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Yamada R, Koike T, Nakakariya M, Kimura H. Orexin receptor 2 agonist activates diaphragm and genioglossus muscle through stimulating inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons in rodents. PLoS One 2024; 19:e0306099. [PMID: 38917189 PMCID: PMC11198781 DOI: 10.1371/journal.pone.0306099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 06/10/2024] [Indexed: 06/27/2024] Open
Abstract
Orexin-mediated stimulation of orexin receptors 1/2 (OX[1/2]R) may stimulate the diaphragm and genioglossus muscle via activation of inspiratory neurons in the pre-Bötzinger complex, which are critical for the generation of inspiratory rhythm, and phrenic and hypoglossal motoneurons. Herein, we assessed the effects of OX2R-selective agonists TAK-925 (danavorexton) and OX-201 on respiratory function. In in vitro electrophysiologic analyses using rat medullary slices, danavorexton and OX-201 showed tendency and significant effect, respectively, in increasing the frequency of inspiratory synaptic currents of inspiratory neurons in the pre-Bötzinger complex. In rat medullary slices, both danavorexton and OX-201 significantly increased the frequency of inspiratory synaptic currents of hypoglossal motoneurons. Danavorexton and OX-201 also showed significant effect and tendency, respectively, in increasing the frequency of burst activity recorded from the cervical (C3-C5) ventral root, which contains axons of phrenic motoneurons, in in vitro electrophysiologic analyses from rat isolated brainstem-spinal cord preparations. Electromyogram recordings revealed that intravenous administration of OX-201 increased burst frequency of the diaphragm and burst amplitude of the genioglossus muscle in isoflurane- and urethane-anesthetized rats, respectively. In whole-body plethysmography analyses, oral administration of OX-201 increased respiratory activity in free-moving mice. Overall, these results suggest that OX2R-selective agonists enhance respiratory function via activation of the diaphragm and genioglossus muscle through stimulation of inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons. OX2R-selective agonists could be promising drugs for various conditions with respiratory dysfunction.
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Affiliation(s)
- Ryuji Yamada
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Tatsuki Koike
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Masanori Nakakariya
- Drug Metabolism and Pharmacokinetics Laboratory, Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Haruhide Kimura
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
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Nomura K, Narimatsu E, Oke Y, Oku Y. The lesion site of organophosphorus-induced central apnea and the effects of antidotes. Sci Rep 2023; 13:20419. [PMID: 37990100 PMCID: PMC10663552 DOI: 10.1038/s41598-023-47745-x] [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: 04/26/2023] [Accepted: 11/17/2023] [Indexed: 11/23/2023] Open
Abstract
Organophosphorus poisoning kills individuals by causing central apnea; however, the underlying cause of death remains unclear. Following findings that the pre-Bötzinger complex impairment alone does not account for central apnea, we analyzed the effect of paraoxon on the brainstem-spinal cord preparation, spanning the lower medulla oblongata to phrenic nucleus. Respiratory bursts were recorded by connecting electrodes to the ventral 4th cervical nerve root of excised brainstem-spinal cord preparations obtained from 6-day-old Sprague-Dawley rats. We observed changes in respiratory bursts when paraoxon, neostigmine, atropine, and 2-pyridine aldoxime methiodide were administered via bath application. The percentage of burst extinction in the paraoxon-poisoning group was 50% compared with 0% and 18.2% in the atropine and 2-pyridine aldoxime methiodide treatment groups, respectively. Both treatments notably mitigated the paraoxon-induced reduction in respiratory bursts. In the neostigmine group, similar to paraoxon, bursts stopped in 66.7% of cases but were fully reversed by atropine. This indicates that the primary cause of central apnea is muscarinic receptor-mediated in response to acetylcholine excess. Paraoxon-induced central apnea is hypothesized to result from neural abnormalities within the inferior medulla oblongata to the phrenic nucleus, excluding pre-Bötzinger complex. These antidotes antagonize central apnea, suggesting that they may be beneficial therapeutic agents.
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Affiliation(s)
- Kazuhito Nomura
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo-Ken, 663-8501, Japan.
- Department of Emergency Medicine, Sapporo Medical University, Sapporo-Shi, 064-8543, Japan.
| | - Eichi Narimatsu
- Department of Emergency Medicine, Sapporo Medical University, Sapporo-Shi, 064-8543, Japan
| | - Yoshihiko Oke
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo-Ken, 663-8501, Japan
| | - Yoshitaka Oku
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo-Ken, 663-8501, Japan
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Rudy SL, Wealing JC, Banayat T, Black C, Funk GD, Revill AL. A muscarinic, GIRK channel-mediated inhibition of inspiratory-related XII nerve motor output emerges in early postnatal development in mice. J Appl Physiol (1985) 2023; 135:1041-1052. [PMID: 37767557 PMCID: PMC10911762 DOI: 10.1152/japplphysiol.00042.2023] [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: 01/19/2023] [Revised: 09/06/2023] [Accepted: 09/21/2023] [Indexed: 09/29/2023] Open
Abstract
In neonatal rhythmic medullary slices, muscarinic acetylcholine receptor (mAChR) activation of hypoglossal (XII) motoneurons that innervate the tongue has a net excitatory effect on XII inspiratory motor output. Conversely, during rapid eye movement sleep in adult rodents, XII motoneurons experience a loss of excitability partly due to activation of mAChRs. This may be mediated by activation of G-protein-coupled inwardly rectifying potassium (GIRK) channels. Therefore, this study was designed to evaluate whether muscarinic modulation of XII inspiratory motor output in mouse rhythmic medullary slices includes GIRK channel-mediated inhibition and, if so, when this inhibitory mechanism emerges. Local pressure injection of the mAChR agonist muscarine potentiated inspiratory bursting by 150 ± 28% in postnatal day (P)0-P5 rhythmic medullary slice preparations. In the absence of muscarine, pharmacological GIRK channel block by Tertiapin-Q did not affect inspiratory burst parameters, whereas activation with ML297 decreased inspiratory burst area. Blocking GIRK channels by local preapplication of Tertiapin-Q revealed a developmental change in muscarinic modulation of inspiratory bursting. In P0-P2 rhythmic medullary slices, Tertiapin-Q preapplication had no significant effect on muscarinic potentiation of inspiratory bursting (a negligible 6% decrease). However, preapplication of Tertiapin-Q to P3-P5 rhythmic medullary slices caused a 19% increase in muscarinic potentiation of XII inspiratory burst amplitude. Immunofluorescence experiments revealed expression of GIRK 1 and 2 subunits and M1, M2, M3, and M5 mAChRs from P0 to P5. Overall, these data support that mechanisms underlying muscarinic modulation of inspiratory burst activity change postnatally and that potent GIRK-mediated inhibition described in adults emerges early in postnatal life.NEW & NOTEWORTHY Muscarinic modulation of inspiratory bursting at hypoglossal motoneurons has a net excitatory effect in neonatal rhythmic medullary slice preparations and a net inhibitory effect in adult animals. We demonstrate that muscarinic modulation of inspiratory bursting undergoes maturational changes from postnatal days 0 to 5 that include emergence of an inhibitory component mediated by G-protein-coupled inwardly rectifying potassium channels after postnatal day 3 in neonatal mouse rhythmic medullary slice preparations.
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Affiliation(s)
- Samantha L Rudy
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Jesse C Wealing
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Tatum Banayat
- Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States
| | - Chody Black
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Gregory D Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Ann L Revill
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
- Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States
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Aroniadou-Anderjaska V, Figueiredo TH, de Araujo Furtado M, Pidoplichko VI, Braga MFM. Mechanisms of Organophosphate Toxicity and the Role of Acetylcholinesterase Inhibition. TOXICS 2023; 11:866. [PMID: 37888716 PMCID: PMC10611379 DOI: 10.3390/toxics11100866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/11/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023]
Abstract
Organophosphorus compounds (OPs) have applications in agriculture (e.g., pesticides), industry (e.g., flame retardants), and chemical warfare (nerve agents). In high doses or chronic exposure, they can be toxic or lethal. The primary mechanism, common among all OPs, that initiates their toxic effects is the inhibition of acetylcholinesterase. In acute OP exposure, the subsequent surge of acetylcholine in cholinergic synapses causes a peripheral cholinergic crisis and status epilepticus (SE), either of which can lead to death. If death is averted without effective seizure control, long-term brain damage ensues. This review describes the mechanisms by which elevated acetylcholine can cause respiratory failure and trigger SE; the role of the amygdala in seizure initiation; the role of M1 muscarinic receptors in the early stages of SE; the neurotoxic pathways activated by SE (excitotoxicity/Ca++ overload/oxidative stress, neuroinflammation); and neurotoxic mechanisms linked to low-dose, chronic exposure (Ca++ dyshomeostasis/oxidative stress, inflammation), which do not depend on SE and do not necessarily involve acetylcholinesterase inhibition. The evidence so far indicates that brain damage from acute OP exposure is a direct result of SE, while the neurotoxic mechanisms activated by low-dose chronic exposure are independent of SE and may not be associated with acetylcholinesterase inhibition.
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Affiliation(s)
- Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (V.A.-A.); (V.I.P.)
- Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Taiza H. Figueiredo
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (V.A.-A.); (V.I.P.)
| | - Marcio de Araujo Furtado
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (V.A.-A.); (V.I.P.)
| | - Volodymyr I. Pidoplichko
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (V.A.-A.); (V.I.P.)
| | - Maria F. M. Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (V.A.-A.); (V.I.P.)
- Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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Patterns of cardio-respiratory motor outputs during acute and subacute exposure to chlorpyrifos in an ex-vivo in situ preparation in rats. Toxicol Appl Pharmacol 2022; 436:115862. [PMID: 34998853 DOI: 10.1016/j.taap.2022.115862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 12/08/2021] [Accepted: 01/02/2022] [Indexed: 10/19/2022]
Abstract
While a considerable body of literature has characterized the clinical features induced by organophosphate pesticides, the field lacks scrutiny into cardio-respiratory changes in different phases of poisoning. Herein, we evaluated the impact of chlorpyrifos (CPF) and its active metabolite chlorpyrifos-oxon (CPO) on the cardiorespiratory system during acute and subacute phases of poisoning using an in situ experimental rodent model. CPF (30 mg/kg) was injected intraperitoneally to rats beforehand (24 h) whereas CPO (15 mg/kg) was added into the perfusate reservoir to evaluate the effects on the motor outputs throughout the three phases of the respiratory cycle: inspiration, post-inspiration and late expiration. Phrenic, recurrent laryngeal (RLN) and thoracic sympathetic nerve activity (tSNA) were recorded. Heart rate was derived from the electrocardiogram (ECG) and the baro- and chemo-reflexes tested. CPF and CPO led to a time-dependent change in cardiorespiratory motor outputs. In the acute phase, the CPO induced bradypnea, transiently reduced the inspiratory time (TI), and increased the amplitude of phrenic. Post-inspiratory (PI) discharge recorded from the RLN was progressively reduced while tSNA was increased. CPO significantly depressed the chemoreflex but had no effect on baroreflex. During subacute phase, CPF prolongated TI with no effect on respiratory rate. Both the RLN PI discharge, the chemoreflex and the baroreflex sympathetic gain were reduced. In addition, both CPF and CPO shifted the cardiac sympatho-vagal balance towards sympathetic dominance. Our data show that different phases of poisoning are associated with specific changes in the cardio-respiratory system and might therefore demand distinct approaches by health care providers.
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Katsuki S, Ikeda K, Onimaru H, Dohi K, Izumizaki M. Effects of acetylcholine on hypoglossal and C4 nerve activity in brainstem-spinal cord preparations from newborn rat. Respir Physiol Neurobiol 2021; 293:103737. [PMID: 34229065 DOI: 10.1016/j.resp.2021.103737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 06/17/2021] [Accepted: 07/01/2021] [Indexed: 11/17/2022]
Abstract
Effects of acetylcholine (ACh) on respiratory activity have been an intriguing theme especially in relation to central chemoreception and the control of hypoglossal nerve activity. We studied the effects of ACh on hypoglossal and phrenic (C4) nerve activities and inspiratory and pre-inspiratory neurons in the rostral ventrolateral medulla in brainstem-spinal cord preparations from newborn rats. ACh application increased respiratory rhythm, decreased inspiratory hypoglossal and C4 nerve burst amplitude, and enhanced pre-inspiratory hypoglossal activity. ACh induced membrane depolarization of pre-inspiratory neurons that might be involved in facilitation of respiratory rhythm by ACh. Effects of ACh on hypoglossal and C4 nerve activity were partially reversed by a nicotinic receptor blocker, mecamylamine. Further application of a muscarinic receptor antagonist, oxybutynin, resulted in slight increase of hypoglossal (but not C4) burst amplitude. Thus, ACh induced different effects on hypoglossal and C4 nerve activity in the brainstem-spinal cord preparation.
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Affiliation(s)
- Shino Katsuki
- Department of Physiology, Showa University School of Medicine, Tokyo 142-8555, Japan; Department of Emergency, Disaster and Critical Care Medicine, Showa University, Tokyo 142-8555, Japan
| | - Keiko Ikeda
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
| | - Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Tokyo 142-8555, Japan.
| | - Kenji Dohi
- Department of Emergency, Disaster and Critical Care Medicine, Showa University, Tokyo 142-8555, Japan
| | - Masahiko Izumizaki
- Department of Physiology, Showa University School of Medicine, Tokyo 142-8555, Japan
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7
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Mechanism of central hypopnoea induced by organic phosphorus poisoning. Sci Rep 2020; 10:15834. [PMID: 32985607 PMCID: PMC7522229 DOI: 10.1038/s41598-020-73003-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 09/10/2020] [Indexed: 11/15/2022] Open
Abstract
Whether central apnoea or hypopnoea can be induced by organophosphorus poisoning remains unknown to date. By using the acute brainstem slice method and multi-electrode array system, we established a paraoxon (a typical acetylcholinesterase inhibitor) poisoning model to investigate the time-dependent changes in respiratory burst amplitudes of the pre-Bötzinger complex (respiratory rhythm generator). We then determined whether pralidoxime or atropine, which are antidotes of paraoxon, could counteract the effects of paraoxon. Herein, we showed that paraoxon significantly decreased the respiratory burst amplitude of the pre-Bötzinger complex (p < 0.05). Moreover, pralidoxime and atropine could suppress the decrease in amplitude by paraoxon (p < 0.05). Paraoxon directly impaired the pre-Bötzinger complex, and the findings implied that this impairment caused central apnoea or hypopnoea. Pralidoxime and atropine could therapeutically attenuate the impairment. This study is the first to prove the usefulness of the multi-electrode array method for electrophysiological and toxicological studies in the mammalian brainstem.
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Zheng F, Nixdorf-Bergweiler BE, Edelmann E, van Brederode JFM, Alzheimer C. Muscarinic Modulation of Morphologically Identified Glycinergic Neurons in the Mouse PreBötzinger Complex. Front Cell Neurosci 2020; 13:562. [PMID: 31998077 PMCID: PMC6962194 DOI: 10.3389/fncel.2019.00562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 12/05/2019] [Indexed: 11/13/2022] Open
Abstract
The cholinergic system plays an essential role in central respiratory control, but the underlying mechanisms remain elusive. We used whole-cell recordings in brainstem slices from juvenile mice expressing enhanced green fluorescent protein (EGFP) under the control of the glycine transporter type 2 (GlyT2) promoter, to examine muscarinic modulation of morphologically identified glycinergic neurons in the preBötzinger complex (preBötC), an area critical for central inspiratory rhythm generation. Biocytin-filled reconstruction of glycinergic neurons revealed that the majority of them had few primary dendrites and had axons arborized within their own dendritic field. Few glycinergic neurons had axon collaterals extended towards the premotor/motor areas or ran towards the contralateral preBötC, and had more primary dendrites and more compact dendritic trees. Spontaneously active glycinergic neurons fired regular spikes, or less frequently in a "burst-like" pattern at physiological potassium concentration. Muscarine suppressed firing in the majority of regular spiking neurons via M2 receptor activation while enhancing the remaining neurons through M1 receptors. Interestingly, rhythmic bursting was augmented by muscarine in a small group of glycinergic neurons. In contrast to its heterogeneous modulation of glycinergic neuronal excitability, muscarine generally depressed inhibitory and excitatory synaptic inputs onto both glycinergic and non-glycinergic preBötC neurons, with a stronger effect on inhibitory input. Notably, presynaptic muscarinic attenuation of excitatory synaptic input was dependent on M1 receptors in glycinergic neurons and on M2 receptors in non-glycinergic neurons. Additional field potential recordings of excitatory synaptic potentials in the M2 receptor knockout mice indicate that glycinergic and non-glycinergic neurons contribute equally to the general suppression by muscarine of excitatory activity in preBötC circuits. In conclusion, our data show that preBötC glycinergic neurons are morphologically heterogeneous, and differ in the properties of synaptic transmission and muscarinic modulation in comparison to non-glycinergic neurons. The dominant and cell-type-specific muscarinic inhibition of synaptic neurotransmission and spiking may contribute to central respiratory disturbances in high cholinergic states.
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Affiliation(s)
- Fang Zheng
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara E Nixdorf-Bergweiler
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Elke Edelmann
- Institut für Physiologie, Otto-von-Guericke-Universität, Magdeburg, Germany
| | - Johannes F M van Brederode
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Department of Physiology and Biophysics, University of Washington, Seattle, WA, United States
| | - Christian Alzheimer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Balanced cholinergic modulation of spinal locomotor circuits via M2 and M3 muscarinic receptors. Sci Rep 2019; 9:14051. [PMID: 31575899 PMCID: PMC6773880 DOI: 10.1038/s41598-019-50452-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/12/2019] [Indexed: 01/05/2023] Open
Abstract
Neuromodulation ensures that neural circuits produce output that is flexible whilst remaining within an optimal operational range. The neuromodulator acetylcholine is released during locomotion to regulate spinal motor circuits. However, the range of receptors and downstream mechanisms by which acetylcholine acts have yet to be fully elucidated. We therefore investigated metabotropic acetylcholine receptor-mediated modulation by using isolated spinal cord preparations from neonatal mice in which locomotor-related output can be induced pharmacologically. We report that M2 receptor blockade decreases the frequency and amplitude of locomotor-related activity, whilst reducing its variability. In contrast, M3 receptor blockade destabilizes locomotor-related bursting. Motoneuron recordings from spinal cord slices revealed that activation of M2 receptors induces an outward current, decreases rheobase, reduces the medium afterhyperpolarization, shortens spike duration and decreases synaptic inputs. In contrast, M3 receptor activation elicits an inward current, increases rheobase, extends action potential duration and increases synaptic inputs. Analysis of miniature postsynaptic currents support that M2 and M3 receptors modulate synaptic transmission via different mechanisms. In summary, we demonstrate that M2 and M3 receptors have opposing modulatory actions on locomotor circuit output, likely reflecting contrasting cellular mechanisms of action. Thus, intraspinal cholinergic systems mediate balanced, multimodal control of spinal motor output.
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The pre-Bötzinger complex: Generation and modulation of respiratory rhythm. NEUROLOGÍA (ENGLISH EDITION) 2019. [DOI: 10.1016/j.nrleng.2018.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Nicole S, Azuma Y, Bauché S, Eymard B, Lochmüller H, Slater C. Congenital Myasthenic Syndromes or Inherited Disorders of Neuromuscular Transmission: Recent Discoveries and Open Questions. J Neuromuscul Dis 2019; 4:269-284. [PMID: 29125502 PMCID: PMC5701762 DOI: 10.3233/jnd-170257] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models. Frontier forms between CMS and congenital myopathy, which have been genetically and clinically identified, underline the poorly understood interplay between the synaptic and extrasynaptic molecules in the neuromuscular system. In addition, precise electrophysiological and histopathological investigations of individuals with CMS suggest an important role of NMJ plasticity in the response to CMS pathogenesis. While efficient drug-based treatments are already available to improve neuromuscular transmission for most forms of CMS, others, as well as neurological and muscular comorbidities, remain resistant. Taken together, the available pathological data point to physiological issues which remain to be understood in order to achieve precision medicine with efficient therapeutics for all individuals suffering from CMS.
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Affiliation(s)
- Sophie Nicole
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Stéphanie Bauché
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France.,AP-HP, Hôpital Pitié-Salpétrière, 75013 Paris, France
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Clarke Slater
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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Tao M, Liu Q, Miyazaki Y, Canning BJ. Nicotinic receptor dependent regulation of cough and other airway defensive reflexes. Pulm Pharmacol Ther 2019; 58:101810. [PMID: 31181318 DOI: 10.1016/j.pupt.2019.101810] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 11/30/2022]
Abstract
Nicotinic receptor activation in the airways evokes airway defensive reflexes including cough. These reflexes are the direct result of bronchopulmonary afferent nerve activation, which may occur directly, through activation of nicotinic receptors expressed on the terminals of airway sensory nerves, or indirectly, secondary to the end organ effects associated with autonomic nerve stimulation. The irritating effects of nicotine delivered topically to the airways are counterbalanced by an inhibitory effect of nicotinic receptor activation in the central nervous system. We present evidence that these nicotinic receptors are components of essential transducing and encoding mechanisms regulating airway defense.
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Affiliation(s)
- Mayuko Tao
- Tokyo Medical & Dental University, Japan
| | - Qi Liu
- Johns Hopkins Asthma and Allergy Center, Baltimore, MD, USA
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Batista TJ, Minassa VS, Aitken AV, Jara BT, Felippe ISA, Beijamini V, Paton JFR, dos Santos L, Sampaio KN. Intermittent Exposure to Chlorpyrifos Differentially Impacts Neuroreflex Control of Cardiorespiratory Function in Rats. Cardiovasc Toxicol 2019; 19:548-564. [DOI: 10.1007/s12012-019-09528-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Rukhadze I, Fenik VB. Neuroanatomical Basis of State-Dependent Activity of Upper Airway Muscles. Front Neurol 2018; 9:752. [PMID: 30250449 PMCID: PMC6139331 DOI: 10.3389/fneur.2018.00752] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 08/20/2018] [Indexed: 12/16/2022] Open
Abstract
Obstructive Sleep Apnea (OSA) is a common sleep-related respiratory disorder that is associated with cognitive, cardiovascular, and metabolic morbidities. The major cause of OSA is the sleep-related reduction of upper airway muscle tone that leads to airway obstructions in individuals with anatomically narrow upper airway. This reduction is mainly due to the suppressant effect of sleep on hypoglossal motoneurons that innervate upper airway muscles. The hypoglossal motoneurons have state-dependent activity, which is decreased during the transition from wakefulness to non-rapid eye movement sleep and is further suppressed during rapid eye movement sleep. Multiple neurotransmitters and their receptors have been implicated in the control of hypoglossal motoneuron activity across the sleep-wake states. However, to date, the results of the rigorous testing show that withdrawal of noradrenergic excitation and cholinergic inhibition essentially contribute to the depression of hypoglossal motoneuron activity during sleep. The present review will focus on origins of noradrenergic and cholinergic innervation of hypoglossal motoneurons and the functional role of these neurons in the state-dependent activity of hypoglossal motoneurons.
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Affiliation(s)
- Irma Rukhadze
- VA West Los Angeles Medical Center, West Los Angeles, CA, United States.,David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States
| | - Victor B Fenik
- VA West Los Angeles Medical Center, West Los Angeles, CA, United States.,Websciences International, Los Angeles, CA, United States
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15
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Ghezzi F, Monni L, Corsini S, Rauti R, Nistri A. Propofol Protects Rat Hypoglossal Motoneurons in an In Vitro Model of Excitotoxicity by Boosting GABAergic Inhibition and Reducing Oxidative Stress. Neuroscience 2017; 367:15-33. [PMID: 29069620 DOI: 10.1016/j.neuroscience.2017.10.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/10/2017] [Accepted: 10/16/2017] [Indexed: 12/14/2022]
Abstract
In brainstem motor networks, hypoglossal motoneurons (HMs) play the physiological role of driving tongue contraction, an activity critical for inspiration, phonation, chewing and swallowing. HMs are an early target of neurodegenerative diseases like amyotrophic lateral sclerosis that, in its bulbar form, is manifested with initial dysphagia and dysarthria. One important pathogenetic component of this disease is the high level of extracellular glutamate due to uptake block that generates excitotoxicity. To understand the earliest phases of this condition we devised a model, the rat brainstem slice, in which block of glutamate uptake is associated with intense bursting of HMs, dysmetabolism and death. Since blocking bursting becomes a goal to prevent cell damage, the present report enquired whether boosting GABAergic inhibition could fulfill this aim and confer beneficial outcome. Propofol (0.5 µM) and midazolam (0.01 µM), two allosteric modulators of GABAA receptors, were used at concentrations yielding analogous potentiation of GABA-mediated currents. Propofol also partly depressed NMDA receptor currents. Both drugs significantly shortened bursting episodes without changing single burst properties, their synchronicity, or their occurrence. Two hours later, propofol prevented the rise in reactive oxygen species (ROS) and, at 4 hours, it inhibited intracellular release of apoptosis-inducing factor (AIF) and prevented concomitant cell loss. Midazolam did not contrast ROS and AIF release. The present work provides experimental evidence for the neuroprotective action of a general anesthetic like propofol, which, in this case, may be achieved through a combination of boosted GABAergic inhibition and reduced ROS production.
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Affiliation(s)
- Filippo Ghezzi
- Department of Neuroscience, International School for Advanced Studies (SISSA), via Bonomea, 265, 34136 Trieste, Italy.
| | - Laura Monni
- Department of Neuroscience, International School for Advanced Studies (SISSA), via Bonomea, 265, 34136 Trieste, Italy.
| | - Silvia Corsini
- Department of Neuroscience, International School for Advanced Studies (SISSA), via Bonomea, 265, 34136 Trieste, Italy.
| | - Rossana Rauti
- Department of Neuroscience, International School for Advanced Studies (SISSA), via Bonomea, 265, 34136 Trieste, Italy.
| | - Andrea Nistri
- Department of Neuroscience, International School for Advanced Studies (SISSA), via Bonomea, 265, 34136 Trieste, Italy.
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16
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Cholanian M, Wealing J, Levine RB, Fregosi RF. Developmental nicotine exposure alters potassium currents in hypoglossal motoneurons of neonatal rat. J Neurophysiol 2017; 117:1544-1552. [PMID: 28148643 DOI: 10.1152/jn.00774.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/26/2017] [Accepted: 01/26/2017] [Indexed: 11/22/2022] Open
Abstract
We previously showed that nicotine exposure in utero and after birth via breast milk [developmental nicotine exposure (DNE)] is associated with many changes in the structure and function of hypoglossal motoneurons (XIIMNs), including a reduction in the size of the dendritic arbor and an increase in cell excitability. Interestingly, the elevated excitability was associated with a reduction in the expression of glutamate receptors on the cell body. Together, these observations are consistent with a homeostatic compensation aimed at restoring cell excitability. Compensation for increased cell excitability could also occur by changing potassium conductance, which plays a critical role in regulating resting potential, spike threshold, and repetitive spiking behavior. Here we test the hypothesis that the previously observed increase in the excitability of XIIMNs from DNE animals is associated with an increase in whole cell potassium currents. Potassium currents were measured in XIIMNs in brain stem slices derived from DNE and control rat pups ranging in age from 0 to 4 days by whole cell patch-clamp electrophysiology. All currents were measured after blockade of action potential-dependent synaptic transmission with tetrodotoxin. Compared with control cells, XIIMNs from DNE animals showed significantly larger transient and sustained potassium currents, but this was observed only under conditions of increased cell and network excitability, which we evoked by raising extracellular potassium from 3 to 9 mM. These observations suggest that the larger potassium currents in nicotine-exposed neurons are an important homeostatic compensation that prevents "runaway" excitability under stressful conditions, when neurons are receiving elevated excitatory synaptic input.NEW & NOTEWORTHY Developmental nicotine exposure is associated with increased cell excitability, which is often accompanied by compensatory changes aimed at normalizing excitability. Here we show that whole cell potassium currents are also increased in hypoglossal motoneurons from nicotine-exposed neonatal rats under conditions of increased cell and network excitability. This is consistent with a compensatory response aimed at preventing instability under conditions in which excitatory synaptic input is high and is compatible with the concept of homeostatic plasticity.
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Affiliation(s)
- Marina Cholanian
- Department of Physiology, The University of Arizona, Tucson, Arizona
| | - Jesse Wealing
- Department of Physiology, The University of Arizona, Tucson, Arizona.,Department of Environmental and Evolutionary Biology, The University of Arizona, Tucson, Arizona; and
| | - Richard B Levine
- Department of Physiology, The University of Arizona, Tucson, Arizona.,Department of Neuroscience, The University of Arizona, Tucson, Arizona
| | - Ralph F Fregosi
- Department of Physiology, The University of Arizona, Tucson, Arizona; .,Department of Neuroscience, The University of Arizona, Tucson, Arizona
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17
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Santin JM, Hartzler LK. Environmentally induced return to juvenile-like chemosensitivity in the respiratory control system of adult bullfrog, Lithobates catesbeianus. J Physiol 2016; 594:6349-6367. [PMID: 27444338 DOI: 10.1113/jp272777] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/19/2016] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The degree to which developmental programmes or environmental signals determine physiological phenotypes remains a major question in physiology. Vertebrates change environments during development, confounding interpretation of the degree to which development (i.e. permanent processes) or phenotypic plasticity (i.e. reversible processes) produces phenotypes. Tadpoles mainly breathe water for gas exchange and frogs may breathe water or air depending on their environment and are, therefore, exemplary models to differentiate the degree to which life-stage vs. environmental context drives developmental phenotypes associated with neural control of lung breathing. Using isolated brainstem preparations and patch clamp electrophysiology, we demonstrate that adult bullfrogs acclimatized to water-breathing conditions do not exhibit CO2 and O2 chemosensitivity of lung breathing, similar to water-breathing tadpoles. Our results establish that phenotypes associated with developmental stage may arise from plasticity per se and suggest that a developmental trajectory coinciding with environmental change obscures origins of stage-dependent physiological phenotypes by masking plasticity. ABSTRACT An unanswered question in developmental physiology is to what extent does the environment vs. a genetic programme produce phenotypes? Developing animals inhabit different environments and switch from one to another. Thus a developmental time course overlapping with environmental change confounds interpretations as to whether development (i.e. permanent processes) or phenotypic plasticity (i.e. reversible processes) generates phenotypes. Tadpoles of the American bullfrog, Lithobates catesbeianus, breathe water at early life-stages and minimally use lungs for gas exchange. As adults, bullfrogs rely on lungs for gas exchange, but spend months per year in ice-covered ponds without lung breathing. Aquatic submergence, therefore, removes environmental pressures requiring lung breathing and enables separation of adulthood from environmental factors associated with adulthood that necessitate control of lung ventilation. To test the hypothesis that postmetamorphic respiratory control phenotypes arise through permanent developmental changes vs. reversible environmental signals, we measured respiratory-related nerve discharge in isolated brainstem preparations and action potential firing from CO2 -sensitive neurons in bullfrogs acclimatized to semi-terrestrial (air-breathing) and aquatic-overwintering (no air-breathing) habitats. We found that aquatic overwintering significantly reduced neuroventilatory responses to CO2 and O2 involved in lung breathing. Strikingly, this gas sensitivity profile reflects that of water-breathing tadpoles. We further demonstrated that aquatic overwintering reduced CO2 -induced firing responses of chemosensitive neurons. In contrast, respiratory rhythm generating processes remained adult-like after submergence. Our results establish that phenotypes associated with life-stage can arise from phenotypic plasticity per se. This provides evidence that developmental time courses coinciding with environmental changes obscure interpretations regarding origins of stage-dependent physiological phenotypes by masking plasticity.
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Affiliation(s)
- Joseph M Santin
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA. .,Biomedical Sciences PhD Program, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA.
| | - Lynn K Hartzler
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA
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18
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Bauché S, O'Regan S, Azuma Y, Laffargue F, McMacken G, Sternberg D, Brochier G, Buon C, Bouzidi N, Topf A, Lacène E, Remerand G, Beaufrere AM, Pebrel-Richard C, Thevenon J, El Chehadeh-Djebbar S, Faivre L, Duffourd Y, Ricci F, Mongini T, Fiorillo C, Astrea G, Burloiu CM, Butoianu N, Sandu C, Servais L, Bonne G, Nelson I, Desguerre I, Nougues MC, Bœuf B, Romero N, Laporte J, Boland A, Lechner D, Deleuze JF, Fontaine B, Strochlic L, Lochmuller H, Eymard B, Mayer M, Nicole S. Impaired Presynaptic High-Affinity Choline Transporter Causes a Congenital Myasthenic Syndrome with Episodic Apnea. Am J Hum Genet 2016; 99:753-761. [PMID: 27569547 DOI: 10.1016/j.ajhg.2016.06.033] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/29/2016] [Indexed: 12/21/2022] Open
Abstract
The neuromuscular junction (NMJ) is one of the best-studied cholinergic synapses. Inherited defects of peripheral neurotransmission result in congenital myasthenic syndromes (CMSs), a clinically and genetically heterogeneous group of rare diseases with fluctuating fatigable muscle weakness as the clinical hallmark. Whole-exome sequencing and Sanger sequencing in six unrelated families identified compound heterozygous and homozygous mutations in SLC5A7 encoding the presynaptic sodium-dependent high-affinity choline transporter 1 (CHT), which is known to be mutated in one dominant form of distal motor neuronopathy (DHMN7A). We identified 11 recessive mutations in SLC5A7 that were associated with a spectrum of severe muscle weakness ranging from a lethal antenatal form of arthrogryposis and severe hypotonia to a neonatal form of CMS with episodic apnea and a favorable prognosis when well managed at the clinical level. As expected given the critical role of CHT for multisystemic cholinergic neurotransmission, autonomic dysfunctions were reported in the antenatal form and cognitive impairment was noticed in half of the persons with the neonatal form. The missense mutations induced a near complete loss of function of CHT activity in cell models. At the human NMJ, a delay in synaptic maturation and an altered maintenance were observed in the antenatal and neonatal forms, respectively. Increased synaptic expression of butyrylcholinesterase was also observed, exposing the dysfunction of cholinergic metabolism when CHT is deficient in vivo. This work broadens the clinical spectrum of human diseases resulting from reduced CHT activity and highlights the complexity of cholinergic metabolism at the synapse.
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Affiliation(s)
- Stéphanie Bauché
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Seana O'Regan
- Membrane transport group, Neurophotonics Laboratory, CNRS UMR8250, Sorbonne Paris Cité-Paris Descartes University, 75005 Paris, France
| | - Yoshiteru Azuma
- The John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
| | - Fanny Laffargue
- Service de Génétique Médicale, Centre de référence Auvergne-Limousin, Neuropathies Périphériques Rares et Maladies Neuromusculaires, Centre Hospitalier Universitaire de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Grace McMacken
- The John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
| | - Damien Sternberg
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France; AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Guy Brochier
- AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France; Unité de pathologies neuromusculaires, Institut de Myologie, Sorbonne Universités, UPMC Université Paris 06 UMRS 974, Inserm U974, CNRS UMR 7215, 75013 Paris, France
| | - Céline Buon
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Nassima Bouzidi
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Ana Topf
- The John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
| | - Emmanuelle Lacène
- AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France; Unité de pathologies neuromusculaires, Institut de Myologie, Sorbonne Universités, UPMC Université Paris 06 UMRS 974, Inserm U974, CNRS UMR 7215, 75013 Paris, France
| | - Ganaelle Remerand
- Service de Néonatologie, Centre Hospitalier Universitaire de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Anne-Marie Beaufrere
- Service d'Anatomie et Cytologie pathologiques, Centre Hospitalier Universitaire de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Céline Pebrel-Richard
- Service de Cytogénétique Médicale, Centre Hospitalier Universitaire de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Julien Thevenon
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), Centre Hospitalier Universitaire Dijon, 21079 Dijon, France; Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, Centre Hospitalier Universitaire Dijon, 21079 Dijon, France
| | - Salima El Chehadeh-Djebbar
- Service de génétique médicale, Institut de génétique médicale d'Alsace (IGMA), Hôpitaux Universitaires de Strasbourg, Hôpital de Hautepierre, 67098 Strasbourg, France
| | - Laurence Faivre
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), Centre Hospitalier Universitaire Dijon, 21079 Dijon, France; Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, Centre Hospitalier Universitaire Dijon, 21079 Dijon, France
| | - Yannis Duffourd
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), Centre Hospitalier Universitaire Dijon, 21079 Dijon, France
| | - Federica Ricci
- Center for Neuromuscular Diseases, Child Neurology and Psychiatry Unit, Regina Margherita Children Hospital, and Department of Neurosciences, University of Torino, 10124 Torino, Italy
| | - Tiziana Mongini
- Center for Neuromuscular Diseases, Child Neurology and Psychiatry Unit, Regina Margherita Children Hospital, and Department of Neurosciences, University of Torino, 10124 Torino, Italy
| | - Chiara Fiorillo
- Molecular Medicine, IRCCS Fondazione Stella Maris, Calambrone, 56018 Pisa, Italy
| | - Guja Astrea
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56018 Pisa, Italy
| | | | - Niculina Butoianu
- Alexandru Obregia Clinical Hospital, sos Berceni 10-12, 041914 Bucharest, Romania
| | - Carmen Sandu
- Alexandru Obregia Clinical Hospital, sos Berceni 10-12, 041914 Bucharest, Romania
| | - Laurent Servais
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, Myology Institute, 75013 Paris, France
| | - Gisèle Bonne
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, Myology Institute, 75013 Paris, France
| | - Isabelle Nelson
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, Myology Institute, 75013 Paris, France
| | - Isabelle Desguerre
- Centre de Référence des Maladies Neuromusculaires de l'Ouest Parisien, Hôpital Necker-Enfants Malades, 75743 Paris, France
| | - Marie-Christine Nougues
- Neuropédiatrie et Unité d'électrophysiologie clinique, Centre de Référence des Maladies Neuromusculaires de l'EST parisien et DHU I2B, Hôpital d'Enfants Armand Trousseau, 75012 Paris, France
| | - Benoit Bœuf
- Service de réanimation néonatale et pédiatrique Hôpital Estaing CHU de Clermont Ferrand, 63000 Clermont-Ferrand, France
| | - Norma Romero
- Unité de pathologies neuromusculaires, Institut de Myologie, Sorbonne Universités, UPMC Université Paris 06 UMRS 974, Inserm U974, CNRS UMR 7215, 75013 Paris, France
| | - Jocelyn Laporte
- Departement Médecine Translationnelle et Neurogénétique, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR 7104, Inserm U 964, 67404 Illkirch, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, 67000 Strasbourg, France
| | - Anne Boland
- Centre National de Génotypage (CNG), 91057 Evry, France
| | - Doris Lechner
- Centre National de Génotypage (CNG), 91057 Evry, France
| | | | - Bertrand Fontaine
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France; AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Laure Strochlic
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Hanns Lochmuller
- The John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France; AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, Myology Institute, 75013 Paris, France
| | - Michèle Mayer
- Neuropédiatrie et Unité d'électrophysiologie clinique, Centre de Référence des Maladies Neuromusculaires de l'EST parisien et DHU I2B, Hôpital d'Enfants Armand Trousseau, 75012 Paris, France
| | - Sophie Nicole
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France.
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Muñoz-Ortiz J, Muñoz-Ortiz E, López-Meraz ML, Beltran-Parrazal L, Morgado-Valle C. Pre-Bötzinger complex: Generation and modulation of respiratory rhythm. Neurologia 2016; 34:461-468. [PMID: 27443242 DOI: 10.1016/j.nrl.2016.05.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 03/14/2016] [Accepted: 05/09/2016] [Indexed: 12/26/2022] Open
Abstract
INTRODUCTION In mammals, the preBötzinger complex (preBötC) is a bilateral and symmetrical neural network located in the brainstem which is essential for the generation and modulation of respiratory rhythm. There are few human studies about the preBötC and, its relationship with neurological diseases has not been described. However, the importance of the preBötC in neural control of breathing and its potential participation in neurological diseases in humans, has been suggested based on pharmacological manipulation and lesion of the preBötC in animal models, both in vivo and in vitro. METHOD In this review, we describe the effects of some drugs on the inspiratory activity in vitro in a transverse slice that contains the preBötC, as well as some in vivo experiments. Drugs were classified according to their effects on the main neurotransmitter systems and their importance as stimulators or inhibitors of preBötC activity and therefore for the generation of the respiratory rhythm. CONCLUSION Clinical neurologists will find this information relevant to understanding how the central nervous system generates the respiratory rhythm and may also relate this information to the findings made in daily practice.
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Affiliation(s)
- J Muñoz-Ortiz
- Doctorado en Investigaciones Cerebrales, Universidad Veracruzana, Xalapa de Enríquez, Veracruz, México
| | - E Muñoz-Ortiz
- Doctorado en Investigaciones Cerebrales, Universidad Veracruzana, Xalapa de Enríquez, Veracruz, México
| | - M L López-Meraz
- Centro de Investigaciones Cerebrales, Dirección General de Investigaciones, Universidad Veracruzana, Xalapa de Enríquez, Veracruz, México
| | - L Beltran-Parrazal
- Centro de Investigaciones Cerebrales, Dirección General de Investigaciones, Universidad Veracruzana, Xalapa de Enríquez, Veracruz, México
| | - C Morgado-Valle
- Centro de Investigaciones Cerebrales, Dirección General de Investigaciones, Universidad Veracruzana, Xalapa de Enríquez, Veracruz, México.
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20
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Rajani V, Zhang Y, Revill A, Funk G. The role of P2Y1 receptor signaling in central respiratory control. Respir Physiol Neurobiol 2016; 226:3-10. [DOI: 10.1016/j.resp.2015.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/06/2015] [Indexed: 12/24/2022]
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21
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Wollman LB, Haggerty J, Pilarski JQ, Levine RB, Fregosi RF. Developmental nicotine exposure alters cholinergic control of respiratory frequency in neonatal rats. Dev Neurobiol 2016; 76:1138-49. [PMID: 26818254 DOI: 10.1002/dneu.22380] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/15/2015] [Accepted: 01/06/2016] [Indexed: 11/11/2022]
Abstract
Prenatal nicotine exposure with continued exposure through breast milk over the first week of life (developmental nicotine exposure, DNE) alters the development of brainstem circuits that control breathing. Here, we test the hypothesis that DNE alters the respiratory motor response to endogenous and exogenous acetylcholine (ACh) in neonatal rats. We used the brainstem-spinal cord preparation in the split-bath configuration, and applied drugs to the brainstem compartment while measuring the burst frequency and amplitude of the fourth cervical ventral nerve roots (C4VR), which contain the axons of phrenic motoneurons. We applied ACh alone; the nicotinic acetylcholine receptor (nAChR) antagonist curare, either alone or in the presence of ACh; and the muscarinic acetylcholine receptor (mAChR) antagonist atropine, either alone or in the presence of ACh. The main findings include: (1) atropine reduced frequency similarly in controls and DNE animals, while curare caused modest slowing in controls but no consistent change in DNE animals; (2) DNE greatly attenuated the increase in C4VR frequency mediated by exogenous ACh; (3) stimulation of nAChRs with ACh in the presence of atropine increased frequency markedly in controls, but not DNE animals; (4) stimulation of mAChRs with ACh in the presence of curare caused a modest increase in frequency, with no treatment group differences. DNE blunts the response of the respiratory central pattern generator to exogenous ACh, consistent with reduced availability of functionally competent nAChRs; DNE did not alter the muscarinic control of respiratory motor output. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1138-1149, 2016.
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Affiliation(s)
- Lila B Wollman
- Department of Physiology, The University of Arizona, Tucson, Arizona, 85724.,Department of Neuroscience, Tucson, Arizona, 85724
| | - Jarl Haggerty
- Department of Physiology, The University of Arizona, Tucson, Arizona, 85724
| | - Jason Q Pilarski
- Department of Physiology, The University of Arizona, Tucson, Arizona, 85724
| | - Richard B Levine
- Department of Physiology, The University of Arizona, Tucson, Arizona, 85724.,Department of Neuroscience, Tucson, Arizona, 85724
| | - Ralph F Fregosi
- Department of Physiology, The University of Arizona, Tucson, Arizona, 85724.,Department of Neuroscience, Tucson, Arizona, 85724
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22
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Proskocil BJ, Bruun DA, Garg JA, Villagomez CC, Jacoby DB, Lein PJ, Fryer AD. The influence of sensitization on mechanisms of organophosphorus pesticide-induced airway hyperreactivity. Am J Respir Cell Mol Biol 2016; 53:738-47. [PMID: 25897622 DOI: 10.1165/rcmb.2014-0444oc] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We previously demonstrated that antigen sensitization increases vulnerability to airway hyperreactivity induced by the organophosphorus pesticide (OP) parathion. Sensitization also changes the mechanism of parathion-induced airway hyperreactivity to one that is dependent on IL-5. To determine whether this effect can be generalized to other OPs, and to other classes of pesticides, we measured airway responsiveness to vagal stimulation or intravenous acetylcholine in nonsensitized and ovalbumin-sensitized guinea pigs 24 hours after a single subcutaneous injection of the OPs diazinon or chlorpyrifos, or the pyrethroid permethrin. Sensitization exacerbated the effects of chlorpyrifos on bronchoconstriction in response to vagal stimulation or intravenous acetylcholine. Pretreatment with function-blocking IL-5 antibody prevented chlorpyrifos-induced airway hyperreactivity in sensitized, but not in nonsensitized, guinea pigs. In sensitized guinea pigs, blocking IL-5 decreased eosinophil activation, as measured by decreased eosinophil major basic protein in the trachea. In contrast, sensitization did not alter diazinon-induced airway hyperreactivity, and permethrin did not cause airway hyperreactivity in either nonsensitized or sensitized guinea pigs. None of the pesticides affected inflammatory cells in the bronchoalveolar lavage fluid or blood. We have previously shown that three different OPs cause airway hyperreactivity via loss of neuronal M2 muscarinic receptor function. Similar to parathion, but unlike diazinon, the mechanism of chlorpyrifos-induced airway hyperreactivity is changed by sensitization. Thus, OP-induced airway hyperreactivity is dependent on sensitization status and on the OP used, which may influence therapeutic approaches.
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Affiliation(s)
- Becky J Proskocil
- 1 Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Donald A Bruun
- 2 Department of Molecular Biosciences, University of California School of Veterinary Medicine, Davis, California
| | - Jasmine A Garg
- 1 Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Chloe C Villagomez
- 1 Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - David B Jacoby
- 1 Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Pamela J Lein
- 2 Department of Molecular Biosciences, University of California School of Veterinary Medicine, Davis, California
| | - Allison D Fryer
- 1 Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon; and
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Role of Astrocytes in Central Respiratory Chemoreception. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:109-145. [PMID: 27714687 DOI: 10.1007/978-3-319-40764-7_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Astrocytes perform various homeostatic functions in the nervous system beyond that of a supportive or metabolic role for neurons. A growing body of evidence indicates that astrocytes are crucial for central respiratory chemoreception. This review presents a classical overview of respiratory central chemoreception and the new evidence for astrocytes as brainstem sensors in the respiratory response to hypercapnia. We review properties of astrocytes for chemosensory function and for modulation of the respiratory network. We propose that astrocytes not only mediate between CO2/H+ levels and motor responses, but they also allow for two emergent functions: (1) Amplifying the responses of intrinsic chemosensitive neurons through feedforward signaling via gliotransmitters and; (2) Recruiting non-intrinsically chemosensitive cells thanks to volume spreading of signals (calcium waves and gliotransmitters) to regions distant from the CO2/H+ sensitive domains. Thus, astrocytes may both increase the intensity of the neuron responses at the chemosensitive sites and recruit of a greater number of respiratory neurons to participate in the response to hypercapnia.
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Sobrinho CR, Kuo FS, Barna BF, Moreira TS, Mulkey DK. Cholinergic control of ventral surface chemoreceptors involves Gq/inositol 1,4,5-trisphosphate-mediated inhibition of KCNQ channels. J Physiol 2015; 594:407-19. [PMID: 26572090 DOI: 10.1113/jp271761] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 11/12/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS ACh is an important modulator of breathing, including at the level of the retrotrapezoid nucleus (RTN), where evidence suggests that ACh is essential for the maintenance of breathing. Despite this potentially important physiological role, little is known about the mechanisms responsible for the cholinergic control of RTN function. In the present study, we show at the cellular level that ACh increases RTN chemoreceptor activity by a CO2/H(+) independent mechanism involving M1/M3 receptor-mediated inositol 1,4,5-trisphosphate/Ca(+2) signalling and downstream inhibition of KCNQ channels. These results dispel the theory that ACh is required for RTN chemoreception by showing that ACh, similar to serotonin and other modulators, controls the activity of RTN chemoreceptors without interfering with the mechanisms by which these cells sense H(+). By identifying the mechanisms by which wake-on neurotransmitters such as ACh modulate RTN chemoreception, the results of the present study provide a framework for understanding the molecular basis of the sleep-wake state-dependent control of breathing. ABSTRACT ACh has long been considered important for the CO2/H(+)-dependent drive to breathe produced by chemosensitive neurons in the retrotrapezoid nucleus (RTN). However, despite this potentially important physiological role, almost nothing is known about the mechanisms responsible for the cholinergic control of RTN function. In the present study, we used slice-patch electrophysiology and pharmacological tools to characterize the effects of ACh on baseline activity and CO2/H(+)-sensitivity of RTN chemoreceptors, as well as to dissect the signalling pathway by which ACh activates these neurons. We found that ACh activates RTN chemoreceptors in a dose-dependent manner (EC50 = 1.2 μm). The firing response of RTN chemoreceptors to ACh was mimicked by a muscarinic receptor agonist (oxotremorine; 1 μm), and blunted by M1- (pirezenpine; 2 μm) and M3- (diphenyl-acetoxy-N-methyl-piperidine; 100 nm) receptor blockers, but not by a nicotinic-receptor blocker (mecamylamine; 10 μm). Furthermore, pirenzepine, diphenyl-acetoxy-N-methyl-piperidine and mecamylamine had no measurable effect on the CO2/H(+)-sensitivity of RTN chemoreceptors. The effects of ACh on RTN chemoreceptor activity were also blunted by inhibition of inositol 1,4,5-trisphosphate receptors with 2-aminoethoxydiphenyl borate (100 μm), depletion of intracellular Ca(2+) stores with thapsigargin (10 μm), inhibition of casein kinase 2 (4,5,6,7-tetrabromobenzotriazole; 10 μm) and blockade of KCNQ channels (XE991; 10 μm). These results show that ACh activates RTN chemoreceptors by a CO2/H(+) independent mechanism involving M1/M3 receptor-mediated inositol 1,4,5-trisphosphate/Ca(+2) signalling and downstream inhibition of KCNQ channels. Identifying the components of the signalling pathway coupling muscarinic receptor activation to changes in chemoreceptor activity may provide new potential therapeutic targets for the treatment of respiratory control disorders.
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Affiliation(s)
- Cleyton R Sobrinho
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil
| | - Fu-Shan Kuo
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Barbara F Barna
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
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Muere C, Neumueller S, Olesiak S, Miller J, Langer T, Hodges MR, Pan L, Forster HV. Combined unilateral blockade of cholinergic, peptidergic, and serotonergic receptors in the ventral respiratory column does not affect breathing in awake or sleeping goats. J Appl Physiol (1985) 2015; 119:308-20. [PMID: 26023224 DOI: 10.1152/japplphysiol.00145.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 05/23/2015] [Indexed: 12/21/2022] Open
Abstract
Previous work in intact awake and sleeping goats has found that unilateral blockade of excitatory inputs in the ventral respiratory column (VRC) elicits changes in the concentrations of multiple neurochemicals, including serotonin (5-HT), substance P, glycine, and GABA, while increasing or having no effect on breathing. These findings are consistent with the concept of interdependence between neuromodulators, whereby attenuation of one modulator elicits compensatory changes in other modulators to maintain breathing. Because there is a large degree of redundancy and multiplicity of excitatory inputs to the VRC, we herein tested the hypothesis that combined unilateral blockade of muscarinic acetylcholine (mACh), neurokinin-1 (NK1, the receptor for substance P), and 5-HT2A receptors would elicit changes in multiple neurochemicals, but would not change breathing. We unilaterally reverse-dialyzed a cocktail of antagonists targeting these receptors into the VRC of intact adult goats. Breathing was continuously monitored while effluent fluid from dialysis was collected for quantification of neurochemicals. We found that neither double blockade of mACh and NK1 receptors, nor triple blockade of mACh, NK1, and 5-HT2A receptors significantly affected breathing (P ≥ 0.05) in goats that were awake or in non-rapid eye movement (NREM) sleep. However, both double and triple blockade increased the effluent concentration of substance P (P < 0.001) and decreased GABA concentrations. These findings support our hypothesis and, together with past data, suggest that both in wakefulness and NREM sleep, multiple neuromodulator systems collaborate to stabilize breathing when a deficit in one or multiple excitatory neuromodulators exists.
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Affiliation(s)
- Clarissa Muere
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Suzanne Neumueller
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Samantha Olesiak
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Justin Miller
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
| | - Thomas Langer
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Lawrence Pan
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin; and
| | - Hubert V Forster
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
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Läer K, Dörk T, Vennemann M, Rothämel T, Klintschar M. Polymorphisms in genes of respiratory control and sudden infant death syndrome. Int J Legal Med 2015. [PMID: 26198620 DOI: 10.1007/s00414-015-1232-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Sudden infant death syndrome (SIDS) is a multifactorial syndrome and assumingly, among other mechanisms, a deficit in respiratory control leads to a failure of arousal and autoresuscitation when the child is challenged by a stressful homeostatic event, e.g., hypoxia. We hypothesize that genetic polymorphisms involved in respiratory control mediated in the medulla oblongata contribute to SIDS. Therefore, a total of 366 SIDS cases and 421 controls were genotyped for 48 SNPs in 41 candidate genes. Genotyping was performed using Fluidigm nanofluidic technology. Results were obtained for 356 SIDS and 406 controls and 38 SNPs. After correction for multiple testing, one SNP retained a nominally significant association with seasonal SIDS: rs1801030 in the phenol sulfotransferase 1A1 gene (subgroup: death occurring during summer). A borderline association could be also observed for rs563649 in the opioid receptor μ1 gene in a recessive model (subgroup: death occurring during autumn). As a conclusion, although these data suggest two SNPs to be associated with different subgroups of SIDS cases, none of them can fully explain the SIDS condition, consistent with its multifactorial etiology. Given the great complexity of respiratory control and our initial findings reported here, we believe it is worthwhile to further investigate genes involved in the respiratory system.
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Affiliation(s)
- Katharina Läer
- Institute of Legal Medicine, Hannover Medical School, Carl-Neuberg-Str.1, D-30625, Hannover, Germany
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27
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Koch H, Caughie C, Elsen FP, Doi A, Garcia AJ, Zanella S, Ramirez JM. Prostaglandin E2 differentially modulates the central control of eupnoea, sighs and gasping in mice. J Physiol 2014; 593:305-19. [PMID: 25556802 DOI: 10.1113/jphysiol.2014.279794] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 09/24/2014] [Indexed: 01/10/2023] Open
Abstract
Prostaglandin E2 (PGE2) augments distinct inspiratory motor patterns, generated within the preBötzinger complex (preBötC), in a dose-dependent way. The frequency of sighs and gasping are stimulated at low concentrations, while the frequency of eupnoea increases only at high concentrations. We used in vivo microinjections into the preBötC and in vitro isolated brainstem slice preparations to investigate the dose-dependent effects of PGE2 on the preBötC activity. Synaptic measurements in whole cell voltage clamp recordings of inspiratory neurons revealed no changes in inhibitory or excitatory synaptic transmission in response to PGE2 exposure. In current clamp recordings obtained from inspiratory neurons of the preBötC, we found an increase in the frequency and amplitude of bursting activity in neurons with intrinsic bursting properties after exposure to PGE2. Riluzole, a blocker of the persistent sodium current, abolished the effect of PGE2 on sigh activity, while flufenamic acid, a blocker of the calcium-activated non-selective cation conductance, abolished the effect on eupnoeic activity caused by PGE2. Prostaglandins are important regulators of autonomic functions in the mammalian organism. Here we demonstrate in vivo that prostaglandin E2 (PGE2) can differentially increase the frequency of eupnoea (normal breathing) and sighs (augmented breaths) when injected into the preBötzinger complex (preBötC), a medullary area that is critical for breathing. Low concentrations of PGE2 (100-300 nm) increased the sigh frequency, while higher concentrations (1-2 μm) were required to increase the eupnoeic frequency. The concentration-dependent effects were similarly observed in the isolated preBötC. This in vitro preparation also revealed that riluzole, a blocker of the persistent sodium current (INap), abolished the modulatory effect on sighs, while flufenamic acid, an antagonist for the calcium-activated non-selective cation conductance (ICAN ) abolished the effect of PGE2 on fictive eupnoea at higher concentrations. At the cellular level PGE2 significantly increased the amplitude and frequency of intrinsic bursting in inspiratory neurons. By contrast PGE2 affected neither excitatory nor inhibitory synaptic transmission. We conclude that PGE2 differentially modulates sigh, gasping and eupnoeic activity by differentially increasing INap and ICAN currents in preBötC neurons.
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Affiliation(s)
- Henner Koch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA; Department of Neurological Surgery, University of Washington, Seattle, WA, 98104, USA; Department of Neurology, University of Tübingen, Hertie Institute for Clinical Brain Research, Tübingen, Germany
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28
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Kimura S, Haji A. Pharmacological strategy for overcoming opioid-induced ventilatory disturbances. Eur J Pharmacol 2014; 725:87-90. [DOI: 10.1016/j.ejphar.2013.08.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 08/21/2013] [Indexed: 01/17/2023]
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Ramirez JM, Doi A, Garcia AJ, Elsen FP, Koch H, Wei AD. The cellular building blocks of breathing. Compr Physiol 2013; 2:2683-731. [PMID: 23720262 DOI: 10.1002/cphy.c110033] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Respiratory brainstem neurons fulfill critical roles in controlling breathing: they generate the activity patterns for breathing and contribute to various sensory responses including changes in O2 and CO2. These complex sensorimotor tasks depend on the dynamic interplay between numerous cellular building blocks that consist of voltage-, calcium-, and ATP-dependent ionic conductances, various ionotropic and metabotropic synaptic mechanisms, as well as neuromodulators acting on G-protein coupled receptors and second messenger systems. As described in this review, the sensorimotor responses of the respiratory network emerge through the state-dependent integration of all these building blocks. There is no known respiratory function that involves only a small number of intrinsic, synaptic, or modulatory properties. Because of the complex integration of numerous intrinsic, synaptic, and modulatory mechanisms, the respiratory network is capable of continuously adapting to changes in the external and internal environment, which makes breathing one of the most integrated behaviors. Not surprisingly, inspiration is critical not only in the control of ventilation, but also in the context of "inspiring behaviors" such as arousal of the mind and even creativity. Far-reaching implications apply also to the underlying network mechanisms, as lessons learned from the respiratory network apply to network functions in general.
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Affiliation(s)
- J M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institut, Seattle, Washington, USA.
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30
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Disruption of cerebellar cholinergic system in hypoxic neonatal rats and its regulation with glucose, oxygen and epinephrine resuscitations. Neuroscience 2013; 236:253-61. [DOI: 10.1016/j.neuroscience.2012.12.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 12/05/2012] [Accepted: 12/17/2012] [Indexed: 11/15/2022]
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31
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Zakharova EI, Germanova EL, Kopaladze RA, Dudchenko AM. Central cholinergic systems in the mechanisms of hypoxic preconditioning: Diverse pathways of synaptic reorganization in vivo. NEUROCHEM J+ 2013. [DOI: 10.1134/s1819712413010108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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Effects of cholinesterase inhibitors and serotonin-1A receptor agonists on morphine-induced ventilatory depression and antinociception in rats. Eur J Pharmacol 2013; 703:33-41. [PMID: 23438874 DOI: 10.1016/j.ejphar.2013.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 02/01/2013] [Accepted: 02/07/2013] [Indexed: 11/24/2022]
Abstract
Ventilatory depression is a serious side-effect of opioid analgesics. Naloxone, an antagonist of opioid receptors, eliminates not only ventilatory depression but also analgesic effect of opioids. Pharmacological dissociation of adverse reactions from the main action is important clinically and basically. Cholinergic and serotonergic mechanisms are suggested to counteract the opioid-induced ventilatory disturbances, but their influence on analgesia is still controversial. The present study evaluated the effects of cholinesterase inhibitors and serotonin-1A (5-HT1A) receptor agonists on morphine (1.0mg/kg, i.v.)-induced ventilatory depression and analgesia in rats. In anesthetized animals, spontaneous ventilation and hind leg withdrawal reflexes against nociceptive thermal stimuli were measured simultaneously. Physostigmine (0.1 and 0.2mg/kg, i.v.) and donepezil (0.5 and 1.0mg/kg, i.v.) relieved the morphine-induced ventilatory depression and enhanced its antinociception. On the other hand, (±)-8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT, 0.03 and 0.1mg/kg, i.v.) and buspirone (0.1 and 0.3mg/kg, i.v.) did not influence antinociception of morphine while they restored the decreased ventilation. In unanesthetized animals, hypercapnic ventilatory response was measured by using whole-body plethysmography. Physostigmine (0.3mg/kg, i.p.), donepezil (1.0mg/kg, i.p.), 8-OH-DPAT (0.3mg/kg, i.p.) and buspirone (3.0mg/kg, i.p.) all recovered the morphine (10mg/kg, i.p.)-induced depression of hypercapnic ventilatory response. The present study suggests that activation of cholinergic or serotonergic (5-HT1A) mechanisms may be a useful therapeutic approach for morphine-induced ventilatory depression without loss of its analgesic action.
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The rhythmic, transverse medullary slice preparation in respiratory neurobiology: contributions and caveats. Respir Physiol Neurobiol 2013; 186:236-53. [PMID: 23357617 DOI: 10.1016/j.resp.2013.01.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 01/18/2013] [Accepted: 01/21/2013] [Indexed: 11/23/2022]
Abstract
Our understanding of the sites and mechanisms underlying rhythmic breathing as well as the neuromodulatory control of respiratory rhythm, pattern, and respiratory motoneuron excitability during perinatal development has advanced significantly over the last 20 years. A major catalyst was the development in 1991 of the rhythmically-active medullary slice preparation, which provided precise mechanical and chemical control over the network as well as enhanced physical and optical access to key brainstem regions. Insights obtained in vitro have informed multiple mechanistic hypotheses. In vivo tests of these hypotheses, performed under conditions of reduced control and precision but more obvious physiological relevance, have clearly established the significance for respiratory neurobiology of the rhythmic slice preparation. We review the contributions of this preparation to current understanding/concepts in respiratory control, and outline the limitations of this approach in the context of studying rhythm and pattern generation, homeostatic control mechanisms and murine models of human genetic disorders that feature prominent breathing disturbances.
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Toporikova N, Butera RJ. Dynamics of neuromodulatory feedback determines frequency modulation in a reduced respiratory network: a computational study. Respir Physiol Neurobiol 2012. [PMID: 23202052 DOI: 10.1016/j.resp.2012.11.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Neuromodulators, such as amines and neuropeptides, alter the activity of neurons and neuronal networks. In this work, we investigate how neuromodulators, which activate G(q)-protein second messenger systems, can modulate the bursting frequency of neurons in a critical portion of the respiratory neural network, the pre-Bötzinger complex (preBötC). These neurons are a vital part of the ponto-medullary neuronal network, which generates a stable respiratory rhythm whose frequency is regulated by neuromodulator release from the nearby Raphe nucleus. Using a simulated 50-cell network of excitatory preBötC neurons with a heterogeneous distribution of persistent sodium conductance and Ca(2+), we determined conditions for frequency modulation in such a network by simulating interaction between Raphe and preBötC nuclei. We found that the positive feedback between the Raphe excitability and preBötC activity induces frequency modulation in the preBötC neurons. In addition, the frequency of the respiratory rhythm can be regulated via phasic release of excitatory neuromodulators from the Raphe nucleus. We predict that the application of a G(q) antagonist will eliminate this frequency modulation by the Raphe and keep the network frequency constant and low. In contrast, application of a G(q) agonist will result in a high frequency for all levels of Raphe stimulation. Our modeling results also suggest that high [K(+)] requirement in respiratory brain slice experiments may serve as a compensatory mechanism for low neuromodulatory tone.
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Affiliation(s)
- Natalia Toporikova
- Department of Biology, Washington and Lee University, Lexington, VA, USA
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35
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Ireland MF, Funk GD, Bellingham MC. Muscarinic acetylcholine receptors enhance neonatal mouse hypoglossal motoneuron excitability in vitro. J Appl Physiol (1985) 2012; 113:1024-39. [DOI: 10.1152/japplphysiol.00699.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In brain stem slices from neonatal ( postnatal days 0–4) CD-1 mice, muscarinic ACh receptors (MAChRs) increased rhythmic inspiratory-related and tonic hypoglossal nerve discharge and depolarized single hypoglossal motoneurons (HMs) via an inward current without changing input resistance. These responses were blocked by the MAChR antagonist 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; 100 nM). MAChRs shifted voltage-dependent activation of the hyperpolarization-activated cation current to more positive levels. MAChRs increased the HM repetitive firing rate and decreased rheobase, with both effects being blocked by 4-DAMP. Muscarinic agonists reduced the afterhyperpolarization of single action potentials (APs), suggesting that small-conductance Ca2+-dependent K+ current inhibition increased the HM firing rate. Muscarinic agonists also reduced the AP amplitude and slowed its time course, suggesting that MAChRs inhibited voltage-gated Na+ channels. To compare muscarinic excitation of single HMs to muscarinic excitatory effects on motor output in thicker brain stem slices requiring higher extracellular K+ for rhythmic activity, we tested the effects of muscarinic agonists on single HM excitability in high-K+ artificial cerebrospinal fluid (aCSF). In high-K+ aCSF, muscarinic agonists still depolarized HMs and altered AP size and shape, as in standard aCSF, but did not increase the steady-state firing rate, decrease afterhyperpolarization, or alter threshold potential. These results indicate that the basic cellular response of HMs to muscarinic receptors is excitatory, via a number of distinct mechanisms, and that this excitatory response will be largely preserved in rhythmically active brain stem slices.
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Affiliation(s)
- Matthew F. Ireland
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; and
| | - Gregory D. Funk
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Mark C. Bellingham
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; and
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Clark CG, Sun Z, Meininger GA, Potts JT. Atomic force microscopy to characterize binding properties of α7-containing nicotinic acetylcholine receptors on neurokinin-1 receptor-expressing medullary respiratory neurons. Exp Physiol 2012; 98:415-24. [PMID: 22962286 DOI: 10.1113/expphysiol.2012.067660] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the present study, we used atomic force microscopy (AFM) to examine the ligand-binding properties of α7-containing nicotinic acetylcholine receptors (nAChRs) expressed on neurons from the ventral respiratory group. We also determined the effect of acute and prolonged exposure to nicotine on the binding probability of nAChRs. Neurons from neonatal (postnatal day 5-10) and juvenile rats (3-4 weeks old) were cultured. Internalization of Alexa Fluor 488-conjugated substance P was used to identify respiratory neurons that expressed the neurokinin-1 receptor (NK1-R), a recognized marker of ventral respiratory group neurons. To assess functional changes in nAChRs, AFM probes conjugated with anti-α7 subunit nAChR antibody were used to interact cyclically with the surface of the soma of NK1-R-positive neurons. Measurements were made of the frequency of antibody adhesion to the α7 receptor subunit and of the detachment forces between the membrane-attached receptor and the AFM probe tip. Addition of α-bungarotoxin (a specific antagonist of α7 subunit-containing nAChRs) to the cell bath produced a 69% reduction in binding to the α7 subunit (P < 0.05, n = 10), supporting specificity of binding. Acute exposure to nicotine (1 μM added to culture media) produced an 80% reduction in nAChR antibody binding to the α7 subunit (P < 0.05, n = 9). Prolonged incubation (72 h) of the cell culture in nicotine significantly reduced α7 binding in a concentration-dependent manner. Collectively, these findings demonstrate that AFM is a sensitive tool for assessment of functional changes in nAChRs expressed on the surface of living NK1-R-expressing medullary neurons. Moreover, these data demonstrate that nicotine exposure decreases the binding probability of α7 subunit-containing nAChRs.
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Affiliation(s)
- Catharine G Clark
- Dalton Cardiovascular Research Center and Departments of Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA.
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Peña-Ortega F. Tonic neuromodulation of the inspiratory rhythm generator. Front Physiol 2012; 3:253. [PMID: 22934010 PMCID: PMC3429030 DOI: 10.3389/fphys.2012.00253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 06/19/2012] [Indexed: 12/15/2022] Open
Abstract
The generation of neural network dynamics relies on the interactions between the intrinsic and synaptic properties of their neural components. Moreover, neuromodulators allow networks to change these properties and adjust their activity to specific challenges. Endogenous continuous (“tonic”) neuromodulation can regulate and sometimes be indispensible for networks to produce basal activity. This seems to be the case for the inspiratory rhythm generator located in the pre-Bötzinger complex (preBötC). This neural network is necessary and sufficient for generating inspiratory rhythms. The preBötC produces normal respiratory activity (eupnea) as well as sighs under normoxic conditions, and it generates gasping under hypoxic conditions after a reconfiguration process. The reconfiguration leading to gasping generation involves changes of synaptic and intrinsic properties that can be mediated by several neuromodulators. Over the past years, it has been shown that endogenous continuous neuromodulation of the preBötC may involve the continuous action of amines and peptides on extrasynaptic receptors. I will summarize the findings supporting the role of endogenous continuous neuromodulation in the generation and regulation of different inspiratory rhythms, exploring the possibility that these neuromodulatory actions involve extrasynaptic receptors along with evidence of glial modulation of preBötC activity.
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Affiliation(s)
- Fernando Peña-Ortega
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, UNAM-Campus Juriquilla Querétaro, Mexico
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Babiec WE, Faull KF, Feldman JL. Cyclothiazide-induced persistent increase in respiratory-related activity in vitro. J Physiol 2012; 590:4897-915. [PMID: 22753547 DOI: 10.1113/jphysiol.2012.232421] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Hypoglossal (XII) motoneurons (MNs) innervate the genioglossus muscle of the tongue, which plays an important role in maintaining upper airway patency, particularly during sleep, and modulating upper airway resistance. Discovering methods for inducing long-term increases in genioglossal motoneuronal excitability to AMPA-mediated drive may help in the development of therapeutics for upper airway motor disorders such as obstructive sleep apnoea. We show that the diuretic, anti-hypertensive, AMPA receptor modulator cyclothiazide (CTZ) induces a profound and long-lasting increase in the amplitude of respiratory-related XII nerve activity in rhythmically active neonatal rat medullary slices. Treatment of the slice with CTZ (90 μM) for 1 h increased the integrated XII ( XII) nerve burst amplitude to 262 ± 23% of pre-treatment control at 1 h post-treatment;much of this increase lasted at least 12 h. The amount of CTZ-induced facilitation (CIF) was dependent upon both CTZ dose and exposure time and was accompanied by a long-lasting increase in endogenous AMPA-mediated drive currents to XII MNs. CIF, however, is not a form of plasticity and does not depend on AMPA or NMDA receptor activation for its induction. Nor does it depend on coincident protein kinase A or C activity. Rather, measurement of mEPSCs along with mass spectrometric analysis of CTZ-treated slices indicates that the cause is prolonged bioavailability of CTZ. These results illustrate a latent residual capacity for potentiating AMPA-mediated inspiratory drive to XII MNs that might be applied to the treatment of upper airway motor deficits.
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Affiliation(s)
- Walter E Babiec
- Department of Physiology, David Geffen School of Medicine, UCLA, Box 951751, C8-161 NPI, Los Angeles,CA 90095-1751, USA.
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Zhou X, Chen Y, Ge D, Yuan W, Wang J. Nicotine enhances both excitatory and inhibitory synaptic inputs to inspiratory-activated airway vagal preganglionic neurons. Exp Physiol 2012; 98:67-80. [PMID: 22750421 DOI: 10.1113/expphysiol.2012.066589] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The airway vagal preganglionic neurons (AVPNs) supply the essential excitatory drive to the postganglionic neurons and dominate the neural control of the airway both physiologically and pathophysiologically. The AVPNs express multiple subunits of nicotinic acetylcholine receptors (nAChRs), but the influences of exogenous nicotine and endogenous acetylcholine are unknown. This study examined the effects of nicotine and endogenous acetylcholine on retrogradely labelled, functionally identified inspiratory-activated AVPNs (IA-AVPNs) using the patch-clamp technique. Nicotine (10 μmol l(-1)) significantly increased the frequency and amplitude of the spontaneous EPSCs of IA-AVPNs, and these effects were insensitive to methyllycaconitine (MLA, 100 nmol l(-1)), an antagonist of the α7 type of nAChR, but was prevented by dihydro-β-erythroidine (DHβE, 3 μmol l(-1)), an antagonist of the α4β2 type of nAChR. Nicotine caused a tonic inward current in IA-AVPNs, which was reduced by MLA or DHβE alone, but was not abolished by co-application of MLA and DHβE. Nicotine caused a significant increase in the frequency of GABAergic and glycinergic spontaneous IPSCs and significantly increased the amplitude of glycinergic spontaneous IPSCs, all of which were prevented by DHβE. Nicotine had no effects on the miniature EPSCs or miniature IPSCs following pretreatment with TTX. Under current clamp, nicotine caused depolarization and increased the firing rate of IA-AVPNs during inspiratory intervals. Neostigmine (10 μmol l(-1)), an acetylcholinesterase inhibitor, mimicked the effects of nicotine. These results demonstrate that nicotine and endogenous ACh enhance the excitatory and inhibitory synaptic inputs of IA-AVPNs and cause a postsynaptic excitatory current and that the nicotinic effects are mediated presynaptically by activation of the α4β2 type of nAChR and postsynaptically by activation of multiple nAChRs, including α7 and α4β2 types.
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Affiliation(s)
- Xujiao Zhou
- The State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University Shanghai Medical College, 138 Yi-Xue-Yuan Road, Shanghai 200032, China
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Identification of a cholinergic modulatory and rhythmogenic mechanism within the lamprey respiratory network. J Neurosci 2011; 31:13323-32. [PMID: 21917815 DOI: 10.1523/jneurosci.2764-11.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Acetylcholine (ACh) is well known to be involved in the control of breathing. However, no information is available on the role of ACh receptors (AChRs) within the lamprey respiratory network. The present study was performed on in vitro brainstem preparations of adult lampreys to investigate whether ACh affects respiratory activity possibly through an action on the paratrigeminal respiratory group (pTRG) that has been identified as an essential component of the respiratory network. Respiratory activity was monitored as vagal motor output. Bath application of 100 μM physostigmine or 1 μM nicotine increased respiratory frequency, while bath application of 100 μM D-tubocurarine or 0.25 μM α-bungarotoxin reduced respiratory frequency and increased the duration of vagal bursts. Since these effects were mimicked by microinjections of the same drugs into the pTRG, ACh proved to influence respiratory activity by acting on α7 nicotinic AChRs located within the pTRG. During apnea caused by partial blockade of ionotropic glutamate receptors at the level of the pTRG, bath application of bicuculline and strychnine restored the respiratory rhythm, although at reduced frequency. Similar results were obtained by the concurrent removal of both fast synaptic excitatory and inhibitory transmission. Blockade of pTRG α7 nicotinic AChRs suppressed this respiratory activity, thus indicating that pTRG neurons expressing these receptors contribute to respiratory rhythm generation. Together, these findings identify a novel cholinergic modulatory and possibly subsidiary rhythmogenic mechanism within the respiratory network of the adult lamprey and encourage further studies on the respiratory role of cholinergic receptors in different animal species.
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M3-receptor activation counteracts opioid-mediated apneusis, but the apneusis per se is not necessarily related to an impaired M3 mechanism in rats. Life Sci 2011; 89:685-90. [DOI: 10.1016/j.lfs.2011.08.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/14/2011] [Accepted: 08/02/2011] [Indexed: 11/23/2022]
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Central respiratory effects on motor nerve activities after organophosphate exposure in a working heart brainstem preparation of the rat. Toxicol Lett 2011; 206:94-9. [PMID: 21767620 DOI: 10.1016/j.toxlet.2011.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/29/2011] [Accepted: 07/04/2011] [Indexed: 01/25/2023]
Abstract
The impact of organophosphorus compound (OP) intoxication on the activity of central respiratory circuitry, causing acetylcholinesterase (AChE) inhibition and accumulation of acetylcholine in the respiratory brainstem circuits, is not understood. We investigated the central effect of the OP Crotylsarin (CRS) on respiratory network activity using the working heart brainstem preparation, which specifically allows for the analysis of central drug effects without changes in brainstem oxygenation possibly caused by drug effects on peripheral cardio-respiratory activity. Respiratory network activity was determined from phrenic and hypoglossal or vagal nerve activities (PNA, HNA, VNA). To investigate combined central and peripheral CRS effects hypo-perfusion was used mimicking additional peripheral cardiovascular collapse. Systemic CRS application induced a brief central apnea and complete AChE-inhibition in the brainstem. Subsequently, respiration was characterised by highly significant reduced PNA minute activity, while HNA showed expiratory related extra bursting indicative for activation of un-specified oro-pharyngeal behaviour. During hypo-perfusion CRS induced significantly prolonged apnoea. In all experiments respiratory activity fully recovered after 1h. We conclude that CRS mediated AChE inhibition causes only transient central breathing disturbance. Apparently intrinsic brainstem mechanisms can compensate for cholinergic over activation. Nevertheless, combination of hypo-perfusion and CRS exposure evoke the characteristic breathing arrests associated with OP poisoning.
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Cifra A, Nani F, Nistri A. Respiratory motoneurons and pathological conditions: lessons from hypoglossal motoneurons challenged by excitotoxic or oxidative stress. Respir Physiol Neurobiol 2011; 179:89-96. [PMID: 21443969 DOI: 10.1016/j.resp.2011.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 03/07/2011] [Accepted: 03/19/2011] [Indexed: 11/27/2022]
Abstract
Hypoglossal motoneurons (HMs) are respiration-related brainstem neurons that command rhythmic contraction of the tongue muscles in concert with the respiratory drive. In experimental conditions, HMs can exhibit a range of rhythmic patterns that may subserve different motor outputs and functions. Neurodegenerative diseases like amyotrophic lateral sclerosis (ALS; Lou-Gehrig disease) often damage HMs with distressing symptoms like dysarthria, dysphagia and breathing difficulty related to degeneration of respiratory motoneurons. While the cause of ALS remains unclear, early diagnosis remains an important goal for potential treatment because fully blown clinical symptoms appear with degeneration of about 30% motoneurons. Using a simple in vitro model of the rat brainstem to study the consequences of excitotoxicity or oxidative stress (believed to occur during the onset of ALS) on HMs, it is possible to observe distinct electrophysiological effects associated with HM experimental pathology. In fact, excitotoxicity caused by glutamate uptake block triggers sustained bursting and enhanced synaptic transmission, whereas oxidative stress generates slow depolarization, augmented repeated firing, and decreased synaptic transmission. In either case, only a subpopulation of HMs shows abnormal functional changes. Although these two insults induce separate functional signatures, the consequences on HMs after a few hours are similar and are preceded by activation of the stress transcription factor ATF-3. The deleterious action of excitotoxicity is inhibited by early administration of riluzole, a drug currently employed for the symptomatic treatment of ALS, demonstrating that this in vitro model can be useful for testing potential neuroprotective agents.
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Affiliation(s)
- Alessandra Cifra
- Neurobiology Sector, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy
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The role of spiking and bursting pacemakers in the neuronal control of breathing. J Biol Phys 2011; 37:241-61. [PMID: 22654176 DOI: 10.1007/s10867-011-9214-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 01/06/2011] [Indexed: 12/19/2022] Open
Abstract
Breathing is controlled by a distributed network involving areas in the neocortex, cerebellum, pons, medulla, spinal cord, and various other subcortical regions. However, only one area seems to be essential and sufficient for generating the respiratory rhythm: the preBötzinger complex (preBötC). Lesioning this area abolishes breathing and following isolation in a brain slice the preBötC continues to generate different forms of respiratory activities. The use of slice preparations led to a thorough understanding of the cellular mechanisms that underlie the generation of inspiratory activity within this network. Two types of inward currents, the persistent sodium current (I(NaP)) and the calcium-activated non-specific cation current (I(CAN)), play important roles in respiratory rhythm generation. These currents give rise to autonomous pacemaker activity within respiratory neurons, leading to the generation of intrinsic spiking and bursting activity. These membrane properties amplify as well as activate synaptic mechanisms that are critical for the initiation and maintenance of inspiratory activity. In this review, we describe the dynamic interplay between synaptic and intrinsic membrane properties in the generation of the respiratory rhythm and we relate these mechanisms to rhythm generating networks involved in other behaviors.
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Dichlorvos-induced central apnea: effects of selective brainstem exposure in the rat. Neurotoxicology 2011; 32:206-14. [PMID: 21241738 DOI: 10.1016/j.neuro.2011.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 11/22/2010] [Accepted: 01/10/2011] [Indexed: 12/21/2022]
Abstract
The area of the brain responsible for organophosphate (OP)-induced central apnea is unknown. Automatic breathing is governed by circuits in the medulla and pons. Respiratory-related neurons in the brainstem are concentrated in a few areas, including ventral regions of the medulla, which contains a number of sites critical for respiratory rhythmogenesis, including the pre-Bötzinger complex (preBötC). The preBötC contains cholinergic receptors, making it a candidate site of action for the apnea-inducing effect of OP. We analyzed respiratory output during a series of experiments using both intact and reduced Wistar rat preparations exposed to dichlorvos (2,2-dichlorovinyl dimethyl phosphate). Exposure of the brainstem using a working heart-brainstem preparation resulted in a central apnea similar to that seen in intact animal models. In contrast, microdialysis of locally toxic doses of dichlorvos to the ventral region of the medulla resulted in delayed and mild respiratory depression in most animals and apnea in only 29% of the animals. We conclude that exposure of the entire brainstem to OP is sufficient to induce central apnea. Our microdialysis experiments suggest that the neural substrate for OP-induced central apnea involves a specific brainstem site other than the ventral region of the medulla, or apnea might result from a distributed effect involving cholinergic toxicities of multiple brainstem sites.
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Pilarski JQ, Wakefield HE, Fuglevand AJ, Levine RB, Fregosi RF. Developmental nicotine exposure alters neurotransmission and excitability in hypoglossal motoneurons. J Neurophysiol 2011; 105:423-33. [PMID: 21068261 PMCID: PMC3023378 DOI: 10.1152/jn.00876.2010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 11/09/2010] [Indexed: 01/24/2023] Open
Abstract
Hypoglossal motoneurons (XII MNs) control muscles of the mammalian tongue and are rhythmically active during breathing. Acetylcholine (ACh) modulates XII MN activity by promoting the release of glutamate from neurons that express nicotinic ACh receptors (nAChRs). Chronic nicotine exposure alters nAChRs on neurons throughout the brain, including brain stem respiratory neurons. Here we test the hypothesis that developmental nicotine exposure (DNE) reduces excitatory synaptic input to XII MNs. Voltage-clamp experiments in rhythmically active medullary slices showed that the frequency of excitatory postsynaptic currents (EPSCs) onto XII MNs from DNE animals is reduced by 61% (DNE = 1.7 ± 0.4 events/s; control = 4.4 ± 0.6 events/s; P < 0.002). We also examine the intrinsic excitability of XII MNs to test whether cells from DNE animals have altered membrane properties. Current-clamp experiments showed XII MNs from DNE animals had higher intrinsic excitability, as evaluated by measuring their response to injected current. DNE cells had high-input resistances (DNE = 131.9 ± 13.7 MΩ, control = 78.6 ± 9.7 MΩ, P < 0.008), began firing at lower current levels (DNE = 144 ± 22 pA, control = 351 ± 45 pA, P < 0.003), and exhibited higher frequency-current gain values (DNE = 0.087 ± 0.012 Hz/pA, control = 0.050 ± 0.004 Hz/pA, P < 0.02). Taken together, our data show previously unreported effects of DNE on XII MN function and may also help to explain the association between DNE and the incidence of central and obstructive apneas.
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Affiliation(s)
- Jason Q Pilarski
- The University of Arizona, College of Medicine, Department of Physiology, P.O. Box 210093, Tucson, AZ 85721-0093, USA.
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Du Y, Wang T, Jiang N, Ren RT, Zhao DL, Li C, Fu FH. Protective effect of sodium aescinate on lung injury induced by methyl parathion. Hum Exp Toxicol 2010; 30:1584-91. [DOI: 10.1177/0960327110393764] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Methyl parathion (MP) is a high venenosus insecticide. It has been used in pest control of agriculture for several years. The present study is performed to investigate the protective effect of sodium aescinate (SA) on lung injury induced by MP. Forty male Sprague-Dawley rats are randomly divided into five groups, with 8 animals in each group: control group, MP administration group, MP plus SA at doses of 0.45 mg/kg, 0.9 mg/kg and 1.8 mg/kg groups. Acetylcholinesterase (AChE) activity and nitric oxide (NO) level in plasma, myeloperoxidase (MPO) activity, NO level, and antioxidative parameters in lung tissue are assayed. Histopathological examination of lung is also performed. The results show that SA has no effect on AChE. Treatment with SA decreases the activity of MPO in lung and the level of NO in plasma and lung. The level of malondialdehyde in lung is decreased after SA treatments. SA increases the activities of superoxide dismutase, glutathione peroxidase and the content of glutathione in lung. SA administration also ameliorates lung injury induced by MP. The findings indicate that SA could protect lung injury induced by MP and the mechanism of action is related to the anti-inflammatory and anti-oxidative effect of SA.
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Affiliation(s)
- Yuan Du
- Department of Pharmacology, School of Pharmacy, Yantai University, NO. 32, Qingquan Road, Yantai 264005, Shandong, China
| | - Tian Wang
- Department of Pharmacology, School of Pharmacy, Yantai University, NO. 32, Qingquan Road, Yantai 264005, Shandong, China
| | - Na Jiang
- Department of Pharmacology, School of Pharmacy, Yantai University, NO. 32, Qingquan Road, Yantai 264005, Shandong, China
| | - Ru-Tong Ren
- Department of Pharmacology, School of Pharmacy, Yantai University, NO. 32, Qingquan Road, Yantai 264005, Shandong, China
| | - De-Lu Zhao
- Institute of Pharmacology & Toxicology, Taiping Road, Beijing, China
| | - Chong Li
- Department of Pharmacology, School of Pharmacy, Yantai University, NO. 32, Qingquan Road, Yantai 264005, Shandong, China
| | - Feng-Hua Fu
- Department of Pharmacology, School of Pharmacy, Yantai University, NO. 32, Qingquan Road, Yantai 264005, Shandong, China
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Motor neuron-specific overexpression of the presynaptic choline transporter: impact on motor endurance and evoked muscle activity. Neuroscience 2010; 171:1041-53. [PMID: 20888396 DOI: 10.1016/j.neuroscience.2010.09.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 09/23/2010] [Accepted: 09/24/2010] [Indexed: 11/23/2022]
Abstract
The presynaptic, hemicholinium-3 sensitive, high-affinity choline transporter (CHT) supplies choline for acetylcholine (ACh) synthesis. In mice, a homozygous deletion of CHT (CHT-/-) leads to premature cessation of spontaneous or evoked neuromuscular signaling and is associated with perinatal cyanosis and lethality within 1 h. Heterozygous (CHT+/-) mice exhibit diminished brain ACh levels and demonstrate an inability to sustain vigorous motor activity. We sought to explore the contribution of CHT gene dosage to motor function in greater detail using transgenic mice where CHT is expressed under control of the motor neuron promoter Hb9 (Hb9:CHT). On a CHT-/- background, the Hb9:CHT transgene conferred mice with the ability to move and breath for a postnatal period of ∼24 h, thus increasing survival. Conversely, Hb9:CHT expression on a wild-type background (CHT+/+;Hb9:CHT) leads to an increased capacity for treadmill running compared to wild-type littermates. Analysis of the stimulated compound muscle action potential (CMAP) in these animals under basal conditions established that CHT+/+;Hb9:CHT mice display an unexpected, bidirectional change, producing either elevated or reduced CMAP amplitude, relative to CHT+/+ animals. To examine whether these two groups arise from underlying changes in synaptic properties, we used high-frequency stimulation of motor axons to assess CMAP recovery kinetics. Although CHT+/+; Hb9:CHT mice in the two groups display an equivalent, time-dependent reduction in CMAP amplitude, animals with a higher basal CMAP amplitude demonstrate a significantly enhanced rate of recovery. To explain our findings, we propose a model whereby CHT support for neuromuscular signaling involves contributions to ACh synthesis as well as cholinergic synaptic vesicle availability.
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State-dependent interactions between excitatory neuromodulators in the neuronal control of breathing. J Neurosci 2010; 30:8251-62. [PMID: 20554877 DOI: 10.1523/jneurosci.5361-09.2010] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
All neuronal networks are modulated by multiple neuropeptides and biogenic amines. Yet, few studies investigate how different modulators interact to regulate network activity. Here we explored the state-dependent functional interactions between three excitatory neuromodulators acting on neurokinin1 (NK1), alpha1 noradrenergic (alpha1 NE), and 5-HT2 serotonin receptors within the pre-Bötzinger complex (pre-BötC), an area critical for the generation of breathing. In anesthetized, in vivo mice, the reliance on endogenous NK1 activation depended on spontaneous breathing frequency and the modulatory state of the animal. Endogenous NK1 activation had no significant respiratory effect when stimulating raphe magnus and/or locus ceruleus, but became critical when alpha1 NE and 5-HT2 receptors were pharmacologically blocked. The dependence of the centrally generated respiratory rhythm on NK1 activation was blunted in the presence of alpha1 NE and 5-HT2 agonists as demonstrated in slices containing the pre-BötC. We conclude that a modulator's action is determined by the concurrent modulation and interaction with other neuromodulators. Deficiencies in one neuromodulator are immediately compensated by the action of other neuromodulators. This interplay could play a role in the state dependency of certain breathing disorders.
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Kobayashi S, Fujito Y, Matsuyama K, Aoki M. Raphe modulation of the pre-Bötzinger complex respiratory bursts in in vitro medullary half-slice preparations of neonatal mice. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:519-28. [DOI: 10.1007/s00359-010-0539-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 04/18/2010] [Accepted: 05/18/2010] [Indexed: 12/19/2022]
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