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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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Arthurs JW, Bowen AJ, Palmiter RD, Baertsch NA. Parabrachial tachykinin1-expressing neurons involved in state-dependent breathing control. Nat Commun 2023; 14:963. [PMID: 36810601 PMCID: PMC9944916 DOI: 10.1038/s41467-023-36603-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
Breathing is regulated automatically by neural circuits in the medulla to maintain homeostasis, but breathing is also modified by behavior and emotion. Mice have rapid breathing patterns that are unique to the awake state and distinct from those driven by automatic reflexes. Activation of medullary neurons that control automatic breathing does not reproduce these rapid breathing patterns. By manipulating transcriptionally defined neurons in the parabrachial nucleus, we identify a subset of neurons that express the Tac1, but not Calca, gene that exerts potent and precise conditional control of breathing in the awake, but not anesthetized, state via projections to the ventral intermediate reticular zone of the medulla. Activating these neurons drives breathing to frequencies that match the physiological maximum through mechanisms that differ from those that underlie the automatic control of breathing. We postulate that this circuit is important for the integration of breathing with state-dependent behaviors and emotions.
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Affiliation(s)
- Joseph W Arthurs
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
| | - Anna J Bowen
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Richard D Palmiter
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA.
- Pulmonary Critical Care and Sleep Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA.
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Interaction between the pulmonary stretch receptor and pontine control of expiratory duration. Respir Physiol Neurobiol 2021; 293:103715. [PMID: 34126261 DOI: 10.1016/j.resp.2021.103715] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/19/2021] [Accepted: 06/08/2021] [Indexed: 11/20/2022]
Abstract
Medial parabrachial nucleus (mPBN) neuronal activity plays a key role in controlling expiratory (E)-duration (TE). Pulmonary stretch receptor (PSR) activity during the E-phase prolongs TE. The aims of this study were to characterize the interaction between the PSR and mPBN control of TE and underlying mechanisms. Decerebrated mechanically ventilated dogs were studied. The mPBN subregion was activated by electrical stimulation via bipolar microelectrode. PSR afferents were activated by low-level currents applied to the transected central vagus nerve. Both stimulus-frequency patterns during the E-phase were synchronized to the phrenic neurogram; TE was measured. A functional mathematical model for the control of TE and extracellular recordings from neurons in the preBötzinger/Bötzinger complex (preBC/BC) were used to understand mechanisms. Findings show that the mPBN gain-modulates, via attenuation, the PSR-mediated reflex. The model suggested functional sites for attenuation and neuronal data suggested correlates. The PSR- and PB-inputs appear to interact on E-decrementing neurons, which synaptically inhibit pre-I neurons, delaying the onset of the next I-phase.
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Revill AL, Katzell A, Del Negro CA, Milsom WK, Funk GD. KCNQ Current Contributes to Inspiratory Burst Termination in the Pre-Bötzinger Complex of Neonatal Rats in vitro. Front Physiol 2021; 12:626470. [PMID: 33927636 PMCID: PMC8078421 DOI: 10.3389/fphys.2021.626470] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/23/2021] [Indexed: 12/23/2022] Open
Abstract
The pre-Bötzinger complex (preBötC) of the ventral medulla generates the mammalian inspiratory breathing rhythm. When isolated in explants and deprived of synaptic inhibition, the preBötC continues to generate inspiratory-related rhythm. Mechanisms underlying burst generation have been investigated for decades, but cellular and synaptic mechanisms responsible for burst termination have received less attention. KCNQ-mediated K+ currents contribute to burst termination in other systems, and their transcripts are expressed in preBötC neurons. Therefore, we tested the hypothesis that KCNQ channels also contribute to burst termination in the preBötC. We recorded KCNQ-like currents in preBötC inspiratory neurons in neonatal rat slices that retain respiratory rhythmicity. Blocking KCNQ channels with XE991 or linopirdine (applied via superfusion or locally) increased inspiratory burst duration by 2- to 3-fold. By contrast, activation of KCNQ with retigabine decreased inspiratory burst duration by ~35%. These data from reduced preparations suggest that the KCNQ current in preBötC neurons contributes to inspiratory burst termination.
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Affiliation(s)
- Ann L. Revill
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Alexis Katzell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | | | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Gregory D. Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
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The neural control of respiration in lampreys. Respir Physiol Neurobiol 2016; 234:14-25. [PMID: 27562521 DOI: 10.1016/j.resp.2016.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 08/08/2016] [Accepted: 08/21/2016] [Indexed: 11/24/2022]
Abstract
This review focuses on past and recent findings that have contributed to characterize the neural networks controlling respiration in the lamprey, a basal vertebrate. As in other vertebrates, respiration in lampreys is generated centrally in the brainstem. It is characterized by the presence of a fast and a slow respiratory rhythm. The anatomical and the basic physiological properties of the neural networks underlying the generation of the fast rhythm have been more thoroughly investigated; less is known about the generation of the slow respiratory rhythm. Comparative aspects with respiratory generators in other vertebrates as well as the mechanisms of modulation of respiration in association with locomotion are discussed.
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Poon CS, Song G. Bidirectional plasticity of pontine pneumotaxic postinspiratory drive: implication for a pontomedullary respiratory central pattern generator. PROGRESS IN BRAIN RESEARCH 2014; 209:235-54. [PMID: 24746051 DOI: 10.1016/b978-0-444-63274-6.00012-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The "pneumotaxic center" in the rostral dorsolateral pons as delineated by Lumsden nine decades ago is known to play an important role in promoting the inspiratory off-switch (IOS) for inspiratory-expiratory phase transition as a fail-safe mechanism for preventing apneusis in the absence of vagal input. Traditionally, the pontine pneumotaxic mechanism has been thought to contribute a tonic descending input that lowers the IOS threshold in medullary respiratory central pattern generator (rCPG) circuits, but otherwise does not constitute part of the rCPG. Recent evidence indicates that descending input from the Kölliker-Fuse nucleus (KFN) within the pneumotaxic center is essential for gating the postinspiratory phase of the three-phase respiratory rhythm to control the IOS in vagotomized animals. A critical question arising is whether such a descending pneumotaxic input from KFN that drives postinspiratory activity is tonic (null hypothesis) or rhythmic with postinspiratory phase modulation (alternative hypothesis). Here, we show that multifarious evidence reported in the literature collectively indicates that the descending pneumotaxic input may exhibit NMDA receptor-dependent short-term plasticity in the form of a biphasic neural differentiator that bidirectionally and phase-selectively modulates postinspiratory phase duration in response to vagal and peripheral chemoreceptor inputs independent of the responses in inspiratory and late-expiratory activities. The phase-selectivity property of the descending pneumotaxic input implicates a population of pontine early-expiratory (postinspiratory/expiratory-decrementing) neurons as the most likely neural correlate of the pneumotaxic mechanism that drives post-I activity, suggesting that the pontine pneumotaxic mechanism may be an integral part of a pontomedullary rCPG that underlies the three-phase respiratory rhythm.
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Affiliation(s)
- Chi-Sang Poon
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Gang Song
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
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Abstract
Pontine respiratory nuclei provide synaptic input to medullary rhythmogenic circuits to shape and adapt the breathing pattern. An understanding of this statement depends on appreciating breathing as a behavior, rather than a stereotypic rhythm. In this review, we focus on the pontine-mediated inspiratory off-switch (IOS) associated with postinspiratory glottal constriction. Further, IOS is examined in the context of pontine regulation of glottal resistance in response to multimodal sensory inputs and higher commands, which in turn rules timing, duration, and patterning of respiratory airflow. In addition, network plasticity in respiratory control emerges during the development of the pons. Synaptic plasticity is required for dynamic and efficient modulation of the expiratory breathing pattern to cope with rapid changes from eupneic to adaptive breathing linked to exploratory (foraging and sniffing) and expulsive (vocalizing, coughing, sneezing, and retching) behaviors, as well as conveyance of basic emotions. The speed and complexity of changes in the breathing pattern of behaving animals implies that "learning to breathe" is necessary to adjust to changing internal and external states to maintain homeostasis and survival.
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Affiliation(s)
- Mathias Dutschmann
- Florey Neurosciences Institutes, University of Melbourne, Victoria, Australia.
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Song G, Wang H, Xu H, Poon CS. Kölliker–Fuse neurons send collateral projections to multiple hypoxia-activated and nonactivated structures in rat brainstem and spinal cord. Brain Struct Funct 2012; 217:835-58. [PMID: 22286911 PMCID: PMC3459144 DOI: 10.1007/s00429-012-0384-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 01/13/2012] [Indexed: 02/07/2023]
Abstract
The Kölliker–Fuse nucleus (KFN) in dorsolateral pons has been implicated in many physiological functions via its extensive efferent connections. Here, we combine iontophoretic anterograde tracing with posthypoxia c-Fos immunohistology to map KFN axonal terminations among hypoxia-activated/nonactivated brain stem and spinal structures in rats. Using a set of stringent inclusion/exclusion criteria to align visualized axons across multiple coronal brain sections, we were able to unequivocally trace axonal trajectories over a long rostrocaudal distance perpendicular to the coronal plane. Structures that were both richly innervated by KFN axonal projections and immunopositive to c-Fos included KFN (contralateral side), ventrolateral pontine area, areas ventral to rostral compact/subcompact ambiguus nucleus, caudal (lateral) ambiguus nucleus, nucleus retroambiguus, and commissural–medial subdivisions of solitary tract nucleus. The intertrigeminal nucleus, facial and hypoglossal nuclei, retrotrapezoid nucleus, parafacial region and spinal cord segment 5 were also richly innervated by KFN axonal projections but were only weakly (or not) immunopositive to c-Fos. The most striking finding was that some descending axons from KFN sent out branches to innervate multiple (up to seven) pontomedullary target structures including facial nucleus, trigeminal sensory nucleus, and various parts of ambiguus nucleus and its surrounding areas. The extensive axonal fan-out from single KFN neurons to multiple brainstem and spinal cord structures("one-to-many relationship"’) provides anatomical evidence that KFN may coordinate diverse physiological functions including hypoxic and hypercapnic respiratory responses, respiratory pattern generation and motor output,diving reflex, modulation of upper airways patency,coughing and vomiting abdominal expiratory reflex, as well as cardiovascular regulation and cardiorespiratory coupling.
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Affiliation(s)
- Gang Song
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
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Gariépy JF, Missaghi K, Chartré S, Robert M, Auclair F, Dubuc R. Bilateral connectivity in the brainstem respiratory networks of lampreys. J Comp Neurol 2012; 520:1442-56. [PMID: 22101947 DOI: 10.1002/cne.22804] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This study examines the connectivity in the neural networks controlling respiration in the lampreys, a basal vertebrate. Previous studies have shown that the lamprey paratrigeminal respiratory group (pTRG) plays a crucial role in the generation of respiration. By using a combination of anatomical and physiological techniques, we characterized the bilateral connections between the pTRGs and descending projections to the motoneurons. Tracers were injected in the respiratory motoneuron pools to identify pre-motor respiratory interneurons. Retrogradely labeled cell bodies were found in the pTRG on both sides. Whole-cell recordings of the retrogradely labeled pTRG neurons showed rhythmical excitatory currents in tune with respiratory motoneuron activity. This confirmed that they were related to respiration. Intracellular labeling of individual pTRG neurons revealed axonal branches to the contralateral pTRG and bilateral projections to the respiratory motoneuronal columns. Stimulation of the pTRG induced excitatory postsynaptic potentials in ipsi- and contralateral respiratory motoneurons as well as in contralateral pTRG neurons. A lidocaine HCl (Xylocaine) injection on the midline at the rostrocaudal level of the pTRG diminished the contralateral motoneuronal EPSPs as well as a local injection of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and (2R)-amino-5-phosphonovaleric acid (AP-5) on the recorded respiratory motoneuron. Our data show that neurons in the pTRG send two sets of axonal projections: one to the contralateral pTRG and another to activate respiratory motoneurons on both sides through glutamatergic synapses.
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Affiliation(s)
- Jean-François Gariépy
- Groupe de Recherche sur le Système Nerveux Central (GRSNC), Département de Physiologie, Université de Montréal, Montréal, Québec, Canada H3T 1J4
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Kumral E, Uzunköprü C, Çiftçi S, Demirci T. Acute respiratory failure due to unilateral dorsolateral bulbar infarction. Eur Neurol 2011; 66:70-4. [PMID: 21778729 DOI: 10.1159/000327538] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 03/18/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND Previous clinicopathological studies have reported central hypoventilation alongside unilateral infarcts in the caudal brainstem. As already known, the respiratory centers are located in the medullary and pontine centers. METHODS We sought patients with acute respiratory failure with brainstem involvement proved by MRI from 4,500 patients with first ischemic stroke consecutively admitted to our stroke unit over a period of 7 years. RESULTS We report six patients with a unilateral dorsolateral medulla oblongata lesion, completely sparing the corticospinal tract, who presented impairments in automatic and voluntary respiratory movements. Topographical analysis showed involvement of the nucleus and tractus solitarius,nucleus ambiguus and retroambiguus,nucleus reticularis medulla oblongata, and nucleus tractus solitarius. CONCLUSIONS Our findings provide insight into the central organization of respiratory control in the dorsolateral medulla oblongata in humans, and the importance of critical respiratory management in these patients.
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Affiliation(s)
- Emre Kumral
- Stroke Unit, Department of Neurology, Faculty of Medicine, Ege University, Izmir, Turkey.
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Tan W, Pagliardini S, Yang P, Janczewski WA, Feldman JL. Projections of preBötzinger complex neurons in adult rats. J Comp Neurol 2010; 518:1862-78. [PMID: 20235095 DOI: 10.1002/cne.22308] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The preBötzinger Complex (preBötC) contains neural microcircuitry essential for normal respiratory rhythm generation in rodents. A subpopulation of preBötC neurons expresses somatostatin, a neuropeptide with a modulatory action on breathing. Acute silencing of a subpopulation of preBötC neurons transfected by a virus driving protein expression under the somatostatin promoter results in persistent apnea in awake adult rats. Given the profound effect of silencing these neurons, their projections are of interest. We used an adeno-associated virus to overexpress enhanced green fluorescent protein driven by the somatostatin promoter in preBötC neurons to label their axons and terminal fields. These neurons send brainstem projections to: 1) contralateral preBötC; 2) ipsi- and contralateral Bötzinger Complex; 3) ventral respiratory column caudal to preBötC; 4) parafacial respiratory group/retrotrapezoid nucleus; 5) parahypoglossal nucleus/nucleus of the solitary tract; 6) parabrachial/Kölliker-Fuse nuclei; and 7) periaqueductal gray. We did not find major projections to either cerebellum or spinal cord. We conclude that there are widespread projections from preBötC somatostatin-expressing neurons specifically targeted to brainstem regions implicated in control of breathing, and provide a network basis for the profound effects and the essential role of the preBötC in breathing.
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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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Bonis JM, Neumueller SE, Krause KL, Kiner T, Smith A, Marshall BD, Qian B, Pan LG, Forster HV. Site-specific effects on respiratory rhythm and pattern of ibotenic acid injections in the pontine respiratory group of goats. J Appl Physiol (1985) 2010; 109:171-88. [PMID: 20431022 DOI: 10.1152/japplphysiol.00934.2009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To probe further the contributions of the rostral pons to eupneic respiratory rhythm and pattern, we tested the hypothesis that ibotenic acid (IA) injections in the pontine respiratory group (PRG) would disrupt eupneic respiratory rhythm and pattern in a site- and state-specific manner. In 15 goats, cannulas were bilaterally implanted into the rostral pontine tegmental nuclei (RPTN; n = 3), the lateral (LPBN; n = 4) or medial parabrachial nuclei (MPBN; n = 4), or the Kölliker-Fuse nucleus (KFN; n = 4). After recovery from surgery, 1- and 10-microl injections (1 wk apart) of IA were made bilaterally through the implanted cannulas during the day. Over the first 5 h after the injections, there were site-specific ventilatory effects, with increased (P < 0.05) breathing frequency in RPTN-injected goats, increased (P < 0.05) pulmonary ventilation (Vi) in LPBN-injected goats, no effect (P < 0.05) in MPBN-injected goats, and a biphasic Vi response (P < 0.05) in KFN-injected goats. This biphasic response consisted of a hyperpnea for 30 min, followed by a prolonged hypopnea and hypoventilation with marked apneas, apneusis-like breathing patterns, and/or shifts in the temporal relationships between inspiratory flow and diaphragm activity. In the awake state, 10-15 h after the 1-microl injections, the number of apneas was greater (P < 0.05) than during other studies at night. However, there were no incidences of terminal apneas. Breathing rhythm and pattern were normal 22 h after the injections. Subsequent histological analysis revealed that for goats with cannulas implanted into the KFN, there were nearly 50% fewer neurons (P < 0.05) in all three PRG subnuclei than in control goats. We conclude that in awake goats, 1) IA injections into the PRG have site-specific effects on breathing, and 2) the KFN contributes to eupneic respiratory pattern generation.
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Affiliation(s)
- J M Bonis
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
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Morris KF, Nuding SC, Segers LS, Baekey DM, Shannon R, Lindsey BG, Dick TE. Respiratory and Mayer wave-related discharge patterns of raphé and pontine neurons change with vagotomy. J Appl Physiol (1985) 2010; 109:189-202. [PMID: 20360432 DOI: 10.1152/japplphysiol.01324.2009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous models have attributed changes in respiratory modulation of pontine neurons after vagotomy to a loss of pulmonary stretch receptor "gating" of an efference copy of inspiratory drive. Recently, our group confirmed that pontine neurons change firing patterns and become more respiratory modulated after vagotomy, although average peak and mean firing rates of the sample did not increase (Dick et al., J Physiol 586: 4265-4282, 2008). Because raphé neurons are also elements of the brain stem respiratory network, we tested the hypotheses that after vagotomy raphé neurons have increased respiratory modulation and that alterations in their firing patterns are similar to those seen for pontine neurons during withheld lung inflation. Raphé and pontine neurons were recorded simultaneously before and after vagotomy in decerebrated cats. Before vagotomy, 14% of 95 raphé neurons had increased activity during single respiratory cycles prolonged by withholding lung inflation; 13% exhibited decreased activity. After vagotomy, the average index of respiratory modulation (eta(2)) increased (0.05 +/- 0.10 to 0.12 +/- 0.18 SD; Student's paired t-test, P < 0.01). Time series and frequency domain analyses identified pontine and raphé neuron firing rate modulations with a 0.1-Hz rhythm coherent with blood pressure Mayer waves. These "Mayer wave-related oscillations" (MWROs) were coupled with central respiratory drive and became synchronized with the central respiratory rhythm after vagotomy (7 of 10 animals). Cross-correlation analysis identified functional connectivity in 52 of 360 pairs of neurons with MWROs. Collectively, the results suggest that a distributed network participates in the generation of MWROs and in the coordination of respiratory and vasomotor rhythms.
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Affiliation(s)
- K F Morris
- Department of Molecular Pharmacology and Physiology, School of Biomedical Sciences, College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612-4799, USA.
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Poon CS, Song G, Tin C. Bilateral Lesions of Pontine Kölliker-Fuse Nuclei Provoke Apnea instead of Apneusis in Anesthetized Adult Rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 669:185-8. [DOI: 10.1007/978-1-4419-5692-7_37] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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Martel B, Guimond JC, Gariépy JF, Gravel J, Auclair F, Kolta A, Lund JP, Dubuc R. Respiratory rhythms generated in the lamprey rhombencephalon. Neuroscience 2007; 148:279-93. [PMID: 17618060 DOI: 10.1016/j.neuroscience.2007.05.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 05/22/2007] [Accepted: 05/24/2007] [Indexed: 10/23/2022]
Abstract
Brainstem networks generating the respiratory rhythm in lampreys are still not fully characterized. In this study, we described the patterns of respiratory activities and we identified the general location of underlying neural networks. In a semi-intact preparation including the brain and gills, rhythmic discharges were recorded bilaterally with surface electrodes placed over the vagal motoneurons. The main respiratory output driving rhythmic gill movements consisted of short bursts (40.9+/-15.6 ms) of discharge occurring at a frequency of 1.0+/-0.3 Hz. This fast pattern was interrupted by long bursts (506.3+/-174.6 ms) recurring with an average period of 37.4+/-24.9 s. After isolating the brainstem by cutting all cranial nerves, the frequency of the short respiratory bursts did not change significantly, but the slow pattern was less frequent. Local injections of a glutamate agonist (AMPA) and antagonists (6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or D,L-amino-5-phosphonopentanoic acid (AP5)) were made over different brainstem regions to influence respiratory output. The results were similar in the semi-intact and isolated-brainstem preparations. Unilateral injection of AP5 or CNQX over a rostral rhombencephalic region, lateral to the rostral pole of the trigeminal motor nucleus, decreased the frequency of the fast respiratory rhythm bilaterally or stopped it altogether. Injection of AMPA at the same site increased the rate of the fast respiratory rhythm and decreased the frequency of the slow pattern. The activity recorded in this area was synchronous with that recorded over the vagal motoneurons. After a complete transverse lesion of the brainstem caudal to the trigeminal motor nucleus, the fast rhythm was confined to the rostral area, while only the slow activity persisted in the vagal motoneurons. Our results support the hypothesis that normal breathing depends on the activity of neurons located in the rostral rhombencephalon in lampreys, whereas the caudal rhombencephalon generates the slow pattern.
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Affiliation(s)
- B Martel
- Centre de Recherche en Sciences Neurologiques, Université de Montréal, Casier Postal 6128, Succursale Centre-Ville, Montréal, Québec, Canada H3C 3J7
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Ezure K, Tanaka I. Distribution and medullary projection of respiratory neurons in the dorsolateral pons of the rat. Neuroscience 2006; 141:1011-1023. [PMID: 16725272 DOI: 10.1016/j.neuroscience.2006.04.020] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 04/09/2006] [Accepted: 04/14/2006] [Indexed: 10/24/2022]
Abstract
The dorsolateral pons around the parabrachial nucleus including the Kölliker-Fuse nucleus is closely linked with the medullary respiratory center and plays an important role in respiratory control. We aimed to elucidate the firing properties, detailed distributions, and medullary projections of pontine respiratory neurons in pentobarbitone-anesthetized, paralyzed, and artificially ventilated rats with intact vagi. A total of 235 respiratory neurons were recorded from the dorsolateral pons in and around the Kölliker-Fuse nucleus. Six types of firing patterns were identified: inspiratory, expiratory-inspiratory phase spanning, inspiratory-expiratory phase spanning, decrementing expiratory, augmenting expiratory, and whole-phase expiratory patterns. Of these, the inspiratory neurons and the expiratory-inspiratory phase spanning neurons, which constituted the largest population (61%), were characterized most carefully by changing lung inflation levels, since under some conditions both showed similar firing patterns. Many (58%) of the 133 respiratory neurons examined were antidromically activated by electrical stimulation of the medulla. They were activated from the ventrolateral medulla around the ventral respiratory group and the Bötzinger complex and from the dorsomedial medulla around the nucleus tractus solitarii and the hypoglossal nucleus. The projections to the dorsomedial medulla were bilateral in many cases, and those to the ventrolateral medulla were unilateral. Of these medullary projections, two specific projections could be characterized in detail. First, many expiratory-inspiratory phase spanning neurons projected to the hypoglossal nucleus, suggesting that these pontine neurons are important premotor neurons of the hypoglossal motoneurons. This projection explains well the hypoglossal inspiratory activity, which is often dissociated from the phrenic inspiratory activity. Second, most whole-phase expiratory neurons that were distributed medially to the KF nucleus sent their axons toward the spinal cord via the midline medulla. These findings provide a new insight into the pontine control of medullary and spinal respiratory function.
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Affiliation(s)
- K Ezure
- Department of Neurobiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
| | - I Tanaka
- Department of Neurobiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan
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Alheid GF, Milsom WK, McCrimmon DR. Pontine influences on breathing: an overview. Respir Physiol Neurobiol 2005; 143:105-14. [PMID: 15519548 DOI: 10.1016/j.resp.2004.06.016] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2004] [Indexed: 11/17/2022]
Abstract
Historical and contemporary views of the functional organization of the lateral pontine regions influencing breathing are reviewed. In vertebrates, the rhombencephalon generates a breathing rhythm and detailed motor pattern that persist throughout life. Key to this process is an essentially continuous column of neurons extending from the spino-medullary border through the ventrolateral medulla, continuing through the ventral pons and arcing into the dorsolateral medulla. Comparative neuroanatomy and physiology indicate this is a richly interconnected network divided into serial, functionally distinct compartments. Serial compartmentalization of pontomedullary structures related to breathing also reflects the developmental segmentation of the rhombencephalon. However, with migration of cell groups such as the facial nucleus from the pons to the medulla during ontogeny, the boundaries of the adult pons are sometimes difficult to precisely define. Accordingly, a working definition of rostral and caudal pontine boundaries for adult mammals is depicted.
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Affiliation(s)
- George F Alheid
- Department of Physiology and Institute for Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL 60611-3008, USA.
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Ezure K. Respiration-related afferents to parabrachial pontine regions. Respir Physiol Neurobiol 2005; 143:167-75. [PMID: 15519553 DOI: 10.1016/j.resp.2004.03.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2004] [Indexed: 11/24/2022]
Abstract
The dorsolateral pons around the parabrachial nucleus is an important participant in respiratory control. This area involves various respiration-related neurons, and their respiratory modulation is thought to arise from afferents from medullary respiratory neurons. Today, however, only a limited number of afferent sources have been identified. First, relatively well-characterized afferents to the pons are those originating from two types of the lung stretch receptors, slowly adapting and rapidly adapting receptors. That is, the majority of the second-order relay neurons of these receptors in the nucleus tractus solitarii project to the pons. Second, certain types of respiratory neurons of the medullary respiratory groups are either known to or presumed to project to the pons. For instance, major inhibitory neurons of the Botzinger complex, augmenting and decrementing expiratory neurons, send afferents to the pons. This article overviews such afferents and discusses their connectivity with pontine neurons.
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Affiliation(s)
- Kazuhisa Ezure
- Department of Neurobiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
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Song G, Poon CS. Functional and structural models of pontine modulation of mechanoreceptor and chemoreceptor reflexes. Respir Physiol Neurobiol 2005; 143:281-92. [PMID: 15519561 DOI: 10.1016/j.resp.2004.05.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2004] [Indexed: 11/30/2022]
Abstract
The dorsolateral and ventrolateral pons (dl-pons, vl-pons) are critical brainstem structures mediating the plasticity of the Hering-Breuer mechanoreflex (HBR) and carotid chemoreflex (CCR). Review of anatomical evidence indicates that dl-pons and vl-pons are connected reciprocally with one another and with medullary nucleus tractus solitarius (NTS) and ventral respiratory group (VRG). With this structural map, functional models of HBR and CCR are proposed in which the respiratory rhythm is modulated by short-term depression (STD) or potentiation (STP) of corresponding primary NTS-VRG and auxiliary pons-VRG excitatory or inhibitory pathways. Behaviorally, STD and STP of respiratory reflexes are akin to non-associative learning such as habituation, sensitization or desensitization to afferent inputs. Computationally, the STD and STP effects amount to signal differentiation and integration in the time domain, or high-pass and low-pass filtering in the frequency domain, respectively. These functional and structural models of pontomedullary signal processing provide a novel conceptual framework that unifies a wealth of experimental observations regarding mechanoreceptor and chemoreceptor reflex control of breathing.
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Affiliation(s)
- Gang Song
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Lalley PM. D1-dopamine receptor blockade slows respiratory rhythm and enhances opioid-mediated depression. Respir Physiol Neurobiol 2005; 145:13-22. [PMID: 15652784 DOI: 10.1016/j.resp.2004.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2004] [Indexed: 11/18/2022]
Abstract
Previous studies indicate that dopamine modulates the excitability of the respiratory network and its susceptibility to depression by exogenous opioids, but the roles of different subtypes of dopamine receptor in these processes are still uncertain. In this study, D1-dopamine receptor (D1R) involvement in dopaminergic modulation of respiratory rhythm and mu-opioid receptor mediated depression were investigated in pentobarbital-anesthetized cats. Intravenous administration of the D1R blocker SCH-23390 (100-200 microg/kg) slowed phrenic nerve and expiratory neuron respiratory rhythms by prolonging the inspiratory and expiratory phases. Phrenic nerve discharge intensity also increased more gradually during the inspiratory phase. SCH-23390 (150 microg/kg) also enhanced dose-dependent depression of phrenic nerve and expiratory neuron excitability, as well as rhythm disturbances, produced by the mu-opioid receptor agonist fentanyl (2-20 microg/kg, i.v.). The results suggest an important role for the D1-subtype of receptor in respiratory rhythm modulation, and indicate that this type of receptor participates in dopaminergic compensatory mechanisms directed against opioid-mediated network depression.
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Affiliation(s)
- Peter M Lalley
- The University of Wisconsin Madison, Medical Sciences Center, Department of Physiology, 1300 University Avenue, 127 Service Memorial Institute, Madison, WI 53706, USA.
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Miyamoto K, Iwase M, Kimura H, Homma I. Central histamine contributes to the inspiratory off-switch mechanism via H1 receptors in mice. Respir Physiol Neurobiol 2004; 144:25-33. [PMID: 15522700 DOI: 10.1016/j.resp.2004.07.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2004] [Indexed: 11/21/2022]
Abstract
Central histaminergic neurons are distributed in areas of the medulla and pons concerned with respiratory rhythm generation, but their effects on breathing pattern are unknown. We examined breathing pattern during hypercapnic responses in wild type (WT) and H1 receptor knockout (H1RKO) mice at 9-10 weeks of age before and after vagotomy. Minute ventilation increased with PaCO(2) increase equally in both genotypes; respiratory rate response was lower and tidal volume (V(T)) response higher in H1RKO mice than in WT mice. The V(T)-inspiratory time (T(I)) relation during hypercapnia was hyperbolic in both groups, with the curve in H1RKO mice shifted right-upward. After vagotomy, the V(T)-T(I) relation was a vertical line, which shifted right in H1RKO mice. We conclude that alterations of inspiratory off-switch and respiratory rhythm generation change breathing pattern without affecting central chemosensitivity in H1RKO. Histamine might affect breathing pattern centrally via H1 receptors.
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Affiliation(s)
- Kenichi Miyamoto
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
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Abstract
The term "eupneic activity pattern" is a trivial phenotypical description of a particular activity pattern in respiratory nerves as recorded under in vivo like experimental conditions. This term is, however, inadequate, because Eupnea describes a behavioral breathing performance that is trouble-free occurring without conscious effort. Obviously, the term "eupneic activity pattern" is meant to describe a neural activity that is normal and comparable with quiet breathing conditions. The various in vivo, in situ and in vitro preparations all generate their specific "normal" activity patterns, when the conditions are undisturbed. The commentary describes some of the numerous reasons why such normal activity patterns must be different in the various preparations without indicating their pathological operation. The conclusion is that special considerations are necessary for any extension of the in vitro and in situ findings into in vivo situations, because the capacity of the respiratory network is greatly reduced and thus not comparable with conditions leading to "eupneic breathing" in the fully intact animal.
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Affiliation(s)
- Diethelm W Richter
- Zentrum Physiologie und Pathophysiologie, Abteilung Neuro- und Sinnesphysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany.
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Simonyan K, Jürgens U. Efferent subcortical projections of the laryngeal motorcortex in the rhesus monkey. Brain Res 2003; 974:43-59. [PMID: 12742623 DOI: 10.1016/s0006-8993(03)02548-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to better understand the descending voluntary vocal control pathway, the efferent subcortical projections of the laryngeal motorcortex were studied in the rhesus monkey (Macaca mulatta). For this purpose, the left motorcortex was exposed in three animals under narcosis. By electrical brain stimulation, sites were identified yielding vocal fold adduction. Effective sites were injected with the anterograde tracer biotin dextran amine. Subcortical projections could be traced within the forebrain to the putamen, caudate nucleus, claustrum, zona incerta, field H of Forel and a number of thalamic nuclei, with the heaviest projections to the nuclei ventralis lateralis, ventralis posteromedialis, including its parvocellular part, medialis dorsalis, centralis medialis, centrum medianum and reuniens. In the midbrain, labeling was found in the deep mesencephalic nucleus. In the lower brainstem, fibers terminated in the pontine and medullary reticular formation, locus coeruleus, nucleus subcoeruleus, medial parabrachial nucleus, nucleus of the spinal trigeminal tract, solitary tract nucleus and facial nucleus. No projections were found to the nucl. ambiguus. The fact that monkeys, in contrast to humans, lack a direct connection of the motorcortex with the laryngeal motoneurons suggests that this connection has evolved in the last few million years and might represent one of the factors that made speech evolution possible.
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Affiliation(s)
- Kristina Simonyan
- Department of Neurobiology, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany.
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Harris MB, Milsom WK. Apneusis follows disruption of NMDA-type glutamate receptors in vagotomized ground squirrels. Respir Physiol Neurobiol 2003; 134:191-207. [PMID: 12660099 DOI: 10.1016/s1569-9048(02)00223-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influences of N-methyl-D-aspartate (NMDA) type glutamate receptor antagonism, by (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine maleate (MK-801), on breathing pattern and ventilatory chemoresponses, were assessed in anaesthetized vagotomized spontaneously breathing golden-mantled ground squirrels, Spermophilus lateralis. MK-801 was administered by either bilateral pressure micro-injection into a region of the rostral dorsolateral pons, containing the medial and lateral Parabrachial and Kölliker-Fuse nuclei (the Parabrachial complex, PbC), or by systemic injection. Both treatments induced apneusis. These data indicate that functional NMDA receptor-mediated processes located within the PbC terminate inspiration and actively prevent apneusis in vagotomized ground squirrels. Although both hypercapnia and hypoxia stimulated breathing during the apneusis, the responses were generally slight. The breathing frequency component of the hypercapnic ventilatory response was completely eliminated supporting the hypothesis that the PbC is an integral component of the control network for CO(2) chemoreflex responses. Differences in the results of systemic versus PbC MK-801 illustrate that NMDA receptor-mediated processes outside the PbC do influence ventilation. Our data also show that such processes outside the PbC lengthen both inspiration and expiration in this species, slowing ventilation, and are necessary for the expression of the hypoxic ventilatory response.
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Affiliation(s)
- Michael B Harris
- Department of Physiology, Dartmouth Hitchcock Medical Center, Dartmouth College, Borwell Building Hinman box, 7700, One Medical Center Drive, Lebanon, NH 03756, USA.
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Abstract
Vocalization is a complex behaviour pattern, consisting of essentially three components: laryngeal activity, respiratory movements and supralaryngeal (articulatory) activity. The motoneurones controlling this behaviour are located in various nuclei in the pons (trigeminal motor nucleus), medulla (facial nucleus, nucl. ambiguus, hypoglossal nucleus) and ventral horn of the spinal cord (cervical, thoracic and lumbar region). Coordination of the different motoneurone pools is carried out by an extensive network comprising the ventrolateral parabrachial area, lateral pontine reticular formation, anterolateral and caudal medullary reticular formation, and the nucl. retroambiguus. This network has a direct access to the phonatory motoneurone pools and receives proprioceptive input from laryngeal, pulmonary and oral mechanoreceptors via the solitary tract nucleus and principal as well as spinal trigeminal nuclei. The motor-coordinating network needs a facilitatory input from the periaqueductal grey of the midbrain and laterally bordering tegmentum in order to be able to produce vocalizations. Voluntary control of vocalization, in contrast to completely innate vocal reactions, such as pain shrieking, needs the intactness of the forebrain. Voluntary control over the initiation and suppression of vocal utterances is carried out by the mediofrontal cortex (including anterior cingulate gyrus and supplementary as well as pre-supplementary motor area). Voluntary control over the acoustic structure of vocalizations is carried out by the motor cortex via pyramidal/corticobulbar as well as extrapyramidal pathways. The most important extrapyramidal pathway seems to be the connection motor cortex-putamen-substantia nigra-parvocellular reticular formation-phonatory motoneurones. The motor cortex depends upon a number of inputs for fulfilling its task. It needs a cerebellar input via the ventrolateral thalamus for allowing a smooth transition between consecutive vocal elements. It needs a proprioceptive input from the phonatory organs via nucl. ventralis posterior medialis thalami, somatosensory cortex and inferior parietal cortex. It needs an input from the ventral premotor and prefrontal cortex, including Broca's area, for motor planning of longer purposeful utterances. And it needs an input from the supplementary and pre-supplementary motor area which give rise to the motor commands executed by the motor cortex.
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Affiliation(s)
- Uwe Jürgens
- German Primate Centre, Kellnerweg 4, 37077 Göttingen, Germany
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Izumizaki M, Iwase M, Kimura H, Kuriyama T, Homma I. Central histamine contributed to temperature-induced polypnea in mice. J Appl Physiol (1985) 2000; 89:770-6. [PMID: 10926664 DOI: 10.1152/jappl.2000.89.2.770] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Breathing pattern is influenced by body temperature. However, the central mechanism for changing breathing patterns is unknown. Central histamine is involved in heat loss mechanisms in behavioral studies, but little is known about its effect on breathing patterns. We examined first the effect of body temperature on breathing patterns with increasing hypercapnia in conscious mice and then that of the depletion of central histamine by S(+)-alpha-fluoromethylhistidine hydrochloride (alpha-FMH) (100 mg/kg ip), a specific inhibitor of histidine decarboxylase, at normal and raised body temperatures. A raised body temperature increased respiratory frequency with reductions in both inspiratory and expiratory time and decreased tidal volume. On the other hand, alpha-FMH lowered respiratory frequency with a prolongation of expiratory time at the raised temperature; however, this was not observed at a normal temperature. These results indicate that central histamine contributes to an increase in respiratory frequency as a result of a reduction in expiratory time when body temperature is raised.
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Affiliation(s)
- M Izumizaki
- Second Department of Physiology, Showa University School of Medicine, Tokyo, Japan
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Gang S, Watanabe A, Aoki M. Axonal projections from the pontine parabrachial-Kölliker-Fuse nuclei to the Bötzinger complex as revealed by antidromic stimulation in cats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 450:67-72. [PMID: 10026965 DOI: 10.1007/978-1-4757-9077-1_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- S Gang
- Department of Physiology, School of Medicine, Sapporo Medical University, Japan
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32
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Chapter 4.7 A neurobehavioral system approach in rats to study the molecular biology of fear. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0921-0709(99)80053-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Mutolo D, Bongianni F, Carfì M, Pantaleo T. Respiratory responses to chemical stimulation of the parabrachial nuclear complex in the rabbit. Brain Res 1998; 807:182-6. [PMID: 9757031 DOI: 10.1016/s0006-8993(98)00775-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The respiratory role of the parabrachial nuclear complex (PNC) was investigated in alpha-chloralose-urethane anesthetized, vagotomized, paralysed and artificially ventilated rabbits by means of unilateral microinjections (10-20 nl) of 20 mM dl-homocysteic acid. Chemical stimulation elicited three main types of site-specific respiratory effects: excitatory, apneustic and inhibitory responses. The results suggest that the PNC plays a complex role in the control of breathing.
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Affiliation(s)
- D Mutolo
- Dipartimento di Scienze Fisiologiche, Università degli Studi di Firenze, Viale G.B. Morgagni 63, I-50134, Florence, Italy
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Hopp FA, Seagard JL. Respiratory responses to selective blockade of carotid sinus baroreceptors in the dog. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R10-8. [PMID: 9688954 DOI: 10.1152/ajpregu.1998.275.1.r10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Activation of carotid sinus (CS) baroreceptors has been shown to increase inspiratory time (TI) and expiratory time (TE) and to have a varied effect on tidal volume. The contribution of two functionally different types of baroreceptors to changes in respiratory function were examined in the current study. The techniques of DC anodal block and bupivacaine anesthetic block were used to selectively block fibers, from largest (type I) to smallest (type II) and smallest to largest, respectively, in the CS nerve (CSN) from an isolated CS in an anesthetized, paralyzed, vagotomized, artificially ventilated dog. Anodal blocking currents from 25 to 60 microA, which blocked primarily large A fibers, produced significant decreases in TI and TE and increased the slope of the average phrenic neurogram [PNG(t)], with no change in peak PNG(t). Further increases in blocking current to levels that also blocked small C fibers did not result in additional changes. Bupivacaine blockade using concentrations that blocked primarily C fibers did not block changes in TI and TE to step CS pressure changes. Increasing bupivacaine concentration to 20 mg/100 ml blocked all CSN conduction, and respiratory responses were eliminated. Therefore respiratory responses arising from CS baroreceptors appear to originate from the larger type I baroreceptors.
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Affiliation(s)
- F A Hopp
- Veterans Affairs Medical Center and Department of Anesthesia, The Medical College of Wisconsin, Milwaukee, Wisconsin 53295, USA
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Seifert E, Trippenbach T. Effects of baclofen on the Hering-Breuer inspiratory-inhibitory and deflation reflexes in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:R462-9. [PMID: 9486305 DOI: 10.1152/ajpregu.1998.274.2.r462] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The objective of this study was to evaluate effects of baclofen, a gamma-aminobutyric acid type B (GABAB) receptor agonist, injected into the nucleus of the solitary tract, on the Hering-Breuer inspiratory-inhibitory (TI-inhibitory) and deflation reflexes in urethan-anesthetized adult Wistar rats (n = 7). The TI-inhibitory reflex was estimated from changes in peak amplitude of the integrated diaphragmatic electromyogram and inspiratory time (TI) provoked by airway occlusion at end expiration. The deflation reflex was evaluated from changes in TI and expiration (TE) of the first two breaths (TI-1, TE-1 and TI-2, TE-2) immediately after a decrease in tracheal pressure (Ptr). Under control conditions, airway occlusion at end-TE prolonged TI (66 +/- 5%; mean +/- SE) and the following TE (54 +/- 11%). Decreases in Ptr, from -2 to -5 cmH2O, evoked an increase in TI and shortening of TE of both breaths. Both effects were Ptr dependent, and TI-1 and TE-1 differed from TI-2 and TE-2, suggesting a rapid adaptation to the stimulus. At Ptr of -5 cmH2O, TI-1 and TI-2 increased by 30 +/- 2 and 43 +/- 6%, respectively, and TE-1 and TE-2 decreased by 53 +/- 4 and 33 +/- 7%, respectively. During unloaded breathing, 60 pmol baclofen prolonged TI by 120 +/- 11% and left TE unaffected. Baclofen abolished vagally mediated changes in TE. On the other hand, the TI increases caused by either airway occlusion (24 +/- 8%) or Ptr of -5 cmH2O (TI-1; 16 +/- 5%) were still significant, but TI-1 and TI-2 were not different. A GABAB receptor antagonist, CGP-35348 (2.8 nmol), reversed these effects of baclofen. These results imply that stimulation of GABAB receptors attenuates but does abolish vagally mediated control of TI. The difference in effects of baclofen on the central and vagal control of TI and TE suggests different distribution of GABAB receptors in neuronal networks controlling each of these respiratory phases.
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Affiliation(s)
- E Seifert
- Department of Physiology, McGill University, Montreal, Quebec, Canada
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36
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Molliex S, Dureuil B, Montravers P, Desmonts JM. [Effects of midazolam on respiratory drive in healthy volunteers]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 1995; 14:271-5. [PMID: 7486297 DOI: 10.1016/s0750-7658(95)80006-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To compare the effects of a sedative dose of midazolam on mean inspiratory flow (VT/TI = index of central respiratory activity), known as being decreased by midazolam and the intercostal muscle activity, known as being increased by this agent. STUDY DESIGN Laboratory study. PATIENTS Seven healthy volunteers. METHODS After assessment of baseline values of ventilatory variables and intercostal electromyographic activity (in arbitrary units), midazolam 0.1 mg.kg-1 was administered by iv route. The measurements were repeated after 5 and 10 min, and finally 2 min after the i.v. injection of flumazenil 1 mg. RESULTS Midazolam decreased VE and VT. Similarly VT/TI ratio decreased from 0.44 +/- 0.04 (baseline value) to 0.26 +/- 0.03 (5 min) and 0.3 +/- 0.03 L.s-1 (10 min later) respectively (P < 0.05). Conversely, midazolam increased the intercostal electromyographic activity from 4.0 +/- 0.7 (baseline value) to 26.5 +/- 16.6 (5 min) and 28.4 +/- 16.6 U (10 min later) respectively (P < 0.05). Within 2 min after flumazenil administration all variables returned to baseline values. CONCLUSIONS The decrease of VT/TI ratio is probably linked to increased resistances in the upper airways. This ratio cannot act as an indicator of respiratory drive during sedation or anaesthesia. The assessment of the ventilatory effects of benzodiazepines must be based simultaneously of the various other indicators of the ventilatory drive, as these agents act on the different stages of the ventilatory cycle and therefore cannot be characterized by a unique variable.
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Affiliation(s)
- S Molliex
- Département d'Anesthésie-Réanimation Chirurgicale, CHRU, Hôpital Bellevue, Saint-Etienne
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Hirano T, Simbulan D, Kumazawa T. Effects of kainic acid in the parabrachial region for ongoing respiratory activity and reflexive respiratory suppression. Brain Res 1994; 665:54-62. [PMID: 7882019 DOI: 10.1016/0006-8993(94)91151-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We previously reported that the electrical stimulation of gastrocnemius muscle nerve afferents given at a suprathreshold intensity for C-fiber afferents induces naloxone-reversible reflexive respiratory suppression ('after suppression'). The effects of kainic acid (KA) microinjections into the parabrachial area (nucleus parabrachialis lateralis: NPBL and nucleus parabrachialis medialis: NPBM) on (1) ongoing respiratory activity and (2) the 'after suppression' were studied in chloralose-urethane anesthetized, bivagotomized, paralyzed, and artificially ventilated cats. A large dose of KA (1.91 nmol in 0.1 microliters) microinjected into the unilateral NPBL induced significant long-lasting respiratory facilitation, while a subsequent KA injection into the ipsilateral NPBM induced significant, long-lasting respiratory depression. A small dose of KA (0.48 nmol in 0.1 microliters) into the unilateral NPBL (right side) induced significant respiratory facilitation, and the 'after suppression' effect was eliminated. A small dose into the unilateral NPBM (right side) caused initial transient respiratory facilitation followed by respiratory depression before 'after suppression' was restored. Subsequent KA injections into the NPBL on the other side (left side) significantly augmented respiration. The 'after suppression' effect was again eliminated after an injection of KA into the bilateral NPBL. It was concluded that NPBL may exhibit tonic inhibitory activities on respiration and play a critical role in the 'after suppression' effect, since an injection of KA into the NPBM counteracted both of these effects in the NPBL.
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Affiliation(s)
- T Hirano
- Department of Neural Regulation, Nagoya University, Japan
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Revest PA, Jones HC, Abbott NJ. Transendothelial electrical potential across pial vessels in anaesthetised rats: a study of ion permeability and transport at the blood-brain barrier. Brain Res 1994; 652:76-82. [PMID: 7525022 DOI: 10.1016/0006-8993(94)90319-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Brain pial microvessels have previously been demonstrated to have blood-brain barrier properties. The potential difference (PD) across exposed brain pial microvessels, 20-60 microns in diameter and superfused with artificial CSF, has been measured in anaesthetised rats using glass microelectrodes. The PD on insertion into venous vessels, V(in), was 3.2 mV lumen negative, and in arterial vessels it was higher at 4.5 mV. Superfusion with high K(+)-CSF, made by replacing Na+ with K+, caused a positive deflection in PD, VK+, whereas reducing the Na+ alone, by replacing Na+ by Tris-HCl, made the lumen more negative. These two effects were additive. Studies on venous vessels showed that ouabain had no effect on V(in) and only affected VK+ under conditions of low Na pre-exposure. Neither histamine nor cimetidine had any effect on V(in) or VK+ whereas tetraethylammonium, a K(+)-channel blocker, reduced VK+ by 20%. These experiments demonstrate that changes in PD caused by changing abluminal Na+ or K+ are due predominantly to movement of ions through channels in the endothelial cell membranes, and that actions that alter the activity of the Na+,K(+)-ATPase or reduce the resistance of the paracellular pathway in parallel with increased membrane permeability have less effect on the PD.
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Affiliation(s)
- P A Revest
- Department of Physiology, Queen Mary and Westfield College, London, UK
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Lara JP, Parkes MJ, Silva-Carvhalo L, Izzo P, Dawid-Milner MS, Spyer KM. Cardiovascular and respiratory effects of stimulation of cell bodies of the parabrachial nuclei in the anaesthetized rat. J Physiol 1994; 477:321-9. [PMID: 7932222 PMCID: PMC1155631 DOI: 10.1113/jphysiol.1994.sp020193] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. In order to assess the importance of the parabrachial nuclei in modulating cardiorespiratory activity, electric current or microinjections of glutamate were used to stimulate discrete regions of the parabrachial nuclei in anaesthetized rats. 2. Stimulation of cell bodies in the medial region of the parabrachial nuclei and in the Kölliker-Fuse nuclei, caused an expiratory facilitatory response. This consisted mainly of a decrease in respiratory rate as measured by observing phrenic nerve activity. 3. Stimulation of cell bodies in the lateral region of the parabrachial nuclei caused an inspiratory facilitatory response. This consisted mainly of an increase in respiratory rate. 4. At the majority of sites (16 out of 20) where changes in respiratory rate were elicited by glutamate injection or electrical stimulation an increase in blood pressure was observed. The coexistence of increases in blood pressure and heart rate indicates the presence of inhibition of the heart rate component of the baroreflex and/or an increase in cardiac sympathetic drive. 5. The expiratory facilitatory response was not evoked reflexly by the rise in blood pressure since it was still present after administration of guanethidine, which abolished the rise in blood pressure. 6. The interactions between the parabrachial nuclei and the medullary respiratory complex in eliciting these changes are discussed.
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Affiliation(s)
- J P Lara
- Department of Physiology, Royal Free Hospital School of Medicine, London
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Abstract
Electrical and chemical lesions in the ventrolateral pons produced apneustic breathing in anesthetized, vagotomized, paralyzed, ventilated adult rats (n = 13). Apneustic breathing did not develop if the vagi remained intact and was reversed partially with vagal (proximal end) stimulation. Physiologically, these data are similar to those obtained following dorsolateral pontine lesion in rat and other mammalian species and support the hypothesis that pontine neurons influence breathing similarly across mammalian species.
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Affiliation(s)
- J S Jodkowski
- Department of Medicine, Case Western Reserve University, Cleveland, OH 44106-5000
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Fung ML, St John WM. Separation of multiple functions in ventilatory control of pneumotaxic mechanisms. RESPIRATION PHYSIOLOGY 1994; 96:83-98. [PMID: 8023023 DOI: 10.1016/0034-5687(94)90108-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Multiple functions have been ascribed to the pontile pneumotaxic center. We hypothesized that these functions might be separable among neurons in different regions. In decerebrate, vagotomized, paralyzed and ventilated cats, activities of the phrenic and triangularis sterni nerves were recorded. Microinjections of kainic acid were used to destroy neurons. Neurons in the rostrolateral tegmentum at the ponto-mesencephalic border controlled the duration of neural inspiration. Expiratory duration was controlled by neurons in the more caudal nucleus parabrachialis medialis and Kolliker-Fuse nucleus. Ventilatory responses to hypercapnia were depressed following injections of kainic acid into regions controlling either inspiratory or expiratory durations. The phases of expiration were regulated by two groups of neurons, located medial and lateral in the rostral pons. We conclude that rostral pontile and mesencephalic mechanisms control multiple aspects of the eupneic ventilatory cycle. There mechanisms are served by neurons in separable anatomical regions.
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Affiliation(s)
- M L Fung
- Department of Physiology, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03755
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Abstract
The pontine respiratory neurons (PRG) in the 'pneumotaxic centre' have been hypothesized to contribute to phase-switching of neural respiratory activity, especially in terminating inspiration. To define the neural elements involved in phase-switching, we recorded respiratory neurons extra- and intracellularly in anesthetized cats with an intact central nervous system. In total, 54 neurons were recorded: 49 neurons with activity modulated by central respiratory rhythm (20 inspiratory, 17 postinspiratory and 12 expiratory) and 5 neurons with activity correlated to tracheal pressure. The recorded neurons were clustered in dorsolateral pontine tegmentum within the Kölliker-Fuse (KF) subnucleus of the parabrachial nuclei. Stable intracellular membrane potential was recorded in 11 of the 49 respiratory neurons (8 postinspiratory, 1 early inspiratory and 2 inspiratory). During continuous injection of chloride ions (n = 6), synaptic noise increased and IPSPs reversed, including a wave of IPSPs during stage-2 expiration in postinspiratory neurons. Further, relative input resistance varied through the respiratory cycle such that the least input resistance occurred during the neuron's (n = 5) quiescent period. No IPSPs nor EPSPs were evoked in pontine respiratory neurons by vagal stimulation. In conclusion, various types of respiratory neurons were recorded in the KF nucleus. Prominent excitatory and inhibitory postsynaptic activities were similar to those described for medullary neurons. These pontine respiratory neurons do not appear to receive a strong afferent input from the vagus. Rather, vagal afferent inputs seem to be directed towards non-respiratory neurons that are located more medially in the dorsal pons.
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Affiliation(s)
- T E Dick
- II. Department of Physiology, University of Götingen, Germany
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Richard CA, Harper RK, Schechtman VL, Ni H, Harper RM. Respiratory patterning following cerebral ventricular administration of cocaine. Pharmacol Biochem Behav 1993; 45:849-56. [PMID: 8415824 DOI: 10.1016/0091-3057(93)90131-c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Intravenous (IV) cocaine in the conscious cat causes extreme tachypnea and reduction in breath-to-breath variability. In this study, we examined respiratory patterning following administration of cocaine into the cerebral ventricles. Intraventricular cocaine elicited a tachypnea that was nearly identical to that for IV cocaine. At the high dose, peak respiratory rate increased by 380%. Breath-to-breath variability was dramatically reduced by cocaine, especially in the early stages of the intoxication; during these stages, the tachypnea was occasionally interrupted by prolonged inspiratory efforts. Procaine was administered as a control for the anesthetic effects of cocaine and caused an initial tachypnea that was similar to that for cocaine. For both cocaine and procaine, the mean ratios of inspiratory to expiratory durations were unaffected, indicating that the tachypnea was accomplished by approximately equal reductions in inspiratory and expiratory durations. We conclude that the tachypnea following cocaine administration results principally from central rather than peripheral mechanisms. In addition, the data suggest that anesthetic actions mediate the principal respiratory effects of cocaine.
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Affiliation(s)
- C A Richard
- Brain Research Institute, UCLA School of Medicine 90024-1761
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Ni H, Zhang J, Harper RK, Harper RM. Discharge dependencies of amygdala central nucleus neurons to the cardiac and respiratory cycle following local cocaine administration. Eur J Pharmacol 1992; 224:157-65. [PMID: 1468505 DOI: 10.1016/0014-2999(92)90800-j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We examined dependencies of amygdala central nucleus neuronal discharge to the cardiac and respiratory cycles in freely behaving cats following local microinjection of cocaine (100 micrograms/0.2 microliter). Cross-correlation histograms showed cycle-by-cycle dependencies between neuronal discharge and the cardiac and respiratory cycles in 10 of 30 cells and 7 of 30 cells, respectively, during baseline periods. After cocaine delivery, the discharge rate of half of the central nucleus of the amygdala cells (16/30, 53%) were partly or completely inhibited in a reversible manner. Excluding cardiac- and respiratory-dependent neurons which ceased firing after cocaine, more than half (5/8) of the remaining cardiac and two-thirds (4/6) of respiratory-dependent neurons altered discharge dependencies following cocaine administration. Of the cells that did not exhibit cardiac and respiratory dependencies pre-cocaine, 2 of 20 developed cardiac correlations and 3 of 23 developed respiratory correlations following cocaine administration. We speculate that a portion of the cardiac and respiratory responses induced by cocaine may be mediated through the central nucleus of the amygdala.
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Affiliation(s)
- H Ni
- Department of Anatomy and Cell Biology, University of California, Los Angeles
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Nozaki K, Boccalini P, Moskowitz MA. Expression of c-fos-like immunoreactivity in brainstem after meningeal irritation by blood in the subarachnoid space. Neuroscience 1992; 49:669-80. [PMID: 1501769 DOI: 10.1016/0306-4522(92)90235-t] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The expression of c-fos protein was examined by immunohistochemistry in serial sections of brainstem following the instillation of either autologous arterial blood (0.3 ml) or mock cerebrospinal fluid (0.3 ml) through a catheter placed in the cisterna magna, or following catheter placement alone in pentobarbital-anesthetized Sprague-Dawley rats. After injection, blood was distributed within the subarachnoid space surrounding the brainstem and in the region of the circle of Willis. c-fos protein-like immunoreactivity was present at 1 h, peaked at 2 h and decreased by 8 h. At 2 h, immunoreactivity was strongly expressed within trigeminal nucleus caudalis (lamina I, IIo), as well as within nucleus of the solitary tract, area postrema, ependyma, pia mater and arachnoid in every animal. Moderate labeling was found in parabrachial nucleus, medullary lateral reticular nucleus and central gray. Sparse labeling was present in trigeminal nucleus caudalis (lamina III-V) and trigeminal nucleus interpolaris; few or no labeled cells were detected in other parts of the trigeminal nuclear complex, thalamus, cerebral cortex, cerebellar cortex or trigeminal ganglion. The number of positive cells was not related to the volume of injectate but was related to the amount of injected blood. The density of cell labeling evoked by injecting mock cerebrospinal fluid or after catheter placement was markedly lower than after blood in all brainstem areas. The number of labeled cells was greatly reduced within trigeminal nuclear complex, parabrachial nucleus and medullary lateral reticular nucleus, but not within the nucleus of the solitary tract, area postrema or ependyma when blood was injected into adult animals in which unmyelinated C-fibers were destroyed by neonatal capsaicin treatment. Similar results were obtained after blood was instilled into the cisterna magna of rats in which meningeal afferents were chronically sectioned at the ethmoidal foramen bilaterally. We conclude that blood in the subarachnoid space is an effective stimulus for activating c-fos expression within subpopulations of brainstem neurons. Activation within trigeminal nucleus caudalis is mediated in large part by excitation of small-caliber meningeal afferents (trigeminovascular fibers), whereas c-fos expression within nucleus of the solitary tract and area postrema may reflect direct stimulation of blood or blood products, or possibly the response to autonomic activation from noxious stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K Nozaki
- Stroke Research Laboratory, Neurosurgery and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston 02114
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Feldman JL, Windhorst U, Anders K, Richter DW. Synaptic interaction between medullary respiratory neurones during apneusis induced by NMDA-receptor blockade in cat. J Physiol 1992; 450:303-23. [PMID: 1432710 PMCID: PMC1176123 DOI: 10.1113/jphysiol.1992.sp019128] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. Termination of inspiration is an essential component of respiratory rhythm generation and its perturbation can result in apneusis, i.e. significant prolongation of mechanisms, we studied the postsynaptic events in respiratory neurones during apneustic respiratory periods, and compared them to normal respiratory cycles. 2. Experiments were performed in pentobarbitone-anaesthetized, paralysed, thoracotomized cats ventilated with a constant volume or a cycle-triggered constant pressure pump. Apneusis, separated by normal cycles, was induced as follows: the animal was ventilated by a cycle-triggered pump that normally inflated the lungs during the inspiratory burst of phrenic nerve discharge. The NMDA-receptor blocker MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-iminemaleate] (0.3-0.7 mg/kg) was administered intravenously, and, for designated breaths, inflation of the lungs was withheld during neural inspiration. 3. Membrane potential trajectories of forty-one late expiratory (E-2) and eight postinspiratory (PI) neurones of the caudal ventral respiratory group were analysed before and/or after MK-801 administration, during normal and apneustic periods. 4. Before MK-801 administration, withholding lung inflation caused modest (10-20%) lengthening of the inspiratory period; after MK-801 administration, withholding inflation caused apneusis. Provided that the lungs were inflated during the inspiratory phase, the temporal pattern of phrenic nerve, recurrent laryngeal nerve and membrane potential trajectories of E-2 and PI neurones were not significantly altered by MK-801. Apneusis following NMDA-receptor blockade produced consistent changes in the synaptic activation patterns of E-2 neurones. In particular, the slow late inspiratory-related depolarization pattern of E-2 neurones was consistently retarded during apneustic inspiratory phases when compared to normal inspiratory phases. This was due to continuation of Cl(-)-mediated synaptic inhibition of E-2 neurones. Superior laryngeal nerve stimulation stopped apneusis and sustained membrane hyperpolarization of E-2 neurones similar to lung inflation. 5. During the plateau phase of apneusis, correlated 10-20 Hz oscillations could be observed in the integrated phrenic and recurrent laryngeal nerve activities as well as in the membrane potential of E-2 neurones. 6. We conclude that: (i) the prolonged inhibition of E-2 neurones during apneusis is indicative of the process responsible for the prolongation of the inspiratory phase.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J L Feldman
- University of Göttingen, Centre of Physiology and Pathophysiology, FRG
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Gang S, Mizuguchi A, Aoki M. Axonal projections from the pontine pneumotaxic region to the nucleus raphe magnus in cats. RESPIRATION PHYSIOLOGY 1991; 85:329-39. [PMID: 1720566 DOI: 10.1016/0034-5687(91)90072-q] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In 15 pentobarbital anesthetized and vagotomized cats, 60 non-respiratory units recorded from the medial parabrachial and Kölliker-Fuse nuclear complex (NPBM-KF), were found to be antidromically activated by electrical stimulation of the nucleus raphe magnus (NRM). Seven respiratory units (6 inspiratory, 1 expiratory), comprising 8.0% of the 87 respiratory units examined, were also antidromically activated by stimulation of the NRM. The antidromic latencies ranged from 0.4 to 2.5 ms (mean 1.2 ms). In 6 cats, following injection of WGA-HRP (wheat germ agglutinin-conjugated horseradish peroxidase) into the NRM, a number of retrogradely labelled neurons were observed mainly in the NPBM-KF complex, and some in subcoeruleus nucleus and adjacent tegmental field. These results demonstrate that predominantly non-respiratory and a portion of respiratory neurons in the rostral pons, especially in the NPBM-KF complex, send a monosynaptic axonal projection to the NRM. It is suggested that the NPBM-KF to NRM pathway could be, in part, involved in the control of respiration as well as nociception control.
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Affiliation(s)
- S Gang
- Department of Physiology, Sapporo Medical College, Japan
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Howard RS, Sears TA. The effects of opiates on the respiratory activity of thoracic motoneurones in the anaesthetized and decerebrate rabbit. J Physiol 1991; 437:181-99. [PMID: 1890632 PMCID: PMC1180042 DOI: 10.1113/jphysiol.1991.sp018590] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. Efferent discharges were recorded from inspiratory and expiratory intercostal nerve filaments (T2-T10) in artificially ventilated, anaesthetized or decerebrate rabbits with or without vagotomy. 2. Hypocapnic apnoea was used to study the fractional end-tidal CO2 (FET,CO2)-dependent tonic discharges of the expiratory motoneurones, the FET,CO2 threshold for rhythm generation and the FET,CO2 response curve of both inspiratory and expiratory burst activity. 3. Incremental doses of morphine (e.g. 1 mg kg-1 I.V.) produced slowing of the respiratory rhythm due to prolongation of the expiratory duration and an elevation of the FET,CO2 threshold for rhythm generation. Eventually apnoea supervened with associated tonic firing of the expiratory motoneurones. At the elevated levels of FET,CO2 bursts of inspiratory activity, with concomitant phasic inhibition of the tonic expiratory activity, could occur either spontaneously or following sensory stimulation. The peak integrated activities of these bursts were closely similar to the values obtained for corresponding levels of FET,CO2 before the administration of morphine. 4. Tonic expiratory activity responded to increased levels of FET,CO2, as it had during hypocapnic apnoea prior to morphine, by an increased discharge frequency of single units or recruitment of new units. 5. All of these effects of morphine were immediately reversed by naloxone (100 micrograms kg-1). 6. Naloxone (greater than 100 micrograms kg-1), without pre-treatment with morphine, led to an increase in respiratory frequency due to a shortening of the expiratory duration and a dose-dependent reduction in the FET,CO2 threshold for rhythm generation. There was little alteration either in the inspiratory response to FET,CO2 during rhythm or in the FET,CO2 response of the expiratory output whether expressed as tonic activity during hypocapnic apnoea or phasic activity following the onset of rhythm. 7. Thus opiates act upon the mechanisms of rhythm generation without depressing the FET,CO2 drive as expressed either as phasic or tonic activation of the motoneurones.
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Affiliation(s)
- R S Howard
- Sobell Department of Neurophysiology, Institute of Neurology, London
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