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Arrigoni E, Chen MC, Fuller PM. The anatomical, cellular and synaptic basis of motor atonia during rapid eye movement sleep. J Physiol 2016; 594:5391-414. [PMID: 27060683 DOI: 10.1113/jp271324] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 03/02/2016] [Indexed: 01/14/2023] Open
Abstract
Rapid eye movement (REM) sleep is a recurring part of the sleep-wake cycle characterized by fast, desynchronized rhythms in the electroencephalogram (EEG), hippocampal theta activity, rapid eye movements, autonomic activation and loss of postural muscle tone (atonia). The brain circuitry governing REM sleep is located in the pontine and medullary brainstem and includes ascending and descending projections that regulate the EEG and motor components of REM sleep. The descending signal for postural muscle atonia during REM sleep is thought to originate from glutamatergic neurons of the sublaterodorsal nucleus (SLD), which in turn activate glycinergic pre-motor neurons in the spinal cord and/or ventromedial medulla to inhibit motor neurons. Despite work over the past two decades on many neurotransmitter systems that regulate the SLD, gaps remain in our knowledge of the synaptic basis by which SLD REM neurons are regulated and in turn produce REM sleep atonia. Elucidating the anatomical, cellular and synaptic basis of REM sleep atonia control is a critical step for treating many sleep-related disorders including obstructive sleep apnoea (apnea), REM sleep behaviour disorder (RBD) and narcolepsy with cataplexy.
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Affiliation(s)
- Elda Arrigoni
- Department of Neurology, Beth Israel Deaconess Medical Center, Division of Sleep Medicine, Harvard Medical School, Boston, MA, 02215, USA.
| | - Michael C Chen
- Department of Neurology, Beth Israel Deaconess Medical Center, Division of Sleep Medicine, Harvard Medical School, Boston, MA, 02215, USA
| | - Patrick M Fuller
- Department of Neurology, Beth Israel Deaconess Medical Center, Division of Sleep Medicine, Harvard Medical School, Boston, MA, 02215, USA.
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Abstract
Cortical electroencephalographic activity arises from corticothalamocortical interactions, modulated by wake-promoting monoaminergic and cholinergic input. These wake-promoting systems are regulated by hypothalamic hypocretin/orexins, while GABAergic sleep-promoting nuclei are found in the preoptic area, brainstem and lateral hypothalamus. Although pontine acetylcholine is critical for REM sleep, hypothalamic melanin-concentrating hormone/GABAergic cells may "gate" REM sleep. Daily sleep-wake rhythms arise from interactions between a hypothalamic circadian pacemaker and a sleep homeostat whose anatomical locus has yet to be conclusively defined. Control of sleep and wakefulness involves multiple systems, each of which presents vulnerability to sleep/wake dysfunction that may predispose to physical and/or neuropsychiatric disorders.
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Affiliation(s)
- Michael D Schwartz
- Biosciences Division, Center for Neuroscience, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA
| | - Thomas S Kilduff
- Biosciences Division, Center for Neuroscience, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA.
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3
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CeA-NPO circuits and REM sleep dysfunction in drug-refractory epilepsy. Epilepsy Behav 2015; 51:273-6. [PMID: 26312989 DOI: 10.1016/j.yebeh.2015.07.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 07/11/2015] [Indexed: 11/20/2022]
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Xu AJ, Liu TT, He ZG, Hong QX, Xiang HB. STN-PPTg circuits and REM sleep dysfunction in drug-refractory epilepsy. Epilepsy Behav 2015; 51:277-80. [PMID: 26312990 DOI: 10.1016/j.yebeh.2015.07.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 07/23/2015] [Indexed: 02/07/2023]
Affiliation(s)
- Ai-Jun Xu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Tao-Tao Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Zhi-Gang He
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Qing-Xiong Hong
- Department of Anesthesiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou 510120, PR China.
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China.
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Xi M, Fung SJ, Yamuy J, Chase MH. Interactions between hypocretinergic and GABAergic systems in the control of activity of neurons in the cat pontine reticular formation. Neuroscience 2015; 298:190-9. [PMID: 25892701 DOI: 10.1016/j.neuroscience.2015.04.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 04/09/2015] [Accepted: 04/11/2015] [Indexed: 11/30/2022]
Abstract
Anatomical studies have demonstrated that hypocretinergic and GABAergic neurons innervate cells in the nucleus pontis oralis (NPO), a nucleus responsible for the generation of active (rapid eye movement (REM)) sleep (AS) and wakefulness (W). Behavioral and electrophysiological studies have shown that hypocretinergic and GABAergic processes in the NPO are involved in the generation of AS as well as W. An increase in hypocretin in the NPO is associated with both AS and W, whereas GABA levels in the NPO are elevated during W. We therefore examined the manner in which GABA modulates NPO neuronal responses to hypocretin. We hypothesized that interactions between the hypocretinergic and GABAergic systems in the NPO play an important role in determining the occurrence of AS or W. To determine the veracity of this hypothesis, we examined the effects of the juxtacellular application of hypocretin-1 and GABA on the activity of NPO neurons, which were recorded intracellularly, in chloralose-anesthetized cats. The juxtacellular application of hypocretin-1 significantly increased the mean amplitude of spontaneous EPSPs and the frequency of discharge of NPO neurons; in contrast, the juxtacellular microinjection of GABA produced the opposite effects, i.e., there was a significant reduction in the mean amplitude of spontaneous EPSPs and a decrease in the discharge of these cells. When hypocretin-1 and GABA were applied simultaneously, the inhibitory effect of GABA on the activity of NPO neurons was reduced or completely blocked. In addition, hypocretin-1 also blocked GABAergic inhibition of EPSPs evoked by stimulation of the laterodorsal tegmental nucleus. These data indicate that hypocretin and GABA function within the context of a neuronal gate that controls the activity of AS-on neurons. Therefore, we suggest that the occurrence of either AS or W depends upon interactions between hypocretinergic and GABAergic processes as well as inputs from other sites that project to AS-on neurons in the NPO.
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Affiliation(s)
- M Xi
- Websciences International, Los Angeles, CA 90024, USA; VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
| | - S J Fung
- Websciences International, Los Angeles, CA 90024, USA; VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - J Yamuy
- VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA; UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - M H Chase
- Websciences International, Los Angeles, CA 90024, USA; VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA; UCLA School of Medicine, Los Angeles, CA 90095, USA
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Wang YQ, Li R, Zhang MQ, Zhang Z, Qu WM, Huang ZL. The Neurobiological Mechanisms and Treatments of REM Sleep Disturbances in Depression. Curr Neuropharmacol 2015; 13:543-53. [PMID: 26412074 PMCID: PMC4790401 DOI: 10.2174/1570159x13666150310002540] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/11/2015] [Accepted: 01/25/2015] [Indexed: 12/23/2022] Open
Abstract
Most depressed patients suffer from sleep abnormalities, which are one of the critical symptoms of depression. They are robust risk factors for the initiation and development of depression. Studies about sleep electroencephalograms have shown characteristic changes in depression such as reductions in non-rapid eye movement sleep production, disruptions of sleep continuity and disinhibition of rapid eye movement (REM) sleep. REM sleep alterations include a decrease in REM sleep latency, an increase in REM sleep duration and REM sleep density with respect to depressive episodes. Emotional brain processing dependent on the normal sleep-wake regulation seems to be failed in depression, which also promotes the development of clinical depression. Also, REM sleep alterations have been considered as biomarkers of depression. The disturbances of norepinephrine and serotonin systems may contribute to REM sleep abnormalities in depression. Lastly, this review also discusses the effects of different antidepressants on REM sleep disturbances in depression.
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Affiliation(s)
- Yi-Qun Wang
- Department of Pharmacology, Shanghai Key Laboratory of Bioactive Small Molecules, and State
Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences
| | - Rui Li
- Department of Pharmacology, Shanghai Key Laboratory of Bioactive Small Molecules, and State
Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences
| | - Meng-Qi Zhang
- Department of Pharmacology, Shanghai Key Laboratory of Bioactive Small Molecules, and State
Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences
| | - Ze Zhang
- Department of Pharmacology, Shanghai Key Laboratory of Bioactive Small Molecules, and State
Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences
- Institutes of Brain
Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai,
China
| | - Wei-Min Qu
- Department of Pharmacology, Shanghai Key Laboratory of Bioactive Small Molecules, and State
Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences
- Institutes of Brain
Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai,
China
| | - Zhi-Li Huang
- Department of Pharmacology, Shanghai Key Laboratory of Bioactive Small Molecules, and State
Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences
- Institutes of Brain
Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai,
China
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7
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Torterolo P, Chase MH. The hypocretins (orexins) mediate the "phasic" components of REM sleep: A new hypothesis. Sleep Sci 2014; 7:19-29. [PMID: 26483897 PMCID: PMC4521687 DOI: 10.1016/j.slsci.2014.07.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 01/27/2014] [Indexed: 12/17/2022] Open
Abstract
In 1998, a group of phenotypically distinct neurons were discovered in the postero-lateral hypothalamus which contained the neuropeptides hypocretin 1 and hypocretin 2 (also called orexin A and orexin B), which are excitatory neuromodulators. Hypocretinergic neurons project throughout the central nervous system and have been involved in the generation and maintenance of wakefulness. The sleep disorder narcolepsy, characterized by hypersomnia and cataplexy, is produced by degeneration of these neurons. The hypocretinergic neurons are active during wakefulness in conjunction with the presence of motor activity that occurs during survival-related behaviors. These neurons decrease their firing rate during non-REM sleep; however there is still controversy upon the activity and role of these neurons during REM sleep. Hence, in the present report we conducted a critical review of the literature of the hypocretinergic system during REM sleep, and hypothesize a possible role of this system in the generation of REM sleep.
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Affiliation(s)
- Pablo Torterolo
- Laboratorio de Neurobiología del Sueño, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, General Flores 2125, 11800 Montevideo, Uruguay
| | - Michael H. Chase
- WebSciences International, Los Angeles, USA
- UCLA School of Medicine, Los Angeles, USA
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Chase MH. Motor control during sleep and wakefulness: Clarifying controversies and resolving paradoxes. Sleep Med Rev 2013; 17:299-312. [DOI: 10.1016/j.smrv.2012.09.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 08/29/2012] [Accepted: 09/12/2012] [Indexed: 11/16/2022]
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Torterolo P, Sampogna S, Chase MH. Hypocretinergic and non-hypocretinergic projections from the hypothalamus to the REM sleep executive area of the pons. Brain Res 2013; 1491:68-77. [PMID: 23122879 PMCID: PMC3529971 DOI: 10.1016/j.brainres.2012.10.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/19/2012] [Accepted: 10/25/2012] [Indexed: 12/28/2022]
Abstract
Within the postero-lateral hypothalamus neurons that utilize hypocretin or melanin-concentrating hormone (MCH) as neuromodulators are co-distributed. These neurons have been involved in the control of behavioral states, and a deficit in the hypocretinergic system is the pathogenic basis of narcolepsy with cataplexy. In this report, utilizing immunohistochemistry and retrograde tracing techniques, we examined the hypocretinergic innervation of the nucleus pontis oralis (NPO), which is the executive site that is responsible for the generation of REM sleep in the cat. The retrograde tracer cholera toxin subunit b (CTb) was administered in pontine regions where carbachol microinjections induced REM sleep. Utilizing immunohistochemical techniques, we found that approximately 1% of hypocretinergic neurons in the tuberal area of the hypothalamus project to the NPO. In addition, approximately 6% of all CTb+ neurons in this region were hypocretinergic. The hypocretinergic innervation of the NPO was also compared with the innervation of the same site by MCH-containing neurons. More than three times as many MCHergic neurons were found to project to the NPO compared with hypocretinergic cells; both neuronal types exhibited bilateral projections. We also identified a group of non-hypocretinergic non-MCHergic neuronal group of neurons that were intermingled with both hypocretinergic and MCHergic neurons that also projected to this same brainstem region. These neurons were grater in number that either hypocretin or MCH-containing neurons; their soma size was also smaller and their projections were mainly ipsilateral. The present anatomical data suggest that hypocretinergic, MCHergic and an unidentified companion group of neurons of the postero-lateral hypothalamus participate in the regulation of the neuronal activity of NPO neurons, and therefore, are likely to participate in the control of wakefulness and REM sleep.
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Affiliation(s)
- Pablo Torterolo
- Laboratorio de Neurobiología del Sueño, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, General Flores 2125, Montevideo, Uruguay.
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10
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Xi M, Fung SJ, Zhang J, Sampogna S, Chase MH. The amygdala and the pedunculopontine tegmental nucleus: Interactions controlling active (rapid eye movement) sleep. Exp Neurol 2012; 238:44-51. [DOI: 10.1016/j.expneurol.2012.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 07/23/2012] [Accepted: 08/01/2012] [Indexed: 11/28/2022]
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11
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Xi M, Fung SJ, Sampogna S, Chase MH. Excitatory projections from the amygdala to neurons in the nucleus pontis oralis in the rat: an intracellular study. Neuroscience 2011; 197:181-90. [PMID: 21955600 DOI: 10.1016/j.neuroscience.2011.09.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/25/2011] [Accepted: 09/11/2011] [Indexed: 11/20/2022]
Abstract
There is a consensus that active (REM) sleep (AS) is controlled by cholinergic projections from the laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT) to neurons in the nucleus pontis oralis (NPO) that generate AS (i.e. AS-Generator neurons). The present study was designed to provide evidence that other projections to the NPO, such as those from the amygdala, are also capable of inducing AS. Accordingly, the responses of neurons, recorded intracellularly in the NPO, were examined following stimulation of the ipsilateral central nucleus of the amygdala (CNA) in urethane-anesthetized rats. Single pulse stimulation in the CNA produced an early, fast depolarizing potential (EPSP) in neurons within the NPO. The mean latency to the onset of these excitatory postsynaptic potentials (EPSPs) was 3.6±0.2 ms. A late, small-amplitude inhibitory synaptic potential (IPSP) was present following EPSPs in a portion of the NPO neurons. Following stimulation of the CNA with a train of 8-10 pulses, NPO neurons exhibited a sustained depolarization (5-10 mV) of their resting membrane potential. When single subthreshold intracellular depolarizing current pulses were delivered to NPO neurons, CNA-induced EPSPs were sufficient to promote the discharge of these cells. Stimulation of the CNA with a short train of stimuli induced potent temporal facilitation of EPSPs in NPO neurons. Two forms of synaptic plasticity were revealed by the patterns of response of NPO neurons following stimulation of the CNA: paired-pulse facilitation (PPF) and post-tetanic potentiation (PTP). Six of recorded NPO neurons were identified morphologically with neurobiotin. They were medium to large, multipolar cells with diameters >20 μM, which resemble AS-on cells in the NPO. The present results demonstrate that amygdalar projections are capable of exerting a powerful excitatory postsynaptic drive that activates NPO neurons. Therefore, we suggest that the amygdala is capable of inducing AS via direct projections to AS-Generator neurons in the NPO.
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Affiliation(s)
- M Xi
- WebSciences International, Los Angeles, CA 90024, USA.
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12
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Cid-Pellitero ED, Garzon M. Hypocretin1/OrexinA Axon Targeting of Laterodorsal Tegmental Nucleus Neurons Projecting to the Rat Medial Prefrontal Cortex. Cereb Cortex 2011; 21:2762-73. [DOI: 10.1093/cercor/bhr070] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Affiliation(s)
- Adrian R Morrison
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Xi M, Chase MH. The injection of hypocretin-1 into the nucleus pontis oralis induces either active sleep or wakefulness depending on the behavioral state when it is administered. Sleep 2010; 33:1236-43. [PMID: 20857871 DOI: 10.1093/sleep/33.9.1236] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
STUDY OBJECTIVES We previously reported that the microinjection of hypocretin (orexin) into the nucleus pontis oralis (NPO) induces a behavioral state that is comparable to naturally occurring active (rapid eye movement) sleep. However, other laboratories have found that wakefulness occurs following injections of hypocretin into the NPO. The present study tested the hypothesis that the discrepancy in behavioral state responses to hypocretin injections is due to the fact that hypocretin was not administered during the same states of sleep or wakefulness. DESIGN Adult cats were implanted with electrodes to record sleep and waking states. Hypocretin-1 (0.25 microL, 500microM) was microinjected into the NPO while the animals were awake or in quiet (non-rapid eye movement) sleep. MEASUREMENTS AND RESULTS When hyprocretin-1 was microinjected into the NPO during quiet sleep, active sleep occurred with a short latency. In addition, there was a significant increase in the time spent in active sleep and in the number of episodes of this state. On the other hand, the injection of hyprocretin-1 during wakefulness resulted not only in a significant increase in wakefulness, but also in a decrease in the percentage and frequency of episodes of active sleep. CONCLUSIONS The present data demonstrate that the behavioral state of the animal dictates whether active sleep or wakefulness is induced following the injection of hypocretin. Therefore, we suggest that hypocretin-1 enhances ongoing states of wakefulness and their accompanying patterns of physiologic activity and that hypocretin-1 is also capable of promoting active sleep and the changes in various processes that occur during this state.
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Affiliation(s)
- Mingchu Xi
- WebSciences International, Los Angeles, CA 90024, USA.
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Dergacheva O, Wang X, Lovett-Barr MR, Jameson H, Mendelowitz D. The lateral paragigantocellular nucleus modulates parasympathetic cardiac neurons: a mechanism for rapid eye movement sleep-dependent changes in heart rate. J Neurophysiol 2010; 104:685-94. [PMID: 20484535 DOI: 10.1152/jn.00228.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rapid eye movement (REM) sleep is generally associated with a withdrawal of parasympathetic activity and heart rate increases; however, episodic vagally mediated heart rate decelerations also occur during REM sleep. This alternating pattern of autonomic activation provides a physiological basis for REM sleep-induced cardiac arrhythmias. Medullary neurons within the lateral paragigantocellular nucleus (LPGi) are thought to be active after REM sleep recovery and play a role in REM sleep control. In proximity to the LPGi are parasympathetic cardiac vagal neurons (CVNs) within the nucleus ambiguus (NA), which are critical for controlling heart rate. This study examined brain stem pathways that may mediate REM sleep-related reductions in parasympathetic cardiac activity. Electrical stimulation of the LPGi evoked inhibitory GABAergic postsynaptic currents in CVNs in an in vitro brain stem slice preparation in rats. Because brain stem cholinergic mechanisms are involved in REM sleep regulation, we also studied the role of nicotinic neurotransmission in modulation of GABAergic pathway from the LGPi to CVNs. Application of nicotine diminished the GABAergic responses evoked by electrical stimulation. This inhibitory effect of nicotine was prevented by the alpha7 nicotinic receptor antagonist alpha-bungarotoxin. Moreover, hypoxia/hypercapnia (H/H) diminished LPGi-evoked GABAergic current in CVNs, and this inhibitory effect was also prevented by alpha-bungarotoxin. In conclusion, stimulation of the LPGi evokes an inhibitory pathway to CVNs, which may constitute a mechanism for the reduced parasympathetic cardiac activity and increase in heart rate during REM sleep. Inhibition of this pathway by nicotinic receptor activation and H/H may play a role in REM sleep-related and apnea-associated bradyarrhythmias.
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Affiliation(s)
- Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037, USA.
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Xi MC, Chase MH. Neuronal mechanisms of active (rapid eye movement) sleep induced by microinjections of hypocretin into the nucleus pontis oralis of the cat. Neuroscience 2006; 140:335-42. [PMID: 16533574 DOI: 10.1016/j.neuroscience.2006.01.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 01/18/2006] [Accepted: 01/26/2006] [Indexed: 10/24/2022]
Abstract
Hypocretinergic (orexinergic) neurons in the hypothalamus project to the nucleus pontis oralis, a nucleus which plays a crucial role in the generation of active (rapid eye movement) sleep. We recently reported that the microinjection of hypocretin into the nucleus pontis oralis of chronically-instrumented, unanesthetized cats induces a behavioral state that is comparable to naturally-occurring active sleep. The present study examined the intracellular signaling pathways underlying the active sleep-inducing effects of hypocretin. Accordingly, hypocretin-1, a protein kinase C inhibitor and a protein kinase A inhibitor were injected into the nucleus pontis oralis in selected combinations in order to determine their effects on sleep and waking states of chronically instrumented, unanesthetized cats. Microinjections of hypocretin-1 into the nucleus pontis oralis elicited active sleep with a short latency. However, a pre-injection of bisindolylmaleimide-I, a protein kinase C-specific inhibitor, completely blocked the active sleep-inducing effects of hypocretin-1. The combined injection of bisindolylmaleimide-I and hypocretin-1 significantly increased the latency to active sleep induced by hypocretin-1; it also abolished the increase in the time spent in active sleep induced by hypocretin-1. On the other hand, the injection of 2'5'-dideoxyadenosine, an adenylyl cyclase inhibitor, did not block the occurrence of active sleep by hypocretin-1. We conclude that the active sleep-inducing effect of hypocretin in the nucleus pontis oralis is mediated by intracellular signaling pathways that act via G-protein stimulation of protein kinase C.
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Affiliation(s)
- M-C Xi
- WebSciences International, 1251 Westwood Boulevard, Los Angeles, CA 90024, USA
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17
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Takakusaki K, Takahashi K, Saitoh K, Harada H, Okumura T, Kayama Y, Koyama Y. Orexinergic projections to the cat midbrain mediate alternation of emotional behavioural states from locomotion to cataplexy. J Physiol 2005; 568:1003-20. [PMID: 16123113 PMCID: PMC1464186 DOI: 10.1113/jphysiol.2005.085829] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Orexinergic neurones in the perifornical lateral hypothalamus project to structures of the midbrain, including the substantia nigra and the mesopontine tegmentum. These areas contain the mesencephalic locomotor region (MLR), and the pedunculopontine and laterodorsal tegmental nuclei (PPN/LDT), which regulate atonia during rapid eye movement (REM) sleep. Deficiencies of the orexinergic system result in narcolepsy, suggesting that these projections are concerned with switching between locomotor movements and muscular atonia. The present study characterizes the role of these orexinergic projections to the midbrain. In decerebrate cats, injecting orexin-A (60 microm to 1.0 mm, 0.20-0.25 microl) into the MLR reduced the intensity of the electrical stimulation required to induce locomotion on a treadmill (4 cats) or even elicit locomotor movements without electrical stimulation (2 cats). On the other hand, when orexin was injected into either the PPN (8 cats) or the substantia nigra pars reticulata (SNr, 4 cats), an increased stimulus intensity at the PPN was required to induce muscle atonia. The effects of orexin on the PPN and the SNr were reversed by subsequently injecting bicuculline (5 mm, 0.20-0.25 microl), a GABA(A) receptor antagonist, into the PPN. These findings indicate that excitatory orexinergic drive could maintain a higher level of locomotor activity by increasing the excitability of neurones in the MLR, while enhancing GABAergic effects on presumably cholinergic PPN neurones, to suppress muscle atonia. We conclude that orexinergic projections from the hypothalamus to the midbrain play an important role in regulating motor behaviour and controlling postural muscle tone and locomotor movements when awake and during sleep. Furthermore, as the excitability is attenuated in the absence of orexin, signals to the midbrain may induce locomotor behaviour when the orexinergic system functions normally but elicit atonia or narcolepsy when the orexinergic function is disturbed.
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Affiliation(s)
- Kaoru Takakusaki
- Department of Physiology, Asahikawa Medical College, Midorigaoka-higashi 2-1, Asahikawa 078-8510, Japan
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