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Furdui A, da Silveira Scarpellini C, Montandon G. Anatomical distribution of µ-opioid receptors, neurokinin-1 receptors, and vesicular glutamate transporter 2 in the mouse brainstem respiratory network. J Neurophysiol 2024; 132:108-129. [PMID: 38748514 DOI: 10.1152/jn.00478.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 05/08/2024] [Accepted: 05/12/2024] [Indexed: 07/03/2024] Open
Abstract
µ-Opioid receptors (MORs) are responsible for mediating both the analgesic and respiratory effects of opioid drugs. By binding to MORs in brainstem regions involved in controlling breathing, opioids produce respiratory depressive effects characterized by slow and shallow breathing, with potential cardiorespiratory arrest and death during overdose. To better understand the mechanisms underlying opioid-induced respiratory depression, thorough knowledge of the regions and cellular subpopulations that may be vulnerable to modulation by opioid drugs is needed. Using in situ hybridization, we determined the distribution and coexpression of Oprm1 (gene encoding MORs) mRNA with glutamatergic (Vglut2) and neurokinin-1 receptor (Tacr1) mRNA in medullary and pontine regions involved in breathing control and modulation. We found that >50% of cells expressed Oprm1 mRNA in the preBötzinger complex (preBötC), nucleus tractus solitarius (NTS), nucleus ambiguus (NA), postinspiratory complex (PiCo), locus coeruleus (LC), Kölliker-Fuse nucleus (KF), and the lateral and medial parabrachial nuclei (LBPN and MPBN, respectively). Among Tacr1 mRNA-expressing cells, >50% coexpressed Oprm1 mRNA in the preBötC, NTS, NA, Bötzinger complex (BötC), PiCo, LC, raphe magnus nucleus, KF, LPBN, and MPBN, whereas among Vglut2 mRNA-expressing cells, >50% coexpressed Oprm1 mRNA in the preBötC, NTS, NA, BötC, PiCo, LC, KF, LPBN, and MPBN. Taken together, our study provides a comprehensive map of the distribution and coexpression of Oprm1, Tacr1, and Vglut2 mRNA in brainstem regions that control and modulate breathing and identifies Tacr1 and Vglut2 mRNA-expressing cells as subpopulations with potential vulnerability to modulation by opioid drugs.NEW & NOTEWORTHY Opioid drugs can cause serious respiratory side-effects by binding to µ-opioid receptors (MORs) in brainstem regions that control breathing. To better understand the regions and their cellular subpopulations that may be vulnerable to modulation by opioids, we provide a comprehensive map of Oprm1 (gene encoding MORs) mRNA expression throughout brainstem regions that control and modulate breathing. Notably, we identify glutamatergic and neurokinin-1 receptor-expressing cells as potentially vulnerable to modulation by opioid drugs and worthy of further investigation using targeted approaches.
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Affiliation(s)
- Andreea Furdui
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | | | - Gaspard Montandon
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Respirology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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2
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Kang J, Lu N, Yang S, Guo B, Zhu Y, Wu S, Huang X, Wong-Riley MTT, Liu YY. Alterations in synapses and mitochondria induced by acute or chronic intermittent hypoxia in the pre-Bötzinger complex of rats: an ultrastructural triple-labeling study with immunocytochemistry and histochemistry. Front Cell Neurosci 2023; 17:1132241. [PMID: 37396926 PMCID: PMC10312010 DOI: 10.3389/fncel.2023.1132241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 06/05/2023] [Indexed: 07/04/2023] Open
Abstract
Introduction The pre-Bötzinger complex (pre-BötC), a kernel of inspiratory rhythmogenesis, is a heterogeneous network with excitatory glutamatergic and inhibitory GABAergic and glycinergic neurons. Inspiratory rhythm generation relies on synchronous activation of glutamatergic neuron, whilst inhibitory neurons play a critical role in shaping the breathing pattern, endowing the rhythm with flexibility in adapting to environmental, metabolic, and behavioral needs. Here we report ultrastructural alterations in excitatory, asymmetric synapses (AS) and inhibitory, symmetric synapses (SS), especially perforated synapses with discontinuous postsynaptic densities (PSDs) in the pre-BötC in rats exposed to daily acute intermittent hypoxia (dAIH) or chronic (C) IH. Methods We utilized for the first time a combination of somatostatin (SST) and neurokinin 1 receptor (NK1R) double immunocytochemistry with cytochrome oxidase histochemistry, to reveal synaptic characteristics and mitochondrial dynamic in the pre-BötC. Results We found perforated synapses with synaptic vesicles accumulated in distinct pools in apposition to each discrete PSD segments. dAIH induced significant increases in the PSD size of macular AS, and the proportion of perforated synapses. AS were predominant in the dAIH group, whereas SS were in a high proportion in the CIH group. dAIH significantly increased SST and NK1R expressions, whereas CIH led to a decrease. Desmosome-like contacts (DLC) were characterized for the first time in the pre-BötC. They were distributed alongside of synapses, especially SS. Mitochondria appeared in more proximity to DLC than synapses, suggestive of a higher energy demand of the DLC. Findings of single spines with dual AS and SS innervation provide morphological evidence of excitation-inhibition interplay within a single spine in the pre-BötC. In particular, we characterized spine-shaft microdomains of concentrated synapses coupled with mitochondrial positioning that could serve as a structural basis for synchrony of spine-shaft communication. Mitochondria were found within spines and ultrastructural features of mitochondrial fusion and fission were depicted for the first time in the pre-BötC. Conclusion We provide ultrastructural evidence of excitation-inhibition synapses in shafts and spines, and DLC in association with synapses that coincide with mitochondrial dynamic in their contribution to respiratory plasticity in the pre-BötC.
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Affiliation(s)
- Junjun Kang
- Department of Neurobiology, The Fourth Military Medical University, Xi’an, China
| | - Naining Lu
- Department of Neurobiology, The Fourth Military Medical University, Xi’an, China
| | - Shoujing Yang
- Department of Pathology, The Fourth Military Medical University, Xi’an, China
| | - Baolin Guo
- Department of Neurobiology, The Fourth Military Medical University, Xi’an, China
| | - Yuanyuan Zhu
- Department of Neurobiology, The Fourth Military Medical University, Xi’an, China
| | - Shengxi Wu
- Department of Neurobiology, The Fourth Military Medical University, Xi’an, China
| | - Xiaofeng Huang
- Department of Pathology, Xi’an Gaoxin Hospital, Xi’an, China
| | - Margaret T. T. Wong-Riley
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Ying-Ying Liu
- Department of Neurobiology, The Fourth Military Medical University, Xi’an, China
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3
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Krohn F, Novello M, van der Giessen RS, De Zeeuw CI, Pel JJM, Bosman LWJ. The integrated brain network that controls respiration. eLife 2023; 12:83654. [PMID: 36884287 PMCID: PMC9995121 DOI: 10.7554/elife.83654] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 01/29/2023] [Indexed: 03/09/2023] Open
Abstract
Respiration is a brain function on which our lives essentially depend. Control of respiration ensures that the frequency and depth of breathing adapt continuously to metabolic needs. In addition, the respiratory control network of the brain has to organize muscular synergies that integrate ventilation with posture and body movement. Finally, respiration is coupled to cardiovascular function and emotion. Here, we argue that the brain can handle this all by integrating a brainstem central pattern generator circuit in a larger network that also comprises the cerebellum. Although currently not generally recognized as a respiratory control center, the cerebellum is well known for its coordinating and modulating role in motor behavior, as well as for its role in the autonomic nervous system. In this review, we discuss the role of brain regions involved in the control of respiration, and their anatomical and functional interactions. We discuss how sensory feedback can result in adaptation of respiration, and how these mechanisms can be compromised by various neurological and psychological disorders. Finally, we demonstrate how the respiratory pattern generators are part of a larger and integrated network of respiratory brain regions.
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Affiliation(s)
- Friedrich Krohn
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | - Manuele Novello
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | | | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands.,Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
| | - Johan J M Pel
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
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4
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Yackle K. Transformation of Our Understanding of Breathing Control by Molecular Tools. Annu Rev Physiol 2023; 85:93-113. [PMID: 36323001 PMCID: PMC9918693 DOI: 10.1146/annurev-physiol-021522-094142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The rhythmicity of breath is vital for normal physiology. Even so, breathing is enriched with multifunctionality. External signals constantly change breathing, stopping it when under water or deepening it during exertion. Internal cues utilize breath to express emotions such as sighs of frustration and yawns of boredom. Breathing harmonizes with other actions that use our mouth and throat, including speech, chewing, and swallowing. In addition, our perception of breathing intensity can dictate how we feel, such as during the slow breathing of calming meditation and anxiety-inducing hyperventilation. Heartbeat originates from a peripheral pacemaker in the heart, but the automation of breathing arises from neural clusters within the brainstem, enabling interaction with other brain areas and thus multifunctionality. Here, we document how the recent transformation of cellular and molecular tools has contributed to our appreciation of the diversity of neuronal types in the breathing control circuit and how they confer the multifunctionality of breathing.
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Affiliation(s)
- Kevin Yackle
- Department of Physiology, University of California, San Francisco, California, USA;
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5
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Ashhad S, Slepukhin VM, Feldman JL, Levine AJ. Microcircuit Synchronization and Heavy-Tailed Synaptic Weight Distribution Augment preBötzinger Complex Bursting Dynamics. J Neurosci 2023; 43:240-260. [PMID: 36400528 PMCID: PMC9838711 DOI: 10.1523/jneurosci.1195-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 11/05/2022] [Accepted: 11/10/2022] [Indexed: 11/19/2022] Open
Abstract
The preBötzinger Complex (preBötC) encodes inspiratory time as rhythmic bursts of activity underlying each breath. Spike synchronization throughout a sparsely connected preBötC microcircuit initiates bursts that ultimately drive the inspiratory motor patterns. Using minimal microcircuit models to explore burst initiation dynamics, we examined the variability in probability and latency to burst following exogenous stimulation of a small subset of neurons, mimicking experiments. Among various physiologically plausible graphs of 1000 excitatory neurons constructed using experimentally determined synaptic and connectivity parameters, directed Erdős-Rényi graphs with a broad (lognormal) distribution of synaptic weights best captured the experimentally observed dynamics. preBötC synchronization leading to bursts was regulated by the efferent connectivity of spiking neurons that are optimally tuned to amplify modest preinspiratory activity through input convergence. Using graph-theoretic and machine learning-based analyses, we found that input convergence of efferent connectivity at the next-nearest neighbor order was a strong predictor of incipient synchronization. Our analyses revealed a crucial role of synaptic heterogeneity in imparting exceptionally robust yet flexible preBötC attractor dynamics. Given the pervasiveness of lognormally distributed synaptic strengths throughout the nervous system, we postulate that these mechanisms represent a ubiquitous template for temporal processing and decision-making computational motifs.SIGNIFICANCE STATEMENT Mammalian breathing is robust, virtually continuous throughout life, yet is inherently labile: to adapt to rapid metabolic shifts (e.g., fleeing a predator or chasing prey); for airway reflexes; and to enable nonventilatory behaviors (e.g., vocalization, breathholding, laughing). Canonical theoretical frameworks-based on pacemakers and intrinsic bursting-cannot account for the observed robustness and flexibility of the preBötzinger Complex rhythm. Experiments reveal that network synchronization is the key to initiate inspiratory bursts in each breathing cycle. We investigated preBötC synchronization dynamics using network models constructed with experimentally determined neuronal and synaptic parameters. We discovered that a fat-tailed (non-Gaussian) synaptic weight distribution-a manifestation of synaptic heterogeneity-augments neuronal synchronization and attractor dynamics in this vital rhythmogenic network, contributing to its extraordinary reliability and responsiveness.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1763
| | - Valentin M Slepukhin
- Department of Physics & Astronomy, University of California, Los Angeles, Los Angeles, California 90095-1596
| | - Jack L Feldman
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1763
| | - Alex J Levine
- Department of Physics & Astronomy, University of California, Los Angeles, Los Angeles, California 90095-1596
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1596
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6
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de la Rosa T, Calvo VS, Gonçalves VC, Ferreira CB, Cabral LM, Souza FDC, Scerni DA, Scorza FA, Moreira TS, Takakura AC. Respiratory deficits in a female rat model of Parkinson's Disease. Exp Physiol 2022; 107:1349-1359. [PMID: 36030407 DOI: 10.1113/ep090378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 08/23/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? How does 6-OHDA-induced Parkinson's Disease model affect the respiratory response in female rats? What effect does ovariectomy have on that response? What is the main finding and its importance? Our results suggest a protective effect of ovarian hormones in maintaining normal neuroanatomical integrity of the medullary respiratory nucleus in females. It was observed that ovariectomy alone reduced NK1r density in preBotc and BotC, and there was an incremental effect of 6-OHDA and ovariectomy on RTN neurons. ABSTRACT Emerging evidence indicates that Parkinson's disease (PD) courses with autonomic and respiratory deficiencies in addition to the classical motor symptoms. The prevalence of PD is lower in women, and it has been hypothesized that neuroprotection by ovarian hormones can explain this difference. While male PD animal models present changes in the central respiratory control areas, as well as ventilatory parameters under normoxia and hypercapnia, little is known about sex differences regarding respiratory deficits in this disease background. This study aimed to explore the neuroanatomical and functional respiratory changes in intact and ovariectomized female rats subjected to chemically induced PD via a bilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA). The respiratory parameters were evaluated by whole-body plethysmography, and the neuroanatomy was monitored using immunohistochemistry. It was found that dopaminergic neurons in the substantia nigra and neurokinin-1 receptor (NK1r) density in the rostral ventrolateral respiratory group, Botzinger and pre-Botzinger complex were reduced in the chemically induced PD animals. Additionally, reduced numbers of Phox2b neurons were only observed in the retrotrapezoid nucleus of PD-ovariectomized rats. Concerning respiratory parameters, in ovariectomized rats, the resting and hypercapnia-induced tidal volume (VT ) is reduced, and ventilation (VE ) changes independently of 6-OHDA administration. Notably, there is a reduction in the number of RTN phox2b neurons and hypercapnia-induced respiratory changes in PD-ovariectomized animals due to a 6-OHDA and OVX interaction. These results suggest a protective effect induced by ovarian hormones in neuroanatomical changes observed in a female experimental PD model. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Tomás de la Rosa
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil.,Neuropsychopharmacology and Psychobiology Research Group, Department of Psychology, University of Cádiz, Cádiz, Spain.,Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain
| | - Viviam S Calvo
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Valeria C Gonçalves
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Caroline B Ferreira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Lais M Cabral
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Felipe da C Souza
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Débora A Scerni
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Fúlvio A Scorza
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
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7
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Zhuang J, Gao X, Zhao L, Wei W, Xu F. Neurokinin 1 and 2 Receptors Are Involved in PEG 2- and Citric Acid-Induced Cough and Ventilatory Responses. Respir Physiol Neurobiol 2022; 306:103952. [PMID: 35905863 DOI: 10.1016/j.resp.2022.103952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/11/2022] [Accepted: 07/24/2022] [Indexed: 10/16/2022]
Abstract
Exposure to aerosolized citric acid (CA, 150mM) and prostaglandin E2 (PGE2, 0.43mM) for 10min in guinea pigs reportedly produces the distinct cough patterns (Type I vs. II) and ventilatory responses (long-lasting hyperventilation vs. brief tachypnea) even though triggering the same cough numbers. Type I and II coughs are primarily mediated by activation of TRPV1 and EP3 receptors (a PGE2 receptor) of vagal C-fibers respectively. Substance P (SP) and neurokinin A (NKA) released by vagal pulmonary sensory fibers peripherally are capable of affecting CA-induced cough and ventilation via preferentially activating neurokinin 1 and 2 receptors (NK1R and NK2R) respectively. This study aimed to define the impacts of CA- and PGE2-exposure on pulmonary SP and NKA levels and the roles of NK1R and NK2R in modulating CA- and PGE2-evoked cough and ventilatory responses. In unanesthetized guinea pigs, we determined: 1) pulmonary SP and NKA contents induced by the CA- or PGE2-exposure; 2) effects of CP-99994 and SR-48968 (a NK1R and a NK2R antagonist respectively) given by intraperitoneal injection (IP) or aerosol inhalation (IH) on the CA- and PGE2-evoked cough and ventilatory responses; and 3) immunocytochemical expressions of NK1R/NK2R in vagal C-neurons labeled by TRPV1 or EP3 receptors. We found that CA- and PGE2-exposure evoked Type I and II cough respectively associated with different degrees of increases in pulmonary SP and NKA. Applications of CP-99994 and SR-48968 via IP and IH efficiently suppressed the cough responses to CA with less impact on the cough response to PGE2. These antagonists inhibited or blocked the ventilatory response to CA and caused hypoventilation in response to PGE2. Moreover, NK1R and NK2R were always co-expressed in vagal C-neurons labeled by TRPV1 or EP3 receptors. These results suggest that SP and NKA endogenously released by CA- and PGE2-exposure play important roles in generating the cough and ventilatory responses to CA and PGE2, at least in part, via activation of NK1R and NK2R expressed in vagal C-neurons (pulmonary C-neurons).
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Affiliation(s)
- Jianguo Zhuang
- Pathophysiology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108
| | - Xiuping Gao
- Pathophysiology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108
| | - Lei Zhao
- Pathophysiology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108; Department of Exercise Physiology, Beijing Sport University, Beijing, China
| | - Wan Wei
- Pathophysiology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108; Dongfang Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, China
| | - Fadi Xu
- Pathophysiology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108.
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8
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Oliveira LM, Fernandes-Junior SA, Cabral LMC, Miranda NCS, Czeisler CM, Otero JJ, Moreira TS, Takakura AC. Regulation of blood vessels by ATP in the ventral medullary surface in a rat model of Parkinson's disease. Brain Res Bull 2022; 187:138-154. [PMID: 35777704 DOI: 10.1016/j.brainresbull.2022.06.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/26/2022] [Accepted: 06/25/2022] [Indexed: 11/17/2022]
Abstract
Parkinson's disease (PD) patients often experience impairment of autonomic and respiratory functions. These include conditions such as orthostatic hypotension and sleep apnea, which are highly correlated with dysfunctional central chemoreception. Blood flow is a fundamental determinant of tissue CO2/H+, yet the extent to which blood flow regulation within chemoreceptor regions contributes to respiratory behavior during neurological disease remains unknown. Here, we tested the hypothesis that 6-hydroxydopamine injection to inducing a known model of PD results in dysfunctional vascular homeostasis, biochemical dysregulation, and glial morphology of the ventral medullary surface (VMS). We show that hypercapnia (FiCO2 = 10%) induced elevated VMS pial vessel constriction in PD animals through a P2-receptor dependent mechanism. Similarly, we found a greater CO2-induced vascular constriction after ARL67156 (an ectonucleotidase inhibitor) in control and PD-induced animals. In addition, we also report that weighted gene correlational network analysis of the proteomic data showed a protein expression module differentially represented between both groups. This module showed that gene ontology enrichment for components of the ATP machinery were reduced in our PD-model compared to control animals. Altogether, our data indicate that dysfunction in purinergic signaling, potentially through altered ATP bioavailability in the VMS region, may compromise the RTN neuroglial vascular unit in a PD animal model.
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Affiliation(s)
- Luiz M Oliveira
- Departamento de Farmacologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, SP, 05508-000, Brazil
| | - Silvio A Fernandes-Junior
- Departamento de Farmacologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, SP, 05508-000, Brazil; The Ohio State University College of Medicine, Department of Pathology, USA
| | - Laís M C Cabral
- Departamento de Farmacologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, SP, 05508-000, Brazil
| | - Nicole C S Miranda
- Departamento de Farmacologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, SP, 05508-000, Brazil
| | | | - José J Otero
- The Ohio State University College of Medicine, Department of Pathology, USA
| | - Thiago S Moreira
- Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, SP, 05508-000, Brazil
| | - Ana C Takakura
- Departamento de Farmacologia, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, SP, 05508-000, Brazil.
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9
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Oliveira LM, Takakura AC, Moreira TS. Forebrain and Hindbrain Projecting-neurons Target the Post-inspiratory Complex Cholinergic Neurons. Neuroscience 2021; 476:102-115. [PMID: 34582982 DOI: 10.1016/j.neuroscience.2021.09.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/19/2021] [Accepted: 09/20/2021] [Indexed: 02/06/2023]
Abstract
The postinspiratory complex (PiCo) is a region located in the ventromedial medulla involved with the post-inspiratory activity. PiCo neurons are excitatory (VGlut2+) and express the enzyme choline acetyl transferase (ChAT+). Evidence also suggests that PiCo is coupled to two additional groups of neurons involved in breathing process, i.e. the pre-Bötzinger complex (preBötC, inspiration) and the retrotrapezoid nucleus (RTN, active expiration), composing all together, the hypothesized triple respiratory oscillator. Here, our main objective is to demonstrate the afferent connections to PiCo region. We mapped projecting-neurons to PiCo by injecting Fluorogold (FG) retrograde tracer into the PiCo of adult Long-Evans Chat-cre male rats. We reported extensive projections from periaqueductal grey matter and Kölliker-Fuse regions and mild projections from the nucleus of the solitary tract, ventrolateral medulla and hypothalamus. We also injected a cre-dependent vector expressing channelrhodopsin 2 (AAV5-ChR2) fused with enhanced mCherry into the PiCo of ChAT-cre rats to optogenetic activate those neurons and investigate the role of PiCo for inspiratory/postinspiratory activity. Both in urethane-anesthetized and unrestrained conscious rats the response of ChR2-transduced neurons to light induced an increase in postinspiratory activity. Our data confirmed that PiCo seems to be dedicated to postinspiratory activity and represent a site of integration for autonomic and motor components of respiratory and non-respiratory pathways.
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Affiliation(s)
- Luiz M Oliveira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 05508-000 Sao Paulo, SP, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 05508-000 Sao Paulo, SP, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 05508-000 Sao Paulo, SP, Brazil.
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10
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Patodia S, Somani A, Thom M. Review: Neuropathology findings in autonomic brain regions in SUDEP and future research directions. Auton Neurosci 2021; 235:102862. [PMID: 34411885 PMCID: PMC8455454 DOI: 10.1016/j.autneu.2021.102862] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 07/16/2021] [Accepted: 07/24/2021] [Indexed: 12/21/2022]
Abstract
Autonomic dysfunction is implicated from clinical, neuroimaging and experimental studies in sudden and unexpected death in epilepsy (SUDEP). Neuropathological analysis in SUDEP series enable exploration of acquired, seizure-related cellular adaptations in autonomic and brainstem autonomic centres of relevance to dysfunction in the peri-ictal period. Alterations in SUDEP compared to control groups have been identified in the ventrolateral medulla, amygdala, hippocampus and central autonomic regions. These involve neuropeptidergic, serotonergic and adenosine systems, as well as specific regional astroglial and microglial populations, as potential neuronal modulators, orchestrating autonomic dysfunction. Future research studies need to extend to clinically and genetically characterized epilepsies, to explore if common or distinct pathways of autonomic dysfunction mediate SUDEP. The ultimate objective of SUDEP research is the identification of disease biomarkers for at risk patients, to improve post-mortem recognition and disease categorisation, but ultimately, for exposing potential treatment targets of pharmacologically modifiable and reversible cellular alterations.
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Affiliation(s)
- Smriti Patodia
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Alyma Somani
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Maria Thom
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK.
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11
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Hülsmann S. The post‐inspiratory complex (PiCo), what is the evidence? J Physiol 2020; 599:357-359. [DOI: 10.1113/jp280492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/13/2020] [Indexed: 12/31/2022] Open
Affiliation(s)
- Swen Hülsmann
- Universitätsmedizin Göttingen Klinik für Anästhesiologie Georg‐August‐Universität Göttingen Germany
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12
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Szereda-Przestaszewska M, Kaczyńska K. Serotonin and substance P: Synergy or competition in the control of breathing. Auton Neurosci 2020; 225:102658. [PMID: 32145695 DOI: 10.1016/j.autneu.2020.102658] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 12/29/2022]
Abstract
Numerous neurotransmitters identified in the central nervous system play role in ventilatory control. This mini-review focuses on the respiratory effects of two neurotransmitters: serotonin (5-HT) and substance P (SP). We discuss their co-localization in medullary raphe nuclei, expression of proper receptors within the specific regions of respiratory related structures and contribution to respiratory rhythmogenesis.
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Affiliation(s)
- Małgorzata Szereda-Przestaszewska
- Department of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, A. Pawińskiego 5, 02-106 Warsaw, Poland
| | - Katarzyna Kaczyńska
- Department of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, A. Pawińskiego 5, 02-106 Warsaw, Poland.
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13
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Baertsch NA, Ramirez JM. Insights into the dynamic control of breathing revealed through cell-type-specific responses to substance P. eLife 2019; 8:51350. [PMID: 31804180 PMCID: PMC6957314 DOI: 10.7554/elife.51350] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/04/2019] [Indexed: 12/23/2022] Open
Abstract
The rhythm generating network for breathing must continuously adjust to changing metabolic and behavioral demands. Here, we examined network-based mechanisms in the mouse preBötzinger complex using substance P, a potent excitatory modulator of breathing frequency and stability, as a tool to dissect network properties that underlie dynamic breathing. We find that substance P does not alter the balance of excitation and inhibition during breaths or the duration of the resulting refractory period. Instead, mechanisms of recurrent excitation between breaths are enhanced such that the rate that excitation percolates through the network is increased. We propose a conceptual framework in which three distinct phases of inspiration, the burst phase, refractory phase, and percolation phase, can be differentially modulated to control breathing dynamics and stability. Unraveling mechanisms that support this dynamic control may improve our understanding of nervous system disorders that destabilize breathing, many of which involve changes in brainstem neuromodulatory systems.
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Affiliation(s)
- Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.,Department of Neurological Surgery, University of Washington School of Medicine, Seattle, United States
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14
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Morinaga R, Nakamuta N, Yamamoto Y. Serotonergic projections to the ventral respiratory column from raphe nuclei in rats. Neurosci Res 2019; 143:20-30. [DOI: 10.1016/j.neures.2018.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 12/22/2022]
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15
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Johnson SM, Randhawa KS, Baker TL, Watters JJ. Respiratory frequency plasticity during development. Respir Physiol Neurobiol 2019; 266:54-65. [PMID: 31055188 DOI: 10.1016/j.resp.2019.04.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/22/2019] [Accepted: 04/26/2019] [Indexed: 01/20/2023]
Abstract
Respiratory frequency plasticity is a long-lasting increase in breathing frequency due to a perturbation. Mechanisms underlying respiratory frequency are poorly understood, and there is little evidence of frequency plasticity in neonates. This hybrid review/research article discusses available literature regarding frequency plasticity and highlights potential research opportunities. Also, we include data demonstrating a model of frequency plasticity using isolated neonatal rat brainstem-spinal cord preparations. Specifically, substance P (SubP) application induced a long-lasting (>60 min) increase in spontaneous respiratory motor burst frequency, particularly in brainstem-spinal cords with the pons attached; there were no male/female differences. SubP-induced frequency plasticity is dependent on the application pattern, such that intermittent (rather than sustained) SubP applications induce more frequency plasticity. SubP-induced frequency plasticity was blocked by a neurokinin-1 receptor antagonist. Thus, the newborn rat respiratory control system has the capacity to express frequency plasticity. Identifying mechanisms that induce frequency plasticity may lead to novel methods to safely treat breathing disorders in premature and newborn infants.
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Affiliation(s)
- Stephen M Johnson
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, United States.
| | - Karanbir S Randhawa
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, United States
| | - Tracy L Baker
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, United States
| | - Jyoti J Watters
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, United States
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16
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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 2019; 260:37-52. [PMID: 30502519 PMCID: PMC6397772 DOI: 10.1016/j.resp.2018.11.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [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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17
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Kang JJ, Guo B, Liang WH, Lam CS, Wu SX, Huang XF, Wong-Riley MTT, Fung ML, Liu YY. Daily acute intermittent hypoxia induced dynamic changes in dendritic mitochondrial ultrastructure and cytochrome oxidase activity in the pre-Bötzinger complex of rats. Exp Neurol 2018; 313:124-134. [PMID: 30586594 DOI: 10.1016/j.expneurol.2018.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/18/2018] [Indexed: 12/29/2022]
Abstract
Mitochondria, as primary energy generators and Ca2+ biosensor, are dynamically coupled to neuronal activities, and thus play a role in neuroplasticity. Here we report that respiratory neuroplasticity induced by daily acute intermittent hypoxia (dAIH) evoked adaptive changes in the ultrastructure and postsynaptic distribution of mitochondria in the pre-Bötzinger complex (pre-BötC). The metabolic marker of neuronal activity, cytochrome c oxidase (CO), and dendritic mitochondria were examined in pre-BötC neurons of adult Sprague-Dawley rats preconditioned with dAIH, which is known to induce long-term facilitation (LTF) in respiratory neural activities. We performed neurokinin 1 receptor (NK1R) pre-embedding immunocytochemistry to define pre-BötC neurons, in combination with CO histochemistry, to depict ultrastructural alterations and CO activity in dendritic mitochondria. We found that the dAIH challenge significantly increased CO activity in pre-BötC neurons. Darkly CO-reactive mitochondria at postsynaptic sites in the dAIH group were much more prevalent than those in the normoxic control. In addition, the length and area of mitochondria were significantly increased in the dAIH group, implying a larger surface area of cristae for ATP generation. There was a fine, structural remodeling, notably enlarged and branching mitochondria or tapered mitochondria extending into dendritic spines. Mitochondrial cristae were mainly in parallel-lamellar arrangement, indicating a high efficiency of energy generation. Moreover, flocculent or filament-like elements were noted between the mitochondria and the postsynaptic membrane. These morphological evidences, together with increased CO activity, demonstrate that dendritic mitochondria in the pre-BötC responded dynamically to respiratory plasticity. Hence, plastic neuronal changes are closely coupled to active mitochondrial bioenergetics, leading to enhanced energy production and Ca2+ buffering that may drive the LTF expression.
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Affiliation(s)
- Jun-Jun Kang
- Department of Neurobiology, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Baolin Guo
- Department of Neurobiology, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Wei-Hua Liang
- Department of Pathology and Pathophysiology, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Chun-Sing Lam
- School of Biomedical Sciences, The University of Hong Kong, PR China
| | - Sheng-Xi Wu
- Department of Neurobiology, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Xiao-Feng Huang
- Department of Pathology and Pathophysiology, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Margaret T T Wong-Riley
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Man-Lung Fung
- School of Biomedical Sciences, The University of Hong Kong, PR China.
| | - Ying-Ying Liu
- Department of Neurobiology, The Fourth Military Medical University, Xi'an 710032, PR China.
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18
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Rajani V, Zhang Y, Jalubula V, Rancic V, SheikhBahaei S, Zwicker JD, Pagliardini S, Dickson CT, Ballanyi K, Kasparov S, Gourine AV, Funk GD. Release of ATP by pre-Bötzinger complex astrocytes contributes to the hypoxic ventilatory response via a Ca 2+ -dependent P2Y 1 receptor mechanism. J Physiol 2018; 596:3245-3269. [PMID: 28678385 PMCID: PMC6068109 DOI: 10.1113/jp274727] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 06/27/2017] [Indexed: 01/03/2023] Open
Abstract
KEY POINTS The ventilatory response to reduced oxygen (hypoxia) is biphasic, comprising an initial increase in ventilation followed by a secondary depression. Our findings indicate that, during hypoxia, astrocytes in the pre-Bötzinger complex (preBötC), a critical site of inspiratory rhythm generation, release a gliotransmitter that acts via P2Y1 receptors to stimulate ventilation and reduce the secondary depression. In vitro analyses reveal that ATP excitation of the preBötC involves P2Y1 receptor-mediated release of Ca2+ from intracellular stores. By identifying a role for gliotransmission and the sites, P2 receptor subtype, and signalling mechanisms via which ATP modulates breathing during hypoxia, these data advance our understanding of the mechanisms underlying the hypoxic ventilatory response and highlight the significance of purinergic signalling and gliotransmission in homeostatic control. Clinically, these findings are relevant to conditions in which hypoxia and respiratory depression are implicated, including apnoea of prematurity, sleep disordered breathing and congestive heart failure. ABSTRACT The hypoxic ventilatory response (HVR) is biphasic, consisting of a phase I increase in ventilation followed by a secondary depression (to a steady-state phase II) that can be life-threatening in premature infants who suffer from frequent apnoeas and respiratory depression. ATP released in the ventrolateral medulla oblongata during hypoxia attenuates the secondary depression. We explored a working hypothesis that vesicular release of ATP by astrocytes in the pre-Bötzinger Complex (preBötC) inspiratory rhythm-generating network acts via P2Y1 receptors to mediate this effect. Blockade of vesicular exocytosis in preBötC astrocytes bilaterally (using an adenoviral vector to specifically express tetanus toxin light chain in astrocytes) reduced the HVR in anaesthetized rats, indicating that exocytotic release of a gliotransmitter within the preBötC contributes to the hypoxia-induced increases in ventilation. Unilateral blockade of P2Y1 receptors in the preBötC via local antagonist injection enhanced the secondary respiratory depression, suggesting that a significant component of the phase II increase in ventilation is mediated by ATP acting at P2Y1 receptors. In vitro responses of the preBötC inspiratory network, preBötC inspiratory neurons and cultured preBötC glia to purinergic agents demonstrated that the P2Y1 receptor-mediated increase in fictive inspiratory frequency involves Ca2+ recruitment from intracellular stores leading to increases in intracellular Ca2+ ([Ca2+ ]i ) in inspiratory neurons and glia. These data suggest that ATP is released by preBötC astrocytes during hypoxia and acts via P2Y1 receptors on inspiratory neurons (and/or glia) to evoke Ca2+ release from intracellular stores and an increase in ventilation that counteracts the hypoxic respiratory depression.
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Affiliation(s)
- Vishaal Rajani
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
- Present address: Neurosciences & Mental Health, Peter Gilgan Centre for Research and Learning (PGCRL)The Hospital for Sick ChildrenTorontoOntarioCanada
| | - Yong Zhang
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
| | - Venkatesh Jalubula
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
| | - Vladimir Rancic
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
| | - Shahriar SheikhBahaei
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS)National Institutes of Health (NIH)BethesdaMDUSA
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonUK
| | - Jennifer D. Zwicker
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
| | - Silvia Pagliardini
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
| | - Clayton T. Dickson
- Department of Psychology, Neuroscience and Mental Health Institute (NMHI)Faculty of ScienceEdmontonAlbertaCanada
| | - Klaus Ballanyi
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
| | - Sergey Kasparov
- Department of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - Alexander V. Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonUK
| | - Gregory D. Funk
- Department of Physiology, Neuroscience and Mental Health Institute (NMHI), Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlbertaCanada
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19
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Bright FM, Vink R, Byard RW. The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS). Neuropeptides 2018; 70:1-8. [PMID: 29908886 DOI: 10.1016/j.npep.2018.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 02/25/2018] [Accepted: 02/25/2018] [Indexed: 12/30/2022]
Abstract
Victims of sudden infant death syndrome (SIDS) are believed to have an underlying dysfunction in medullary homeostatic control that impairs critical responses to life threatening challenges such as hypoxia, hypercarbia and asphyxia, often during a sleep period. This failure is thought to result from abnormalities in a network of neural pathways in the medulla oblongata that control respiration, chemosensitivity, autonomic function and arousal. Studies have mainly focused on the role of serotonin, 5-hydroxytyptamine (5HT), although the neuropeptide substance P (SP) has also been shown to play an integral role in the modulation of medullary homeostatic function, often in conjunction with 5-HT. Actions of SP include regulation of respiratory rhythm generation, integration of cardiovascular control, modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may, therefore, also play a significant role in homeostatic dysfunction of the neurotransmitter network in SIDS. This review focuses on the pathways within the medulla involving SP and its tachykinin NK1 receptor, their potential relationship with the medullary 5-HT system, and possible involvement in the pathogenesis of SIDS.
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Affiliation(s)
- Fiona M Bright
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, SA, Australia.
| | - Robert Vink
- Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Roger W Byard
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, SA, Australia
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20
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Breathing responses produced by optogenetic stimulation of adrenergic C1 neurons are dependent on the connection with preBötzinger complex in rats. Pflugers Arch 2018; 470:1659-1672. [DOI: 10.1007/s00424-018-2186-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 07/11/2018] [Accepted: 07/20/2018] [Indexed: 01/14/2023]
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21
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Abstract
Breathing is a well-described, vital and surprisingly complex behaviour, with behavioural and physiological outputs that are easy to directly measure. Key neural elements for generating breathing pattern are distinct, compact and form a network amenable to detailed interrogation, promising the imminent discovery of molecular, cellular, synaptic and network mechanisms that give rise to the behaviour. Coupled oscillatory microcircuits make up the rhythmic core of the breathing network. Primary among these is the preBötzinger Complex (preBötC), which is composed of excitatory rhythmogenic interneurons and excitatory and inhibitory pattern-forming interneurons that together produce the essential periodic drive for inspiration. The preBötC coordinates all phases of the breathing cycle, coordinates breathing with orofacial behaviours and strongly influences, and is influenced by, emotion and cognition. Here, we review progress towards cracking the inner workings of this vital core.
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Affiliation(s)
- Christopher A Del Negro
- Department of Applied Science, Integrated Science Center, William & Mary, Williamsburg, VA, USA
| | - Gregory D Funk
- Department of Physiology, Neuroscience and Mental Health Institute, Women's and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jack L Feldman
- Department of Neurobiology, David Geffen School of Medicine, Center for Health Sciences, University of California at Los Angeles, Los Angeles, CA, USA.
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22
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da Silva GSF, Sabino JPJ, Rajani V, Alvares TS, Pagliardini S, Branco LGS, Funk GD. Excitatory Modulation of the preBötzinger Complex Inspiratory Rhythm Generating Network by Endogenous Hydrogen Sulfide. Front Physiol 2017; 8:452. [PMID: 28713283 PMCID: PMC5492353 DOI: 10.3389/fphys.2017.00452] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/14/2017] [Indexed: 12/18/2022] Open
Abstract
Hydrogen Sulfide (H2S) is one of three gasotransmitters that modulate excitability in the CNS. Global application of H2S donors or inhibitors of H2S synthesis to the respiratory network has suggested that inspiratory rhythm is modulated by exogenous and endogenous H2S. However, effects have been variable, which may reflect that the RTN/pFRG (retrotrapezoid nucleus, parafacial respiratory group) and the preBötzinger Complex (preBötC, critical for inspiratory rhythm generation) are differentially modulated by exogenous H2S. Importantly, site-specific modulation of respiratory nuclei by H2S means that targeted, rather than global, manipulation of respiratory nuclei is required to understand the role of H2S signaling in respiratory control. Thus, our aim was to test whether endogenous H2S, which is produced by cystathionine-β-synthase (CBS) in the CNS, acts specifically within the preBötC to modulate inspiratory activity under basal (in vitro/in vivo) and hypoxic conditions (in vivo). Inhibition of endogenous H2S production by bath application of the CBS inhibitor, aminooxyacetic acid (AOAA, 0.1-1.0 mM) to rhythmic brainstem spinal cord (BSSC) and medullary slice preparations from newborn rats, or local application of AOAA into the preBötC (slices only) caused a dose-dependent decrease in burst frequency. Unilateral injection of AOAA into the preBötC of anesthetized, paralyzed adult rats decreased basal inspiratory burst frequency, amplitude and ventilatory output. AOAA in vivo did not affect the initial hypoxia-induced (10% O2, 5 min) increase in ventilatory output, but enhanced the secondary hypoxic respiratory depression. These data suggest that the preBötC inspiratory network receives tonic excitatory modulation from the CBS-H2S system, and that endogenous H2S attenuates the secondary hypoxic respiratory depression.
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Affiliation(s)
- Glauber S. F. da Silva
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
- Department of Morphology and Animal Physiology, Sao Paulo State UniversityJaboticabal, Brazil
| | - João P. J. Sabino
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
- Department of Biophysics and Physiology, Federal University of PiauiTeresina, Brazil
| | - Vishaal Rajani
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
| | - Tucaauê S. Alvares
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
| | - Silvia Pagliardini
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
| | - Luiz G. S. Branco
- Department of Physiology, Faculty of Dentistry of Ribeirao Preto, University of Sao PauloRibeirao Preto, Brazil
| | - Gregory D. Funk
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
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23
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Menuet C, Le S, Dempsey B, Connelly AA, Kamar JL, Jancovski N, Bassi JK, Walters K, Simms AE, Hammond A, Fong AY, Goodchild AK, McMullan S, Allen AM. Excessive Respiratory Modulation of Blood Pressure Triggers Hypertension. Cell Metab 2017; 25:739-748. [PMID: 28215844 DOI: 10.1016/j.cmet.2017.01.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/09/2016] [Accepted: 01/28/2017] [Indexed: 02/07/2023]
Abstract
The etiology of hypertension, the world's biggest killer, remains poorly understood, with treatments targeting the established symptom, not the cause. The development of hypertension involves increased sympathetic nerve activity that, in experimental hypertension, may be driven by excessive respiratory modulation. Using selective viral and cell lesion techniques, we identify adrenergic C1 neurons in the medulla oblongata as critical for respiratory-sympathetic entrainment and the development of experimental hypertension. We also show that a cohort of young, normotensive humans, selected for an exaggerated blood pressure response to exercise and thus increased hypertension risk, has enhanced respiratory-related blood pressure fluctuations. These studies pinpoint a specific neuronal target for ameliorating excessive sympathetic activity during the developmental phase of hypertension and identify a group of pre-hypertensive subjects that would benefit from targeting these cells.
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Affiliation(s)
- Clément Menuet
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Sheng Le
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Bowen Dempsey
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Angela A Connelly
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jessica L Kamar
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Nikola Jancovski
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jaspreet K Bassi
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Keryn Walters
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Annabel E Simms
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Andrew Hammond
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Angelina Y Fong
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ann K Goodchild
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Simon McMullan
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Andrew M Allen
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia; Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia.
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24
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Dempsey B, Le S, Turner A, Bokiniec P, Ramadas R, Bjaalie JG, Menuet C, Neve R, Allen AM, Goodchild AK, McMullan S. Mapping and Analysis of the Connectome of Sympathetic Premotor Neurons in the Rostral Ventrolateral Medulla of the Rat Using a Volumetric Brain Atlas. Front Neural Circuits 2017; 11:9. [PMID: 28298886 PMCID: PMC5331070 DOI: 10.3389/fncir.2017.00009] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/06/2017] [Indexed: 01/27/2023] Open
Abstract
Spinally projecting neurons in the rostral ventrolateral medulla (RVLM) play a critical role in the generation of vasomotor sympathetic tone and are thought to receive convergent input from neurons at every level of the neuraxis; the factors that determine their ongoing activity remain unresolved. In this study we use a genetically restricted viral tracing strategy to definitively map their spatially diffuse connectome. We infected bulbospinal RVLM neurons with a recombinant rabies variant that drives reporter expression in monosynaptically connected input neurons and mapped their distribution using an MRI-based volumetric atlas and a novel image alignment and visualization tool that efficiently translates the positions of neurons captured in conventional photomicrographs to Cartesian coordinates. We identified prominent inputs from well-established neurohumoral and viscero-sympathetic sensory actuators, medullary autonomic and respiratory subnuclei, and supramedullary autonomic nuclei. The majority of inputs lay within the brainstem (88–94%), and included putative respiratory neurons in the pre-Bötzinger Complex and post-inspiratory complex that are therefore likely to underlie respiratory-sympathetic coupling. We also discovered a substantial and previously unrecognized input from the region immediately ventral to nucleus prepositus hypoglossi. In contrast, RVLM sympathetic premotor neurons were only sparsely innervated by suprapontine structures including the paraventricular nucleus, lateral hypothalamus, periaqueductal gray, and superior colliculus, and we found almost no evidence of direct inputs from the cortex or amygdala. Our approach can be used to quantify, standardize and share complete neuroanatomical datasets, and therefore provides researchers with a platform for presentation, analysis and independent reanalysis of connectomic data.
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Affiliation(s)
- Bowen Dempsey
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Sheng Le
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Anita Turner
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Phil Bokiniec
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Radhika Ramadas
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Jan G Bjaalie
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Clement Menuet
- Department of Physiology, University of Melbourne Melbourne, VIC, Australia
| | - Rachael Neve
- Viral Core Facility, McGovern Institute for Brain Research, Massachusetts Institute of Technology Cambridge, MA, USA
| | - Andrew M Allen
- Department of Physiology, University of Melbourne Melbourne, VIC, Australia
| | - Ann K Goodchild
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Simon McMullan
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
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Catecholaminergic neurons in synaptic connections with pre-Bötzinger complex neurons in the rostral ventrolateral medulla in normoxic and daily acute intermittent hypoxic rats. Exp Neurol 2017; 287:165-175. [DOI: 10.1016/j.expneurol.2016.05.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 04/12/2016] [Accepted: 05/26/2016] [Indexed: 02/07/2023]
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Morinaga R, Nakamuta N, Yamamoto Y. Hypoxia-induced increases in serotonin-immunoreactive nerve fibers in the medulla oblongata of the rat. Acta Histochem 2016; 118:806-817. [PMID: 27825705 DOI: 10.1016/j.acthis.2016.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 10/20/2022]
Abstract
Hypoxia induces respiratory responses in mammals and serotonergic neurons in the medulla oblongata participate in respiratory control. However, the morphological changes in serotonergic neurons induced by hypoxia have not yet been examined and respiratory controls of serotonergic neurons have not been clarified. We herein investigated the distribution of immunoreactivity for serotonin (5-hydroxytryptamine; 5-HT) in the medulla oblongata of control rats and rats exposed to 1-6h of hypoxia (10% O2). We also examined the medulla oblongata by multiple immunofluorescence labeling for 5-HT, neurokinin 1 receptors (NK1R), a marker for some respiratory neurons in the pre-Bötzinger complex (PBC), and dopamine β-hydroxylase (DBH), a marker for catecholaminergic neurons. The number of 5-HT-immunoreactive nerve cell bodies in the raphe nuclei was higher in rats exposed to hypoxia than in control rats. The number of 5-HT-immunoreactive nerve fibers significantly increased in the rostral ventrolateral medulla of rats exposed to 1-6h of hypoxia, caudal ventrolateral medulla of rats exposed to 2-6h of hypoxia, and lateral part of the nucleus of the solitary tract and dorsal motor nucleus of the vagus nerve of rats exposed to 1-2h of hypoxia. Multiple immunofluorescence labeling showed that 5-HT-immunoreactive nerve fibers were close to NK1R-immunoreactive neurons in ventrolateral medulla and to DBH-immunoreactive neurons in the medulla. These results suggest that serotonergic neurons partly regulate respiratory control under hypoxic conditions by modulating the activity of NK1R-expressing and catecholaminergic neurons.
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Deschênes M, Takatoh J, Kurnikova A, Moore JD, Demers M, Elbaz M, Furuta T, Wang F, Kleinfeld D. Inhibition, Not Excitation, Drives Rhythmic Whisking. Neuron 2016; 90:374-87. [PMID: 27041498 PMCID: PMC4929009 DOI: 10.1016/j.neuron.2016.03.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 02/10/2016] [Accepted: 02/22/2016] [Indexed: 02/07/2023]
Abstract
Sniffing and whisking typify the exploratory behavior of rodents. These actions involve separate oscillators in the medulla, located respectively in the pre-Bötzinger complex (preBötC) and the vibrissa-related region of the intermediate reticular formation (vIRt). We examine how these oscillators synergize to control sniffing and whisking. We find that the vIRt contains glycinergic/GABAergic cells that rhythmically inhibit vibrissa facial motoneurons. As a basis for the entrainment of whisking by breathing, but not vice versa, we provide evidence for unidirectional connections from the preBötC to the vIRt. The preBötC further contributes to the control of the mystacial pad. Lastly, we show that bilateral synchrony of whisking relies on the respiratory rhythm, consistent with commissural connections between preBötC cells. These data yield a putative circuit in which the preBötC acts as a master clock for the synchronization of vibrissa, pad, and snout movements, as well as for the bilateral synchronization of whisking.
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Affiliation(s)
- Martin Deschênes
- Department of Psychiatry and Neuroscience, Laval University, Québec City, QC G1J 2R3, Canada.
| | - Jun Takatoh
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Anastasia Kurnikova
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jeffrey D Moore
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Maxime Demers
- Department of Psychiatry and Neuroscience, Laval University, Québec City, QC G1J 2R3, Canada
| | - Michael Elbaz
- Department of Psychiatry and Neuroscience, Laval University, Québec City, QC G1J 2R3, Canada
| | - Takahiro Furuta
- Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Fan Wang
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - David Kleinfeld
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA
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28
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Inhibitory Effect of Endomorphin-2 Binding to the μ-Opioid Receptor in the Rat Pre-Bötzinger Complex on the Breathing Activity. Mol Neurobiol 2016; 54:461-469. [DOI: 10.1007/s12035-015-9624-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/08/2015] [Indexed: 12/13/2022]
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Le S, Turner AJ, Parker LM, Burke PG, Kumar NN, Goodchild AK, McMullan S. Somatostatin 2a receptors are not expressed on functionally identified respiratory neurons in the ventral respiratory column of the rat. J Comp Neurol 2015; 524:1384-98. [PMID: 26470751 DOI: 10.1002/cne.23912] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 10/09/2015] [Accepted: 10/12/2015] [Indexed: 01/09/2023]
Abstract
Microinjection of somatostatin (SST) causes site-specific effects on respiratory phase transition, frequency, and amplitude when microinjected into the ventrolateral medulla (VLM) of the anesthetized rat, suggesting selective expression of SST receptors on different functional classes of respiratory neurons. Of the six subtypes of SST receptor, somatostatin 2a (sst2a ) is the most prevalent in the VLM, and other investigators have suggested that glutamatergic neurons in the preBötzinger Complex (preBötC) that coexpress neurokinin-1 receptor (NK1R), SST, and sst2a are critical for the generation of respiratory rhythm. However, quantitative data describing the distribution of sst2a in respiratory compartments other than preBötC, or on functionally identified respiratory neurons, is absent. Here we examine the medullary expression of sst2a with particular reference to glycinergic/expiratory neurons in the Bötzinger Complex (BötC) and NK1R-immunoreactive/inspiratory neurons in the preBötC. We found robust sst2a expression at all rostrocaudal levels of the VLM, including a large proportion of catecholaminergic neurons, but no colocalization of sst2a and glycine transporter 2 mRNA in the BötC. In the preBötC 54% of sst2a -immunoreactive neurons were also positive for NK1R. sst2a was not observed in any of 52 dye-labeled respiratory interneurons, including seven BötC expiratory-decrementing and 11 preBötC preinspiratory neurons. We conclude that sst2a is not expressed on BötC respiratory neurons and that phasic respiratory activity is a poor predictor of sst2a expression in the preBötC. Therefore, sst2a is unlikely to underlie responses to BötC SST injection, and is sparse or absent on respiratory neurons identified by classical functional criteria. J. Comp. Neurol. 524:1384-1398, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Sheng Le
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Anita J Turner
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Lindsay M Parker
- ARC Center of Excellence for Nanoscale BioPhotonics, Macquarie University, NSW, Australia
| | - Peter G Burke
- Neuroscience Research Australia, Randwick, NSW, Australia
| | - Natasha N Kumar
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Ann K Goodchild
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Simon McMullan
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
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30
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Respiratory deficits in a rat model of Parkinson’s disease. Neuroscience 2015; 297:194-204. [DOI: 10.1016/j.neuroscience.2015.03.048] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/11/2015] [Accepted: 03/19/2015] [Indexed: 11/19/2022]
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31
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Wakai J, Takamura D, Morinaga R, Nakamuta N, Yamamoto Y. Differences in respiratory changes and Fos expression in the ventrolateral medulla of rats exposed to hypoxia, hypercapnia, and hypercapnic hypoxia. Respir Physiol Neurobiol 2015; 215:64-72. [PMID: 26001678 DOI: 10.1016/j.resp.2015.05.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 04/30/2015] [Accepted: 05/01/2015] [Indexed: 11/25/2022]
Abstract
Respiratory responses to hypoxia and/or hypercapnia, and their relationship to neural activity in the ventrolateral medulla (VLM), which includes the respiratory center, have not yet been elucidated in detail. We herein examined respiratory responses during exposure of 10% O2 (hypoxia), 10% CO2 (hypercapnia), and 10% O2-10% CO2 (hypercapnic hypoxia) using plethysmography. In addition to recording respiration, Fos expressions were examined in the VLM of the rat exposed to each gas to analyze neural activity. Respiratory frequency was increased in rats exposed to hypoxia, and Fos-positive neurons were observed in the caudal VLM (cVLM) and medial VLM (mVLM). Tidal volume was increased in rats exposed to hypercapnia, and Fos-positive neurons were observed in the rostral VLM (rVLM) includes the retrotrapezoid nucleus (RTN) and mVLM. Tidal volume was enhanced in rats exposed to hypercapnic hypoxia, similar to that in hypercapnia-exposed rats, and Fos-positive neurons were observed in the entire region of the VLM. In the mVLM and cVLM, double immunofluorescence showed Fos-immunoreactive nerve cells were also immunoreactive to dopamine β-hydroxylase, the marker for A1/C1 catecholaminergic neuron. These results suggested that hypoxia and hypercapnia modulated rhythmogenic microcircuits in the mVLM via A1/C1 neurons and the RTN, respectively.
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Affiliation(s)
- Jun Wakai
- Laboratory Animal Research Center, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Daichi Takamura
- Laboratory of Veterinary Biochemistry and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Ryosuke Morinaga
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan.
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32
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Muere C, Neumueller S, Olesiak S, Miller J, Hodges MR, Pan L, Forster HV. Blockade of neurokinin-1 receptors in the ventral respiratory column does not affect breathing but alters neurochemical release. J Appl Physiol (1985) 2015; 118:732-41. [PMID: 25635003 DOI: 10.1152/japplphysiol.00884.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Substance P (SP) and its receptor, neurokinin-1 (NK1R), have been shown to be excitatory modulators of respiratory frequency and to stabilize breathing regularity. Studies in anesthetized mice suggest that tonic activation of NK1Rs is particularly important when other excitatory inputs to the pre-Bötzinger complex in the ventral respiratory column (VRC) are attenuated. Consistent with these findings, muscarinic receptor blockade in the VRC of intact goats elicits an increase in breathing frequency associated with increases in SP and serotonin concentrations, suggesting an involvement of these substances in neuromodulator compensation. To gain insight on the contribution to breathing of endogenous SP and NK1R activation, and how NK1R modulates the release of other neurochemicals, we individually dialyzed antagonists to NK1R (133, 267, 500 μM Spantide; 3 mM RP67580) throughout the VRC of awake and sleeping goats. We found that NK1R blockade with either Spantide at any dose or RP67580 had no effect on breathing or regularity. Both antagonists significantly (P < 0.001) increased SP, while RP67580 also increased serotonin and glycine and decreased thyrotropin-releasing hormone concentrations in the dialysate. Taken together, these data support the concept of neuromodulator interdependence, and we believe that the loss of excitatory input from NK1Rs was locally compensated by changes in other neurochemicals.
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Affiliation(s)
- Clarissa Muere
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Suzanne Neumueller
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Samantha Olesiak
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Justin Miller
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Lawrence Pan
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin; and
| | - Hubert V Forster
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
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Dempsey B, Turner AJ, Le S, Sun QJ, Bou Farah L, Allen AM, Goodchild AK, McMullan S. Recording, labeling, and transfection of single neurons in deep brain structures. Physiol Rep 2015; 3:3/1/e12246. [PMID: 25602013 PMCID: PMC4387759 DOI: 10.14814/phy2.12246] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Genetic tools that permit functional or connectomic analysis of neuronal circuits are rapidly transforming neuroscience. The key to deployment of such tools is selective transfection of target neurons, but to date this has largely been achieved using transgenic animals or viral vectors that transduce subpopulations of cells chosen according to anatomical rather than functional criteria. Here, we combine single‐cell transfection with conventional electrophysiological recording techniques, resulting in three novel protocols that can be used for reliable delivery of conventional dyes or genetic material in vitro and in vivo. We report that techniques based on single cell electroporation yield reproducible transfection in vitro, and offer a simple, rapid and reliable alternative to established dye‐labeling techniques in vivo, but are incompatible with targeted transfection in deep brain structures. In contrast, we show that intracellular electrophoresis of plasmid DNA transfects brainstem neurons recorded up to 9 mm deep in the anesthetized rat. The protocols presented here require minimal, if any, modification to recording hardware, take seconds to deploy, and yield high recovery rates in vitro (dye labeling: 89%, plasmid transfection: 49%) and in vivo (dye labeling: 66%, plasmid transfection: 27%). They offer improved simplicity compared to the juxtacellular labeling technique and for the first time offer genetic manipulation of functionally characterized neurons in previously inaccessible brain regions. The ability to label individual neurons after electrophysiological characterization of their functional properties is a foundational technique in neuroscience. A number of approaches that achieve this goal have been described, but all are technically challenging. Here, we describe a simple approach that is rapid, reliable, and compatible with delivery of conventional dyes or large plasmid DNA molecules.
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Affiliation(s)
- Bowen Dempsey
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Anita J Turner
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Sheng Le
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Qi-Jian Sun
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Lama Bou Farah
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Andrew M Allen
- Department of Physiology, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Ann K Goodchild
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
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Ruangkittisakul A, Kottick A, Picardo MCD, Ballanyi K, Del Negro CA. Identification of the pre-Bötzinger complex inspiratory center in calibrated "sandwich" slices from newborn mice with fluorescent Dbx1 interneurons. Physiol Rep 2014; 2:2/8/e12111. [PMID: 25138790 PMCID: PMC4246597 DOI: 10.14814/phy2.12111] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Inspiratory active pre‐Bötzinger complex (preBötC) networks produce the neural rhythm that initiates and controls breathing movements. We previously identified the preBötC in the newborn rat brainstem and established anatomically defined transverse slices in which the preBötC remains active when exposed at one surface. This follow‐up study uses a neonatal mouse model in which the preBötC as well as a genetically defined class of respiratory interneurons can be identified and selectively targeted for physiological recordings. The population of glutamatergic interneurons whose precursors express the transcription factor Dbx1 putatively comprises the core respiratory rhythmogenic circuit. Here, we used intersectional mouse genetics to identify the brainstem distribution of Dbx1‐derived neurons in the context of observable respiratory marker structures. This reference brainstem atlas enabled online histology for generating calibrated sandwich slices to identify the preBötC location, which was heretofore unspecified for perinatal mice. Sensitivity to opioids ensured that slice rhythms originated from preBötC neurons and not parafacial respiratory group/retrotrapezoid nucleus (pFRG/RTN) cells because opioids depress preBötC, but not pFRG/RTN rhythms. We found that the preBötC is centered ~0.4 mm caudal to the facial motor nucleus in this Cre/lox reporter mouse during postnatal days 0–4. Our findings provide the essential basis for future optically guided electrophysiological and fluorescence imaging‐based studies, as well as the application of other Cre‐dependent tools to record or manipulate respiratory rhythmogenic neurons. These resources will ultimately help elucidate the mechanisms that promote respiratory‐related oscillations of preBötC Dbx1‐derived neurons and thus breathing. Breathing movements emanate from Dbx1‐derived interneurons of the brainstem pre‐Bötzinger complex (preBötC). We generated a histology atlas of the medulla in newborn Dbx1 Cre/lox reporter mice and performed physiological tests to pinpoint the preBötC location and map the Dbx1 neuron distribution, which will facilitate neurobiological studies of respiratory rhythm generation.
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Affiliation(s)
- Araya Ruangkittisakul
- Department of Physiology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew Kottick
- Department of Applied Science, The College of William & Mary, Williamsburg, Virginia
| | - Maria C D Picardo
- Department of Applied Science, The College of William & Mary, Williamsburg, Virginia
| | - Klaus Ballanyi
- Department of Physiology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Subramanian HH, Holstege G. Stimulation of the midbrain periaqueductal gray modulates preinspiratory neurons in the ventrolateral medulla in the rat in vivo. J Comp Neurol 2014; 521:3083-98. [PMID: 23630049 PMCID: PMC3761193 DOI: 10.1002/cne.23334] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 03/06/2013] [Accepted: 03/13/2013] [Indexed: 12/11/2022]
Abstract
The midbrain periaqueductal gray (PAG) is involved in many basic survival behaviors that affect respiration. We hypothesized that the PAG promotes these behaviors by changing the firing of preinspiratory (pre-I) neurons in the pre-Bötzinger complex, a cell group thought to be important in generating respiratory rhythm. We tested this hypothesis by recording single unit activity of pre-Bötzinger pre-I neurons during stimulation in different parts of the PAG. Stimulation in the dorsal PAG increased the firing of pre-I neurons, resulting in tachypnea. Stimulation in the medial part of the lateral PAG converted the pre-I neurons into inspiratory phase-spanning cells, resulting in inspiratory apneusis. Stimulation in the lateral part of the lateral PAG generated an early onset of the pre-I neuronal discharge, which continued throughout the inspiratory phase, while at the same time attenuating diaphragm contraction. Stimulation in the ventral part of the lateral PAG induced tachypnea but inhibited pre-I cell firing, whereas stimulation in the ventrolateral PAG inhibited not only pre-I cells but also the diaphragm, leading to apnea. These findings show that PAG stimulation changes the activity of the pre-Bötzinger pre-I neurons. These changes are in line with the different behaviors generated by the PAG, such as the dorsal PAG generating avoidance behavior, the lateral PAG generating fight and flight, and the ventrolateral PAG generating freezing and immobility. J. Comp. Neurol. 521: 3083–3098, 2013. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Hari H Subramanian
- The University of Queensland Centre for Clinical Research, Herston, Queensland, 4029, Australia
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36
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Remote control of respiratory neural network by spinal locomotor generators. PLoS One 2014; 9:e89670. [PMID: 24586951 PMCID: PMC3930745 DOI: 10.1371/journal.pone.0089670] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/21/2014] [Indexed: 12/03/2022] Open
Abstract
During exercise and locomotion, breathing rate rapidly increases to meet the suddenly enhanced oxygen demand. The extent to which direct central interactions between the spinal networks controlling locomotion and the brainstem networks controlling breathing are involved in this rhythm modulation remains unknown. Here, we show that in isolated neonatal rat brainstem-spinal cord preparations, the increase in respiratory rate observed during fictive locomotion is associated with an increase in the excitability of pre-inspiratory neurons of the parafacial respiratory group (pFRG/Pre-I). In addition, this locomotion-induced respiratory rhythm modulation is prevented both by bilateral lesion of the pFRG region and by blockade of neurokinin 1 receptors in the brainstem. Thus, our results assign pFRG/Pre-I neurons a new role as elements of a previously undescribed pathway involved in the functional interaction between respiratory and locomotor networks, an interaction that also involves a substance P-dependent modulating mechanism requiring the activation of neurokinin 1 receptors. This neurogenic mechanism may take an active part in the increased respiratory rhythmicity produced at the onset and during episodes of locomotion in mammals.
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37
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Ramirez JM, Doi A, Garcia AJ, Elsen FP, Koch H, Wei AD. The cellular building blocks of breathing. Compr Physiol 2013; 2:2683-731. [PMID: 23720262 DOI: 10.1002/cphy.c110033] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Respiratory brainstem neurons fulfill critical roles in controlling breathing: they generate the activity patterns for breathing and contribute to various sensory responses including changes in O2 and CO2. These complex sensorimotor tasks depend on the dynamic interplay between numerous cellular building blocks that consist of voltage-, calcium-, and ATP-dependent ionic conductances, various ionotropic and metabotropic synaptic mechanisms, as well as neuromodulators acting on G-protein coupled receptors and second messenger systems. As described in this review, the sensorimotor responses of the respiratory network emerge through the state-dependent integration of all these building blocks. There is no known respiratory function that involves only a small number of intrinsic, synaptic, or modulatory properties. Because of the complex integration of numerous intrinsic, synaptic, and modulatory mechanisms, the respiratory network is capable of continuously adapting to changes in the external and internal environment, which makes breathing one of the most integrated behaviors. Not surprisingly, inspiration is critical not only in the control of ventilation, but also in the context of "inspiring behaviors" such as arousal of the mind and even creativity. Far-reaching implications apply also to the underlying network mechanisms, as lessons learned from the respiratory network apply to network functions in general.
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Affiliation(s)
- J M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institut, Seattle, Washington, USA.
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38
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Bron R, Yin L, Russo D, Furness JB. Expression of the ghrelin receptor gene in neurons of the medulla oblongata of the rat. J Comp Neurol 2013; 521:2680-702. [DOI: 10.1002/cne.23309] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 12/12/2012] [Accepted: 01/17/2013] [Indexed: 01/29/2023]
Affiliation(s)
- Romke Bron
- Department of Anatomy & Neuroscience; University of Melbourne; Parkville; Victoria 3010; Australia
| | - Lei Yin
- Department of Anatomy & Neuroscience; University of Melbourne; Parkville; Victoria 3010; Australia
| | - Domenico Russo
- Department of Veterinary Morphophysiology and Animal Production; University of Bologna; 40064 Ozzano Emilia; Bologna; Italy
| | - John B. Furness
- Department of Anatomy & Neuroscience; University of Melbourne; Parkville; Victoria 3010; Australia
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Kang JJ, Wei XY, Liu JP, Wong-Riley MTT, Ju G, Liu YY. Expression of phospho-Ca(2+) /calmodulin-dependent protein kinase II in the pre-Bötzinger complex of rats. J Neurochem 2013; 126:349-59. [PMID: 23651084 DOI: 10.1111/jnc.12297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 05/06/2013] [Indexed: 11/28/2022]
Abstract
The pre-Bötzinger complex (pre-BötC) in the ventrolateral medulla oblongata is a presumed kernel of respiratory rhythmogenesis. Ca(2+) -activated non-selective cationic current is an essential cellular mechanism for shaping inspiratory drive potentials. Ca(2+) /calmodulin-dependent protein kinase II (CaMKII), an ideal 'interpreter' of diverse Ca(2+) signals, is highly expressed in neurons in mediating various physiological processes. Yet, less is known about CaMKII activity in the pre-BötC. Using neurokinin-1 receptor as a marker of the pre-BötC, we examined phospho (P)-CaMKII subcellular distribution, and found that P-CaMKII was extensively expressed in the region. P-CaMKII-ir neurons were usually oval, fusiform, or pyramidal in shape. P-CaMKII immunoreactivity was distributed within somas and dendrites, and specifically in association with the post-synaptic density. In dendrites, most synapses (93.1%) examined with P-CaMKII expression were of asymmetric type, occasionally with symmetric type (6.9%), whereas in somas, 38.1% were of symmetric type. P-CaMKII asymmetric synaptic identification implicates that CaMKII may sense and monitor Ca(2+) activity, and phosphorylate post-synaptic proteins to modulate excitatory synaptic transmission, which may contribute to respiratory modulation and plasticity. In somas, CaMKII acts on both symmetric and asymmetric synapses, mediating excitatory and inhibitory synaptic transmission. P-CaMKII was also localized to the perisynaptic and extrasynaptic regions in the pre-BötC.
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Affiliation(s)
- Jun-Jun Kang
- Institute of Neurosciences, The Fourth Military Medical University, Xi'an, China
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Turner A, Kumar N, Farnham M, Lung M, Pilowsky P, McMullan S. Rostroventrolateral medulla neurons with commissural projections provide input to sympathetic premotor neurons: anatomical and functional evidence. Eur J Neurosci 2013; 38:2504-15. [PMID: 23651135 DOI: 10.1111/ejn.12232] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/21/2013] [Accepted: 03/27/2013] [Indexed: 01/09/2023]
Abstract
The activity of neurons in the rostral ventrolateral medulla (RVLM) is critical for the generation of vasomotor sympathetic tone. Multiple pre-sympathetic pathways converge on spinally projecting RVLM neurons, but the origin and circumstances in which such inputs are active are poorly understood. We have previously shown that input from the contralateral brainstem contributes to the baseline activity of this population: in the current study we investigate the distribution, phenotype and functional properties of RVLM neurons with commissural projections in the rat. We firstly used retrograde transport of fluorescent microspheres to identify neurons that project to the contralateral RVLM. Labelled neurons were prominent in a longitudinal column that extended over 1 mm caudal from the facial nucleus and contained hybridisation products indicating enkephalin (27%), GABA (15%) and adrenaline (3%) synthesis and included 6% of bulbospinal neurons identified by transport of cholera toxin B. Anterograde transport of fluorescent dextran-conjugate from the contralateral RVLM revealed extensive inputs throughout the RVLM that frequently terminated in close apposition with catecholaminergic and bulbospinal neurons. In urethane-anaesthetised rats we verified that 28/37 neurons antidromically activated by electrical stimulation of the contralateral pressor region were spontaneously active, of which 13 had activity locked to central respiratory drive and 15 displayed ongoing tonic discharge. In six tonically active neurons sympathoexcitatory roles were indicated by spike-triggered averages of splanchnic sympathetic nerve activity. We conclude that neurons in the RVLM project to the contralateral brainstem, form synapses with sympathetic premotor neurons, and have functional properties consistent with sympthoexcitatory function.
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Affiliation(s)
- Anita Turner
- Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, 2109, Australia
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41
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Abstract
Breathing is an essential behavior that presents a unique opportunity to understand how the nervous system functions normally, how it balances inherent robustness with a highly regulated lability, how it adapts to both rapidly and slowly changing conditions, and how particular dysfunctions result in disease. We focus on recent advancements related to two essential sites for respiratory rhythmogenesis: (a) the preBötzinger Complex (preBötC) as the site for the generation of inspiratory rhythm and (b) the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) as the site for the generation of active expiration.
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Affiliation(s)
- Jack L Feldman
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095-1763, USA.
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42
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Clark CG, Sun Z, Meininger GA, Potts JT. Atomic force microscopy to characterize binding properties of α7-containing nicotinic acetylcholine receptors on neurokinin-1 receptor-expressing medullary respiratory neurons. Exp Physiol 2012; 98:415-24. [PMID: 22962286 DOI: 10.1113/expphysiol.2012.067660] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the present study, we used atomic force microscopy (AFM) to examine the ligand-binding properties of α7-containing nicotinic acetylcholine receptors (nAChRs) expressed on neurons from the ventral respiratory group. We also determined the effect of acute and prolonged exposure to nicotine on the binding probability of nAChRs. Neurons from neonatal (postnatal day 5-10) and juvenile rats (3-4 weeks old) were cultured. Internalization of Alexa Fluor 488-conjugated substance P was used to identify respiratory neurons that expressed the neurokinin-1 receptor (NK1-R), a recognized marker of ventral respiratory group neurons. To assess functional changes in nAChRs, AFM probes conjugated with anti-α7 subunit nAChR antibody were used to interact cyclically with the surface of the soma of NK1-R-positive neurons. Measurements were made of the frequency of antibody adhesion to the α7 receptor subunit and of the detachment forces between the membrane-attached receptor and the AFM probe tip. Addition of α-bungarotoxin (a specific antagonist of α7 subunit-containing nAChRs) to the cell bath produced a 69% reduction in binding to the α7 subunit (P < 0.05, n = 10), supporting specificity of binding. Acute exposure to nicotine (1 μM added to culture media) produced an 80% reduction in nAChR antibody binding to the α7 subunit (P < 0.05, n = 9). Prolonged incubation (72 h) of the cell culture in nicotine significantly reduced α7 binding in a concentration-dependent manner. Collectively, these findings demonstrate that AFM is a sensitive tool for assessment of functional changes in nAChRs expressed on the surface of living NK1-R-expressing medullary neurons. Moreover, these data demonstrate that nicotine exposure decreases the binding probability of α7 subunit-containing nAChRs.
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Affiliation(s)
- Catharine G Clark
- Dalton Cardiovascular Research Center and Departments of Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA.
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Tan W, Sherman D, Turesson J, Shao XM, Janczewski WA, Feldman JL. Reelin demarcates a subset of pre-Bötzinger complex neurons in adult rat. J Comp Neurol 2012; 520:606-19. [PMID: 21858819 DOI: 10.1002/cne.22753] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Identification of two markers of neurons in the pre-Bötzinger complex (pre-BötC), the neurokinin 1 receptor (NK1R) and somatostatin (Sst) peptide, has been of great utility in understanding the essential role of the pre-BötC in breathing. Recently, the transcription factor dbx1 was identified as a critical, but transient, determinant of glutamatergic pre-BötC neurons. Here, to identify additional markers, we constructed and screened a single-cell subtractive cDNA library from pre-BötC inspiratory neurons. We identified the glycoprotein reelin as a potentially useful marker, because it is expressed in distinct populations of pre-BötC and inspiratory bulbospinal ventral respiratory group (ibsVRG) neurons. Reelin ibsVRG neurons were larger (27.1 ± 3.8 μm in diameter) and located more caudally (>12.8 mm caudal to Bregma) than reelin pre-BötC neurons (15.5 ± 2.4 μm in diameter, <12.8 mm rostral to Bregma). Pre-BötC reelin neurons coexpress NK1R and Sst. Reelin neurons were also found in the parahypoglossal and dorsal parafacial regions, pontine respiratory group, and ventromedial medulla. Reelin-deficient (Reeler) mice exhibited impaired respones to hypoxia compared with littermate controls. We suggest that reelin is a useful molecular marker for pre-BötC neurons in adult rodents and may play a functional role in pre-BötC microcircuits.
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Affiliation(s)
- Wenbin Tan
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA
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Wei XY, Zhao Y, Wong-Riley MTT, Ju G, Liu YY. Synaptic relationship between somatostatin- and neurokinin-1 receptor-immunoreactive neurons in the pre-Bötzinger complex of rats. J Neurochem 2012; 122:923-33. [DOI: 10.1111/j.1471-4159.2012.07862.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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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] [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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Spirovski D, Li Q, Pilowsky PM. Brainstem galanin-synthesizing neurons are differentially activated by chemoreceptor stimuli and represent a subpopulation of respiratory neurons. J Comp Neurol 2011; 520:154-73. [DOI: 10.1002/cne.22723] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Koch H, Garcia AJ, Ramirez JM. Network reconfiguration and neuronal plasticity in rhythm-generating networks. Integr Comp Biol 2011; 51:856-68. [PMID: 21856733 DOI: 10.1093/icb/icr099] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neuronal networks are highly plastic and reconfigure in a state-dependent manner. The plasticity at the network level emerges through multiple intrinsic and synaptic membrane properties that imbue neurons and their interactions with numerous nonlinear properties. These properties are continuously regulated by neuromodulators and homeostatic mechanisms that are critical to maintain not only network stability and also adapt networks in a short- and long-term manner to changes in behavioral, developmental, metabolic, and environmental conditions. This review provides concrete examples from neuronal networks in invertebrates and vertebrates, and illustrates that the concepts and rules that govern neuronal networks and behaviors are universal.
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Affiliation(s)
- Henner Koch
- Center for Integrative Brain Research, Seattle Children's Research Institute, 1900 9th Street, Seattle, WA 98101, USA
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48
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Voituron N, Frugière A, Mc Kay LC, Romero-Granados R, Domínguez-Del-Toro E, Saadani-Makki F, Champagnat J, Bodineau L. The kreisler mutation leads to the loss of intrinsically hypoxia-activated spots in the region of the retrotrapezoid nucleus/parafacial respiratory group. Neuroscience 2011; 194:95-111. [PMID: 21839147 DOI: 10.1016/j.neuroscience.2011.07.062] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 07/14/2011] [Accepted: 07/25/2011] [Indexed: 12/19/2022]
Abstract
Acute hypoxia elicits a biphasic respiratory response characterized in the newborn by a transient hyperventilation followed by a severe decrease in respiratory drive known as hypoxic respiratory depression. Medullary O(2) chemosensitivity is known to contribute to respiratory depression induced by hypoxia, although precise involvement of cell populations remains to be determined. Having a thorough knowledge of these populations is of relevance because perturbations in the respiratory response to hypoxia may participate in respiratory diseases in newborns. We aimed to analyze the hypoxic response of ponto-medullary cell populations of kreisler mutant mice. These mice have defects in a gene expressed in two rhombomeres encompassing a part of the medulla oblongata implicated in hypoxic respiratory depression. Central responses to hypoxia were analyzed in newborn mice by measuring respiratory rhythm in ex vivo caudal pons-medullary-spinal cord preparations and c-fos expression in wild-type and kreisler mutants. The homozygous kreisler mutation, which eliminates most of rhombomere 5 and mis-specifies rhombomere 6, abolished (1) an early decrease in respiratory frequency within 10 min of hypoxia and (2) an intrinsic hypoxic activation, which is characterized by an increase in c-fos expression in the region of the ventral medullary surface encompassing the retrotrapezoid nucleus/parafacial respiratory group expressing Phox2b. This increase in c-fos expression persisted in wild-type Phox2b-negative and Phox2b-positive cells after blockade of synaptic transmission and rhythmogenesis by a low [Ca(2+)](0). Another central response was retained in homozygous kreisler mutant mice; it was distinguished by (1) a delayed (10-30 min) depression of respiratory frequency and (2) a downregulation of c-fos expression in the ventrolateral reticular nucleus of the medulla, the nucleus of the solitary tract, and the area of the A5 region. Thus, two types of ponto-medullary cell groups, with distinct anatomical locations, participate in central hypoxic respiratory depression in newborns.
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Affiliation(s)
- N Voituron
- UPRES EA 3901, Faculté de Médecine, Université de Picardie Jules Verne, Amiens, F-80036, France
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Zwicker JD, Rajani V, Hahn LB, Funk GD. Purinergic modulation of preBötzinger complex inspiratory rhythm in rodents: the interaction between ATP and adenosine. J Physiol 2011; 589:4583-600. [PMID: 21788352 DOI: 10.1113/jphysiol.2011.210930] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
ATP signalling in the CNS is mediated by a three-part system comprising the actions of ATP (and ADP) at P2 receptors (P2Rs), adenosine (ADO) at P1 receptors (P1Rs), and ectonucleotidases that degrade ATP into ADO. ATP excites preBötzinger complex (preBötC) inspiratory rhythm-generating networks where its release attenuates the hypoxic depression of breathing. Its metabolite, ADO, inhibits breathing through unknown mechanisms that may involve the preBötC. Our objective is to understand the dynamics of this signalling system and its influence on preBötC networks. We show that the preBötC of mouse and rat is sensitive to P2Y(1) purinoceptor (P2Y(1)R) activation, responding with a >2-fold increase in frequency. Remarkably, the mouse preBötC is insensitive to ATP. Only after block of A(1) ADORs is the ATP-evoked, P2Y(1)R-mediated frequency increase observed. This demonstrates that ATP is rapidly degraded to ADO, which activates inhibitory A(1)Rs, counteracting the P2Y(1)R-mediated excitation. ADO sensitivity of mouse preBötC was confirmed by a frequency decrease that was absent in rat. Differential ectonucleotidase activities are likely to contribute to the negligible ATP sensitivity of mouse preBötC. Real-time PCR analysis of ectonucleotidase isoforms in preBötC punches revealed TNAP (degrades ATP to ADO) or ENTPDase2 (favours production of excitatory ADP) as the primary constituent in mouse and rat, respectively. These data further establish the sensitivity of this vital network to P2Y(1)R-mediated excitation, emphasizing that individual components of the three-part signalling system dramatically alter network responses to ATP. Data also suggest therapeutic potential may derive from methods that alter the ATP-ADO balance to favour the excitatory actions of ATP.
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Affiliation(s)
- J D Zwicker
- Departments of Physiology and Pediatrics, Centre for Neuroscience, Women and Children’s Health Research Institute (WCHRI), Faculty of Medicineand Dentistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
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Caudal nuclei of the rat nucleus of the solitary tract differentially innervate respiratory compartments within the ventrolateral medulla. Neuroscience 2011; 190:207-27. [PMID: 21704133 DOI: 10.1016/j.neuroscience.2011.06.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 05/27/2011] [Accepted: 06/01/2011] [Indexed: 12/15/2022]
Abstract
A substantial array of respiratory, cardiovascular, visceral and somatic afferents are relayed via the nucleus of the solitary tract (NTS) to the brainstem (and forebrain). Despite some degree of overlap within the NTS, specificity is maintained in central respiratory reflexes driven by second order afferent relay neurons in the NTS. While the topographic arrangement of respiratory-related afferents targeting the NTS has been extensively investigated, their higher order brainstem targets beyond the NTS has only rarely been defined with any precision. Nonetheless, the various brainstem circuits serving blood gas homeostasis and airway protective reflexes must clearly receive a differential innervation from the NTS in order to evoke stimulus appropriate behavioral responses. Accordingly, we have examined the question of which specific NTS nuclei project to particular compartments within the ventral respiratory column (VRC) of the ventrolateral medulla. Our analyses of NTS labeling after retrograde tracer injections in the VRC and the nearby neuronal groups controlling autonomic function indicate a significant distinction between projections to the Bötzinger complex and preBötzinger complex compared to the remainder of the VRC. Specifically, the caudomedial NTS, including caudal portions of the medial solitary nucleus and the commissural division of NTS project relatively densely to the region of the retrotrapezoid nucleus and rostral ventrolateral medullary nucleus as well as to the rostral ventral respiratory group while avoiding the intervening Bötzinger and preBötzinger complexes. Area postrema appears to demonstrate a pattern of projections similar to that of caudal medial and commissural NTS nuclei. Other, less pronounced differential projections of lateral NTS nuclei to the various VRC compartments are additionally noted.
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