151
|
González-Castillo C, Muñoz-Ortiz E, Guzmán-Brambila C, Rojas-Mayorquín AE, Beltran-Parrazal L, Ortuño-Sahagún D, Morgado-Valle C. Differential Expression of Ion Channels in Adult and Neonatal Rat Ventral Respiratory Column. J Mol Neurosci 2017; 64:51-61. [DOI: 10.1007/s12031-017-1001-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/10/2017] [Indexed: 12/14/2022]
|
152
|
Phasic inhibition as a mechanism for generation of rapid respiratory rhythms. Proc Natl Acad Sci U S A 2017; 114:12815-12820. [PMID: 29133427 DOI: 10.1073/pnas.1711536114] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Central neural networks operate continuously throughout life to control respiration, yet mechanisms regulating ventilatory frequency are poorly understood. Inspiration is generated by the pre-Bötzinger complex of the ventrolateral medulla, where it is thought that excitation increases inspiratory frequency and inhibition causes apnea. To test this model, we used an in vitro optogenetic approach to stimulate select populations of hindbrain neurons and characterize how they modulate frequency. Unexpectedly, we found that inhibition was required for increases in frequency caused by stimulation of Phox2b-lineage, putative CO2-chemosensitive neurons. As a mechanistic explanation for inhibition-dependent increases in frequency, we found that phasic stimulation of inhibitory neurons can increase inspiratory frequency via postinhibitory rebound. We present evidence that Phox2b-mediated increases in frequency are caused by rebound excitation following an inhibitory synaptic volley relayed by expiration. Thus, although it is widely thought that inhibition between inspiration and expiration simply prevents activity in the antagonistic phase, we instead propose a model whereby inhibitory coupling via postinhibitory rebound excitation actually generates fast modes of inspiration.
Collapse
|
153
|
Barnett WH, Jenkin SEM, Milsom WK, Paton JFR, Abdala AP, Molkov YI, Zoccal DB. The Kölliker-Fuse nucleus orchestrates the timing of expiratory abdominal nerve bursting. J Neurophysiol 2017; 119:401-412. [PMID: 29070631 DOI: 10.1152/jn.00499.2017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Coordination of respiratory pump and valve muscle activity is essential for normal breathing. A hallmark respiratory response to hypercapnia and hypoxia is the emergence of active exhalation, characterized by abdominal muscle pumping during the late one-third of expiration (late-E phase). Late-E abdominal activity during hypercapnia has been attributed to the activation of expiratory neurons located within the parafacial respiratory group (pFRG). However, the mechanisms that control emergence of active exhalation, and its silencing in restful breathing, are not completely understood. We hypothesized that inputs from the Kölliker-Fuse nucleus (KF) control the emergence of late-E activity during hypercapnia. Previously, we reported that reversible inhibition of the KF reduced postinspiratory (post-I) motor output to laryngeal adductor muscles and brought forward the onset of hypercapnia-induced late-E abdominal activity. Here we explored the contribution of the KF for late-E abdominal recruitment during hypercapnia by pharmacologically disinhibiting the KF in in situ decerebrate arterially perfused rat preparations. These data were combined with previous results and incorporated into a computational model of the respiratory central pattern generator. Disinhibition of the KF through local parenchymal microinjections of gabazine (GABAA receptor antagonist) prolonged vagal post-I activity and inhibited late-E abdominal output during hypercapnia. In silico, we reproduced this behavior and predicted a mechanism in which the KF provides excitatory drive to post-I inhibitory neurons, which in turn inhibit late-E neurons of the pFRG. Although the exact mechanism proposed by the model requires testing, our data confirm that the KF modulates the formation of late-E abdominal activity during hypercapnia. NEW & NOTEWORTHY The pons is essential for the formation of the three-phase respiratory pattern, controlling the inspiratory-expiratory phase transition. We provide functional evidence of a novel role for the Kölliker-Fuse nucleus (KF) controlling the emergence of abdominal expiratory bursts during active expiration. A computational model of the respiratory central pattern generator predicts a possible mechanism by which the KF interacts indirectly with the parafacial respiratory group and exerts an inhibitory effect on the expiratory conditional oscillator.
Collapse
Affiliation(s)
- William H Barnett
- Department of Mathematics and Statistics, Georgia State University , Atlanta, Georgia
| | - Sarah E M Jenkin
- Department of Zoology, University of British Columbia , Vancouver, British Columbia , Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol , Bristol , United Kingdom.,Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland , Auckland , New Zealand
| | - Ana P Abdala
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol , Bristol , United Kingdom
| | - Yaroslav I Molkov
- Department of Mathematics and Statistics, Georgia State University , Atlanta, Georgia.,Neuroscience Institute, Georgia State University , Atlanta, Georgia
| | - Daniel B Zoccal
- Department of Physiology and Pathology, São Paulo State University , Araraquara , Brazil
| |
Collapse
|
154
|
Harris KD, Dashevskiy T, Mendoza J, Garcia AJ, Ramirez JM, Shea-Brown E. Different roles for inhibition in the rhythm-generating respiratory network. J Neurophysiol 2017; 118:2070-2088. [PMID: 28615332 PMCID: PMC5626906 DOI: 10.1152/jn.00174.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/25/2017] [Accepted: 06/12/2017] [Indexed: 12/20/2022] Open
Abstract
Unraveling the interplay of excitation and inhibition within rhythm-generating networks remains a fundamental issue in neuroscience. We use a biophysical model to investigate the different roles of local and long-range inhibition in the respiratory network, a key component of which is the pre-Bötzinger complex inspiratory microcircuit. Increasing inhibition within the microcircuit results in a limited number of out-of-phase neurons before rhythmicity and synchrony degenerate. Thus unstructured local inhibition is destabilizing and cannot support the generation of more than one rhythm. A two-phase rhythm requires restructuring the network into two microcircuits coupled by long-range inhibition in the manner of a half-center. In this context, inhibition leads to greater stability of the two out-of-phase rhythms. We support our computational results with in vitro recordings from mouse pre-Bötzinger complex. Partial excitation block leads to increased rhythmic variability, but this recovers after blockade of inhibition. Our results support the idea that local inhibition in the pre-Bötzinger complex is present to allow for descending control of synchrony or robustness to adverse conditions like hypoxia. We conclude that the balance of inhibition and excitation determines the stability of rhythmogenesis, but with opposite roles within and between areas. These different inhibitory roles may apply to a variety of rhythmic behaviors that emerge in widespread pattern-generating circuits of the nervous system.NEW & NOTEWORTHY The roles of inhibition within the pre-Bötzinger complex (preBötC) are a matter of debate. Using a combination of modeling and experiment, we demonstrate that inhibition affects synchrony, period variability, and overall frequency of the preBötC and coupled rhythmogenic networks. This work expands our understanding of ubiquitous motor and cognitive oscillatory networks.
Collapse
Affiliation(s)
| | - Tatiana Dashevskiy
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Joshua Mendoza
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Alfredo J Garcia
- Institute for Integrative Physiology and Section of Emergency Medicine, University of Chicago, Chicago, Illinois; and
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
- Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington
| | - Eric Shea-Brown
- Department of Applied Mathematics, University of Washington, Seattle, Washington
| |
Collapse
|
155
|
Brainstem mechanisms underlying the cough reflex and its regulation. Respir Physiol Neurobiol 2017; 243:60-76. [DOI: 10.1016/j.resp.2017.05.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 12/12/2022]
|
156
|
Sun JJ, Huang TW, Neul JL, Ray RS. Embryonic hindbrain patterning genes delineate distinct cardio-respiratory and metabolic homeostatic populations in the adult. Sci Rep 2017; 7:9117. [PMID: 28831138 PMCID: PMC5567350 DOI: 10.1038/s41598-017-08810-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/10/2017] [Indexed: 12/21/2022] Open
Abstract
Previous studies based on mouse genetic mutations suggest that proper partitioning of the hindbrain into transient, genetically-defined segments called rhombomeres is required for normal respiratory development and function in neonates. Less clear is what role these genes and the neurons they define play in adult respiratory circuit organization. Several Cre drivers are used to access and study developmental rhombomeric domains (Eng1Cre, HoxA2-Cre, Egr2Cre, HoxB1Cre, and HoxA4-Cre) in the adult. However, these drivers show cumulative activity beyond the brainstem while being used in intersectional genetic experiments to map central respiratory circuitry. We crossed these drivers to conditional DREADD mouse lines to further characterize the functional contributions of Cre defined populations. In the adult, we show that acute DREADD inhibition of targeted populations results in a variety of not only respiratory phenotypes but also metabolic and temperature changes that likely play a significant role in the observed respiratory alterations. DREADD mediated excitation of targeted domains all resulted in death, with unique differences in the patterns of cardio-respiratory failure. These data add to a growing body of work aimed at understanding the role of early embryonic patterning genes in organizing adult respiratory homeostatic networks that may be perturbed in congenital pathophysiologies.
Collapse
Affiliation(s)
- Jenny J Sun
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
| | - Teng-Wei Huang
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas, USA
| | - Jeffrey L Neul
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA.,Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, USA
| | - Russell S Ray
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. .,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA. .,Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA. .,Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, USA. .,McNair Medical Institute, TX-77030, Houston, USA.
| |
Collapse
|
157
|
Hayes JA, Kottick A, Picardo MCD, Halleran AD, Smith RD, Smith GD, Saha MS, Del Negro CA. Transcriptome of neonatal preBötzinger complex neurones in Dbx1 reporter mice. Sci Rep 2017; 7:8669. [PMID: 28819234 PMCID: PMC5561182 DOI: 10.1038/s41598-017-09418-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/24/2017] [Indexed: 12/14/2022] Open
Abstract
We sequenced the transcriptome of brainstem interneurons in the specialized respiratory rhythmogenic site dubbed preBötzinger Complex (preBötC) from newborn mice. To distinguish molecular characteristics of the core oscillator we compared preBötC neurons derived from Dbx1-expressing progenitors that are respiratory rhythmogenic to neighbouring non-Dbx1-derived neurons, which support other respiratory and non-respiratory functions. Results in three categories are particularly salient. First, Dbx1 preBötC neurons express κ-opioid receptors in addition to μ-opioid receptors that heretofore have been associated with opiate respiratory depression, which may have clinical applications. Second, Dbx1 preBötC neurons express the hypoxia-inducible transcription factor Hif1a at levels three-times higher than non-Dbx1 neurons, which links core rhythmogenic microcircuits to O2-related chemosensation for the first time. Third, we detected a suite of transcription factors including Hoxa4 whose expression pattern may define the rostral preBötC border, Pbx3 that may influence ipsilateral connectivity, and Pax8 that may pertain to a ventrally-derived subset of Dbx1 preBötC neurons. These data establish the transcriptomic signature of the core respiratory oscillator at a perinatal stage of development.
Collapse
Affiliation(s)
- John A Hayes
- Department of Applied Science, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Andrew Kottick
- Department of Applied Science, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Maria Cristina D Picardo
- Department of Applied Science, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Andrew D Halleran
- Department of Biology, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Ronald D Smith
- Department of Applied Science, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Gregory D Smith
- Department of Applied Science, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Margaret S Saha
- Department of Biology, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA
| | - Christopher A Del Negro
- Department of Applied Science, Integrated Science Center, 540 Landrum Dr., The College of William and Mary, Williamsburg, VA, 23185, USA.
| |
Collapse
|
158
|
Chevalier M, Cardoit L, Moreau M, Sans N, Montcouquiol M, Simmers J, Thoby-Brisson M. The embryonic development of hindbrain respiratory networks is unaffected by mutation of the planar polarity protein Scribble. Neuroscience 2017; 357:160-171. [PMID: 28583412 DOI: 10.1016/j.neuroscience.2017.05.046] [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: 03/10/2017] [Revised: 05/17/2017] [Accepted: 05/26/2017] [Indexed: 11/29/2022]
Abstract
The central command for breathing arises mainly from two interconnected rhythmogenic hindbrain networks, the parafacial respiratory group (pFRG or epF at embryonic stages) and the preBötzinger complex (preBötC), which are comprised of a limited number of neurons located in confined regions of the ventral medulla. In rodents, both networks become active toward the end of gestation but little is known about the signaling pathways involved in their anatomical and functional establishment during embryogenesis. During embryonic development, epF and preBötC neurons migrate from their territories of origin to their final positions in ventral brainstem areas. Planar Cell Polarity (PCP) signaling, including the molecule Scrib, is known to control the developmental migration of several hindbrain neuronal groups. Accordingly, a homozygous mutation of Scrib leads to severe disruption of hindbrain anatomy and function. Here, we aimed to determine whether Scrib is also involved in the prenatal development of the hindbrain nuclei controlling breathing. We combined immunostaining, calcium imaging and electrophysiological recordings of neuronal activity in isolated in vitro preparations. In the Scrib mutant, despite severe neural tube defects, epF and preBötC neurons settled at their expected hindbrain positions. Furthermore, both networks remained capable of generating rhythmically organized, respiratory-related activities and exhibited normal sensitivity to pharmacological agents known to modify respiratory circuit function. Thus Scrib is not required for the proper migration of epF and preBötC neurons during mouse embryogenesis. Our findings thus further illustrate the robustness and specificity of the developmental processes involved in the establishment of hindbrain respiratory circuits.
Collapse
Affiliation(s)
- Marc Chevalier
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33076 Bordeaux, France.
| | - Laura Cardoit
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33076 Bordeaux, France.
| | - Maïté Moreau
- INSERM, Neurocentre Magendie, U1215, F-33077 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, U1215, F-33077 Bordeaux, France.
| | - Nathalie Sans
- INSERM, Neurocentre Magendie, U1215, F-33077 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, U1215, F-33077 Bordeaux, France.
| | - Mireille Montcouquiol
- INSERM, Neurocentre Magendie, U1215, F-33077 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, U1215, F-33077 Bordeaux, France.
| | - John Simmers
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33076 Bordeaux, France.
| | - Muriel Thoby-Brisson
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33076 Bordeaux, France.
| |
Collapse
|
159
|
Genetic identification of a hindbrain nucleus essential for innate vocalization. Proc Natl Acad Sci U S A 2017; 114:8095-8100. [PMID: 28698373 DOI: 10.1073/pnas.1702893114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vocalization in young mice is an innate response to isolation or mechanical stimulation. Neuronal circuits that control vocalization and breathing overlap and rely on motor neurons that innervate laryngeal and expiratory muscles, but the brain center that coordinates these motor neurons has not been identified. Here, we show that the hindbrain nucleus tractus solitarius (NTS) is essential for vocalization in mice. By generating genetically modified newborn mice that specifically lack excitatory NTS neurons, we show that they are both mute and unable to produce the expiratory drive required for vocalization. Furthermore, the muteness of these newborns results in maternal neglect. We also show that neurons of the NTS directly connect to and entrain the activity of spinal (L1) and nucleus ambiguus motor pools located at positions where expiratory and laryngeal motor neurons reside. These motor neurons control expiratory pressure and laryngeal tension, respectively, thereby establishing the essential biomechanical parameters used for vocalization. In summary, our work demonstrates that the NTS is an obligatory component of the neuronal circuitry that transforms breaths into calls.
Collapse
|
160
|
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.
Collapse
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
| |
Collapse
|
161
|
Abstract
Breathing is vital for survival but also interesting from the perspective of rhythm generation. This rhythmic behavior is generated within the brainstem and is thought to emerge through the interaction between independent oscillatory neuronal networks. In mammals, breathing is composed of three phases - inspiration, post-inspiration, and active expiration - and this article discusses the concept that each phase is generated by anatomically distinct rhythm-generating networks: the preBötzinger complex (preBötC), the post-inspiratory complex (PiCo), and the lateral parafacial nucleus (pF L), respectively. The preBötC was first discovered 25 years ago and was shown to be both necessary and sufficient for the generation of inspiration. More recently, networks have been described that are responsible for post-inspiration and active expiration. Here, we attempt to collate the current knowledge and hypotheses regarding how respiratory rhythms are generated, the role that inhibition plays, and the interactions between the medullary networks. Our considerations may have implications for rhythm generation in general.
Collapse
Affiliation(s)
- Tatiana M. Anderson
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, USA
- Graduate Program for Neuroscience, University of Washington School of Medicine, Seattle, WA, USA
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, USA
- Department of Neurological Surgery and Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
| |
Collapse
|
162
|
Withey SL, Hill R, Lyndon A, Dewey WL, Kelly E, Henderson G. Effect of Tamoxifen and Brain-Penetrant Protein Kinase C and c-Jun N-Terminal Kinase Inhibitors on Tolerance to Opioid-Induced Respiratory Depression in Mice. J Pharmacol Exp Ther 2017; 361:51-59. [PMID: 28130265 DOI: 10.1124/jpet.116.238329] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/25/2017] [Indexed: 01/20/2023] Open
Abstract
Respiratory depression is the major cause of death in opioid overdose. We have previously shown that prolonged treatment of mice with morphine induces profound tolerance to the respiratory-depressant effects of the drug (Hill et al., 2016). The aim of the present study was to investigate whether tolerance to opioid-induced respiratory depression is mediated by protein kinase C (PKC) and/or c-Jun N-terminal kinase (JNK). We found that although mice treated for up to 6 days with morphine developed tolerance, as measured by the reduced responsiveness to an acute challenge dose of morphine, administration of the brain-penetrant PKC inhibitors tamoxifen and calphostin C restored the ability of acute morphine to produce respiratory depression in morphine-treated mice. Importantly, reversal of opioid tolerance was dependent on the nature of the opioid ligand used to induce tolerance, as these PKC inhibitors did not reverse tolerance induced by prolonged treatment of mice with methadone nor did they reverse the protection to acute morphine-induced respiratory depression afforded by prolonged treatment with buprenorphine. We found no evidence for the involvement of JNK in morphine-induced tolerance to respiratory depression. These results indicate that PKC represents a major mechanism underlying morphine tolerance, that the mechanism of opioid tolerance to respiratory depression is ligand-dependent, and that coadministration of drugs with PKC-inhibitory activity and morphine (as well as heroin, largely metabolized to morphine in the body) may render individuals more susceptible to overdose death by reversing tolerance to the effects of morphine.
Collapse
Affiliation(s)
- Sarah L Withey
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Rob Hill
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Abigail Lyndon
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - William L Dewey
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Eamonn Kelly
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Graeme Henderson
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| |
Collapse
|
163
|
Beltrán-Castillo S, Morgado-Valle C, Eugenín J. The Onset of the Fetal Respiratory Rhythm: An Emergent Property Triggered by Chemosensory Drive? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1015:163-192. [PMID: 29080027 DOI: 10.1007/978-3-319-62817-2_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mechanisms responsible for the onset of respiratory activity during fetal life are unknown. The onset of respiratory rhythm may be a consequence of the genetic program of each of the constituents of the respiratory network, so they start to interact and generate respiratory cycles when reaching a certain degree of maturation. Alternatively, generation of cycles might require the contribution of recently formed sensory inputs that will trigger oscillatory activity in the nascent respiratory neural network. If this hypothesis is true, then sensory input to the respiratory generator must be already formed and become functional before the onset of fetal respiration. In this review, we evaluate the timing of the onset of the respiratory rhythm in comparison to the appearance of receptors, neurotransmitter machinery, and afferent projections provided by two central chemoreceptive nuclei, the raphe and locus coeruleus nuclei.
Collapse
Affiliation(s)
- Sebastián Beltrán-Castillo
- Laboratorio de Sistemas Neurales, Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, PO 9170022, Santiago, Chile
| | - Consuelo Morgado-Valle
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Campus Xalapa, Berlin 7, Fracc., Monte Magno Animas, C.P. 91190, Xalapa, Veracruz, Mexico.
| | - Jaime Eugenín
- Laboratorio de Sistemas Neurales, Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, PO 9170022, Santiago, Chile.
| |
Collapse
|
164
|
Microcircuits in respiratory rhythm generation: commonalities with other rhythm generating networks and evolutionary perspectives. Curr Opin Neurobiol 2016; 41:53-61. [PMID: 27589601 DOI: 10.1016/j.conb.2016.08.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 02/07/2023]
Abstract
Rhythmicity is critical for the generation of rhythmic behaviors and higher brain functions. This review discusses common mechanisms of rhythm generation, including the role of synaptic inhibition and excitation, with a focus on the mammalian respiratory network. This network generates three phases of breathing and is highly integrated with brain regions associated with numerous non-ventilatory behaviors. We hypothesize that during evolution multiple rhythmogenic microcircuits were recruited to accommodate the generation of each breathing phase. While these microcircuits relied primarily on excitatory mechanisms, synaptic inhibition became increasingly important to coordinate the different microcircuits and to integrate breathing into a rich behavioral repertoire that links breathing to sensory processing, arousal, and emotions as well as learning and memory.
Collapse
|