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Borrus DS, Stettler MK, Grover CJ, Kalajian EJ, Gu J, Conradi Smith GD, Del Negro CA. Inspiratory and sigh breathing rhythms depend on distinct cellular signalling mechanisms in the preBötzinger complex. J Physiol 2024; 602:809-834. [PMID: 38353596 PMCID: PMC10940220 DOI: 10.1113/jp285582] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/21/2023] [Indexed: 02/21/2024] Open
Abstract
Breathing behaviour involves the generation of normal breaths (eupnoea) on a timescale of seconds and sigh breaths on the order of minutes. Both rhythms emerge in tandem from a single brainstem site, but whether and how a single cell population can generate two disparate rhythms remains unclear. We posit that recurrent synaptic excitation in concert with synaptic depression and cellular refractoriness gives rise to the eupnoea rhythm, whereas an intracellular calcium oscillation that is slower by orders of magnitude gives rise to the sigh rhythm. A mathematical model capturing these dynamics simultaneously generates eupnoea and sigh rhythms with disparate frequencies, which can be separately regulated by physiological parameters. We experimentally validated key model predictions regarding intracellular calcium signalling. All vertebrate brains feature a network oscillator that drives the breathing pump for regular respiration. However, in air-breathing mammals with compliant lungs susceptible to collapse, the breathing rhythmogenic network may have refashioned ubiquitous intracellular signalling systems to produce a second slower rhythm (for sighs) that prevents atelectasis without impeding eupnoea. KEY POINTS: A simplified activity-based model of the preBötC generates inspiratory and sigh rhythms from a single neuron population. Inspiration is attributable to a canonical excitatory network oscillator mechanism. Sigh emerges from intracellular calcium signalling. The model predicts that perturbations of calcium uptake and release across the endoplasmic reticulum counterintuitively accelerate and decelerate sigh rhythmicity, respectively, which was experimentally validated. Vertebrate evolution may have adapted existing intracellular signalling mechanisms to produce slow oscillations needed to optimize pulmonary function in mammals.
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Affiliation(s)
- Daniel S. Borrus
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
| | - Marco K. Stettler
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
| | - Cameron J. Grover
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
| | - Eva J. Kalajian
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
| | - Jeffrey Gu
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
| | - Gregory D. Conradi Smith
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
- Conradi Smith and Del Negro contributed equally
| | - Christopher A. Del Negro
- Applied Science and Neuroscience, William & Mary, Williamsburg, VA 23185
- Conradi Smith and Del Negro contributed equally
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2
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Chou GM, Bush NE, Phillips RS, Baertsch NA, Harris KD. Modeling Effects of Variable preBötzinger Complex Network Topology and Cellular Properties on Opioid-Induced Respiratory Depression and Recovery. eNeuro 2024; 11:ENEURO.0284-23.2023. [PMID: 38253582 PMCID: PMC10921262 DOI: 10.1523/eneuro.0284-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/22/2023] [Accepted: 11/02/2023] [Indexed: 01/24/2024] Open
Abstract
The preBötzinger complex (preBötC), located in the medulla, is the essential rhythm-generating neural network for breathing. The actions of opioids on this network impair its ability to generate robust, rhythmic output, contributing to life-threatening opioid-induced respiratory depression (OIRD). The occurrence of OIRD varies across individuals and internal and external states, increasing the risk of opioid use, yet the mechanisms of this variability are largely unknown. In this study, we utilize a computational model of the preBötC to perform several in silico experiments exploring how differences in network topology and the intrinsic properties of preBötC neurons influence the sensitivity of the network rhythm to opioids. We find that rhythms produced by preBötC networks in silico exhibit variable responses to simulated opioids, similar to the preBötC network in vitro. This variability is primarily due to random differences in network topology and can be manipulated by imposed changes in network connectivity and intrinsic neuronal properties. Our results identify features of the preBötC network that may regulate its susceptibility to opioids.
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Affiliation(s)
- Grant M Chou
- Department of Computer Science, Western Washington University, Bellingham, Washington 98225
| | - Nicholas E Bush
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, Washington 90101
| | - Ryan S Phillips
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, Washington 90101
| | - Nathan A Baertsch
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, Washington 90101
- Department of Pediatrics, University of Washington, Seattle, Washington 98195
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195
| | - Kameron Decker Harris
- Department of Computer Science, Western Washington University, Bellingham, Washington 98225
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Vafadari B, Oku Y, Tacke C, Harb A, Hülsmann S. In-vivo optogenetic identification and electrophysiology of glycinergic neurons in pre-Bötzinger complex of mice. Respir Physiol Neurobiol 2024; 320:104188. [PMID: 37939866 DOI: 10.1016/j.resp.2023.104188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 11/01/2023] [Accepted: 11/06/2023] [Indexed: 11/10/2023]
Abstract
Breathing requires distinct patterns of neuronal activity in the brainstem. The most critical part of the neuronal network responsible for respiratory rhythm generation is the preBötzinger Complex (preBötC), located in the ventrolateral medulla. This area contains both rhythmogenic glutamatergic neurons and also a high number of inhibitory neurons. Here, we aimed to analyze the activity of glycinergic neurons in the preBötC in anesthetized mice. To identify inhibitory neurons, we used a transgenic mouse line that allows expression of Channelrhodopsin 2 in glycinergic neurons. Using juxtacellular recordings and optogenetic activation via a single recording electrode, we were able to identify neurons as inhibitory and define their activity pattern in relation to the breathing rhythm. We could show that the activity pattern of glycinergic respiratory neurons in the preBötC was heterogeneous. Interestingly, only a minority of the identified glycinergic neurons showed a clear phase-locked activity pattern in every respiratory cycle. Taken together, we could show that neuron identification is possible by a combination of juxtacellular recordings and optogenetic activation via a single recording electrode.
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Affiliation(s)
- Behnam Vafadari
- Department of Anesthesiology, University Medical Center, Georg-August University, Göttingen, Germany
| | - Yoshitaka Oku
- Division of Physiome, Department of Physiology, Hyogo Medical University, Nishinomiya, Japan
| | - Charlotte Tacke
- Department of Anesthesiology, University Medical Center, Georg-August University, Göttingen, Germany
| | - Ali Harb
- Department of Anesthesiology, University Medical Center, Georg-August University, Göttingen, Germany
| | - Swen Hülsmann
- Department of Anesthesiology, University Medical Center, Georg-August University, Göttingen, Germany.
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Okazaki M, Matsumoto M, Koganezawa T. Hydrogen sulfide production in the medullary respiratory center modulates the neural circuit for respiratory pattern and rhythm generations. Sci Rep 2023; 13:20046. [PMID: 38049443 PMCID: PMC10696040 DOI: 10.1038/s41598-023-47280-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/11/2023] [Indexed: 12/06/2023] Open
Abstract
Hydrogen sulfide (H2S), which is synthesized in the brain, modulates the neural network. Recently, the importance of H2S in respiratory central pattern generation has been recognized, yet the function of H2S in the medullary respiratory network remains poorly understood. Here, to evaluate the functional roles of H2S in the medullary respiratory network, the Bötzinger complex (BötC), the pre-Bötzinger complex (preBötC), and the rostral ventral respiratory group (rVRG), we observed the effects of inhibition of H2S synthesis at each region on the respiratory pattern by using an in situ arterially perfused preparation of decerebrated male rats. After microinjection of an H2S synthase inhibitor, cystathionine β-synthase, into the BötC or preBötC, the amplitude of the inspiratory burst decreased and the respiratory frequency increased according to shorter expiration and inspiration, respectively. These alterations were abolished or attenuated in the presence of a blocker of excitatory synaptic transmission. On the other hand, after microinjection of the H2S synthase inhibitor into the rVRG, the amplitude of the inspiratory burst was attenuated, and the respiratory frequency decreased, which was the opposite effect to those obtained by blockade of inhibitory synaptic transmission at the rVRG. These results suggest that H2S synthesized in the BötC and preBötC functions to limit respiratory frequency by sustaining the respiratory phase and to maintain the power of inspiration. In contrast, H2S synthesized in the rVRG functions to promote respiratory frequency by modulating the interval of inspiration and to maintain the power of inspiration. The underlying mechanism might facilitate excitatory synaptic transmission and/or attenuate inhibitory synaptic transmission.
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Affiliation(s)
- Minako Okazaki
- Department of Neurophysiology, Division of Biomedical Science, Institute of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
- Doctoral Program in Neuroscience, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Masayuki Matsumoto
- Department of Cognitive and Behavioral Neuroscience, Division of Biomedical Science, Institute of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
- Transborder Medical Research Center, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Tadachika Koganezawa
- Department of Neurophysiology, Division of Biomedical Science, Institute of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan.
- Transborder Medical Research Center, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan.
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Ciumas C, Bolay M, Bouet R, Rheims S, Ibarrola D, Hampson JP, Lhatoo SD, Ryvlin P. Subject-Specific Activation of Central Respiratory Centers during Breath-Holding Functional Magnetic Resonance Imaging. Respiration 2023; 102:274-286. [PMID: 36750046 DOI: 10.1159/000529388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 01/06/2023] [Indexed: 02/09/2023] Open
Abstract
BACKGROUND Voluntary breath-holding (BH) triggers responses from central neural control and respiratory centers in order to restore breathing. Such responses can be observed using functional MRI (fMRI). OBJECTIVES We used this paradigm in healthy volunteers with the view to develop a biomarker that could be used to investigate disorders of the central control of breathing at the individual patient level. METHOD In 21 healthy human subjects (mean age±SD, 32.8 ± 9.9 years old), fMRI was used to determine, at both the individual and group levels, the physiological neural response to expiratory and inspiratory voluntary apneas, within respiratory control centers in the brain and brainstem. RESULTS Group analysis showed that expiratory BH, but not inspiratory BH, triggered activation of the pontine respiratory group and raphe nuclei at the group level, with a significant relationship between the levels of activation and drop in SpO2. Using predefined ROIs, expiratory BH, and to a lesser extent, inspiratory BH were associated with activation of most respiratory centers. The right ventrolateral nucleus of the thalamus, right pre-Bötzinger complex, right VRG, right nucleus ambiguus, and left Kölliker-Fuse-parabrachial complex were only activated during inspiratory BH. Individual analysis identified activations of cortical/subcortical and brainstem structures related to respiratory control in 19 out of 21 subjects. CONCLUSION Our study shows that BH paradigm allows to reliably trigger fMRI response from brainstem and cortical areas involved in respiratory control at the individual level, suggesting that it might serve as a clinically relevant biomarker to investigate conditions associated with an altered central control of respiration.
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Affiliation(s)
- Carolina Ciumas
- Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Lyon Neuroscience Research Center, Institut National de la Santé et de la Recherche Médicale U1028/CNRS UMR 5292 Lyon 1 University, Bron, France
- IDEE Epilepsy Institute, Lyon, France
| | - Mayara Bolay
- Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Romain Bouet
- Eduwell team, Lyon Neuroscience Research Center (CRNL), Inserm U1028, CNRS UMR5292, UCBL1, UJM, Lyon, France
| | - Sylvain Rheims
- Lyon Neuroscience Research Center, Institut National de la Santé et de la Recherche Médicale U1028/CNRS UMR 5292 Lyon 1 University, Bron, France
- IDEE Epilepsy Institute, Lyon, France
- Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon, France
| | | | - Johnson P Hampson
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Samden D Lhatoo
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Philippe Ryvlin
- Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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David CK, Sugimura YK, Kallurkar PS, Picardo MCD, Saha MS, Conradi Smith GD, Del Negro CA. Single cell transcriptome sequencing of inspiratory neurons of the preBötzinger complex in neonatal mice. Sci Data 2022; 9:457. [PMID: 35907922 PMCID: PMC9338969 DOI: 10.1038/s41597-022-01569-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 07/19/2022] [Indexed: 02/06/2023] Open
Abstract
Neurons in the brainstem preBötzinger complex (preBötC) generate the rhythm and rudimentary motor pattern for inspiratory breathing movements. We performed whole-cell patch-clamp recordings from inspiratory neurons in the preBötC of neonatal mouse slices that retain breathing-related rhythmicity in vitro. We classified neurons based on their electrophysiological properties and genetic background, and then aspirated their cellular contents for single-cell RNA sequencing (scRNA-seq). This data set provides the raw nucleotide sequences (FASTQ files) and annotated files of nucleotide sequences mapped to the mouse genome (mm10 from Ensembl), which includes the fragment counts, gene lengths, and fragments per kilobase of transcript per million mapped reads (FPKM). These data reflect the transcriptomes of the neurons that generate the rhythm and pattern for inspiratory breathing movements.
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Affiliation(s)
- Caroline K David
- Department of Applied Science, William & Mary, 540 Landrum Drive, Williamsburg, Virginia, 23185, USA
| | - Yae K Sugimura
- Department of Neuroscience, Jikei University School of Medicine, 3-25-8 Nishi-shimbashi, Minato, Tokyo, 105-8461, Japan
| | - Prajkta S Kallurkar
- Department of Applied Science, William & Mary, 540 Landrum Drive, Williamsburg, Virginia, 23185, USA
| | - Maria Cristina D Picardo
- Department of Applied Science, William & Mary, 540 Landrum Drive, Williamsburg, Virginia, 23185, USA
| | - Margaret S Saha
- Department of Biology, William & Mary, 540 Landrum Drive, Williamsburg, Virginia, 23185, USA
| | - Gregory D Conradi Smith
- Department of Applied Science, William & Mary, 540 Landrum Drive, Williamsburg, Virginia, 23185, USA
| | - Christopher A Del Negro
- Department of Applied Science, William & Mary, 540 Landrum Drive, Williamsburg, Virginia, 23185, USA.
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Huff A, Karlen-Amarante M, Pitts T, Ramirez JM. Optogenetic stimulation of pre-Bötzinger complex reveals novel circuit interactions in swallowing-breathing coordination. Proc Natl Acad Sci U S A 2022; 119:e2121095119. [PMID: 35858334 PMCID: PMC9304034 DOI: 10.1073/pnas.2121095119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 05/31/2022] [Indexed: 02/02/2023] Open
Abstract
The coordination of swallowing with breathing, in particular inspiration, is essential for homeostasis in most organisms. While much has been learned about the neuronal network critical for inspiration in mammals, the pre-Bötzinger complex (preBötC), little is known about how this network interacts with swallowing. Here we activate within the preBötC excitatory neurons (defined as Vglut2 and Sst neurons) and inhibitory neurons (defined as Vgat neurons) and inhibit and activate neurons defined by the transcription factor Dbx1 to gain an understanding of the coordination between the preBötC and swallow behavior. We found that stimulating inhibitory preBötC neurons did not mimic the premature shutdown of inspiratory activity caused by water swallows, suggesting that swallow-induced suppression of inspiratory activity is not directly mediated by the inhibitory neurons in the preBötC. By contrast, stimulation of preBötC Dbx1 neurons delayed laryngeal closure of the swallow sequence. Inhibition of Dbx1 neurons increased laryngeal closure duration and stimulation of Sst neurons pushed swallow occurrence to later in the respiratory cycle, suggesting that excitatory neurons from the preBötC connect to the laryngeal motoneurons and contribute to the timing of swallowing. Interestingly, the delayed swallow sequence was also caused by chronic intermittent hypoxia (CIH), a model for sleep apnea, which is 1) known to destabilize inspiratory activity and 2) associated with dysphagia. This delay was not present when inhibiting Dbx1 neurons. We propose that a stable preBötC is essential for normal swallow pattern generation and disruption may contribute to the dysphagia seen in obstructive sleep apnea.
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Affiliation(s)
- Alyssa Huff
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101
| | - Marlusa Karlen-Amarante
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101
| | - Teresa Pitts
- Department of Neurological Surgery, School of Medicine, University of Louisville, Louisville, KY 40202
| | - Jan Marino Ramirez
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101
- Department of Neurological Surgery, School of Medicine, University of Washington, Seattle, WA 98108
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Abstract
Breathing is a vital rhythmic motor behavior with a surprisingly broad influence on the brain and body. The apparent simplicity of breathing belies a complex neural control system, the breathing central pattern generator (bCPG), that exhibits diverse operational modes to regulate gas exchange and coordinate breathing with an array of behaviors. In this review, we focus on selected advances in our understanding of the bCPG. At the core of the bCPG is the preBötzinger complex (preBötC), which drives inspiratory rhythm via an unexpectedly sophisticated emergent mechanism. Synchronization dynamics underlying preBötC rhythmogenesis imbue the system with robustness and lability. These dynamics are modulated by inputs from throughout the brain and generate rhythmic, patterned activity that is widely distributed. The connectivity and an emerging literature support a link between breathing, emotion, and cognition that is becoming experimentally tractable. These advances bring great potential for elucidating function and dysfunction in breathing and other mammalian neural circuits.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
| | - Kaiwen Kam
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | | | - Jack L Feldman
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
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Burgraff NJ, Bush NE, Ramirez JM, Baertsch NA. Dynamic Rhythmogenic Network States Drive Differential Opioid Responses in the In Vitro Respiratory Network. J Neurosci 2021; 41:9919-9931. [PMID: 34697095 PMCID: PMC8638687 DOI: 10.1523/jneurosci.1329-21.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/02/2021] [Accepted: 09/07/2021] [Indexed: 11/21/2022] Open
Abstract
Death from opioid overdose is typically caused by opioid-induced respiratory depression (OIRD). A particularly dangerous characteristic of OIRD is its apparent unpredictability. The respiratory consequences of opioids can be surprisingly inconsistent, even within the same individual. Despite significant clinical implications, most studies have focused on average dose-r esponses rather than individual variation, and there remains little insight into the etiology of this apparent unpredictability. The preBötzinger complex (preBötC) in the ventral medulla is an important site for generating the respiratory rhythm and OIRD. Here, using male and female C57-Bl6 mice in vitro, we demonstrate that the preBötC can assume different network states depending on the excitability of the preBötC and the intrinsic membrane properties of preBötC neurons. These network states predict the functional consequences of opioids in the preBötC, and depending on network state, respiratory rhythmogenesis can be either stabilized or suppressed by opioids. We hypothesize that the dynamic nature of preBötC rhythmogenic properties, required to endow breathing with remarkable flexibility, also plays a key role in the dangerous unpredictability of OIRD.SIGNIFICANCE STATEMENT Opioids can cause unpredictable, life-threatening suppression of breathing. This apparent unpredictability makes clinical management of opioids difficult while also making it challenging to define the underlying mechanisms of OIRD. Here, we find in brainstem slices that the preBötC, an opioid-sensitive subregion of the brainstem, has an optimal configuration of cellular and network properties that results in a maximally stable breathing rhythm. These properties are dynamic, and the state of each individual preBötC network relative to the optimal configuration of the network predicts how vulnerable rhythmogenesis is to the effects of opioids. These insights establish a framework for understanding how endogenous and exogenous modulation of the rhythmogenic state of the preBötC can increase or decrease the risk of OIRD.
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Affiliation(s)
- Nicholas J Burgraff
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington 98101
| | - Nicholas E Bush
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington 98101
| | - Jan M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington 98101
- Departments of Pediatrics, University of Washington, Seattle, Washington 98195
- Neurological Surgery, University of Washington, Seattle, Washington 98195
| | - Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington 98101
- Departments of Pediatrics, University of Washington, Seattle, Washington 98195
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Sun X, Thörn Pérez C, Halemani D N, Shao XM, Greenwood M, Heath S, Feldman JL, Kam K. Opioids modulate an emergent rhythmogenic process to depress breathing. eLife 2019; 8:e50613. [PMID: 31841107 PMCID: PMC6938398 DOI: 10.7554/elife.50613] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 12/11/2019] [Indexed: 12/13/2022] Open
Abstract
How mammalian neural circuits generate rhythmic activity in motor behaviors, such as breathing, walking, and chewing, remains elusive. For breathing, rhythm generation is localized to a brainstem nucleus, the preBötzinger Complex (preBötC). Rhythmic preBötC population activity consists of strong inspiratory bursts, which drive motoneuronal activity, and weaker burstlets, which we hypothesize reflect an emergent rhythmogenic process. If burstlets underlie inspiratory rhythmogenesis, respiratory depressants, such as opioids, should reduce burstlet frequency. Indeed, in medullary slices from neonatal mice, the μ-opioid receptor (μOR) agonist DAMGO slowed burstlet generation. Genetic deletion of μORs in a glutamatergic preBötC subpopulation abolished opioid-mediated depression, and the neuropeptide Substance P, but not blockade of inhibitory synaptic transmission, reduced opioidergic effects. We conclude that inspiratory rhythmogenesis is an emergent process, modulated by opioids, that does not rely on strong bursts of activity associated with motor output. These findings also point to strategies for ameliorating opioid-induced depression of breathing.
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Affiliation(s)
- Xiaolu Sun
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesUnited States
| | - Carolina Thörn Pérez
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesUnited States
| | - Nagaraj Halemani D
- Department of Cell Biology and AnatomyChicago Medical School, Rosalind Franklin University of Medicine and ScienceNorth ChicagoUnited States
| | - Xuesi M Shao
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesUnited States
| | - Morgan Greenwood
- RFUMS/DePaul Research Internship ProgramRosalind Franklin University of Medicine and ScienceNorth ChicagoUnited States
| | - Sarah Heath
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesUnited States
| | - Jack L Feldman
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesUnited States
| | - Kaiwen Kam
- Department of Cell Biology and AnatomyChicago Medical School, Rosalind Franklin University of Medicine and ScienceNorth ChicagoUnited States
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11
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Phillips RS, Rubin JE. Effects of persistent sodium current blockade in respiratory circuits depend on the pharmacological mechanism of action and network dynamics. PLoS Comput Biol 2019; 15:e1006938. [PMID: 31469828 PMCID: PMC6742421 DOI: 10.1371/journal.pcbi.1006938] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 09/12/2019] [Accepted: 06/15/2019] [Indexed: 02/05/2023] Open
Abstract
The mechanism(s) of action of most commonly used pharmacological blockers of voltage-gated ion channels are well understood; however, this knowledge is rarely considered when interpreting experimental data. Effects of blockade are often assumed to be equivalent, regardless of the mechanism of the blocker involved. Using computer simulations, we demonstrate that this assumption may not always be correct. We simulate the blockade of a persistent sodium current (INaP), proposed to underlie rhythm generation in pre-Bötzinger complex (pre-BötC) respiratory neurons, via two distinct pharmacological mechanisms: (1) pore obstruction mediated by tetrodotoxin and (2) altered inactivation dynamics mediated by riluzole. The reported effects of experimental application of tetrodotoxin and riluzole in respiratory circuits are diverse and seemingly contradictory and have led to considerable debate within the field as to the specific role of INaP in respiratory circuits. The results of our simulations match a wide array of experimental data spanning from the level of isolated pre-BötC neurons to the level of the intact respiratory network and also generate a series of experimentally testable predictions. Specifically, in this study we: (1) provide a mechanistic explanation for seemingly contradictory experimental results from in vitro studies of INaP block, (2) show that the effects of INaP block in in vitro preparations are not necessarily equivalent to those in more intact preparations, (3) demonstrate and explain why riluzole application may fail to effectively block INaP in the intact respiratory network, and (4) derive the prediction that effective block of INaP by low concentration tetrodotoxin will stop respiratory rhythm generation in the intact respiratory network. These simulations support a critical role for INaP in respiratory rhythmogenesis in vivo and illustrate the importance of considering mechanism when interpreting and simulating data relating to pharmacological blockade. The application of pharmacological agents that affect transmembrane ionic currents in neurons is a commonly used experimental technique. A simplistic interpretation of experiments involving these agents suggests that antagonist application removes the impacted current and that subsequently observed changes in activity are attributable to the loss of that current’s effects. The more complex reality, however, is that different drugs may have distinct mechanisms of action, some corresponding not to a removal of a current but rather to a changing of its properties. We use computational modeling to explore the implications of the distinct mechanisms associated with two drugs, riluzole and tetrodotoxin, that are often characterized as sodium channel blockers. Through this approach, we offer potential explanations for disparate findings observed in experiments on neural respiratory circuits and show that the experimental results are consistent with a key role for the persistent sodium current in respiratory rhythm generation.
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Affiliation(s)
- Ryan S. Phillips
- Department of Mathematics and Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| | - Jonathan E. Rubin
- Department of Mathematics and Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
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Tschida K, Michael V, Takatoh J, Han BX, Zhao S, Sakurai K, Mooney R, Wang F. A Specialized Neural Circuit Gates Social Vocalizations in the Mouse. Neuron 2019; 103:459-472.e4. [PMID: 31204083 PMCID: PMC6687542 DOI: 10.1016/j.neuron.2019.05.025] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 03/25/2019] [Accepted: 05/15/2019] [Indexed: 11/29/2022]
Abstract
Vocalizations are fundamental to mammalian communication, but the underlying neural circuits await detailed characterization. Here, we used an intersectional genetic method to label and manipulate neurons in the midbrain periaqueductal gray (PAG) that are transiently active in male mice when they produce ultrasonic courtship vocalizations (USVs). Genetic silencing of PAG-USV neurons rendered males unable to produce USVs and impaired their ability to attract females. Conversely, activating PAG-USV neurons selectively triggered USV production, even in the absence of any female cues. Optogenetic stimulation combined with axonal tracing indicates that PAG-USV neurons gate downstream vocal-patterning circuits. Indeed, activating PAG neurons that innervate the nucleus retroambiguus, but not those innervating the parabrachial nucleus, elicited USVs in both male and female mice. These experiments establish that a dedicated population of PAG neurons gives rise to a descending circuit necessary and sufficient for USV production while also demonstrating the communicative salience of male USVs. VIDEO ABSTRACT.
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Affiliation(s)
- Katherine Tschida
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Valerie Michael
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Jun Takatoh
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Bao-Xia Han
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Shengli Zhao
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Katsuyasu Sakurai
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Richard Mooney
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Fan Wang
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
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13
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Cook-Snyder DR, Miller JR, Navarrete-Opazo AA, Callison JJ, Peterson RC, Hopp FA, Stuth EAE, Zuperku EJ, Stucke AG. The contribution of endogenous glutamatergic input in the ventral respiratory column to respiratory rhythm. Respir Physiol Neurobiol 2018; 260:37-52. [PMID: 30502519 DOI: 10.1016/j.resp.2018.11.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/22/2018] [Accepted: 11/25/2018] [Indexed: 12/28/2022]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the ventral respiratory column; however, the contribution of glutamatergic excitation in the individual subregions to respiratory rhythm generation has not been fully delineated. In an adult, in vivo, decerebrate rabbit model during conditions of mild hyperoxic hypercapnia we blocked glutamatergic excitation using the receptor antagonists 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX) and d(-)-2-amino-5-phosphonopentanoic acid (AP5). Disfacilitation of the preBötzinger Complex caused a decrease in inspiratory and expiratory duration as well as peak phrenic amplitude and ultimately apnea. Disfacilitation of the Bötzinger Complex caused a decrease in inspiratory and expiratory duration; subsequent disfacilitation of the preBötzinger Complex resulted in complete loss of the respiratory pattern but maintained tonic inspiratory activity. We conclude that glutamatergic drive to the preBötzinger Complex is essential for respiratory rhythm generation. Glutamatergic drive to the Bötzinger Complex significantly affects inspiratory and expiratory phase duration. Bötzinger Complex neurons are responsible for maintaining the silent expiratory phase of the phrenic neurogram.
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Affiliation(s)
| | - Justin R Miller
- Department of Biology, Carthage College, Kenosha, WI, United States
| | | | - Jennifer J Callison
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Robin C Peterson
- Department of Neuroscience, Carthage College, Kenosha, WI, United States
| | - Francis A Hopp
- Zablocki VA Medical Center, Milwaukee, WI, United States
| | - Eckehard A E Stuth
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States; Children's Hospital of Wisconsin, Milwaukee, WI, United States
| | - Edward J Zuperku
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States; Zablocki VA Medical Center, Milwaukee, WI, United States
| | - Astrid G Stucke
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States; Children's Hospital of Wisconsin, Milwaukee, WI, United States.
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14
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Abstract
Recently, based on functional differences, we subdivided neurons juxtaposed to the facial nucleus into two distinct populations, the parafacial ventral and lateral regions, i.e., pFV and pFL. Little is known about the composition of these regions, i.e., are they homogenous or heterogeneous populations? Here, we manipulated their excitability in spontaneously breathing vagotomized urethane anesthetized adult rats to further characterize their role in breathing. In the pFL, disinhibition or excitation decreased breathing frequency (f) with a concomitant increase of tidal volume (VT), and induced active expiration; in contrast, reducing excitation had no effect. This result is congruent with pFL neurons constituting a conditional expiratory oscillator comprised of a functionally homogeneous set of excitatory neurons that are tonically suppressed at rest. In the pFV, disinhibition increased f with a presumptive reflexive decrease in VT; excitation increased f, VT and sigh rate; reducing excitation decreased VT with a presumptive reflexive increase in f. Therefore, the pFV, has multiple functional roles that require further parcellation. Interestingly, while hyperpolarization of the pFV reduces ongoing expiratory activity, no perturbation of pFV excitability induced active expiration. Thus, while the pFV can affect ongoing expiratory activity, presumably generated by the pFL, it does not appear capable of directly inducing active expiration. We conclude that the pFL contains neurons that can initiate, modulate, and sustain active expiration, whereas the pFV contains subpopulations of neurons that differentially affect various aspects of breathing pattern, including but not limited to modulation of ongoing expiratory activity.
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Affiliation(s)
- Robert T. R. Huckstepp
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Kathryn P. Cardoza
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Lauren E. Henderson
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jack L. Feldman
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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15
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Vann NC, Pham FD, Dorst KE, Del Negro CA. Dbx1 Pre-Bötzinger Complex Interneurons Comprise the Core Inspiratory Oscillator for Breathing in Unanesthetized Adult Mice. eNeuro 2018; 5:ENEURO.0130-18.2018. [PMID: 29845107 PMCID: PMC5971373 DOI: 10.1523/eneuro.0130-18.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 04/23/2018] [Accepted: 04/25/2018] [Indexed: 01/20/2023] Open
Abstract
The brainstem pre-Bötzinger complex (preBötC) generates inspiratory breathing rhythms, but which neurons comprise its rhythmogenic core? Dbx1-derived neurons may play the preeminent role in rhythm generation, an idea well founded at perinatal stages of development but incompletely evaluated in adulthood. We expressed archaerhodopsin or channelrhodopsin in Dbx1 preBötC neurons in intact adult mice to interrogate their function. Prolonged photoinhibition slowed down or stopped breathing, whereas prolonged photostimulation sped up breathing. Brief inspiratory-phase photoinhibition evoked the next breath earlier than expected, whereas brief expiratory-phase photoinhibition delayed the subsequent breath. Conversely, brief inspiratory-phase photostimulation increased inspiratory duration and delayed the subsequent breath, whereas brief expiratory-phase photostimulation evoked the next breath earlier than expected. Because they govern the frequency and precise timing of breaths in awake adult mice with sensorimotor feedback intact, Dbx1 preBötC neurons constitute an essential core component of the inspiratory oscillator, knowledge directly relevant to human health and physiology.
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Affiliation(s)
- Nikolas C Vann
- Department of Applied Science, Integrated Science Center, William & Mary, Williamsburg, VA 23185
| | - Francis D Pham
- Department of Applied Science, Integrated Science Center, William & Mary, Williamsburg, VA 23185
| | - Kaitlyn E Dorst
- Department of Applied Science, Integrated Science Center, William & Mary, Williamsburg, VA 23185
| | - Christopher A Del Negro
- Department of Applied Science, Integrated Science Center, William & Mary, Williamsburg, VA 23185
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16
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Harris KD, Dashevskiy T, Mendoza J, Garcia AJ, Ramirez JM, Shea-Brown E. Different roles for inhibition in the rhythm-generating respiratory network. J Neurophysiol 2017; 118:2070-2088. [PMID: 28615332 PMCID: PMC5626906 DOI: 10.1152/jn.00174.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/25/2017] [Accepted: 06/12/2017] [Indexed: 12/20/2022] Open
Abstract
Unraveling the interplay of excitation and inhibition within rhythm-generating networks remains a fundamental issue in neuroscience. We use a biophysical model to investigate the different roles of local and long-range inhibition in the respiratory network, a key component of which is the pre-Bötzinger complex inspiratory microcircuit. Increasing inhibition within the microcircuit results in a limited number of out-of-phase neurons before rhythmicity and synchrony degenerate. Thus unstructured local inhibition is destabilizing and cannot support the generation of more than one rhythm. A two-phase rhythm requires restructuring the network into two microcircuits coupled by long-range inhibition in the manner of a half-center. In this context, inhibition leads to greater stability of the two out-of-phase rhythms. We support our computational results with in vitro recordings from mouse pre-Bötzinger complex. Partial excitation block leads to increased rhythmic variability, but this recovers after blockade of inhibition. Our results support the idea that local inhibition in the pre-Bötzinger complex is present to allow for descending control of synchrony or robustness to adverse conditions like hypoxia. We conclude that the balance of inhibition and excitation determines the stability of rhythmogenesis, but with opposite roles within and between areas. These different inhibitory roles may apply to a variety of rhythmic behaviors that emerge in widespread pattern-generating circuits of the nervous system.NEW & NOTEWORTHY The roles of inhibition within the pre-Bötzinger complex (preBötC) are a matter of debate. Using a combination of modeling and experiment, we demonstrate that inhibition affects synchrony, period variability, and overall frequency of the preBötC and coupled rhythmogenic networks. This work expands our understanding of ubiquitous motor and cognitive oscillatory networks.
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Affiliation(s)
| | - Tatiana Dashevskiy
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Joshua Mendoza
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Alfredo J Garcia
- Institute for Integrative Physiology and Section of Emergency Medicine, University of Chicago, Chicago, Illinois; and
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
- Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington
| | - Eric Shea-Brown
- Department of Applied Mathematics, University of Washington, Seattle, Washington
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17
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Langer TM, Neumueller SE, Crumley E, Burgraff NJ, Talwar S, Hodges MR, Pan L, Forster HV. Effects on breathing of agonists to μ-opioid or GABA A receptors dialyzed into the ventral respiratory column of awake and sleeping goats. Respir Physiol Neurobiol 2017; 239:10-25. [PMID: 28137700 PMCID: PMC5996971 DOI: 10.1016/j.resp.2017.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 01/09/2017] [Accepted: 01/12/2017] [Indexed: 01/01/2023]
Abstract
Pulmonary ventilation (V̇I) in awake and sleeping goats does not change when antagonists to several excitatory G protein-coupled receptors are dialyzed unilaterally into the ventral respiratory column (VRC). Concomitant changes in excitatory neuromodulators in the effluent mock cerebral spinal fluid (mCSF) suggest neuromodulatory compensation. Herein, we studied neuromodulatory compensation during dialysis of agonists to inhibitory G protein-coupled or ionotropic receptors into the VRC. Microtubules were implanted into the VRC of goats for dialysis of mCSF mixed with agonists to either μ-opioid (DAMGO) or GABAA (muscimol) receptors. We found: (1) V̇I decreased during unilateral but increased during bilateral dialysis of DAMGO, (2) dialyses of DAMGO destabilized breathing, (3) unilateral dialysis of muscimol increased V̇I, and (4) dialysis of DAMGO decreased GABA in the effluent mCSF. We conclude: (1) neuromodulatory compensation can occur during altered inhibitory neuromodulator receptor activity, and (2) the mechanism of compensation differs between G protein-coupled excitatory and inhibitory receptors and between G protein-coupled and inotropic inhibitory receptors.
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Affiliation(s)
- Thomas M Langer
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Suzanne E Neumueller
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Emma Crumley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Nicholas J Burgraff
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Sawan Talwar
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Lawrence Pan
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Department of Physical Therapy, Marquette University, Milwaukee, WI 53226, United States
| | - Hubert V Forster
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Zablocki Veterans Affairs Medical Center, Milwaukee, WI 53226, United States.
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18
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Lal A, Oku Y, Someya H, Miwakeichi F, Tamura Y. Emergent Network Topology within the Respiratory Rhythm-Generating Kernel Evolved In Silico. PLoS One 2016; 11:e0154049. [PMID: 27152967 PMCID: PMC4859517 DOI: 10.1371/journal.pone.0154049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 04/07/2016] [Indexed: 12/30/2022] Open
Abstract
We hypothesize that the network topology within the pre-Bötzinger Complex (preBötC), the mammalian respiratory rhythm generating kernel, is not random, but is optimized in the course of ontogeny/phylogeny so that the network produces respiratory rhythm efficiently and robustly. In the present study, we attempted to identify topology of synaptic connections among constituent neurons of the preBötC based on this hypothesis. To do this, we first developed an effective evolutionary algorithm for optimizing network topology of a neuronal network to exhibit a ‘desired characteristic’. Using this evolutionary algorithm, we iteratively evolved an in silico preBötC ‘model’ network with initial random connectivity to a network exhibiting optimized synchronous population bursts. The evolved ‘idealized’ network was then analyzed to gain insight into: (1) optimal network connectivity among different kinds of neurons—excitatory as well as inhibitory pacemakers, non-pacemakers and tonic neurons—within the preBötC, and (2) possible functional roles of inhibitory neurons within the preBötC in rhythm generation. Obtained results indicate that (1) synaptic distribution within excitatory subnetwork of the evolved model network illustrates skewed/heavy-tailed degree distribution, and (2) inhibitory subnetwork influences excitatory subnetwork primarily through non-tonic pacemaker inhibitory neurons. Further, since small-world (SW) network is generally associated with network synchronization phenomena and is suggested as a possible network structure within the preBötC, we compared the performance of SW network with that of the evolved model network. Results show that evolved network is better than SW network at exhibiting synchronous bursts.
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Affiliation(s)
- Amit Lal
- Department of Biomedical Engineering, Peking University, Beijing, 100871 P. R. China
| | - Yoshitaka Oku
- Department of Physiology, Hyogo College of Medicine, Nishinomiya, 663-8501 Japan
- * E-mail:
| | - Hiroshi Someya
- School of Information Science and Technology, Tokai University, Hiratsuka, 259-1292 Japan
| | - Fumikazu Miwakeichi
- Department of Statistical Modeling, The Institute of Statistical Mathematics, Tachikawa, 190-8562 Japan
- Department of Statistical Science, School of Multidisciplinary Sciences, The Graduate University for Advanced Studies, Tachikawa, 190-8562, Japan
| | - Yoshiyasu Tamura
- Department of Statistical Modeling, The Institute of Statistical Mathematics, Tachikawa, 190-8562 Japan
- Department of Statistical Science, School of Multidisciplinary Sciences, The Graduate University for Advanced Studies, Tachikawa, 190-8562, Japan
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19
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Nierat MC, Demiri S, Dupuis-Lozeron E, Allali G, Morélot-Panzini C, Similowski T, Adler D. When Breathing Interferes with Cognition: Experimental Inspiratory Loading Alters Timed Up-and-Go Test in Normal Humans. PLoS One 2016; 11:e0151625. [PMID: 26978782 PMCID: PMC4792478 DOI: 10.1371/journal.pone.0151625] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/29/2016] [Indexed: 12/14/2022] Open
Abstract
Human breathing stems from automatic brainstem neural processes. It can also be operated by cortico-subcortical networks, especially when breathing becomes uncomfortable because of external or internal inspiratory loads. How the “irruption of breathing into consciousness” interacts with cognition remains unclear, but a case report in a patient with defective automatic breathing (Ondine's curse syndrome) has shown that there was a cognitive cost of breathing when the respiratory cortical networks were engaged. In a pilot study of putative breathing-cognition interactions, the present study relied on a randomized design to test the hypothesis that experimentally loaded breathing in 28 young healthy subjects would have a negative impact on cognition as tested by “timed up-and-go” test (TUG) and its imagery version (iTUG). Progressive inspiratory threshold loading resulted in slower TUG and iTUG performance. Participants consistently imagined themselves faster than they actually were. However, progressive inspiratory loading slowed iTUG more than TUG, a finding that is unexpected with regard to the known effects of dual tasking on TUG and iTUG (slower TUG but stable iTUG). Insofar as the cortical networks engaged in response to inspiratory loading are also activated during complex locomotor tasks requiring cognitive inputs, we infer that competition for cortical resources may account for the breathing-cognition interference that is evidenced here.
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Affiliation(s)
- Marie-Cécile Nierat
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie respiratoire expérimentale et clinique, Paris, France
| | - Suela Demiri
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie respiratoire expérimentale et clinique, Paris, France
| | - Elise Dupuis-Lozeron
- Division of Pulmonary Diseases, Geneva University Hospital and University of Geneva, Geneva, Switzerland
- Research Center for Statistics, Geneva School of Economics and Management, University of Geneva, Geneva, Switzerland
| | - Gilles Allali
- Department of Neurology, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
- Department of Neurology, Division of Cognitive and Motor Aging, Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Capucine Morélot-Panzini
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie respiratoire expérimentale et clinique, Paris, France
- AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France
| | - Thomas Similowski
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie respiratoire expérimentale et clinique, Paris, France
- AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France
- * E-mail:
| | - Dan Adler
- Division of Pulmonary Diseases, Geneva University Hospital and University of Geneva, Geneva, Switzerland
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20
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Abstract
Breathing requires complex interactions of the central and peripheral nervous systems with the respiratory system. It involves cortical (volitional) as well as subcortical (automatic) output. Cortical output is mainly through the corticospinal tract, whereas the brainstem sends signals via the reticulospinal tract. Groups of nuclei in the brainstem (pneumotaxic center, dorsal and ventral respiratory group), situated in the pons and medulla, function as rhythm generators. Some of these nuclei have intrinsic pacemaker activity; however, their output is affected extensively by various chemical (through aortic and carotid bodies), mechanical (stretch reflexes), and neural feedbacks from the peripheral nervous system involving cranial nerves V, VII, IX, X, and XI. Brainstem nuclei also have central chemoreceptors that detect changes in serum carbon dioxide and pH. Various neurologic disorders such as stroke or neurodegenerative diseases (Parkinson's disease, multiple system atrophy) can adversely affect respiration and may even be the first sign of disease onset. Clinicians should have a better understanding of this complex but important physiological process to better appreciate pathologies affecting it. Future research is needed to enhance our understanding of this intricate process.
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Affiliation(s)
- Mian Zain Urfy
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Jose I Suarez
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA.
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21
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Abstract
"Sighs, tears, grief, distress" expresses Johann Sebastian Bach in a musical example for the relationship between sighs and deep emotions. This review explores the neurobiological basis of the sigh and its relationship with psychology, physiology, and pathology. Sighs monitor changes in brain states, induce arousal, and reset breathing variability. These behavioral roles homeostatically regulate breathing stability under physiological and pathological conditions. Sighs evoked in hypoxia evoke arousal and thereby become critical for survival. Hypoarousal and failure to sigh have been associated with sudden infant death syndrome. Increased breathing irregularity may provoke excessive sighing and hyperarousal, a behavioral sequence that may play a role in panic disorders. Essential for generating sighs and breathing is the pre-Bötzinger complex. Modulatory and synaptic interactions within this local network and between networks located in the brainstem, cerebellum, cortex, hypothalamus, amygdala, and the periaqueductal gray may govern the relationships between physiology, psychology, and pathology. Unraveling these circuits will lead to a better understanding of how we balance emotions and how emotions become pathological.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Neurological Surgery, University of Washington, Seattle, WA, USA.
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22
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Johnson RA, Mitchell GS. Common mechanisms of compensatory respiratory plasticity in spinal neurological disorders. Respir Physiol Neurobiol 2013; 189:419-28. [PMID: 23727226 PMCID: PMC3812344 DOI: 10.1016/j.resp.2013.05.025] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/18/2013] [Accepted: 05/21/2013] [Indexed: 12/11/2022]
Abstract
In many neurological disorders that disrupt spinal function and compromise breathing (e.g. ALS, cervical spinal injury, MS), patients often maintain ventilatory capacity well after the onset of severe CNS pathology. In progressive neurodegenerative diseases, patients ultimately reach a point where compensation is no longer possible, leading to catastrophic ventilatory failure. In this brief review, we consider evidence that common mechanisms of compensatory respiratory plasticity preserve breathing capacity in diverse clinical disorders, despite the onset of severe pathology (e.g. respiratory motor neuron denervation and/or death). We propose that a suite of mechanisms, operating at distinct sites in the respiratory control system, underlies compensatory respiratory plasticity, including: (1) increased (descending) central respiratory drive, (2) motor neuron plasticity, (3) plasticity at the neuromuscular junction or spared respiratory motor neurons, and (4) shifts in the balance from more to less severely compromised respiratory muscles. To establish this framework, we contrast three rodent models of neural dysfunction, each posing unique problems for the generation of adequate inspiratory motor output: (1) respiratory motor neuron death, (2) de- or dysmyelination of cervical spinal pathways, and (3) cervical spinal cord injury, a neuropathology with components of demyelination and motor neuron death. Through this contrast, we hope to understand the multilayered strategies used to "fight" for adequate breathing in the face of mounting pathology.
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Affiliation(s)
- Rebecca A Johnson
- Department of Surgical Sciences, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, United States.
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23
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Chen Z, Luo F, Ma XL, Lin HJ, Shi LP, Du LZ. [Application of neurally adjusted ventilatory assist in preterm infants with respiratory distress syndrome]. Zhongguo Dang Dai Er Ke Za Zhi 2013; 15:709-712. [PMID: 24034909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
OBJECTIVE To observe the effects of neurally adjusted ventilatory assist (NAVA) on the patient-ventilator synchrony, gas exchange, and ventilatory parameters in preterm infants with respiratory distress syndrome (RDS) during mechanical ventilation. METHODS Ten preterm infants with RDS received mechanical ventilation in NAVA mode for 60 minutes and in synchronized intermittent mandatory ventilation (SIMV) mode for 60 minutes, and the two modes were given in a random order. The vital signs, patient-ventilator synchrony, blood gas values, and ventilatory parameters were compared between the two ventilation modes. RESULTS Inspiratory trigger delay was significantly shorter with NAVA than with SIMV (P<0.05). There were no significant differences in arterial pH, PaCO2, PaO2 and PaO2/FiO2 between the two modes. The spontaneous respiratory rate, peak inspiratory pressure (PIP), electrical activity of the diaphragm and work of breathing were significantly lower in NAVA than in SIMV (P<0.05). CONCLUSIONS Compared with SIMV, NAVA appears to improve patient-ventilator synchrony, decrease PIP, and reduce diaphragmatic muscle load and work of breathing in preterm infants with RDS during mechanical ventilation.
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Affiliation(s)
- Zheng Chen
- Children's Hospital of Zhejiang University School of Medicine, Hangzhou 310003, China.
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24
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Liu ZD, Qiu ZH, Tan KX, Xiao SC, Liu MF, Luo YM. [Assessment of neural respiratory drive in humans]. Zhonghua Jie He He Hu Xi Za Zhi 2013; 36:493-496. [PMID: 24262083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
OBJECTIVE Assessment of neural respiratory drive is useful for diagnosis of dyspnea and respiratory failure with unknown causes. The purpose of the study was to compare the sensitivity of trandiaphragmatic pressure (Pdi) and diaphragm electromyogram (EMGdi) in assessment of neural respiratory drive. METHODS A combined catheter with 10 electrodes and 2 balloons was used to record EMGdi and Pdi during CO2 rebreathing. Three different inspiratory maneuvers-inspiration from functional residual capacity to total lung capacity (TLC), deep inspiration from functional residual capacity against closed airway (MIP), and short sharp inspiration through the nose (Sniff) were performed. Ten healthy subjects [male 4 and female 6; age (26 ± 4) years] were studied. RESULTS Linear relationship between EMGdi and end-tidal CO2 (r = 0.83-0.98, all P < 0.01) was better than that between Pdi and end-tidal CO2 (r = 0.48-0.96, all P < 0.01) during CO2 rebreathing, Z = -2.731, P < 0.05. The slope of linear relation between EMGdi and end-tidal CO2 (16.3-32.5) was significantly higher than that between Pdi and end-tidal CO2 (0.4-11.1), Z = -3.780, P < 0.01. The maximal EMGdi derived from TLC maneuver (211 ± 48) µV was larger than those from the MIP maneuver (161 ± 48) µV and the Sniff maneuver (145 ± 37) µV, F = 5.931, P < 0.05, whereas the maximal Pdi derived from TLC maneuver (58 ± 27) cm H2O (1 cm H2O = 0.098 kPa) was significantly lower than those from the MIP maneuver (92 ± 32) cm H2O and the Sniff maneuver (95 ± 27) cm H2O, F = 5.155, P < 0.05. CONCLUSION EMGdi is more sensitive than Pdi in the assessment of neural respiratory drive.
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Affiliation(s)
- Zhi-da Liu
- State Key Laboratory of Respiratory Diseases (Guangzhou Medical College), the First Affiliated Hospital of Guangzhou Medical College, Guangzhou 510120, China
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Wong-Riley MTT, Liu Q, Gao XP. Peripheral-central chemoreceptor interaction and the significance of a critical period in the development of respiratory control. Respir Physiol Neurobiol 2013; 185:156-69. [PMID: 22684042 PMCID: PMC3467325 DOI: 10.1016/j.resp.2012.05.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 05/30/2012] [Accepted: 05/30/2012] [Indexed: 01/09/2023]
Abstract
Respiratory control entails coordinated activities of peripheral chemoreceptors (mainly the carotid bodies) and central chemosensors within the brain stem respiratory network. Candidates for central chemoreceptors include Phox2b-containing neurons of the retrotrapezoid nucleus, serotonergic neurons of the medullary raphé, and/or multiple sites within the brain stem. Extensive interconnections among respiratory-related nuclei enable central chemosensitive relay. Both peripheral and central respiratory centers are not mature at birth, but undergo considerable development during the first two postnatal weeks in rats. A critical period of respiratory development (∼P12-P13 in the rat) exists when abrupt neurochemical, metabolic, ventilatory, and electrophysiological changes occur. Environmental perturbations, including hypoxia, intermittent hypoxia, hypercapnia, and hyperoxia alter the development of the respiratory system. Carotid body denervation during the first two postnatal weeks in the rat profoundly affects the development and functions of central respiratory-related nuclei. Such denervation delays and prolongs the critical period, but does not eliminate it, suggesting that the critical period may be intrinsically and genetically determined.
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Affiliation(s)
- Margaret T T Wong-Riley
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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Karapetian MA, Adamian NI, Arutiunian RS. [The influence of bulbus olfactorius at the reticular neurons of bulbar respiratory center in hypoxia]. Ross Fiziol Zh Im I M Sechenova 2012; 98:767-776. [PMID: 23013014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Under conditions of oxygen deficiency the influence of electrical stimulation of bulbus olfactorius on the impulse activity of reticular neurons of bulbar respiratory center was studied. Under conditions ofnormoxia both activation and inhibition of impulse activity of bulbar respiratory neurons are observed with a predominance of stimulating action. The changes in the dynamic of hypoxia had phase character. At the initial stage of oxygen deficiency (4000-5000 m altitude), during hypoxic activation, the stimulating action of bulbus olfactorius is less expressed than under the conditions ofnormoxia. At the second stage ofhypoxia (7500-8000 m altitude) the stimulating influence of this nucleus was significant.
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Abstract
How brain functions degenerate in the face of progressive cell loss is an important issue that pertains to neurodegenerative diseases and basic properties of neural networks. We developed an automated system that uses two-photon microscopy to detect rhythmic neurons from calcium activity, and then individually laser ablates the targets while monitoring network function in real time. We applied this system to the mammalian respiratory oscillator located in the pre-Bötzinger Complex (preBötC) of the ventral medulla, which spontaneously generates breathing-related motor activity in vitro. Here, we show that cumulatively deleting preBötC neurons progressively decreases respiratory frequency and the amplitude of motor output. On average, the deletion of 120 ± 45 neurons stopped spontaneous respiratory rhythm, and our data suggest ≈82% of the rhythm-generating neurons remain unlesioned. Cumulative ablations in other medullary respiratory regions did not affect frequency but diminished the amplitude of motor output to a lesser degree. These results suggest that the preBötC can sustain insults that destroy no more than ≈18% of its constituent interneurons, which may have implications for the onset of respiratory pathologies in disease states.
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Affiliation(s)
- John A. Hayes
- Departments of Applied Science and
- Biology, College of William and Mary, Williamsburg, VA 23187-8795
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Ramírez-Jarquín JO, Lara-Hernández S, López-Guerrero JJ, Aguileta MA, Rivera-Angulo AJ, Sampieri A, Vaca L, Ordaz B, Peña-Ortega F. Somatostatin modulates generation of inspiratory rhythms and determines asphyxia survival. Peptides 2012; 34:360-72. [PMID: 22386651 DOI: 10.1016/j.peptides.2012.02.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 02/15/2012] [Accepted: 02/15/2012] [Indexed: 10/28/2022]
Abstract
Breathing and the activity of its generator (the pre-Bötzinger complex; pre-BötC) are highly regulated functions. Among neuromodulators of breathing, somatostatin (SST) is unique: it is synthesized by a subset of glutamatergic pre-BötC neurons, but acts as an inhibitory neuromodulator. Moreover, SST regulates breathing both in normoxic and in hypoxic conditions. Although it has been implicated in the neuromodulation of breathing, neither the locus of SST modulation, nor the receptor subtypes involved have been identified. In this study, we aimed to fill in these blanks by characterizing the SST-induced regulation of inspiratory rhythm generation in vitro and in vivo. We found that both endogenous and exogenous SST depress all preBötC-generated rhythms. While SST abolishes sighs, it also decreases the frequency and increases the regularity of eupnea and gasping. Pharmacological experiments showed that SST modulates inspiratory rhythm generation by activating SST receptor type-2, whose mRNA is abundantly expressed in the pre-Bötzinger complex. In vivo, blockade of SST receptor type-2 reduces gasping amplitude and consequently, it precludes auto-resuscitation after asphyxia. Based on our findings, we suggest that SST functions as an inhibitory neuromodulator released by excitatory respiratory neurons when they become overactivated in order to stabilize breathing rhythmicity in normoxic and hypoxic conditions.
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Affiliation(s)
- Josué O Ramírez-Jarquín
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, UNAM-Campus Juriquilla, Mexico.
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Bochorishvili G, Stornetta RL, Coates MB, Guyenet PG. Pre-Bötzinger complex receives glutamatergic innervation from galaninergic and other retrotrapezoid nucleus neurons. J Comp Neurol 2012; 520:1047-61. [PMID: 21935944 PMCID: PMC3925347 DOI: 10.1002/cne.22769] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The retrotrapezoid nucleus (RTN) contains CO(2) -responsive neurons that regulate breathing frequency and amplitude. These neurons (RTN-Phox2b neurons) contain the transcription factor Phox2b, vesicular glutamate transporter 2 (VGLUT2) mRNA, and a subset contains preprogalanin mRNA. We wished to determine whether the terminals of RTN-Phox2b neurons contain galanin and VGLUT2 proteins, to identify the specific projections of the galaninergic subset, to test whether RTN-Phox2b neurons contact neurons in the pre-Bötzinger complex, and to identify the ultrastructure of these synapses. The axonal projections of RTN-Phox2b neurons were traced by using biotinylated dextran amine (BDA), and many BDA-ir boutons were found to contain galanin immunoreactivity. RTN galaninergic neurons had ipsilateral projections that were identical with those of this nucleus at large: the ventral respiratory column, the caudolateral nucleus of the solitary tract, and the pontine Kölliker-Fuse, intertrigeminal region, and lateral parabrachial nucleus. For ultrastructural studies, RTN-Phox2b neurons (galaninergic and others) were transfected with a lentiviral vector that expresses mCherry almost exclusively in Phox2b-ir neurons. After spinal cord injections of a catecholamine neuron-selective toxin, there was a depletion of C1 neurons in the RTN area; thus it was determined that the mCherry-positive terminals located in the pre-Bötzinger complex originated almost exclusively from the RTN-Phox2b (non-C1) neurons. These terminals were generally VGLUT2-immunoreactive and formed numerous close appositions with neurokinin-1 receptor-ir pre-Bötzinger complex neurons. Their boutons (n = 48) formed asymmetric synapses filled with small clear vesicles. In summary, RTN-Phox2b neurons, including the galaninergic subset, selectively innervate the respiratory pattern generator plus a portion of the dorsolateral pons. RTN-Phox2b neurons establish classic excitatory glutamatergic synapses with pre-Bötzinger complex neurons presumed to generate the respiratory rhythm.
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Affiliation(s)
| | - Ruth L. Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Melissa B. Coates
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Patrice G. Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
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Onimaru H, Dutschmann M. Calcium imaging of neuronal activity in the most rostral parafacial respiratory group of the newborn rat. J Physiol Sci 2012; 62:71-7. [PMID: 22052247 PMCID: PMC10717724 DOI: 10.1007/s12576-011-0179-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 10/18/2011] [Indexed: 11/28/2022]
Abstract
The parafacial respiratory group (pFRG) is thought to be involved in respiratory rhythm generation in neonates. This subgroup expresses the transcription factor, Phox2b, and contains intrinsically CO(2) sensitive neurons. Calcium imaging has been widely used for analysis of neuronal activity at the cellular and network level. In the present study, we applied calcium imaging to analyze neuronal activity of the most-rostral pFRG in an in vitro brainstem-spinal cord preparation from neonatal rats. We detected strong pre-inspiratory neuron activity in the most rostral pFRG, suggesting that significant numbers of pre-inspiratory neurons are localized in the ventrolateral medulla near the rostral end of the medulla. We show that usage of calcium imaging would be very useful for analysis of neuronal activity over different time scales, and discuss the advantages and disadvantages of this method.
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Affiliation(s)
- Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan.
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Voituron N, Hilaire G, Quintin L. Dexmedetomidine and clonidine induce long-lasting activation of the respiratory rhythm generator of neonatal mice: possible implication for critical care. Respir Physiol Neurobiol 2011; 180:132-40. [PMID: 22108092 DOI: 10.1016/j.resp.2011.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/05/2011] [Accepted: 11/05/2011] [Indexed: 11/19/2022]
Abstract
Dexmedetomidine and clonidine are alpha-2 adrenoceptor agonists increasingly used in the critical care unit as sedative agents for their benzodiazepine-sparing effects and their limited depressing effect on breathing. However adverse effects on breathing have been also reported with alpha-2 adrenoceptor agonists and their central effects on the respiratory rhythm generator are poorly known. We therefore examined the effects of dexmedetomidine, clonidine, the alpha-2 adrenoceptor antagonist yohimbine and the benzodiazepine midazolam on the activity of the isolated respiratory rhythm generator of neonatal mice using medullary preparations where the respiratory rhythm generator continued to function in vitro. For the first time, we showed that 5min bath applications of dexmedetomidine or clonidine activated the respiratory rhythm generator for periods over than 30min. Second, we showed that the long-lasting effect of dexmedetomidine implicated receptors other than alpha-2 adrenoceptors as it persisted after their blockade with yohimbine. Third, we reported that 5min bath applications of the benzodiazepine midazolam significantly depressed the respiratory rhythm generator, and that this depression was prevented by pre-treatment with either dexmedetomidine or clonidine. Although further experiments are still required to identify the mechanisms through which dexmedetomidine and clonidine activate the respiratory rhythm generator, our current in vitro results in neonatal mice support the use of dexmedetomidine and clonidine in the critical care unit.
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Affiliation(s)
- Nicolas Voituron
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, Unité Mixte de Recherche 6231 Centre National Recherche Scientifique/Université Aix-Marseille II et III, Team mp3-Respiration, Faculté Saint-Jérôme (case 362), 13397 Marseille Cedex 20, France
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Nishino T. [Studies on mechanism and treatment of dyspnea]. Masui 2011; 60 Suppl:S170-S176. [PMID: 22458036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Dunmyre JR, Del Negro CA, Rubin JE. Interactions of persistent sodium and calcium-activated nonspecific cationic currents yield dynamically distinct bursting regimes in a model of respiratory neurons. J Comput Neurosci 2011; 31:305-28. [PMID: 21234794 PMCID: PMC3370680 DOI: 10.1007/s10827-010-0311-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 12/19/2010] [Accepted: 12/21/2010] [Indexed: 11/25/2022]
Abstract
The preBötzinger complex (preBötC) is a heterogeneous neuronal network within the mammalian brainstem that has been experimentally found to generate robust, synchronous bursts that drive the inspiratory phase of the respiratory rhythm. The persistent sodium (NaP) current is observed in every preBötC neuron, and significant modeling effort has characterized its contribution to square-wave bursting in the preBötC. Recent experimental work demonstrated that neurons within the preBötC are endowed with a calcium-activated nonspecific cationic (CAN) current that is activated by a signaling cascade initiated by glutamate. In a preBötC model, the CAN current was shown to promote robust bursts that experience depolarization block (DB bursts). We consider a self-coupled model neuron, which we represent as a single compartment based on our experimental finding of electrotonic compactness, under variation of g (NaP), the conductance of the NaP current, and g (CAN), the conductance of the CAN current. Varying these two conductances yields a spectrum of activity patterns, including quiescence, tonic activity, square-wave bursting, DB bursting, and a novel mixture of square-wave and DB bursts, which match well with activity that we observe in experimental preparations. We elucidate the mechanisms underlying these dynamics, as well as the transitions between these regimes and the occurrence of bistability, by applying the mathematical tools of bifurcation analysis and slow-fast decomposition. Based on the prevalence of NaP and CAN currents, we expect that the generalizable framework for modeling their interactions that we present may be relevant to the rhythmicity of other brain areas beyond the preBötC as well.
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Affiliation(s)
- Justin R. Dunmyre
- Department of Mathematics and Complex Biological Systems Group, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, PA 15260, USA
| | | | - Jonathan E. Rubin
- Department of Mathematics and Complex Biological Systems Group, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, PA 15260, USA
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Baranov VM, Popova IA, Kovalev AS, Baranov MV. [Change in sensitivity of the central respiration mechanism in the 21-hour bedrest conditions]. Aviakosm Ekolog Med 2011; 45:35-38. [PMID: 21970041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The investigation was aimed at studying the mechanisms for change in the respiration center sensitivity in consequence of 21-hr bed rest with head-end tilted at -15 degrees combined with liquid loss (lasix, 20 ml) and recovery (IV infucol and glucose). Time of maximal breath-holding, capillary and venous O2 and CO2 pressure values were measured in the baseline data collection period, during and shortly after BR. Data analysis showed that extension of the maximal breath-holding time both during inspiration and expiration was statistically significant in the initial 10 minutes of tilting. Comparison of the breath-holding test data between the experimental series demonstrated that infusion of equally glucose and infucol did not affect voluntary apnea during inspiration or expiration. From BR hour 17, partial pressure of venous O2 showed a significant rise, while venous CO2 pressure decreased, also significantly. It is hypothesized that degradation of the respiration center sensitivity was connected most likely with blood pooling in the upper body and altered pressure on the baroreceptors.
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Adamian NI, Arutiunian RS, Karapetian MA. [Effect of vault irritation on the bulbar respiratory neurons during hypoxia]. Aviakosm Ekolog Med 2011; 45:47-51. [PMID: 21916252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Influence of the vault on the impulse activity of respiration center neurons in medulla oblongata and respiration was studied in the norm and during hypoxia. Hypoxia stages served as a test model for ensuing vault effect summation. In normoxia, electrical irritation of the vault had largely an activating effect. Moderate pO2 reduction with rising to the altitudes of 4000-5000 m activated pulsation of the respiratory neurons; influence of vault irritation was less evident than in normoxia even though it prevailed over inhibition. The respiratory neurons activity declined conspicuously at the peak altitude of 7500-8000 m and critical hypoxia; it was then that the facilitatory effect of vault irritation was especially strong. On "descent" to normal atmospheric pressure the spontaneous rhythmic activity of neurons and reaction to irritation returned gradually to baseline values.
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Abstract
The 2010 Julius H. Comroe, Jr., Lecture of the American Physiological Society focuses on evolving ideas in chemoreception for CO₂/pH in terms of what is "sensed," where it is sensed, and how the sensed information is used physiologically. Chemoreception is viewed as involving neurons (and glia) at many sites within the hindbrain, including, but not limited to, the retrotrapezoid nucleus, the medullary raphe, the locus ceruleus, the nucleus tractus solitarius, the lateral hypothalamus (orexin neurons), and the caudal ventrolateral medulla. Central chemoreception also has an important nonadditive interaction with afferent information arising at the carotid body. While ventilation has been viewed as the primary output variable, it appears that airway resistance, arousal, and blood pressure can also be significantly affected. Emphasis is placed on the importance of data derived from studies performed in the absence of anesthesia.
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Affiliation(s)
- Eugene Nattie
- Department of Physiology, Dartmouth Medical School, Lebanon New Hampshire 03756-0001, USA.
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Lazarenko RM, Stornetta RL, Bayliss DA, Guyenet PG. Orexin A activates retrotrapezoid neurons in mice. Respir Physiol Neurobiol 2010; 175:283-7. [PMID: 21145990 DOI: 10.1016/j.resp.2010.12.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/26/2010] [Accepted: 12/03/2010] [Indexed: 11/19/2022]
Abstract
The retrotrapezoid nucleus (RTN), located at the ventral surface of the medulla oblongata, contains glutamatergic Phox2b-expressing interneurons that have central respiratory chemoreceptor properties. RTN also operates as a relay for hypothalamic pathways that regulate breathing, one of which probably originates from the orexinergic neurons (Dias et al., 2009. J. Physiol. 587, 2059-2067). The present study explores this hypothesis at the cellular level. Using immunohistochemistry in adult Phox2b-eGFP transgenic mice, we demonstrate the presence of numerous close appositions between orexin-containing axonal varicosities and RTN chemoreceptor neurons. Using electrophysiological recordings in slices from neonatal (P6-P10) Phox2b-eGFP mice, we show that orexin A produces a robust dose-dependent excitation of the acid-sensitive RTN neurons (ED(50) ∼250nM). These data support the idea that RTN neurons are a point of convergence for several groups of CNS neurons that contribute to respiratory chemoreflexes, now including serotonergic and orexinergic neurons.
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Affiliation(s)
- Roman M Lazarenko
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, United States
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Wenker IC, Kréneisz O, Nishiyama A, Mulkey DK. Astrocytes in the retrotrapezoid nucleus sense H+ by inhibition of a Kir4.1-Kir5.1-like current and may contribute to chemoreception by a purinergic mechanism. J Neurophysiol 2010; 104:3042-52. [PMID: 20926613 PMCID: PMC3007661 DOI: 10.1152/jn.00544.2010] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 09/29/2010] [Indexed: 11/22/2022] Open
Abstract
Central chemoreception is the mechanism by which CO(2)/pH sensors regulate breathing in response to tissue pH changes. There is compelling evidence that pH-sensitive neurons in the retrotrapezoid nucleus (RTN) are important chemoreceptors. Evidence also indicates that CO(2)/H(+)-evoked adenosine 5'-triphosphate (ATP) release in the RTN, from pH-sensitive astrocytes, contributes to chemoreception. However, mechanism(s) by which RTN astrocytes sense pH is unknown and their contribution to chemoreception remains controversial. Here, we use the brain slice preparation and a combination of patch-clamp electrophysiology and immunohistochemistry to confirm that RTN astrocytes are pH sensitive and to determine mechanisms by which they sense pH. We show that pH-sensitive RTN glia are immunoreactive for aldehyde dehydrogenase 1L1, a marker of astrocytes. In HEPES buffer the pH-sensitive current expressed by RTN astrocytes reversed near E(K(+)) (the equilibrium potential for K(+)) and was inhibited by Ba(2+) and desipramine (blocker of Kir4.1-containing channels), characteristics most consistent with heteromeric Kir4.1-Kir5.1 channels. In bicarbonate buffer, the sodium/bicarbonate cotransporter also contributed to the CO(2)/H(+)-sensitive current in RTN astrocytes. To test the hypothesis that RTN astrocytes contribute to chemoreception by a purinergic mechanism, we used fluorocitrate to selectively depolarize astrocytes while measuring neuronal activity. We found that fluorocitrate increased baseline activity and pH sensitivity of RTN neurons by a P2-receptor-dependent mechanism, suggesting that astrocytes may release ATP to activate RTN chemoreceptors. We also found in bicarbonate but not HEPES buffer that P2-receptor antagonists decreased CO(2) sensitivity of RTN neurons. We conclude that RTN astrocytes sense CO(2)/H(+) in part by inhibition of a Kir4.1-Kir5.1-like current and may provide an excitatory purinergic drive to pH-sensitive neurons.
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Affiliation(s)
- Ian C Wenker
- University of Connecticut, Department of Physiology and Neurobiology, 75 N. Eagleville Rd., Storrs, CT 06269, USA
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Nishino T. [Clinically oriented respiratory physiology]. Masui 2010; 59 Suppl:S147-S156. [PMID: 21698856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Powers MA. Obesity hypoventilation syndrome: bicarbonate concentration and acetazolamide. Respir Care 2010; 55:1504-1505. [PMID: 20979680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Raurich JM, Rialp G, Ibáñez J, Llompart-Pou JA, Ayestarán I. Hypercapnic respiratory failure in obesity-hypoventilation syndrome: CO₂ response and acetazolamide treatment effects. Respir Care 2010; 55:1442-1448. [PMID: 20979670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
OBJECTIVE In obesity-hypoventilation-syndrome patients mechanically ventilated for hypercapnic respiratory failure we investigated the relationship between CO₂ response, body mass index, and plasma bicarbonate concentration, and the effect of acetazolamide on bicarbonate concentration and CO₂ response. METHODS CO₂ response tests and arterial blood gas analysis were performed in 25 patients ready for a spontaneous breathing test, and repeated in a subgroup of 8 patients after acetazolamide treatment. CO₂ response test was measured as (1) hypercapnic drive response (the ratio of the change in airway occlusion pressure 0.1 s after the start of inspiratory flow to the change in P(aCO₂)), and (2) hypercapnic ventilatory response (the ratio of the change in minute volume to the change in P(aCO₂)). RESULTS We did not find a significant relationship between CO₂ response and body mass index. Patients with higher bicarbonate concentration had a more blunted CO₂ response. Grouping the patients according to the first, second, and third tertiles of the bicarbonate concentration, the hypercapnic drive response was 0.32 ± 0.17 cm H₂O/mm Hg, 0.22 ± 0.15 cm H₂O/mm Hg, and 0.10 ± 0.06 cm H₂O/mm Hg, respectively (P = .01), and hypercapnic ventilatory response was 0.46 ± 0.23 L/min/mm Hg, 0.48 ± 0.36 L/min/mm Hg, and 0.22 ± 0.16 L/min/mm Hg, respectively (P = .04). After acetazolamide treatment, bicarbonate concentration was reduced by 8.4 ± 3.0 mmol/L (P = .01), and CO₂ response was shifted to the left, with an increase in hypercapnic drive response, by 0.14 ± 0.16 cm H₂O/mm Hg (P = .02), and hypercapnic ventilatory response, by 0.11 ± 0.22 L/min/mm Hg (P = .33). CONCLUSIONS Patients with obesity-hypoventilation syndrome and higher bicarbonate concentrations had a more blunted CO₂ response. Body mass index was not related to CO₂ response. Acetazolamide decreased bicarbonate concentration and increased CO₂ response.
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Affiliation(s)
- Joan-Maria Raurich
- Intensive Care Unit, Hospital Universitari Son Dureta, Andrea Doria 55, 07014, Palma de Mallorca, Illes Balears, Spain.
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43
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Guyenet PG, Mulkey DK. Retrotrapezoid nucleus and parafacial respiratory group. Respir Physiol Neurobiol 2010; 173:244-55. [PMID: 20188865 PMCID: PMC2891992 DOI: 10.1016/j.resp.2010.02.005] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 02/09/2010] [Accepted: 02/10/2010] [Indexed: 11/26/2022]
Abstract
The rat retrotrapezoid nucleus (RTN) contains about 2000 Phox2b-expressing glutamatergic neurons (ccRTN neurons; 800 in mice) with a well-understood developmental lineage. ccRTN neuron development fails in mice carrying a Phox2b mutation commonly present in the congenital central hypoventilation syndrome. In adulthood, ccRTN neurons regulate the breathing rate and intensity, and may regulate active expiration along with other neighboring respiratory neurons. Prenatally, ccRTN neurons form an autonomous oscillator (embryonic parafacial group, e-pF) that activates and possibly paces inspiration. The pacemaker properties of the ccRTN neurons probably vanish after birth to be replaced by synaptic drives. The neonatal parafacial respiratory group (pfRG) may represent a transitional phase during which ccRTN neurons lose their group pacemaker properties. ccRTN neurons are activated by acidification via an intrinsic mechanism or via ATP released by glia. In summary, throughout life, ccRTN neurons seem to be a critical hub for the regulation of CO(2) via breathing.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908-0735, USA.
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44
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Rubin JE, Bacak BJ, Molkov YI, Shevtsova NA, Smith JC, Rybak IA. Interacting oscillations in neural control of breathing: modeling and qualitative analysis. J Comput Neurosci 2010; 30:607-32. [PMID: 20927576 DOI: 10.1007/s10827-010-0281-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 08/24/2010] [Accepted: 09/21/2010] [Indexed: 10/19/2022]
Abstract
In mammalian respiration, late-expiratory (late-E, or pre-inspiratory) oscillations emerge in abdominal motor output with increasing metabolic demands (e.g., during hypercapnia, hypoxia, etc.). These oscillations originate in the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) and couple with the respiratory oscillations generated by the interacting neural populations of the Bötzinger (BötC) and pre-Bötzinger (pre-BötC) complexes, representing the kernel of the respiratory central pattern generator. Recently, we analyzed experimental data on the generation of late-E oscillations and proposed a large-scale computational model that simulates the possible interactions between the BötC/pre-BötC and RTN/pFRG oscillations under different conditions. Here we describe a reduced model that maintains the essential features and architecture of the large-scale model, but relies on simplified activity-based descriptions of neural populations. This simplification allowed us to use methods of dynamical systems theory, such as fast-slow decomposition, bifurcation analysis, and phase plane analysis, to elucidate the mechanisms and dynamics of synchronization between the RTN/pFRG and BötC/pre-BötC oscillations. Three physiologically relevant behaviors have been analyzed: emergence and quantal acceleration of late-E oscillations during hypercapnia, transformation of the late-E activity into a biphasic-E activity during hypercapnic hypoxia, and quantal slowing of BötC/pre-BötC oscillations with the reduction of pre-BötC excitability. Each behavior is elicited by gradual changes in excitatory drives or other model parameters, reflecting specific changes in metabolic and/or physiological conditions. Our results provide important theoretical insights into interactions between RTN/pFRG and BötC/pre-BötC oscillations and the role of these interactions in the control of breathing under different metabolic conditions.
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Affiliation(s)
- Jonathan E Rubin
- Department of Mathematics, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, PA 15260, USA.
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45
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Abstract
By definition central respiratory chemoreceptors (CRCs) are cells that are sensitive to changes in brain PCO(2) or pH and contribute to the stimulation of breathing elicited by hypercapnia or metabolic acidosis. CO(2) most likely works by lowering pH. The pertinent proton receptors have not been identified and may be ion channels. CRCs are probably neurons but may also include acid-sensitive glia and vascular cells that communicate with neurons via paracrine mechanisms. Retrotrapezoid nucleus (RTN) neurons are the most completely characterized CRCs. Their high sensitivity to CO(2) in vivo presumably relies on their intrinsic acid sensitivity, excitatory inputs from the carotid bodies and brain regions such as raphe and hypothalamus, and facilitating influences from neighboring astrocytes. RTN neurons are necessary for the respiratory network to respond to CO(2) during the perinatal period and under anesthesia. In conscious adults, RTN neurons contribute to an unknown degree to the pH-dependent regulation of breathing rate, inspiratory, and expiratory activity. The abnormal prenatal development of RTN neurons probably contributes to the congenital central hypoventilation syndrome. Other CRCs presumably exist, but the supportive evidence is less complete. The proposed locations of these CRCs are the medullary raphe, the nucleus tractus solitarius, the ventrolateral medulla, the fastigial nucleus, and the hypothalamus. Several wake-promoting systems (serotonergic and catecholaminergic neurons, orexinergic neurons) are also putative CRCs. Their contribution to central respiratory chemoreception may be behavior dependent or vary according to the state of vigilance.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA.
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46
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Toporikova N, Butera RJ. Two types of independent bursting mechanisms in inspiratory neurons: an integrative model. J Comput Neurosci 2010; 30:515-28. [PMID: 20838868 DOI: 10.1007/s10827-010-0274-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 08/19/2010] [Accepted: 08/25/2010] [Indexed: 02/02/2023]
Abstract
The network of coupled neurons in the pre-Bötzinger complex (pBC) of the medulla generates a bursting rhythm, which underlies the inspiratory phase of respiration. In some of these neurons, bursting persists even when synaptic coupling in the network is blocked and respiratory rhythmic discharge stops. Bursting in inspiratory neurons has been extensively studied, and two classes of bursting neurons have been identified, with bursting mechanism depends on either persistent sodium current or changes in intracellular Ca(2+), respectively. Motivated by experimental evidence from these intrinsically bursting neurons, we present a two-compartment mathematical model of an isolated pBC neuron with two independent bursting mechanisms. Bursting in the somatic compartment is modeled via inactivation of a persistent sodium current, whereas bursting in the dendritic compartment relies on Ca(2+) oscillations, which are determined by the neuromodulatory tone. The model explains a number of conflicting experimental results and is able to generate a robust bursting rhythm, over a large range of parameters, with a frequency adjusted by neuromodulators.
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Affiliation(s)
- Natalia Toporikova
- Laboratory for Neuroengineering, School of Electrical and Computer Engineering, Atlanta, GA 30332-0250, USA
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47
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Zheng QH, Li GC, Fang F, Wu ZH, Jiao YG. [Group II metabotropic glutamate receptors is involved in the modulation of respiratory rhythmical discharge activity in neonatal rat medullary brain slices]. Nan Fang Yi Ke Da Xue Xue Bao 2010; 30:1813-1816. [PMID: 20813672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
OBJECTIVE To explore the role of group II metabotropic glutamate receptors in the modulation of basic respiratory rhythm. METHODS Neonatal (0-3 days) SD rats of either sex were used. The medulla oblongata brain slice containing the medial region of the nucleus retrofacialis (mNRF) and the hypoglossal nerve rootlets was prepared, and the surgical procedure was performed in the modified Kreb's solution (MKS) with continuous carbogen (95% O2 and 5% CO2) within 3 min. The brain slices were quickly transferred to a recording chamber and continuously perfused with oxygen-saturated MKS at a rate of 4-6 ml/min at 27-29 degrees celsius. Eighteen medulla oblongata slices were divided into 3 groups and treated for 10 min with group II metabotropic glutamate receptor-specific agonist 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (APDC) (at concentrations of 10, 20, 50 micromol/L), group II metabotropic glutamate receptor antagonist (2S)-alpha-ethylglutamic acid (EGLU) (300 micromol/L), or APDC (50 micromol/L)+EGLU (300 micromol/L) after a 10 min APDC (50 micromol/L) application. Respiratory rhythmical discharge activity (RRDA) of the rootlets of the hypoglossal nerve was recorded by suction electrodes. RESULTS APDC produced a dose-dependent inhibitory effect on the RRDA, prolonging the respiratory cycle and expiratory time and decreasing the integral amplitude and inspiratory time. EGLU induced a significant decrease in the respiratory cycle and expiratory time. The effect of APDC on the respiratory rhythm was partially reversed by the application of APDC+EGLU. CONCLUSION Group II metabotropic glutamate receptors are probably involved in the modulation of the RRDA in isolated neonatal rat brainstem slice.
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Affiliation(s)
- Qi-hui Zheng
- Department of Physiology, Southern Medical University, Guangzhou 510515, China.
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Inyushkina EM, Merkulova NA, Inyushkin AN. Mechanisms of the respiratory activity of leptin at the level of the solitary tract nucleus. ACTA ACUST UNITED AC 2010; 40:707-13. [PMID: 20635220 DOI: 10.1007/s11055-010-9316-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/15/2009] [Indexed: 12/20/2022]
Abstract
Acute experiments on anesthetized laboratory rats were performed to study the effects microinjections of 10(-4) M leptin into the solitary tract nucleus on the extent of the Hering-Breuer inflation reflex in ventilatory reactions to hypercapnia. Local administration of leptin into this area led to inhibition of the Hering-Breuer reflex. The extent of ventilatory responses to hypercapnia, conversely, increased, which may provide evidence that leptin has a modulatory influence on central chemoreceptors. These physiological mechanisms of action probably play a leading role in mediating the stimulatory respiratory effects of leptin at the level of the solitary tract nucleus.
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Affiliation(s)
- E M Inyushkina
- Samara State University, 1 Academician Pavlov St., 443016, Samara, Russia
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Kobayashi S, Fujito Y, Matsuyama K, Aoki M. Spontaneous respiratory rhythm generation in in vitro upper cervical slice preparations of neonatal mice. J Physiol Sci 2010; 60:303-7. [PMID: 20419361 PMCID: PMC10717023 DOI: 10.1007/s12576-010-0091-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 04/01/2010] [Indexed: 10/19/2022]
Abstract
Isolated upper cervical slice preparations were prepared from neonatal mice to examine whether spontaneous respiratory activity could be generated in the preparations. By using brainstem-spinal cord preparations, we first recorded from the cervical C1-C2 and C4 ventral roots rhythmic bursts which were synchronized with respiratory burst activity of the hypoglossal (XIIth) nerve. Following transection just above the C1 segment, smaller and slower rhythmic bursts still persisted in the C1/C2 ventral roots and these were synchronized with those in the C4 ventral root. The present result, that a bursting rhythm remained in the C1/C2 slices, suggests that the spinal neuronal circuit for generating respiratory rhythm is localized in the upper cervical segments which contain upper cervical inspiratory neurons.
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Affiliation(s)
- Suguru Kobayashi
- Department of Physiology, Sapporo Medical University School of Medicine, Minami 1-jo, Nishi 17, Sapporo, 060-8556 Japan
- Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa 769-2193 Japan
| | - Yutaka Fujito
- Department of Physiology, Sapporo Medical University School of Medicine, Minami 1-jo, Nishi 17, Sapporo, 060-8556 Japan
- Department of System Neuroscience, Sapporo Medical University School of Medicine, Minami 1-jo, Nishi 17, Sapporo, 060-8556 Japan
| | - Kiyoji Matsuyama
- Department of Physiology, Sapporo Medical University School of Medicine, Minami 1-jo, Nishi 17, Sapporo, 060-8556 Japan
- Department of Occupational Therapy, Sapporo Medical University School of Health Sciences, Minami 1-jo, Nishi 17, Sapporo, 060-8556 Japan
| | - Mamoru Aoki
- Department of Physiology, Sapporo Medical University School of Medicine, Minami 1-jo, Nishi 17, Sapporo, 060-8556 Japan
- Department of Physical Therapy, Faculty of Human Science, Hokkaido Bunkyo University, 5-196-1 Kogane-chuo, Eniwa, 061-1449 Japan
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Klauchek SV, Klitochenko GV, Kochegura TN, Kudrin RA, Akhundova RE, Fokina AS. [Use of controlled respiratory rhythm to enhance stress resistance in pupils]. Gig Sanit 2010:52-54. [PMID: 20737689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
To enhance stress resistance in pupils is now a very urgent problem. The influence of a method affecting the central nervous system as acquisition of the averaged value of intrinsic respiratory rhythm has been studied. There has been a positive result of using the procedure to increase working capacity during performance by pupils and positive changes in electroencephalographic readings, by optimizing the autonomic provision for their activity.
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