1
|
Rudy SL, Wealing JC, Banayat T, Black C, Funk GD, Revill AL. A muscarinic, GIRK channel-mediated inhibition of inspiratory-related XII nerve motor output emerges in early postnatal development in mice. J Appl Physiol (1985) 2023; 135:1041-1052. [PMID: 37767557 PMCID: PMC10911762 DOI: 10.1152/japplphysiol.00042.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 09/06/2023] [Accepted: 09/21/2023] [Indexed: 09/29/2023] Open
Abstract
In neonatal rhythmic medullary slices, muscarinic acetylcholine receptor (mAChR) activation of hypoglossal (XII) motoneurons that innervate the tongue has a net excitatory effect on XII inspiratory motor output. Conversely, during rapid eye movement sleep in adult rodents, XII motoneurons experience a loss of excitability partly due to activation of mAChRs. This may be mediated by activation of G-protein-coupled inwardly rectifying potassium (GIRK) channels. Therefore, this study was designed to evaluate whether muscarinic modulation of XII inspiratory motor output in mouse rhythmic medullary slices includes GIRK channel-mediated inhibition and, if so, when this inhibitory mechanism emerges. Local pressure injection of the mAChR agonist muscarine potentiated inspiratory bursting by 150 ± 28% in postnatal day (P)0-P5 rhythmic medullary slice preparations. In the absence of muscarine, pharmacological GIRK channel block by Tertiapin-Q did not affect inspiratory burst parameters, whereas activation with ML297 decreased inspiratory burst area. Blocking GIRK channels by local preapplication of Tertiapin-Q revealed a developmental change in muscarinic modulation of inspiratory bursting. In P0-P2 rhythmic medullary slices, Tertiapin-Q preapplication had no significant effect on muscarinic potentiation of inspiratory bursting (a negligible 6% decrease). However, preapplication of Tertiapin-Q to P3-P5 rhythmic medullary slices caused a 19% increase in muscarinic potentiation of XII inspiratory burst amplitude. Immunofluorescence experiments revealed expression of GIRK 1 and 2 subunits and M1, M2, M3, and M5 mAChRs from P0 to P5. Overall, these data support that mechanisms underlying muscarinic modulation of inspiratory burst activity change postnatally and that potent GIRK-mediated inhibition described in adults emerges early in postnatal life.NEW & NOTEWORTHY Muscarinic modulation of inspiratory bursting at hypoglossal motoneurons has a net excitatory effect in neonatal rhythmic medullary slice preparations and a net inhibitory effect in adult animals. We demonstrate that muscarinic modulation of inspiratory bursting undergoes maturational changes from postnatal days 0 to 5 that include emergence of an inhibitory component mediated by G-protein-coupled inwardly rectifying potassium channels after postnatal day 3 in neonatal mouse rhythmic medullary slice preparations.
Collapse
Affiliation(s)
- Samantha L Rudy
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Jesse C Wealing
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Tatum Banayat
- Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States
| | - Chody Black
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
| | - Gregory D Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Ann L Revill
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States
- Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States
| |
Collapse
|
2
|
Bolte KN, Wealing JC, Revill AL. Arginine vasopressin potentiates inspiratory bursting in hypoglossal motoneurons of neonatal mice. Respir Physiol Neurobiol 2023; 314:104087. [PMID: 37269889 PMCID: PMC10443434 DOI: 10.1016/j.resp.2023.104087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/24/2023] [Accepted: 05/26/2023] [Indexed: 06/05/2023]
Abstract
Vasopressin (AVP) acts as a neurotransmitter and its activity can potentiate respiratory activity. Hypoglossal (XII) motoneurons that innervate the tongue express V1a vasopressin receptors, which are excitatory. Therefore, we hypothesized that V1a receptor activation at XII motoneurons would potentiate inspiratory bursting. We developed this study to determine whether AVP can potentiate inspiratory bursting in rhythmic medullary slice preparations in neonatal (postnatal, P0-5) mice. Bath or local application of AVP potentiated inspiratory bursting compared to baseline XII inspiratory burst amplitude. Antagonizing V1a receptors revealed significant attenuation of the AVP-mediated potentiation of inspiratory bursting, while antagonism of oxytocin receptors (at which AVP has similar binding affinity) revealed a trend to attenuate AVP-mediated potentiation of inspiratory bursting. Finally, we discovered that the AVP-mediated potentiation of inspiratory bursting increases significantly with postnatal maturation from P0-5. Overall, these data support that AVP potentiates inspiratory bursting directly at XII motoneurons.
Collapse
Affiliation(s)
- K N Bolte
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, United States
| | - J C Wealing
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, United States
| | - A L Revill
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, United States; Department of Physiology, College of Graduate Studies, Midwestern University, Glendale, AZ, United States.
| |
Collapse
|
3
|
da Silva MP, Moraes DJA, Bonagamba LGH, Mecawi ADS, Varanda WA, Machado BH. Hyperexcitability and plasticity induced by sustained hypoxia on rectus abdominis motoneurons. J Physiol 2019; 597:1935-1956. [PMID: 30747446 DOI: 10.1113/jp277030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 02/06/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Acute hypoxia induces active expiration in rectus abdominis (RA) muscles in conscious freely moving rats, although its overall contribution is smaller than in internal oblique (IO) muscles. Tonically active and silent RA motoneurons were identified in in vitro preparations of rat spinal cords. Sustained hypoxia (SH) increased the synaptic strength and induced morphological changes in tonically active RA motoneurons. Expiratory RA motoneurons were recorded in the in situ preparation and SH enhanced both the excitability and the synaptic transmission in those firing during the stage 2 expiration. The present study contributes to a better understanding of the mechanisms involved in SH recruitment of RA motoneurons to induce active expiration in rats. ABSTRACT Rectus abdominis (RA) motoneurons translate the complex respiratory brainstem inputs into effective muscle contractions. Despite their fundamental role in respiration, their functional and morphological properties are not fully understood. In the present study, we investigated for the first time the contribution of RA muscle to active expiration and characterized RA motoneurons regarding their electrical, molecular and morphological profiles in control rats and in rats submitted to sustained hypoxia (SH), which induces chronic recruitment of abdominal muscles. Electromyographic experiments in conscious freely moving control rats and SH rats showed that RA contributes to active expiration induced by acute hypoxia, although its contribution is smaller than in internal oblique muscles. in vitro whole-cell patch clamp recordings from RA motoneurons revealed two populations of cells: tonically active and silent. SH induced hyperexcitability in the tonically active cells by changing their action potential properties, and EPSCs. Three-dimensional morphological reconstructions of these cells showed that SH increased the dendritic complexity, stimulated the appearance of dendrite spines, and increased the somatic area and volume. Physiologically identified RA motoneurons, firing in two distinct phases of expiration, were recorded in the brainstem-spinal cord in situ preparation of rats. SH increased the firing frequency and EPSCs of neurons firing during stage 2 expiration. Taken together, our results show that RA motoneurons reconfigure their biophysical properties, morphology and synaptic strength to produce an appropriate expiratory drive in response to SH in rats.
Collapse
Affiliation(s)
- Melina P da Silva
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Davi José A Moraes
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Leni G H Bonagamba
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - André de Souza Mecawi
- Paulista School of Medicine, Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil
| | - Wamberto A Varanda
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Benedito H Machado
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| |
Collapse
|
4
|
Substance P receptor in the rat indusium griseum during postnatal development. Neurosci Res 2018; 130:23-38. [DOI: 10.1016/j.neures.2017.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/09/2017] [Accepted: 08/18/2017] [Indexed: 11/21/2022]
|
5
|
Barbaresi P, Mensà E, Bastioli G, Amoroso S. Substance P NK1 receptor in the rat corpus callosum during postnatal development. Brain Behav 2017; 7:e00713. [PMID: 28638718 PMCID: PMC5474716 DOI: 10.1002/brb3.713] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
INTRODUCTION The expression of substance P (SP) receptor (neurokinin 1, NK1) was studied in the rat corpus callosum (cc) from postnatal day 0 (the first 24 hr from birth, P0) to P30. METHODS We used immunocytochemistry to study the presence of intracallosal NK1-immunopositive neurons (NK1IP-n) during cc development. RESULTS NK1IP-n first appeared on P5. Their number increased significantly between P5 and P10, it remained almost constant between P10 and P15, then declined slightly until P30. The size of intracallosal NK1IP-n increased constantly from P5 (102.3 μm2) to P30 (262.07 μm2). From P5 onward, their distribution pattern was adult-like, that is, they were more numerous in the lateral and intermediate parts of the cc, and declined to few or none approaching the midline. At P5, intracallosal NK1IP-n had a predominantly round cell bodies with primary dendrites of different thickness from which originated thinner secondary branches. Between P10 and P15, dendrites were longer and more thickly branched, and displayed several varicosities as well as short, thin appendages. Between P20 and P30, NK1IP-n were qualitatively indistinguishable from those of adult animals and could be classified as bipolar (fusiform and rectangular), round-polygonal, and pyramidal (triangular-pyriform). CONCLUSIONS Number of NK1IP-n increase between P5 and P10, then declines, but unlike other intracallosal neurons, NK1IP-n make up a significant population in the adult cc. These findings suggest that NK1IP-n may be involved in the myelination of callosal axons, could play an important role in their pathfinding. Since they are also found in adult rat cc, it is likely that their role changes during lifetime.
Collapse
Affiliation(s)
- Paolo Barbaresi
- Section of Neuroscience and Cell Biology Department of Experimental and Clinical Medicine Marche Polytechnic University Ancona Italy
| | - Emanuela Mensà
- Section of Neuroscience and Cell Biology Department of Experimental and Clinical Medicine Marche Polytechnic University Ancona Italy
| | - Guendalina Bastioli
- Department of Biomedical Sciences and Public Health Marche Polytechnic University Ancona Italy
| | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health Marche Polytechnic University Ancona Italy
| |
Collapse
|
6
|
Liu ZL, Wu X, Luo YJ, Wang L, Qu WM, Li SQ, Huang ZL. Signaling mechanism underlying the histamine-modulated action of hypoglossal motoneurons. J Neurochem 2016; 137:277-86. [PMID: 26811198 DOI: 10.1111/jnc.13548] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 12/28/2015] [Accepted: 01/13/2016] [Indexed: 01/14/2023]
Abstract
Histamine, an important modulator of the arousal states of the central nervous system, has been reported to contribute an excitatory drive at the hypoglossal motor nucleus to the genioglossus (GG) muscle, which is involved in the pathogenesis of obstructive sleep apnea. However, the effect of histamine on hypoglossal motoneurons (HMNs) and the underlying signaling mechanisms have remained elusive. Here, whole-cell patch-clamp recordings were conducted using neonatal rat brain sections, which showed that histamine excited HMNs with an inward current under voltage-clamp and a depolarization membrane potential under current-clamp via histamine H1 receptors (H1Rs). The phospholipase C inhibitor U-73122 blocked H1Rs-mediated excitatory effects, but protein kinase A inhibitor and protein kinase C inhibitor did not, indicating that the signal transduction cascades underlying the excitatory action of histamine on HMNs were H1R/Gq/11 /phospholipase C/inositol-1,4,5-trisphosphate (IP3). The effects of histamine were also dependent on extracellular Na(+) and intracellular Ca(2+), which took place via activation of Na(+)-Ca(2+) exchangers. These results identify the signaling molecules associated with the regulatory effect of histamine on HMNs. The findings of this study may provide new insights into therapeutic approaches in obstructive sleep apnea. We proposed the post-synaptic mechanisms underlying the modulation effect of histamine on hypoglossal motoneuron. Histamine activates the H1Rs via PLC and IP3, increases Ca(2+) releases from intracellular stores, promotes Na(+) influx and Ca(2+) efflux via the NCXs, and then produces an inward current and depolarizes the neurons. Histamine modulates the excitability of HMNs with other neuromodulators, such as noradrenaline, serotonin and orexin. We think that these findings should provide an important new direction for drug development for the treatment of obstructive sleep apnea.
Collapse
Affiliation(s)
- Zi-Long Liu
- Department of Pulmonary Medicine, Center of Snoring and Sleep Apnea Medicine, Zhongshan Hospital of Fudan University, Shanghai, China.,State Key Laboratory of Medical Neurobiology, and Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,The Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Xu Wu
- Department of Pulmonary Medicine, Center of Snoring and Sleep Apnea Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Yan-Jia Luo
- State Key Laboratory of Medical Neurobiology, and Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,The Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Lu Wang
- State Key Laboratory of Medical Neurobiology, and Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Wei-Min Qu
- State Key Laboratory of Medical Neurobiology, and Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,The Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Shan-Qun Li
- Department of Pulmonary Medicine, Center of Snoring and Sleep Apnea Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Zhi-Li Huang
- State Key Laboratory of Medical Neurobiology, and Shanghai Key Laboratory of Bioactive Small Molecules, Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,The Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| |
Collapse
|
7
|
Alvares TS, Revill AL, Huxtable AG, Lorenz CD, Funk GD. P2Y1 receptor-mediated potentiation of inspiratory motor output in neonatal rat in vitro. J Physiol 2014; 592:3089-111. [PMID: 24879869 DOI: 10.1113/jphysiol.2013.268136] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PreBötzinger complex inspiratory rhythm-generating networks are excited by metabotropic purinergic receptor subtype 1 (P2Y1R) activation. Despite this, and the fact that inspiratory MNs express P2Y1Rs, the role of P2Y1Rs in modulating motor output is not known for any MN pool. We used rhythmically active brainstem-spinal cord and medullary slice preparations from neonatal rats to investigate the effects of P2Y1R signalling on inspiratory output of phrenic and XII MNs that innervate diaphragm and airway muscles, respectively. MRS2365 (P2Y1R agonist, 0.1 mm) potentiated XII inspiratory burst amplitude by 60 ± 9%; 10-fold higher concentrations potentiated C4 burst amplitude by 25 ± 7%. In whole-cell voltage-clamped XII MNs, MRS2365 evoked small inward currents and potentiated spontaneous EPSCs and inspiratory synaptic currents, but these effects were absent in TTX at resting membrane potential. Voltage ramps revealed a persistent inward current (PIC) that was attenuated by: flufenamic acid (FFA), a blocker of the Ca(2+)-dependent non-selective cation current ICAN; high intracellular concentrations of BAPTA, which buffers Ca(2+) increases necessary for activation of ICAN; and 9-phenanthrol, a selective blocker of TRPM4 channels (candidate for ICAN). Real-time PCR analysis of mRNA extracted from XII punches and laser-microdissected XII MNs revealed the transcript for TRPM4. MRS2365 potentiated the PIC and this potentiation was blocked by FFA, which also blocked the MRS2365 potentiation of glutamate currents. These data suggest that XII MNs are more sensitive to P2Y1R modulation than phrenic MNs and that the P2Y1R potentiation of inspiratory output occurs in part via potentiation of TRPM4-mediated ICAN, which amplifies inspiratory inputs.
Collapse
Affiliation(s)
- T S Alvares
- Department of Physiology, Centre for Neuroscience, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - A L Revill
- Department of Physiology, Centre for Neuroscience, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - A G Huxtable
- Department of Physiology, Centre for Neuroscience, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - C D Lorenz
- Department of Physiology, Centre for Neuroscience, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - G D Funk
- Department of Physiology, Centre for Neuroscience, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
8
|
Abstract
Movement is accomplished by the controlled activation of motor unit populations. Our understanding of motor unit physiology has been derived from experimental work on the properties of single motor units and from computational studies that have integrated the experimental observations into the function of motor unit populations. The article provides brief descriptions of motor unit anatomy and muscle unit properties, with more substantial reviews of motoneuron properties, motor unit recruitment and rate modulation when humans perform voluntary contractions, and the function of an entire motor unit pool. The article emphasizes the advances in knowledge on the cellular and molecular mechanisms underlying the neuromodulation of motoneuron activity and attempts to explain the discharge characteristics of human motor units in terms of these principles. A major finding from this work has been the critical role of descending pathways from the brainstem in modulating the properties and activity of spinal motoneurons. Progress has been substantial, but significant gaps in knowledge remain.
Collapse
Affiliation(s)
- C J Heckman
- Northwestern University, Evanston, Illinois, USA.
| | | |
Collapse
|
9
|
Grace KP, Hughes SW, Shahabi S, Horner RL. K+ channel modulation causes genioglossus inhibition in REM sleep and is a strategy for reactivation. Respir Physiol Neurobiol 2013; 188:277-88. [PMID: 23872455 DOI: 10.1016/j.resp.2013.07.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 12/23/2022]
Abstract
Rapid eye movement (REM) sleep is accompanied by periods of upper airway motor suppression that cause hypoventilation and obstructive apneas in susceptible individuals. A common idea has been that upper airway motor suppression in REM sleep is caused by the neurotransmitters glycine and γ-amino butyric acid (GABA) acting at pharyngeal motor pools to inhibit motoneuron activity. Data refute this as a workable explanation because blockade of this putative glycine/GABAergic mechanism releases pharyngeal motor activity in all states, and least of all in REM sleep. Here we summarize a novel motor-inhibitory mechanism that suppresses hypoglossal motor activity largely in REM sleep, this being a muscarinic receptor mechanism linked to G-protein-coupled inwardly rectifying potassium (GIRK) channels. We then outline how this discovery informs efforts to pursue therapeutic targets to reactivate hypoglossal motor activity throughout sleep via potassium channel modulation. One such target is the inwardly rectifying potassium channel Kir2.4 whose expression in the brain is almost exclusive to cranial motor nuclei.
Collapse
Affiliation(s)
- Kevin P Grace
- Departments of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8
| | | | | | | |
Collapse
|