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Wang J, Yan Z, Dong X, Li J, Zhao L, Zhang X, Lv C, Zhao Z, Strohl KP, Han F. Diurnal changes in blood pressure and heart rate in children with narcolepsy with cataplexy. J Sleep Res 2023; 32:e13736. [PMID: 36163423 DOI: 10.1111/jsr.13736] [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: 03/23/2020] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 11/27/2022]
Abstract
The hypocretin neurons in the lateral hypothalamus are connected not only to brain alertness systems but also to brainstem nuclei that regulate blood pressure and heart rate. The premise is that regulation of blood pressure and heart rate is altered and affected by methylphenidate, a stimulant drug in children with narcolepsy with cataplexy. The changes in 24-hr ambulatory systolic and diastolic blood pressure and heart rate were compared among pre-treated narcolepsy with cataplexy patients (40 males, 10 females), with mean age 10.4 ± 3.5 years (M ± SD, range 5-17 years) with values from 100 archival age-sex-body mass index matched controls. Patients had a lower diurnal systolic blood pressure (-6.5 mmHg; p = 0.000) but higher heart rate (+11.0 bpm; p = 0.000), particularly evident in the waketime, while diastolic blood pressure was comparable. With methylphenidate (18 mg sustained release at 08:00 hours), patients with narcolepsy with cataplexy had higher systolic blood pressure (+4.6 mmHg, p = 0.015), diastolic blood pressure (+3.3 mmHg, p = 0.005) and heart rate (+7.1 bpm, p = 0.028) during wake time, but nighttime cardiovascular values were unchanged from pre-treated values; amplitude variation in cardiovascular values was unchanged over 24 hr. In conclusion, children with narcolepsy with cataplexy had downregulation blood pressure profile but a higher heart rate, and lesser non-dipping profiles. Daytime methylphenidate treatment increases only waketime blood pressure and further elevated heart rate values.
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Affiliation(s)
- Jingyu Wang
- Division of Sleep Medicine, Peking University People's Hospital, Beijing, China.,Department of Respiratory and Critical Care Medicine, Binzhou Medical University Hospital, Binzhou, China
| | - Zhihui Yan
- Institute of Materia Medica, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinnan, China
| | - Xiaosong Dong
- Division of Sleep Medicine, Peking University People's Hospital, Beijing, China
| | - Jing Li
- Division of Sleep Medicine, Peking University People's Hospital, Beijing, China
| | - Long Zhao
- Division of Sleep Medicine, Peking University People's Hospital, Beijing, China
| | - Xueli Zhang
- Division of Sleep Medicine, Peking University People's Hospital, Beijing, China
| | - Changjun Lv
- Department of Respiratory and Critical Care Medicine, Binzhou Medical University Hospital, Binzhou, China
| | - Ziyan Zhao
- Institute of Materia Medica, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinnan, China
| | - Kingman P Strohl
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University, and Cleveland Louis Stokes VA Medical Center, Cleveland, Ohio, USA
| | - Fang Han
- Division of Sleep Medicine, Peking University People's Hospital, Beijing, China
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2
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Wang Y, Sun Q, Tang Q, Zhang Y, Tang M, Wang D, Wang Z. Progress of autonomic disturbances in narcolepsy type 1. Front Neurol 2023; 14:1107632. [PMID: 36949858 PMCID: PMC10025459 DOI: 10.3389/fneur.2023.1107632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 02/03/2023] [Indexed: 03/08/2023] Open
Abstract
Narcolepsy type 1 is a kind of sleep disorder characterized by a specific loss of hypocretin neurons in the lateral hypothalamus and reduced levels of hypocretin-1 in the cerebrospinal fluid. Hypocretin deficiency is associated with autonomic disorders. This article summarizes the autonomic disorders and possible mechanisms associated with narcolepsy type 1. Patients with narcolepsy type 1 often have various systemic autonomic symptoms, including non-dipping blood pressure, reduced heart rate variability, dynamic cerebral autoregulation impairment, reduced gastric motility and emptying, sleep-related erectile dysfunction, skin temperature abnormalities, and blunted pupillary light reflex. Similar findings should strengthen the recognition and intervention of these disturbances in clinical practice. In addition to hypocretin deficiency, current evidence also indicates that pharmacological therapy (including psychostimulants and anti-cataplectic drugs) and comorbidities may contribute to the alterations of autonomic system observed in narcolepsy type 1.
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Kim H, Jung HR, Kim JB, Kim DJ. Autonomic Dysfunction in Sleep Disorders: From Neurobiological Basis to Potential Therapeutic Approaches. J Clin Neurol 2022; 18:140-151. [PMID: 35274834 PMCID: PMC8926769 DOI: 10.3988/jcn.2022.18.2.140] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/20/2021] [Accepted: 12/20/2021] [Indexed: 11/25/2022] Open
Abstract
Sleep disorder has been portrayed as merely a common dissatisfaction with sleep quality and quantity. However, sleep disorder is actually a medical condition characterized by inconsistent sleep patterns that interfere with emotional dynamics, cognitive functioning, and even physical performance. This is consistent with sleep abnormalities being more common in patients with autonomic dysfunction than in the general population. The autonomic nervous system coordinates various visceral functions ranging from respiration to neuroendocrine secretion in order to maintain homeostasis of the body. Because the cell population and efferent signals involved in autonomic regulation are spatially adjacent to those that regulate the sleep-wake system, sleep architecture and autonomic coordination exert effects on each other, suggesting the presence of a bidirectional relationship in addition to shared pathology. The primary goal of this review is to highlight the bidirectional and shared relationship between sleep and autonomic regulation. It also introduces the effects of autonomic dysfunction on insomnia, breathing disorders, central disorders of hypersomnolence, parasomnias, and movement disorders. This information will assist clinicians in determining how neuromodulation can have the greatest therapeutic effects in patients with sleep disorders.
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Affiliation(s)
- Hakseung Kim
- Department of Brain and Cognitive Engineering, Korea University, Seoul, Korea
| | - Hee Ra Jung
- Department of Psychological and Brain Sciences, Washington University in St. Louis, St. Louis, MO, USA
| | - Jung Bin Kim
- Department of Neurology, Korea University College of Medicine, Seoul, Korea
| | - Dong-Joo Kim
- Department of Brain and Cognitive Engineering, Korea University, Seoul, Korea
- Department of Neurology, Korea University College of Medicine, Seoul, Korea
- Department of Artificial Intelligence, Korea University, Seoul, Korea
- NeuroTx, Co., Ltd., Seoul, Korea
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4
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Orjatsalo M, Partinen E, Wallukat G, Alakuijala A, Partinen M. Activating autoantibodies against G protein-coupled receptors in narcolepsy type 1. Sleep Med 2020; 77:82-87. [PMID: 33341642 DOI: 10.1016/j.sleep.2020.11.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 11/26/2020] [Accepted: 11/29/2020] [Indexed: 12/01/2022]
Abstract
STUDY OBJECTIVES Narcolepsy type 1 is a rare hypersomnia of central origin, which is caused by loss of hypothalamic neurons that produce the neuropeptides hypocretin-1 and -2. Hypocretin-containing nerve terminals are found in areas known to play a central role in autonomic control and in pain signaling. Cholinergic M2 receptors are found in brain areas involved with the occurrence of hallucinations and cataplexy. In addition to classical symptoms of narcolepsy, the patients suffer frequently from autonomic dysfunction, chronic pain, and hypnagogic/hypnopompic hallucinations. We aimed to test whether narcolepsy type 1 patients have autoantibodies against autonomic β2 adrenergic receptor, M2 muscarinic receptors, or nociception receptors. METHODS We tested the serum of ten narcolepsy type 1 patients (five female) for activating β2 adrenergic receptor autoantibodies, M2 muscarinic receptor autoantibodies, and nociception receptor autoantibodies. RESULTS Ten of ten patients were positive for muscarinic M2 receptor autoantibodies (P < 0.001), 9/10 were positive for autoantibodies against nociception receptors (P < 0.001), and 5/10 were positive for β2 adrenergic receptor autoantibodies (P < 0.001). CONCLUSIONS Narcolepsy type 1 patients harbored activating autoantibodies against M2 muscarinic receptors, nociception receptors, and β2 adrenergic receptors. M2 receptor autoantibodies may be related to the occurrence of cataplexy and, moreover, hallucinations in narcolepsy since they are found in the same brain areas that are involved with these symptoms. The occurrence of nociception receptor autoantibodies strengthens the association between narcolepsy type 1 and pain. The connection between narcolepsy type 1, autonomic complaints, and the presumed cardiovascular morbidity might be associated with the occurrence of β2 adrenergic receptor autoantibodies. On the other hand, the presence of the autoantibodies may be secondary to the destruction of the hypocretin pathways.
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Affiliation(s)
- Maija Orjatsalo
- Department of Clinical Neurophysiology, HUS Medical Imaging Center, Helsinki University Hospital, Finland; Department of Neurological Sciences, University of Helsinki, Helsinki, Finland.
| | - Eemil Partinen
- Department of Neurological Sciences, University of Helsinki, Helsinki, Finland; Vitalmed Research Center, Helsinki Sleep Clinic, Valimotie 21, 00380, Helsinki, Finland
| | | | - Anniina Alakuijala
- Department of Clinical Neurophysiology, HUS Medical Imaging Center, Helsinki University Hospital, Finland; Department of Neurological Sciences, University of Helsinki, Helsinki, Finland
| | - Markku Partinen
- Department of Neurological Sciences, University of Helsinki, Helsinki, Finland; Vitalmed Research Center, Helsinki Sleep Clinic, Valimotie 21, 00380, Helsinki, Finland
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5
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Amodeo LR, Liu W, Wills DN, Vetreno RP, Crews FT, Ehlers CL. Adolescent alcohol exposure increases orexin-A/hypocretin-1 in the anterior hypothalamus. Alcohol 2020; 88:65-72. [PMID: 32619610 DOI: 10.1016/j.alcohol.2020.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 12/30/2022]
Abstract
Adolescence is a time of marked changes in sleep, neuromaturation, and alcohol use. While there is substantial evidence that alcohol disrupts sleep and that disrupted sleep may play a role in the development of alcohol use disorders (AUD), there is very little known about the brain mechanisms underlying this phenomenon. The orexin (also known as hypocretin) system is fundamental for a number of homeostatic mechanisms, including the initiation and maintenance of wakefulness that may be impacted by adolescent alcohol exposure. The current study investigated the impact of adolescent ethanol exposure on adult orexin-A/hypocretin-1 immunoreactive (orexin-A + IR) cells in hypothalamic nuclei in two models of adolescent intermittent ethanol (AIE) exposure. Both models assess adult hypothalamic orexin following either an AIE vapor exposure paradigm, or an AIE intragastric gavage paradigm during adolescence. Both AIE exposure models found that binge levels of ethanol intoxication during adolescence significantly increased adult orexin-A + IR expression in the anterior hypothalamic nucleus (AHN). Further, both AIE models found no change in orexin-A + IR in the posterior hypothalamic area (PH), perifornical nucleus (PeF), dorsomedial hypothalamic nucleus dorsal part (DMD) or lateral hypothalamic area (LH). However, AIE vapor exposure reduced orexin-A + IR in the paraventricular nucleus (PVN), but AIE gavage exposure did not. These findings suggest that the AHN orexinergic system is increased in adults following binge-like patterns of intoxication during adolescence. Altered adult AHN orexin could contribute to long-lasting changes in sleep.
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Affiliation(s)
- Leslie R Amodeo
- Department of Psychology, California State University, San Bernardino, San Bernardino, CA, 92407, United States
| | - Wen Liu
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, United States
| | - Derek N Wills
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, 92037, United States
| | - Ryan P Vetreno
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, United States
| | - Fulton T Crews
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, United States
| | - Cindy L Ehlers
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, 92037, United States.
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Autonomic symptoms, cardiovascular and sudomotor evaluation in de novo type 1 narcolepsy. Clin Auton Res 2020; 30:557-562. [PMID: 32852663 DOI: 10.1007/s10286-020-00718-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/06/2020] [Indexed: 02/03/2023]
Abstract
PURPOSE To evaluate cardiovascular and sudomotor function during wakefulness and to assess autonomic symptoms in de novo patients with type 1 narcolepsy compared to healthy controls. METHODS De novo patients with type 1 narcolepsy (NT1) and healthy controls underwent cardiovascular function tests including head-up tilt test, Valsalva maneuver, deep breathing, hand grip, and cold face, and sudomotor function was assessed through Sudoscan. Autonomic symptoms were investigated using the Scales for Outcomes in Parkinson's Disease-Autonomic Dysfunction (SCOPA-AUT) questionnaire. RESULTS Twelve de novo patients with NT1 and 14 healthy controls were included. In supine rest condition and at 3 min and 10 min head-up tilt test, the systolic blood pressure values were significantly higher in the NT1 group than in controls (p < 0.05). A lower Valsalva ratio (p < 0.01), significantly smaller inspiratory-expiratory difference in deep breathing (p < 0.05), and lower delta heart rate in the cold face test (p < 0.01) were also observed in the NT1 group. The mean hand electrochemical skin conductance values were significantly lower (p < 0.05) and the mean SCOPA-AUT total scores were significantly higher in patients with NT1 than in healthy subjects (p < 0.001), with greater involvement of cardiovascular and thermoregulatory items. CONCLUSION De novo patients with NT1 exhibit blunted parasympathetic activity during wakefulness, mild sudomotor dysfunction, and a large variety of autonomic symptoms.
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Straat ME, Schinkelshoek MS, Fronczek R, Lammers GJ, Rensen PCN, Boon MR. Role of Brown Adipose Tissue in Adiposity Associated With Narcolepsy Type 1. Front Endocrinol (Lausanne) 2020; 11:145. [PMID: 32373062 PMCID: PMC7176868 DOI: 10.3389/fendo.2020.00145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 03/02/2020] [Indexed: 11/23/2022] Open
Abstract
Narcolepsy type 1 is a neurological sleep-wake disorder caused by the destruction of orexin (hypocretin)-producing neurons. These neurons are particularly located in the lateral hypothalamus and have widespread projections throughout the brain, where they are involved, e.g., in the regulation of the sleep-wake cycle and appetite. Interestingly, a higher prevalence of obesity has been reported in patients with narcolepsy type 1 compared to healthy controls, despite a normal to decreased food intake and comparable physical activity. This suggests the involvement of tissues implicated in total energy expenditure, including skeletal muscle, liver, white adipose tissue (WAT), and brown adipose tissue (BAT). Recent evidence from pre-clinical studies with orexin knock-out mice demonstrates a crucial role for the orexin system in the functionality of brown adipose tissue (BAT), probably through multiple pathways. Since BAT is a highly metabolically active organ that combusts fatty acids and glucose toward heat, thereby contributing to energy metabolism, this raises the question of whether BAT plays a role in the development of obesity and related metabolic diseases in narcolepsy type 1. BAT is densely innervated by the sympathetic nervous system that activates BAT, for instance, following cold exposure. The sympathetic outflow toward BAT is mainly mediated by the dorsomedial, ventromedial, arcuate, and paraventricular nuclei in the hypothalamus. This review focuses on the current knowledge on the role of the orexin system in the control of energy balance, with specific focus on BAT metabolism and adiposity in both preclinical and clinical studies.
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Affiliation(s)
- Maaike E. Straat
- Division of Endocrinology, Department of Medicine, Leiden University Medical Center, Leiden, Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, Netherlands
- *Correspondence: Maaike E. Straat
| | - Mink S. Schinkelshoek
- Department of Neurology, Leiden University Medical Center, Leiden, Netherlands
- Sleep Wake Centre SEIN, Heemstede, Netherlands
| | - Rolf Fronczek
- Department of Neurology, Leiden University Medical Center, Leiden, Netherlands
- Sleep Wake Centre SEIN, Heemstede, Netherlands
| | - Gerrit Jan Lammers
- Department of Neurology, Leiden University Medical Center, Leiden, Netherlands
- Sleep Wake Centre SEIN, Heemstede, Netherlands
| | - Patrick C. N. Rensen
- Division of Endocrinology, Department of Medicine, Leiden University Medical Center, Leiden, Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, Netherlands
| | - Mariëtte R. Boon
- Division of Endocrinology, Department of Medicine, Leiden University Medical Center, Leiden, Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, Netherlands
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8
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Aslan S, Erbil N, Tezer FI. Heart Rate Variability During Nocturnal Sleep and Daytime Naps in Patients With Narcolepsy Type 1 and Type 2. J Clin Neurophysiol 2019; 36:104-111. [DOI: 10.1097/wnp.0000000000000544] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Enevoldsen LH, Tindborg M, Hovmand NL, Christoffersen C, Ellingsgaard H, Suetta C, Stallknecht BM, Jennum PJ, Kjær A, Gammeltoft S. Functional brown adipose tissue and sympathetic activity after cold exposure in humans with type 1 narcolepsy. Sleep 2018; 41:4996398. [DOI: 10.1093/sleep/zsy092] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lotte Hahn Enevoldsen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Denmark
| | - Marie Tindborg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | | | - Christina Christoffersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
- Department of Clinical Biochemistry, Rigshospitalet, Denmark
| | | | - Charlotte Suetta
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Denmark
| | - Bente Merete Stallknecht
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | | | - Andreas Kjær
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
- Cluster for Molecular Imaging, Rigshospitalet and University of Copenhagen, Denmark
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Antelmi E, Plazzi G, Pizza F, Vandi S, Aricò D, Ferri R. Impact of acute administration of sodium oxybate on heart rate variability in children with type 1 narcolepsy. Sleep Med 2018; 47:1-6. [PMID: 29880141 DOI: 10.1016/j.sleep.2018.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 01/25/2023]
Abstract
BACKGROUND Currently, cardiovascular measurements in children affected with type 1 narcolepsy (NT1) have never been investigated, and neither have their modulation by the administration of sodium oxybate (SO). METHODS Twelve drug-naïve NT1 children (four males, eight females) with a mean age of 11 ± 3.16 years underwent a nocturnal polysomnography, at baseline and during the first night of SO administration. Data were contrasted with those recorded in 23 age-matched healthy controls. Heart rate variability (HRV) analysis was performed by analyzing the electrocardiogram signal for automatic detection of R waves with a computer program calculating a series of standard time-domain measures and obtaining spectral parameters, by means of a Fast-Fourier Transform. RESULTS In sleep stages N2 and N3, NT1 children showed increased power in the low-frequency (LF) and very-LF (VLF) ranges, when compared to controls. In addition, HRV (as measured by time domain parameters) during all sleep stages tended to be slightly higher in patients when compared to controls. Treatment with SO did not change significantly any parameter, but an overall trend to mildly decreased HRV that reached a significant value only during R sleep. CONCLUSIONS HRV during all sleep stages tended to be slightly higher in young patients when compared to controls, confirming the presence of a slight sympathovagal system imbalance even in NT1 children. SO tends to decrease these values especially during REM sleep and in that regard, further studies supporting these preliminary findings and considering the long-term effects of SO on heart rate parameters are warranted.
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Affiliation(s)
- Elena Antelmi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy.
| | - Giuseppe Plazzi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Fabio Pizza
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Stefano Vandi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Debora Aricò
- Sleep Research Centre, Department of Neurology I.C., Oasi Institute IRCCS, Troina, Italy
| | - Raffaele Ferri
- Sleep Research Centre, Department of Neurology I.C., Oasi Institute IRCCS, Troina, Italy
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11
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Sieminski M, Chwojnicki K, Sarkanen T, Partinen M. The relationship between orexin levels and blood pressure changes in patients with narcolepsy. PLoS One 2017; 12:e0185975. [PMID: 29023559 PMCID: PMC5638315 DOI: 10.1371/journal.pone.0185975] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 09/24/2017] [Indexed: 11/18/2022] Open
Abstract
STUDY OBJECTIVE Narcolepsy type 1 (NT1) is caused by a deficiency or absence of the neurotransmitter orexin. NT1 is also associated with a reduced nocturnal "dipping" of blood pressure (BP). The study objective was to analyze whether nocturnal BP values differed in patients depleted of orexin, versus those in whom production was preserved. METHODS We performed a retrospective analysis of the polysomnographic recordings, orexin levels, and BP values of patients with NT1. Data was collected from a total of 21 patients, divided into two groups as follows: those with a complete depletion of orexin (n = 11) (Group1), and those with a remaining, limited presence of orexin (n = 10) (Group 2). RESULTS The groups did not differ in terms of the clinical features of NT1 or sleep characteristics, with an exception of increased number of cataplexy episodes and increased percentage of sleep stage 2 in the Group 1. Daytime and nocturnal BP did not differ between the groups. Most patients, regardless of group, had a non-dipping blood pressure pattern, and no difference in dipping prevalence was observed between groups. The amplitude of the daytime to nighttime change in BP did not differ between the groups. CONCLUSIONS Non-dipping BP patterns are frequent among patients with narcolepsy type 1, but we saw no evidence that they depended on whether orexin levels were above or below the assay detection threshold. Therefore, our results do not support the hypothesis that in patients with narcolepsy type 1 residual orexin levels play a role in the control of nocturnal BP dipping.
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Affiliation(s)
- Mariusz Sieminski
- Department of Adults’ Neurology, Medical University of Gdansk, Gdansk, Poland
- * E-mail:
| | - Kamil Chwojnicki
- Department of Adults’ Neurology, Medical University of Gdansk, Gdansk, Poland
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12
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The link between narcolepsy and autonomic cardiovascular dysfunction: a translational perspective. Clin Auton Res 2017; 28:545-555. [DOI: 10.1007/s10286-017-0473-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/25/2017] [Indexed: 01/09/2023]
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13
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Silvani A. Orexins and the cardiovascular events of awakening. Temperature (Austin) 2017; 4:128-140. [PMID: 28680929 DOI: 10.1080/23328940.2017.1295128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 02/09/2017] [Accepted: 02/09/2017] [Indexed: 10/20/2022] Open
Abstract
This brief review aims to provide an updated account of the cardiovascular events of awakening, proposing a testable conceptual framework that links these events with the neural control of sleep and the autonomic nervous system, with focus on the hypothalamic orexin (hypocretin) neurons. Awakening from non-rapid-eye-movement sleep entails coordinated changes in brain and cardiovascular activity: the neural "flip-flop" switch that governs state transitions becomes biased toward the ascending arousal systems, arterial blood pressure and heart rate rise toward waking values, and distal skin temperature falls. Arterial blood pressure and skin temperature are sensed by baroreceptors and thermoreceptors and may positively feedback on the brain wake-sleep switch, thus contributing to sharpen, coordinate, and stabilize awakening. These effects may be enhanced by the hypothalamic orexin neurons, which may modulate the changes in blood pressure, heart rate, and skin temperature upon awakening, while biasing the wake-sleep switch toward wakefulness through direct neural projections. A deeper understanding of the cardiovascular events of awakening and of their links with skin temperature and the wake-sleep neural switch may lead to better treatments options for patients with narcolepsy type 1, who lack the orexin neurons.
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Affiliation(s)
- Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
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14
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Abstract
Narcolepsy is a chronic sleep disorder that has a typical onset in adolescence and is characterized by excessive daytime sleepiness, which can have severe consequences for the patient. Problems faced by patients with narcolepsy include social stigma associated with this disease, difficulties in obtaining an education and keeping a job, a reduced quality of life and socioeconomic consequences. Two subtypes of narcolepsy have been described (narcolepsy type 1 and narcolepsy type 2), both of which have similar clinical profiles, except for the presence of cataplexy, which occurs only in patients with narcolepsy type 1. The pathogenesis of narcolepsy type 1 is hypothesized to be the autoimmune destruction of the hypocretin-producing neurons in the hypothalamus; this hypothesis is supported by immune-related genetic and environmental factors associated with the disease. However, direct evidence in support of the autoimmune hypothesis is currently unavailable. Diagnosis of narcolepsy encompasses clinical, electrophysiological and biological evaluations, but simpler and faster procedures are needed. Several medications are available for the symptomatic treatment of narcolepsy, all of which have quite good efficacy and safety profiles. However, to date, no treatment hinders or slows disease development. Improved diagnostic tools and increased understanding of the pathogenesis of narcolepsy type 1 are needed and might lead to therapeutic or even preventative interventions.
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Affiliation(s)
- Birgitte R Kornum
- Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Forskerparken, Nordre Ringvej 69, 2600 Glostrup, Denmark.,Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark
| | - Stine Knudsen
- Norwegian Centre of Expertise for Neurodevelopmental Disorders and Hypersomnias, Oslo University Hospital, Oslo, Norway
| | - Hanna M Ollila
- Department of Psychiatry and Behavioral Sciences, Center for Sleep Sciences, Stanford University, Stanford, California, USA
| | - Fabio Pizza
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, AUSL di Bologna, Bologna, Italy
| | - Poul J Jennum
- Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark
| | - Yves Dauvilliers
- Sleep Unit, Narcolepsy Reference Center, Department of Neurology, Gui de Chauliac Hospital, INSERM 1061, Montpellier, France
| | - Sebastiaan Overeem
- Sleep Medicine Center Kempenhaeghe, Heeze, The Netherlands.,Department of Industrial Design, Eindhoven University of Technology, Eindhoven, The Netherlands
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15
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Dergacheva O, Yamanaka A, Schwartz AR, Polotsky VY, Mendelowitz D. Optogenetic identification of hypothalamic orexin neuron projections to paraventricular spinally projecting neurons. Am J Physiol Heart Circ Physiol 2017; 312:H808-H817. [PMID: 28159808 DOI: 10.1152/ajpheart.00572.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 01/31/2017] [Accepted: 01/31/2017] [Indexed: 02/07/2023]
Abstract
Orexin neurons, and activation of orexin receptors, are generally thought to be sympathoexcitatory; however, the functional connectivity between orexin neurons and a likely sympathetic target, the hypothalamic spinally projecting neurons (SPNs) in the paraventricular nucleus of the hypothalamus (PVN) has not been established. To test the hypothesis that orexin neurons project directly to SPNs in the PVN, channelrhodopsin-2 (ChR2) was selectively expressed in orexin neurons to enable photoactivation of ChR2-expressing fibers while examining evoked postsynaptic currents in SPNs in rat hypothalamic slices. Selective photoactivation of orexin fibers elicited short-latency postsynaptic currents in all SPNs tested (n = 34). These light-triggered responses were heterogeneous, with a majority being excitatory glutamatergic responses (59%) and a minority of inhibitory GABAergic (35%) and mixed glutamatergic and GABAergic currents (6%). Both glutamatergic and GABAergic responses were present in the presence of tetrodotoxin and 4-aminopyridine, suggesting a monosynaptic connection between orexin neurons and SPNs. In addition to generating postsynaptic responses, photostimulation facilitated action potential firing in SPNs (current clamp configuration). Glutamatergic, but not GABAergic, postsynaptic currents were diminished by application of the orexin receptor antagonist almorexant, indicating orexin release facilitates glutamatergic neurotransmission in this pathway. This work identifies a neuronal circuit by which orexin neurons likely exert sympathoexcitatory control of cardiovascular function.NEW & NOTEWORTHY This is the first study to establish, using innovative optogenetic approaches in a transgenic rat model, that there are robust heterogeneous projections from orexin neurons to paraventricular spinally projecting neurons, including excitatory glutamatergic and inhibitory GABAergic neurotransmission. Endogenous orexin release modulates glutamatergic, but not GABAergic, neurotransmission in these pathways.
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Affiliation(s)
- Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, Washington, District of Columbia;
| | - Akihiro Yamanaka
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Alan R Schwartz
- Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, Washington, District of Columbia
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16
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Sforza E, Roche F, Barthélémy JC, Pichot V. Diurnal and nocturnal cardiovascular variability and heart rate arousal response in idiopathic hypersomnia. Sleep Med 2016; 24:131-136. [PMID: 27810179 DOI: 10.1016/j.sleep.2016.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Autonomic nervous system dysfunction has been described in narcolepsy with cataplexy affecting sympathetic functions. In this study we analyzed whether altered diurnal and nocturnal cardiovascular control is present in idiopathic hypersomnia (IH). METHODS Fourteen drug-free patients aged 26.2 ± 7 years and 14 age-matched controls were examined. Clinical data, 24-h polysomnography, heart rate (HR) variability, and the HR response to spontaneous arousal were available. RESULTS Sleep macrostructure was comparable between controls and patients, with the latter having significantly longer sleep time, a higher number of sleep cycles (p < 0.0001), and low sleep efficiency (p < 0.01). The HR variability indices did not differ between groups, except for the rise of high frequency (HF) and HFnu in patients (p < 0.05) associated with blunted sympathetic indices (p < 0.01). These parasympathetic alterations were present for light, slow wave, and rapid eye-movement sleep and persisted for all sleep cycles. Compared to controls, the HR arousal response was significantly higher (p < 0.01) in patients starting before the arousal onset and persisting into the post-arousal period. CONCLUSIONS In IH patients a dysfunction of the parasympathetic activity during awake and sleep and an altered autonomic response to arousals are present. These findings suggest an impaired parasympathetic function that may explain some vegetative symptoms present in this type of central hypersomnia.
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Affiliation(s)
- Emilia Sforza
- Service de Physiologie Clinique et de l'Exercice (Pole Hospitalier NOL), CHU Nord, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, Saint-Etienne, SNA EPIS EA 4607, PRES de Lyon, France.
| | - Frédéric Roche
- Service de Physiologie Clinique et de l'Exercice (Pole Hospitalier NOL), CHU Nord, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, Saint-Etienne, SNA EPIS EA 4607, PRES de Lyon, France
| | - Jean Claude Barthélémy
- Service de Physiologie Clinique et de l'Exercice (Pole Hospitalier NOL), CHU Nord, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, Saint-Etienne, SNA EPIS EA 4607, PRES de Lyon, France
| | - Vincent Pichot
- Service de Physiologie Clinique et de l'Exercice (Pole Hospitalier NOL), CHU Nord, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, Saint-Etienne, SNA EPIS EA 4607, PRES de Lyon, France
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17
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Calandra-Buonaura G, Provini F, Guaraldi P, Plazzi G, Cortelli P. Cardiovascular autonomic dysfunctions and sleep disorders. Sleep Med Rev 2016; 26:43-56. [DOI: 10.1016/j.smrv.2015.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/08/2015] [Accepted: 05/25/2015] [Indexed: 10/23/2022]
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18
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Joustra SD, Reijntjes RH, Pereira AM, Lammers GJ, Biermasz NR, Thijs RD. The Role of the Suprachiasmatic Nucleus in Cardiac Autonomic Control during Sleep. PLoS One 2016; 11:e0152390. [PMID: 27010631 PMCID: PMC4807027 DOI: 10.1371/journal.pone.0152390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 03/14/2016] [Indexed: 01/21/2023] Open
Abstract
Background The suprachiasmatic nucleus (SCN) may play an important role in central autonomic control, since its projections connect to (para)sympathetic relay stations in the brainstem and spinal cord. The cardiac autonomic modifications during nighttime may therefore not only result from direct effects of the sleep-related changes in the central autonomic network, but also from endogenous circadian factors as directed by the SCN. To explore the influence of the SCN on autonomic fluctuations during nighttime, we studied heart rate and its variability (HRV) in a clinical model of SCN damage. Methods Fifteen patients in follow-up after surgical treatment for nonfunctioning pituitary macroadenoma (NFMA) compressing the optic chiasm (8 females, 26–65 years old) and fifteen age-matched healthy controls (5 females, 30–63 years) underwent overnight ambulatory polysomnography. Eleven patients had hypopituitarism and received adequate replacement therapy. HRV was calculated for each 30-second epoch and corrected for sleep stage, arousals, and gender using mixed effect regression models. Results Compared to controls, patients spent more time awake after sleep onset and in NREM1-sleep, and less in REM-sleep. Heart rate, low (LF) and high frequency (HF) power components and the LF/HF ratio across sleep stages were not significantly different between groups. Conclusions These findings suggest that the SCN does not play a dominant role in cardiac autonomic control during sleep.
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Affiliation(s)
- S. D. Joustra
- Department of Medicine, Division of Endocrinology, Centre for Endocrine Tumours Leiden, Leiden University Medical Centre, Leiden, Netherlands
- * E-mail:
| | - R. H. Reijntjes
- Department of Neurology, Leiden University Medical Centre, Leiden, Netherlands
| | - A. M. Pereira
- Department of Medicine, Division of Endocrinology, Centre for Endocrine Tumours Leiden, Leiden University Medical Centre, Leiden, Netherlands
| | - G. J. Lammers
- Department of Neurology, Leiden University Medical Centre, Leiden, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - N. R. Biermasz
- Department of Medicine, Division of Endocrinology, Centre for Endocrine Tumours Leiden, Leiden University Medical Centre, Leiden, Netherlands
| | - R. D. Thijs
- Department of Neurology, Leiden University Medical Centre, Leiden, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
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19
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Autonomic dysfunction in primary sleep disorders. Sleep Med 2016; 19:40-9. [DOI: 10.1016/j.sleep.2015.10.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/08/2015] [Accepted: 10/12/2015] [Indexed: 11/20/2022]
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20
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Torterolo P, Castro-Zaballa S, Cavelli M, Velasquez N, Brando V, Falconi A, Chase MH, Migliaro ER. Heart rate variability during carbachol-induced REM sleep and cataplexy. Behav Brain Res 2015; 291:72-79. [DOI: 10.1016/j.bbr.2015.05.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/05/2015] [Accepted: 05/09/2015] [Indexed: 12/14/2022]
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21
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van der Meijden WP, te Lindert BHW, Bijlenga D, Coppens JE, Gómez-Herrero G, Bruijel J, Kooij JJS, Cajochen C, Bourgin P, Van Someren EJW. Post-illumination pupil response after blue light: Reliability of optimized melanopsin-based phototransduction assessment. Exp Eye Res 2015. [PMID: 26209783 DOI: 10.1016/j.exer.2015.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Melanopsin-containing retinal ganglion cells have recently been shown highly relevant to the non-image forming effects of light, through their direct projections on brain circuits that regulate alertness, mood and circadian rhythms. A quantitative assessment of functionality of the melanopsin-signaling pathway could be highly relevant in order to mechanistically understand individual differences in the effects of light on these regulatory systems. We here propose and validate a reliable quantification of the melanopsin-dependent Post-Illumination Pupil Response (PIPR) after blue light, and evaluated its sensitivity to dark adaptation, time of day, body posture, and light exposure history. Pupil diameter of the left eye was continuously measured during a series of light exposures to the right eye, of which the pupil was dilated using tropicamide 0.5%. The light exposure paradigm consisted of the following five consecutive blocks of five minutes: baseline dark; monochromatic red light (peak wavelength: 630 nm, luminance: 375 cd/m(2)) to maximize the effect of subsequent blue light; dark; monochromatic blue light (peak wavelength: 470 nm, luminance: 375 cd/m(2)); and post-blue dark. PIPR was quantified as the difference between baseline dark pupil diameter and post-blue dark pupil diameter (PIPR-mm). In addition, a relative PIPR was calculated by dividing PIPR by baseline pupil diameter (PIPR-%). In total 54 PIPR assessments were obtained in 25 healthy young adults (10 males, mean age ± SD: 26.9 ± 4.0 yr). From repeated measurements on two consecutive days in 15 of the 25 participants (6 males, mean age ± SD: 27.8 ± 4.3 yrs) test-retest reliability of both PIPR outcome parameters was calculated. In the presence of considerable between-subject differences, both outcome parameters had very high test-retest reliability: Cronbach's α > 0.90 and Intraclass Correlation Coefficient > 0.85. In 12 of the 25 participants (6 males, mean age ± SD: 26.5 ± 3.6 yr) we examined the potential confounding effects of dark adaptation, time of the day (morning vs. afternoon), body posture (upright vs. supine position), and 24-h environmental light history on the PIPR assessment. Mixed effect regression models were used to analyze these possible confounders. A supine position caused larger PIPR-mm (β = 0.29 mm, SE = 0.10, p = 0.01) and PIPR-% (β = 4.34%, SE = 1.69, p = 0.02), which was due to an increase in baseline dark pupil diameter; this finding is of relevance for studies requiring a supine posture, as in functional Magnetic Resonance Imaging, constant routine protocols, and bed-ridden patients. There were no effects of dark adaptation, time of day, and light history. In conclusion, the presented method provides a reliable and robust assessment of the PIPR to allow for studies on individual differences in melanopsin-based phototransduction and effects of interventions.
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Affiliation(s)
- Wisse P van der Meijden
- Netherlands Institute for Neuroscience, Dept. Sleep and Cognition, Amsterdam, The Netherlands.
| | - Bart H W te Lindert
- Netherlands Institute for Neuroscience, Dept. Sleep and Cognition, Amsterdam, The Netherlands
| | - Denise Bijlenga
- PsyQ Psycho-Medical Programs, Program Adult ADHD, The Hague, The Netherlands
| | - Joris E Coppens
- Netherlands Institute for Neuroscience, Dept. Sleep and Cognition, Amsterdam, The Netherlands
| | - Germán Gómez-Herrero
- Netherlands Institute for Neuroscience, Dept. Sleep and Cognition, Amsterdam, The Netherlands
| | - Jessica Bruijel
- Netherlands Institute for Neuroscience, Dept. Sleep and Cognition, Amsterdam, The Netherlands
| | - J J Sandra Kooij
- PsyQ Psycho-Medical Programs, Program Adult ADHD, The Hague, The Netherlands
| | - Christian Cajochen
- Center for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Patrice Bourgin
- Sleep Disorders Center, CHU and FMTS, CNRS-UPR 3212, Institute of Cellular and Integrative Neurosciences, University of Strasbourg, Strasbourg, France
| | - Eus J W Van Someren
- Netherlands Institute for Neuroscience, Dept. Sleep and Cognition, Amsterdam, The Netherlands; Depts. of Integrative Neurophysiology and Medical Psychology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University and Medical Center, Amsterdam, The Netherlands
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22
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van der Heide A, Donjacour CEHM, Pijl H, Reijntjes RHAM, Overeem S, Lammers GJ, Van Someren EJW, Fronczek R. The effects of sodium oxybate on core body and skin temperature regulation in narcolepsy. J Sleep Res 2015; 24:566-75. [PMID: 25913575 DOI: 10.1111/jsr.12303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/24/2015] [Indexed: 01/08/2023]
Abstract
Patients suffering from narcolepsy type 1 show altered skin temperatures, resembling the profile that is related to sleep onset in healthy controls. The aim of the present study is to investigate the effects of sodium oxybate, a widely used drug to treat narcolepsy, on the 24-h profiles of temperature and sleep-wakefulness in patients with narcolepsy and controls. Eight hypocretin-deficient male narcolepsy type 1 patients and eight healthy matched controls underwent temperature measurement of core body and proximal and distal skin twice, and the sleep-wake state for 24 h. After the baseline assessment, 2 × 3 g of sodium oxybate was administered for 5 nights, immediately followed by the second assessment. At baseline, daytime core body temperature and proximal skin temperature were significantly lower in patients with narcolepsy (core: 36.8 ± 0.05 °C versus 37.0 ± 0.05 °C, F = 8.31, P = 0.01; proximal: 33.4 ± 0.26 °C versus 34.3 ± 0.26 °C, F = 5.66, P = 0.03). In patients, sodium oxybate administration increased proximal skin temperature during the day (F = 6.46, P = 0.04) to a level similar as in controls, but did not affect core body temperature, distal temperature or distal-proximal temperature gradient. Sodium oxybate administration normalised the predictive value of distal skin temperature and distal-proximal temperature gradient for the onset of daytime naps (P < 0.01). In conclusion, sodium oxybate administration resulted in a partial normalisation of the skin temperature profile, by increasing daytime proximal skin temperature, and by strengthening the known relationship between skin temperature and daytime sleep propensity. These changes seem to be related to the clinical improvement induced by sodium oxybate treatment. A causal relationship is not proven.
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Affiliation(s)
| | - Claire E H M Donjacour
- Leiden University Medical Centre, Leiden, the Netherlands.,SleepWake Centre SEIN, Zwolle, the Netherlands
| | - Hanno Pijl
- Leiden University Medical Centre, Leiden, the Netherlands
| | | | - Sebastiaan Overeem
- Sleep Medicine Centre 'Kempenhaeghe', Heeze, the Netherlands.,Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Gert J Lammers
- Leiden University Medical Centre, Leiden, the Netherlands.,SleepWake Centre SEIN, Heemstede, the Netherlands
| | - Eus J W Van Someren
- Department of Sleep & Cognition, Netherlands Institute for Neuroscience, Amsterdam, the Netherlands.,Departments of Integrative Neurophysiology and Medical Psychology, Centre for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University and Medical Centre, Amsterdam, the Netherlands
| | - Rolf Fronczek
- Leiden University Medical Centre, Leiden, the Netherlands
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