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Fenik VB, Rukhadze I. Activity of Pontine A7 Noradrenergic Neurons is suppressed during REM sleep. J Appl Physiol (1985) 2022; 133:130-143. [PMID: 35616303 PMCID: PMC9255708 DOI: 10.1152/japplphysiol.00771.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The activity of hypoglossal motoneurons plays a key role in the maintenance of upper airway patency. The withdrawal of noradrenergic excitatory drive and increase of cholinergic inhibition markedly decreases excitability of hypoglossal motoneurons during sleep and especially during rapid-eye-movement (REM) stage. This leads to increased collapsibility of upper airway during sleep, which is the major neurological factor of obstructive sleep apnea (OSA) pathophysiology. Anatomical and functional data suggests that noradrenergic A7 neurons are the main source of noradrenergic drive to hypoglossal motoneurons. However, it is unknown whether the behavior of A7 neurons during sleep-wake cycle is in accord with their proposed involvement in sleep-related depression of hypoglossal motoneuron activity. Therefore, we sought to assess the behavior of A7 neurons during sleep and wakefulness in naturally sleeping head-restrained rats. We have found that, similar to other pontine noradrenergic neurons, the putative A7 noradrenergic neurons fired with relatively long-lasting action potentials with a low frequency regular discharge. Importantly, all noradrenergic A7 neurons were predominantly silent during REM sleep. The REM-off activity of the A7 neurons supports our hypothesis that these neurons may significantly contribute to the withdrawal of excitatory noradrenergic drive from upper airway motoneurons during REM sleep and, consequently, play a critical role in maintaining upper airway patency and pathophysiology of OSA. Therefore, noradrenergic A7 neurons may serve as an additional target for designing pharmacological approaches to treat OSA.
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Affiliation(s)
- Victor B Fenik
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States.,VA Greater Los Angeles Healthcare System, West Los Angeles, CA, United States
| | - Irma Rukhadze
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States.,VA Greater Los Angeles Healthcare System, West Los Angeles, CA, United States.,Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
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Gretenkord S, Olthof BMJ, Stylianou M, Rees A, Gartside SE, LeBeau FEN. Electrical stimulation of the ventral tegmental area evokes sleep-like state transitions under urethane anaesthesia in the rat medial prefrontal cortex via dopamine D 1 -like receptors. Eur J Neurosci 2020; 52:2915-2930. [PMID: 31891427 PMCID: PMC7497269 DOI: 10.1111/ejn.14665] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/20/2019] [Accepted: 12/27/2019] [Indexed: 12/19/2022]
Abstract
The role of dopamine in regulating sleep-state transitions during, both natural sleep and under anaesthesia, is still unclear. Recording in vivo in the rat mPFC under urethane anaesthesia, we observed predominantly slow wave activity (SWA) of <1 Hz in the local field potential interrupted by occasional spontaneous transitions to a low-amplitude-fast (LAF) pattern of activity. During periods of SWA, transitions to LAF activity could be rapidly and consistently evoked by electrical stimulation of the ventral tegmental area (VTA). Spontaneous LAF activity, and that evoked by stimulation of the VTA, consisted of fast oscillations similar to those seen in the rapid eye movement (REM)-like sleep state. Spontaneous and VTA stimulation-evoked LAF activity occurred simultaneously along the dorsoventral extent of all mPFC subregions. Evoked LAF activity depended on VTA stimulation current and could be elicited using either regular (25-50 Hz) or burst stimulation patterns and was reproducible upon repeated stimulation. Simultaneous extracellular single-unit recordings showed that during SWA, presumed pyramidal cells fired phasically and almost exclusively on the Up state, while during both spontaneous and VTA-evoked LAF activity, they fired tonically. The transition to LAF activity evoked by VTA stimulation depended on dopamine D1 -like receptor activation as it was almost completely blocked by systemic administration of the D1 -like receptor antagonist SCH23390. Overall, our data demonstrate that activation of dopamine D1 -like receptors in the mPFC is important for regulating sleep-like state transitions.
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Affiliation(s)
- Sabine Gretenkord
- Biosciences InstituteMedical SchoolNewcastle UniversityNewcastle Upon TyneUK
| | - Bas M. J. Olthof
- Biosciences InstituteMedical SchoolNewcastle UniversityNewcastle Upon TyneUK
| | - Myrto Stylianou
- Biosciences InstituteMedical SchoolNewcastle UniversityNewcastle Upon TyneUK
| | - Adrian Rees
- Biosciences InstituteMedical SchoolNewcastle UniversityNewcastle Upon TyneUK
| | - Sarah E. Gartside
- Biosciences InstituteMedical SchoolNewcastle UniversityNewcastle Upon TyneUK
| | - Fiona E. N. LeBeau
- Biosciences InstituteMedical SchoolNewcastle UniversityNewcastle Upon TyneUK
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Rukhadze I, Fenik VB. Neuroanatomical Basis of State-Dependent Activity of Upper Airway Muscles. Front Neurol 2018; 9:752. [PMID: 30250449 PMCID: PMC6139331 DOI: 10.3389/fneur.2018.00752] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 08/20/2018] [Indexed: 12/16/2022] Open
Abstract
Obstructive Sleep Apnea (OSA) is a common sleep-related respiratory disorder that is associated with cognitive, cardiovascular, and metabolic morbidities. The major cause of OSA is the sleep-related reduction of upper airway muscle tone that leads to airway obstructions in individuals with anatomically narrow upper airway. This reduction is mainly due to the suppressant effect of sleep on hypoglossal motoneurons that innervate upper airway muscles. The hypoglossal motoneurons have state-dependent activity, which is decreased during the transition from wakefulness to non-rapid eye movement sleep and is further suppressed during rapid eye movement sleep. Multiple neurotransmitters and their receptors have been implicated in the control of hypoglossal motoneuron activity across the sleep-wake states. However, to date, the results of the rigorous testing show that withdrawal of noradrenergic excitation and cholinergic inhibition essentially contribute to the depression of hypoglossal motoneuron activity during sleep. The present review will focus on origins of noradrenergic and cholinergic innervation of hypoglossal motoneurons and the functional role of these neurons in the state-dependent activity of hypoglossal motoneurons.
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Affiliation(s)
- Irma Rukhadze
- VA West Los Angeles Medical Center, West Los Angeles, CA, United States.,David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States
| | - Victor B Fenik
- VA West Los Angeles Medical Center, West Los Angeles, CA, United States.,Websciences International, Los Angeles, CA, United States
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Rukhadze I, Carballo NJ, Bandaru SS, Malhotra A, Fuller PM, Fenik VB. Catecholaminergic A1/C1 neurons contribute to the maintenance of upper airway muscle tone but may not participate in NREM sleep-related depression of these muscles. Respir Physiol Neurobiol 2017; 244:41-50. [PMID: 28711601 DOI: 10.1016/j.resp.2017.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 12/12/2022]
Abstract
Neural mechanisms of obstructive sleep apnea, a common sleep-related breathing disorder, are incompletely understood. Hypoglossal motoneurons, which provide tonic and inspiratory activation of genioglossus (GG) muscle (a major upper airway dilator), receive catecholaminergic input from medullary A1/C1 neurons. We aimed to determine the contribution of A1/C1 neurons in control of GG muscle during sleep and wakefulness. To do so, we placed injections of a viral vector into DBH-cre mice to selectively express the hMD4i inhibitory chemoreceptors in A1/C1 neurons. Administration of the hM4Di ligand, clozapine-N-oxide (CNO), in these mice decreased GG muscle activity during NREM sleep (F1,1,3=17.1, p<0.05); a similar non-significant decrease was observed during wakefulness. CNO administration had no effect on neck muscle activity, respiratory parameters or state durations. In addition, CNO-induced inhibition of A1/C1 neurons did not alter the magnitude of the naturally occurring depression of GG activity during transitions from wakefulness to NREM sleep. These findings suggest that A1/C1 neurons have a net excitatory effect on GG activity that is most likely mediated by hypoglossal motoneurons. However, the activity of A1/C1 neurons does not appear to contribute to NREM sleep-related inhibition of GG muscle activity, suggesting that A1/C1 neurons regulate upper airway patency in a state-independent manner.
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Affiliation(s)
- Irma Rukhadze
- Department of Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA.
| | - Nancy J Carballo
- Department of Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Sathyajit S Bandaru
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Atul Malhotra
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California San Diego, La Jolla, CA, USA
| | - Patrick M Fuller
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Victor B Fenik
- Department of Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, CA, USA; WebSience International, Los Angeles, CA, USA
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Kubin L. Neural Control of the Upper Airway: Respiratory and State-Dependent Mechanisms. Compr Physiol 2016; 6:1801-1850. [PMID: 27783860 DOI: 10.1002/cphy.c160002] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Upper airway muscles subserve many essential for survival orofacial behaviors, including their important role as accessory respiratory muscles. In the face of certain predisposition of craniofacial anatomy, both tonic and phasic inspiratory activation of upper airway muscles is necessary to protect the upper airway against collapse. This protective action is adequate during wakefulness, but fails during sleep which results in recurrent episodes of hypopneas and apneas, a condition known as the obstructive sleep apnea syndrome (OSA). Although OSA is almost exclusively a human disorder, animal models help unveil the basic principles governing the impact of sleep on breathing and upper airway muscle activity. This article discusses the neuroanatomy, neurochemistry, and neurophysiology of the different neuronal systems whose activity changes with sleep-wake states, such as the noradrenergic, serotonergic, cholinergic, orexinergic, histaminergic, GABAergic and glycinergic, and their impact on central respiratory neurons and upper airway motoneurons. Observations of the interactions between sleep-wake states and upper airway muscles in healthy humans and OSA patients are related to findings from animal models with normal upper airway, and various animal models of OSA, including the chronic-intermittent hypoxia model. Using a framework of upper airway motoneurons being under concurrent influence of central respiratory, reflex and state-dependent inputs, different neurotransmitters, and neuropeptides are considered as either causing a sleep-dependent withdrawal of excitation from motoneurons or mediating an active, sleep-related inhibition of motoneurons. Information about the neurochemistry of state-dependent control of upper airway muscles accumulated to date reveals fundamental principles and may help understand and treat OSA. © 2016 American Physiological Society. Compr Physiol 6:1801-1850, 2016.
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Affiliation(s)
- Leszek Kubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Kubin L. Sleep-wake control of the upper airway by noradrenergic neurons, with and without intermittent hypoxia. PROGRESS IN BRAIN RESEARCH 2014; 209:255-74. [PMID: 24746052 PMCID: PMC4498577 DOI: 10.1016/b978-0-444-63274-6.00013-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hypoglossal (XII) motoneurons innervate muscles of the tongue whose tonic and inspiratory modulated activity protects the upper airway from collapse in patients affected by the obstructive sleep apnea (OSA) syndrome. Both norepinephrine and serotonin provide wakefulness-related excitatory drives that maintain activity in XII motoneurons, with the noradrenergic system playing a particularly prominent role in rats. When noradrenergic and serotonergic drives are antagonized, no further decline of XII nerve activity occurs during pharmacologically induced rapid eye movement (REM) sleep-like state. This is the best evidence to date that, at least in this model, the entire REM sleep-related decline of upper airway muscle tone results from withdrawal of these two excitatory inputs. A major component of noradrenergic input to XII motoneurons originates from pontine noradrenergic neurons that have state-dependent patterns of activity, maximal during wakefulness, and minimal, or absent during REM sleep. Our data suggest that not all ventrolateral medullary catecholaminergic neurons follow this pattern, with adrenergic C1 neurons probably increasing their activity during REM sleep. When rats are subjected to chronic-intermittent hypoxia, noradrenergic drive to XII motoneurons is increased by mechanisms that include sprouting of noradrenergic terminals in the XII nucleus, and increased expression of α1-adrenoceptors; an outcome that may underlie the elevated baseline activity of upper airway muscles during wakefulness in OSA patients.
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Affiliation(s)
- Leszek Kubin
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Breathing and brain state: Urethane anesthesia as a model for natural sleep. Respir Physiol Neurobiol 2013; 188:324-32. [DOI: 10.1016/j.resp.2013.05.035] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/06/2013] [Accepted: 05/28/2013] [Indexed: 01/26/2023]
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Burgess C, Peever J. A Noradrenergic Mechanism Functions to Couple Motor Behavior with Arousal State. Curr Biol 2013; 23:1719-25. [DOI: 10.1016/j.cub.2013.07.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/03/2013] [Accepted: 07/03/2013] [Indexed: 10/26/2022]
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Fenik VB, Marchenko V, Davies RO, Kubin L. Inhibition of A5 Neurons Facilitates the Occurrence of REM Sleep-Like Episodes in Urethane-Anesthetized Rats: A New Role for Noradrenergic A5 Neurons? Front Neurol 2012; 3:119. [PMID: 22855683 PMCID: PMC3405460 DOI: 10.3389/fneur.2012.00119] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 07/09/2012] [Indexed: 01/12/2023] Open
Abstract
When rapid eye movement (REM) sleep occurs, noradrenergic cells become silent, with the abolition of activity in locus coeruleus (LC) neurons seen as a key event permissive for the occurrence of REM sleep. However, it is not known whether silencing of other than LC noradrenergic neurons contributes to the generation of REM sleep. In urethane-anesthetized rats, stereotyped REM sleep-like episodes can be repeatedly elicited by injections of the cholinergic agonist, carbachol, into a discrete region of the dorsomedial pons. We used this preparation to test whether inhibition of ventrolateral pontine noradrenergic A5 neurons only, or together with LC neurons, also can elicit REM sleep-like effects. To silence noradrenergic cells, we sequentially injected the α2-adrenergic agonist clonidine (20–40 nl, 0.75 mM) into both A5 regions and then the LC. In two rats, successful bilateral clonidine injections into the A5 region elicited the characteristic REM sleep-like episodes (hippocampal theta rhythm, suppression of hypoglossal nerve activity, reduced respiratory rate). In five rats, bilateral clonidine injections into the A5 region and then into one LC triggered REM sleep-like episodes, and in two rats injections into both A5 and then both LC were needed to elicit the effect. In contrast, in three rats, uni- or bilateral clonidine injections only into the LC had no effect, and clonidine injections placed in another six rats outside of the A5 and/or LC regions were without effect. The REM sleep-like episodes elicited by clonidine had similar magnitude of suppression of hypoglossal nerve activity (by 75%), similar pattern of hippocampal changes, and similar durations (2.5–5.3 min) to the episodes triggered in the same preparation by carbachol injections into the dorsomedial pontine reticular formation. Thus, silencing of A5 cells may importantly enable the occurrence of REM sleep-like episodes, at least under anesthesia. This is a new role for noradrenergic A5 neurons.
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Affiliation(s)
- Victor B Fenik
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania Philadelphia, PA, USA
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