Newell Drive Gainesville, FL 32610, USA
| | - B.J. Dougherty
- Department of Physical Therapy College of Public Health and Health Professions McKnight Brain Institute University of Florida P.O. Box 100154, 100 S. Newell Drive Gainesville, FL 32610, USA
- Department of Neuroscience College of Medicine McKnight Brain Institute University of Florida PO Box 100244 100 Newell Dr Gainesville FL 32610−0244, USA
| | - M.A. Lane
- Department of Neuroscience College of Medicine McKnight Brain Institute University of Florida PO Box 100244 100 Newell Dr Gainesville FL 32610−0244, USA
| | - D.C. Bolser
- Department of Physiological Sciences College of Veterinary Medicine PO Box 100144, 1600 SW Archer Rd Gainesville, FL 32610−0144, USA
| | - P.A. Kirkwood
- Sobell Dept for Motor Neuroscience and Movement Disorders UCL Institute of Neurology Queen Square, London WC1N 3BG United Kingdom
| | - P.J. Reier
- Department of Neuroscience College of Medicine McKnight Brain Institute University of Florida PO Box 100244 100 Newell Dr Gainesville FL 32610−0244, USA
| | - D.D. Fuller
- Department of Physical Therapy College of Public Health and Health Professions McKnight Brain Institute University of Florida P.O. Box 100154, 100 S. Newell Drive Gainesville, FL 32610, USA
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Fouad K, Ghosh M, Vavrek R, Tse AD, Pearse DD. Dose and chemical modification considerations for continuous cyclic AMP analog delivery to the injured CNS. J Neurotrauma 2009; 26:733-40. [PMID: 19397425 DOI: 10.1089/neu.2008.0730] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In this investigation, two cell-permeable synthetic analogs of cAMP, dibutyryl-cAMP (db-cAMP) and 8-bromo-cAMP, which are widely used to elevate intracellular cAMP levels under experimental conditions, were investigated for their ability to dose-dependently improve histological and functional outcomes following continuous delivery in two models of incomplete spinal cord injury (SCI). The cAMP analogs were delivered via osmotic minipumps at 1-250 mM through an indwelling cortical cannula or by intrathecal infusion for up to 4 weeks after either a T8 unilateral over-hemisection or a C2-3 dorsolateral quadrant lesion, respectively. In both SCI models, continuous db-cAMP delivery was associated with histopathological changes that included sporadic micro-hemorrhage formation and cavitation, enhanced macrophage infiltration and tissue damage at regions beyond the immediate application site; no deleterious or beneficial effect of agent delivery was observed at the spinal injury site. Furthermore, these changes were accompanied by pronounced behavioral deficits that included an absence of progressive locomotor recovery, increased extensor tone, paralysis, and sensory abnormalities. These deleterious effects were not observed in saline-treated animals, in animals in which the db-cAMP dose did not exceed 1 mM, or in those animals that received a high dose (250 mM) of the alternative cAMP analog, 8-bromo-cAMP. These results demonstrate that, for continuous intraparenchymal or intrathecal administration of cAMP analogs for the study of biological or therapeutic effects within the central nervous system (CNS), consideration of the effective concentration applied as well as the potential toxicity of chemical moieties on the parent molecule and/or their activity needs to be taken into account.
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Affiliation(s)
- Karim Fouad
- University of Alberta, Edmonton, Alberta, Canada
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Seeds NW, Akison L, Minor K. Role of plasminogen activator in spinal cord remodeling after spinal cord injury. Respir Physiol Neurobiol 2009; 169:141-9. [PMID: 19651246 DOI: 10.1016/j.resp.2009.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/24/2009] [Accepted: 07/25/2009] [Indexed: 12/22/2022]
Abstract
Plasminogen activators play an active role in synaptic plasticity associated with the crossed phrenic phenomenon (CPP) and recovery of respiratory function following spinal cord injury. A genetic approach has been used to identify molecular mechanisms underlying this synaptic plasticity. Knockout mice lacking different genes in the plasminogen activator/plasmin system demonstrate that expression of urokinase plasminogen activator (uPA) is required during the critical 1-2h delay period following C2-hemisection for the acquisition of a good CPP response. uPA knockout mice fail to show the structural remodeling of phrenic motorneuron synapses that underlie the CPP response. Potential mechanisms by which uPA may promote phrenic motorneuron synaptic plasticity have been explored. Expression of uPA receptors, uPAR and LRP-1, are both up-regulated in the ipsilateral phrenic motor nucleus (PMN) following C2-hemisection. A comparison of microarray data and real-time PCR analysis of mRNAs induced in the PMN after hemisection indicate potential cell signaling pathways downstream of uPA's interaction with these cell surface receptors in the PMN. Knowledge of these uPA-mediated signaling pathways may identify potential means for the pharmacological activation of the synaptic plasticity required for recovery of phrenic motorneuron activity.
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Affiliation(s)
- Nicholas W Seeds
- Department of Biochemistry & Molecular Genetics and Neuroscience Program, University of Colorado School of Medicine, Aurora, CO 80045, United States.
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Goshgarian HG. The crossed phrenic phenomenon and recovery of function following spinal cord injury. Respir Physiol Neurobiol 2009; 169:85-93. [PMID: 19539790 DOI: 10.1016/j.resp.2009.06.005] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 05/22/2009] [Accepted: 06/09/2009] [Indexed: 11/27/2022]
Abstract
This review will focus on neural plasticity and recovery of respiratory function after spinal cord injury and feature the "crossed phrenic phenomenon" (CPP) as a model for demonstrating such plasticity and recovery. A very brief summary of the earlier literature on the CPP will be followed by a more detailed review of the more recent studies. Two aspects of plasticity associated with the CPP that have been introduced in the literature recently have been spontaneous recovery of ipsilateral hemidiaphragmatic function following chronic spinal cord injury and drug-induced persistent recovery of the ipsilateral hemidiaphragm lasting long after animals have been weaned from drug treatment. The underlying mechanisms for this plasticity and resultant recovery will be discussed in this review. Moreover, two new models involving the CPP have been introduced: a mouse model which now provides for an opportunity to study CPP plasticity at a molecular level using a genetic approach and light-stimulated induction of the CPP accomplished by transfecting mammalian cells with channelrhodopsin. Both models provide an opportunity to sort out the intracellular signaling cascades that may be involved in motor recovery in the respiratory system after spinal cord injury. Finally, the review will examine developmental plasticity of the CPP and discuss how the expression of the CPP changes in neonatal rats as they mature to adults. Understanding the underlying mechanisms behind the spontaneous expression of the crossed phrenic pathway either in the developing animal or after chronic spinal cord injury in the adult animal may provide clues to initiating respiratory recovery sooner to alleviate human suffering and eventually eliminate the leading cause of death in human cases of spinal cord injury.
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Affiliation(s)
- Harry G Goshgarian
- Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, MI 48201, United States.
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