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Koyama Y. The role of orexinergic system in the regulation of cataplexy. Peptides 2023; 169:171080. [PMID: 37598758 DOI: 10.1016/j.peptides.2023.171080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/06/2023] [Accepted: 08/18/2023] [Indexed: 08/22/2023]
Abstract
Loss of orexin/hypocretin causes serious sleep disorder; narcolepsy. Cataplexy is the most striking symptom of narcolepsy, characterized by abrupt muscle paralysis induced by emotional stimuli, and has been considered pathological activation of REM sleep atonia system. Clinical treatments for cataplexy/narcolepsy and early pharmacological studies in narcoleptic dogs tell us about the involvement of monoaminergic and cholinergic systems in the control of cataplexy/narcolepsy. Muscle atonia may be induced by activation of REM sleep-atonia generating system in the brainstem. Emotional stimuli may be processed in the limbic systems including the amygdala, nucleus accumbens, and medial prefrontal cortex. It is now considered that orexin/hypocretin prevents cataplexy by modulating the activity of different points of cataplexy-inducing circuit, including monoaminergic/cholinergic systems, muscle atonia-generating systems, and emotion-related systems. This review will describe the recent advances in understanding the neural mechanisms controlling cataplexy, with a focus on the involvement of orexin/hypocretin system, and will discuss future experimental strategies that will lead to further understanding and treatment of this disease.
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Affiliation(s)
- Yoshimasa Koyama
- Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanaya-gawa, Fukushima 960-1296, Japan..
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2
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Fraigne JJ, Luppi PH, Mahoney CE, De Luca R, Shiromani PJ, Weber F, Adamantidis A, Peever J. Dopamine neurons in the ventral tegmental area modulate rapid eye movement sleep. Sleep 2023; 46:zsad024. [PMID: 36775897 DOI: 10.1093/sleep/zsad024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 01/13/2023] [Indexed: 02/14/2023] Open
Affiliation(s)
- Jimmy J Fraigne
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Pierre H Luppi
- Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM, and Université Claude Bernard Lyon 1, Lyon, France
| | - Carrie E Mahoney
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Roberto De Luca
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Priyattam J Shiromani
- Laboratory of Sleep Medicine and Chronobiology, Department of Psychiatry, Medical University of South Carolina, Charleston, SC, USA
| | - Franz Weber
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Antoine Adamantidis
- Departments of Neurology and Biomedical Research, Centre for Experimental Neurology, Inselspital University Hospital Bern, University of Bern, Bern, Switzerland
| | - John Peever
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
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3
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Szabo ST, Thorpy MJ, Mayer G, Peever JH, Kilduff TS. Neurobiological and immunogenetic aspects of narcolepsy: Implications for pharmacotherapy. Sleep Med Rev 2018; 43:23-36. [PMID: 30503715 DOI: 10.1016/j.smrv.2018.09.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 09/22/2018] [Accepted: 09/27/2018] [Indexed: 01/19/2023]
Abstract
Excessive daytime sleepiness (EDS) and cataplexy are common symptoms of narcolepsy, a sleep disorder associated with the loss of hypocretin/orexin (Hcrt) neurons. Although only a few drugs have received regulatory approval for narcolepsy to date, treatment involves diverse medications that affect multiple biochemical targets and neural circuits. Clinical trials have demonstrated efficacy for the following classes of drugs as narcolepsy treatments: alerting medications (amphetamine, methylphenidate, modafinil/armodafinil, solriamfetol [JZP-110]), antidepressants (tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors), sodium oxybate, and the H3-receptor inverse agonist/antagonist pitolisant. Enhanced catecholamine availability and regulation of locus coeruleus (LC) norepinephrine (NE) neuron activity is likely central to the therapeutic activity of most of these compounds. LC NE neurons are integral to sleep/wake regulation and muscle tone; reduced excitatory input to the LC due to compromise of Hcrt/orexin neurons (likely due to autoimmune factors) results in LC NE dysregulation and contributes to narcolepsy/cataplexy symptoms. Agents that increase catecholamines and/or LC activity may mitigate EDS and cataplexy by elevating NE regulation of GABAergic inputs from the amygdala. Consequently, novel medications and treatment strategies aimed at preserving and/or modulating Hcrt/orexin-LC circuit integrity are warranted in narcolepsy/cataplexy.
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Affiliation(s)
- Steven T Szabo
- Duke University Medical Center, Durham, NC, USA; Durham Veterans Affairs Medical Center, Durham, NC, USA.
| | | | | | - John H Peever
- University of Toronto, Toronto, Ontario M5S 3G5, Canada.
| | - Thomas S Kilduff
- Center for Neuroscience, Biosciences Division, SRI International, Menlo Park, CA 94025, USA.
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Koblinger K, Jean-Xavier C, Sharma S, Füzesi T, Young L, Eaton SEA, Kwok CHT, Bains JS, Whelan PJ. Optogenetic Activation of A11 Region Increases Motor Activity. Front Neural Circuits 2018; 12:86. [PMID: 30364230 PMCID: PMC6193508 DOI: 10.3389/fncir.2018.00086] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 09/21/2018] [Indexed: 11/13/2022] Open
Abstract
Limbic brain regions drive goal-directed behaviors. These behaviors often require dynamic motor responses, but the functional connectome of limbic structures in the diencephalon that control locomotion is not well known. The A11 region, within the posterior diencephalon has been postulated to contribute to motor function and control of pain. Here we show that the A11 region initiates movement. Photostimulation of channelrhodopsin 2 (ChR2) transfected neurons in A11 slice preparations showed that neurons could follow stimulation at frequencies of 20 Hz. Our data show that photostimulation of ChR2 transfected neurons in the A11 region enhances motor activity often leading to locomotion. Using vGluT2-reporter and vGAT-reporter mice we show that the A11 tyrosine hydroxylase positive (TH) dopaminergic neurons are vGluT2 and vGAT negative. We find that in addition to dopaminergic neurons within the A11 region, there is another neuronal subtype which expresses the monoenzymatic aromatic L-amino acid decarboxylase (AADC), but not TH, a key enzyme involved in the synthesis of catecholamines including dopamine. This monoaminergic-based motor circuit may be involved in the control of motor behavior as part of a broader diencephalic motor region.
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Affiliation(s)
- Kathrin Koblinger
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Céline Jean-Xavier
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Sandeep Sharma
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Tamás Füzesi
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Leanne Young
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Shane E A Eaton
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Charlie Hong Ting Kwok
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Jaideep Singh Bains
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Patrick J Whelan
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
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Fraigne JJ, Torontali ZA, Snow MB, Peever JH. REM Sleep at its Core - Circuits, Neurotransmitters, and Pathophysiology. Front Neurol 2015; 6:123. [PMID: 26074874 PMCID: PMC4448509 DOI: 10.3389/fneur.2015.00123] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 05/13/2015] [Indexed: 01/03/2023] Open
Abstract
Rapid eye movement (REM) sleep is generated and maintained by the interaction of a variety of neurotransmitter systems in the brainstem, forebrain, and hypothalamus. Within these circuits lies a core region that is active during REM sleep, known as the subcoeruleus nucleus (SubC) or sublaterodorsal nucleus. It is hypothesized that glutamatergic SubC neurons regulate REM sleep and its defining features such as muscle paralysis and cortical activation. REM sleep paralysis is initiated when glutamatergic SubC cells activate neurons in the ventral medial medulla, which causes release of GABA and glycine onto skeletal motoneurons. REM sleep timing is controlled by activity of GABAergic neurons in the ventrolateral periaqueductal gray and dorsal paragigantocellular reticular nucleus as well as melanin-concentrating hormone neurons in the hypothalamus and cholinergic cells in the laterodorsal and pedunculo-pontine tegmentum in the brainstem. Determining how these circuits interact with the SubC is important because breakdown in their communication is hypothesized to underlie narcolepsy/cataplexy and REM sleep behavior disorder (RBD). This review synthesizes our current understanding of mechanisms generating healthy REM sleep and how dysfunction of these circuits contributes to common REM sleep disorders such as cataplexy/narcolepsy and RBD.
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Affiliation(s)
- Jimmy J Fraigne
- Department of Cell and Systems Biology, University of Toronto , Toronto, ON , Canada
| | - Zoltan A Torontali
- Department of Cell and Systems Biology, University of Toronto , Toronto, ON , Canada
| | - Matthew B Snow
- Department of Cell and Systems Biology, University of Toronto , Toronto, ON , Canada
| | - John H Peever
- Department of Cell and Systems Biology, University of Toronto , Toronto, ON , Canada
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Jennum P, Frandsen R, Knudsen S. Characteristics of rapid eye movement sleep behavior disorder in narcolepsy. Sleep Biol Rhythms 2013. [DOI: 10.1111/j.1479-8425.2012.00556.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Plazzi G, Pizza F, Palaia V, Franceschini C, Poli F, Moghadam KK, Cortelli P, Nobili L, Bruni O, Dauvilliers Y, Lin L, Edwards MJ, Mignot E, Bhatia KP. Complex movement disorders at disease onset in childhood narcolepsy with cataplexy. ACTA ACUST UNITED AC 2011; 134:3477-89. [PMID: 21930661 PMCID: PMC3235554 DOI: 10.1093/brain/awr244] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Narcolepsy with cataplexy is characterized by daytime sleepiness, cataplexy (sudden loss of bilateral muscle tone triggered by emotions), sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. Narcolepsy with cataplexy is most often associated with human leucocyte antigen-DQB1*0602 and is caused by the loss of hypocretin-producing neurons in the hypothalamus of likely autoimmune aetiology. Noting that children with narcolepsy often display complex abnormal motor behaviours close to disease onset that do not meet the classical definition of cataplexy, we systematically analysed motor features in 39 children with narcolepsy with cataplexy in comparison with 25 age- and sex-matched healthy controls. We found that patients with narcolepsy with cataplexy displayed a complex array of ‘negative’ (hypotonia) and ‘active’ (ranging from perioral movements to dyskinetic–dystonic movements or stereotypies) motor disturbances. ‘Active’ and ‘negative’ motor scores correlated positively with the presence of hypotonic features at neurological examination and negatively with disease duration, whereas ‘negative’ motor scores also correlated negatively with age at disease onset. These observations suggest that paediatric narcolepsy with cataplexy often co-occurs with a complex movement disorder at disease onset, a phenomenon that may vanish later in the course of the disease. Further studies are warranted to assess clinical course and whether the associated movement disorder is also caused by hypocretin deficiency or by additional neurochemical abnormalities.
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Affiliation(s)
- Giuseppe Plazzi
- Department of Neurological Sciences, University of Bologna, 40123 Bologna, Italy.
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8
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Chang JH, Lee KY, Kim TB, Yoon SJ, Lee T, Kim KH. Clinical and urodynamic effect of methylphenidate for the treatment of giggle incontinence (enuresis risoria). Neurourol Urodyn 2011; 30:1338-42. [PMID: 21520251 DOI: 10.1002/nau.21046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 11/08/2010] [Indexed: 11/10/2022]
Abstract
AIMS We retrospectively investigated the efficacy of methylphenidate (MPH) in giggle incontinence (GI), and the relationship between GI and urodynamic parameters. METHODS Nine (n = 9) female GI patients underwent 1 year of treatment with 5 mg MPH. Three questionnaires, voiding diaries, and UDS were conducted before and after treatment. The severity of GI was classified into mild, moderate, and severe. Clinical success was characterized as: full response, response, partial response, and non-response. RESULTS The mean age of all patients was 16.2 ± 2.3 years. Five patients had mild, one had moderate, and three had severe grade incontinent. All patients reported complete cessation of wetting after MPH treatment. The mean duration of asymptomatic period was 7 ± 3.2 months. There were no statistically significant score changes in all three questionnaires: Urgency Perception Scale (UPS), Overactive Bladder Symptom Score (OABSS) and Primary Overactive Symptom Questionnaire (POSQ), and voiding diaries (P > 0.05). In UDS, there were no statistically significant altered parameters, except maximum urethral closure pressure (MUCP) and maximum urethral pressure (MUP). After treatment, the mean MUCP was increased from 52.2 ± 6.8 to 73.0 ± 5.4 cmH(2) O (P < 0.05), and the mean MUP was increased from 48.6 ± 7.3 to 70.2 ± 5.0 cmH(2) O (P < 0.05). CONCLUSIONS MPH can be a viable option for the primary treatment of GI, and it may be related to increasing urethral closure pressure. It was not possible to establish if a relationship between GI and detrusor overactivity exists.
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Affiliation(s)
- Joo-Hyun Chang
- Department of Urology, Gachon University Gil Hospital, Incheon, Korea
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9
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Sinton CM. Orexin/hypocretin plays a role in the response to physiological disequilibrium. Sleep Med Rev 2011; 15:197-207. [PMID: 21269851 DOI: 10.1016/j.smrv.2010.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 12/14/2010] [Accepted: 12/15/2010] [Indexed: 11/28/2022]
Abstract
In the decade since the discovery that pathology of the orexin/hypocretin system is causative for the sleep disorder narcolepsy, considerable progress has been made in understanding the functional role of the neuropeptide. Two, apparently separate functions of orexin have emerged as a consensus from studies to date. The first is the effect on vigilance state boundaries, as exemplified by narcolepsy. Thus the absence of orexin severely limits the ability to maintain prolonged periods of wakefulness or sleep and also allows the unregulated appearance of cataplexy as sudden muscle weakness during wakefulness. The second function is that orexin acts as a signaling molecule in transferring information about physiological disequilibrium to the central nervous system. Orexin activates the central arousal and motor systems during such disequilibrium and so may facilitate the necessary response and adaptation to restore equilibrium. A feasible relationship between these two functions is therefore that the maintenance of prolonged and active wakefulness is an integral part of this adaptive process. Furthermore, the limit placed on the onset of sleep by orexin suggests that these adaptive processes then continue during sleep to become integrated into the development of a coping strategy for the longer term.
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Affiliation(s)
- Christopher M Sinton
- Department of Internal Medicine, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8874, USA.
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10
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Neuroanatomical study of the A11 diencephalospinal pathway in the non-human primate. PLoS One 2010; 5:e13306. [PMID: 20967255 PMCID: PMC2954154 DOI: 10.1371/journal.pone.0013306] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 09/21/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The A11 diencephalospinal pathway is crucial for sensorimotor integration and pain control at the spinal cord level. When disrupted, it is thought to be involved in numerous painful conditions such as restless legs syndrome and migraine. Its anatomical organization, however, remains largely unknown in the non-human primate (NHP). We therefore characterized the anatomy of this pathway in the NHP. METHODS AND FINDINGS In situ hybridization of spinal dopamine receptors showed that D1 receptor mRNA is absent while D2 and D5 receptor mRNAs are mainly expressed in the dorsal horn and D3 receptor mRNA in both the dorsal and ventral horns. Unilateral injections of the retrograde tracer Fluoro-Gold (FG) into the cervical spinal enlargement labeled A11 hypothalamic neurons quasi-exclusively among dopamine areas. Detailed immunohistochemical analysis suggested that these FG-labeled A11 neurons are tyrosine hydroxylase-positive but dopa-decarboxylase and dopamine transporter-negative, suggestive of a L-DOPAergic nucleus. Stereological cell count of A11 neurons revealed that this group is composed by 4002±501 neurons per side. A 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) intoxication with subsequent development of a parkinsonian syndrome produced a 50% neuronal cell loss in the A11 group. CONCLUSION The diencephalic A11 area could be the major source of L-DOPA in the NHP spinal cord, where it may play a role in the modulation of sensorimotor integration through D2 and D3 receptors either directly or indirectly via dopamine formation in spinal dopa-decarboxylase-positives cells.
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Burgess CR, Tse G, Gillis L, Peever JH. Dopaminergic regulation of sleep and cataplexy in a murine model of narcolepsy. Sleep 2010; 33:1295-304. [PMID: 21061851 PMCID: PMC2941415 DOI: 10.1093/sleep/33.10.1295] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVES To determine if the dopaminergic system modulates cataplexy, sleep attacks and sleep-wake behavior in narcoleptic mice. DESIGN Hypocretin/orexin knockout (i.e., narcoleptic) and wild-type mice were administered amphetamine and specific dopamine receptor modulators to determine their effects on sleep, cataplexy and sleep attacks. PATIENTS OR PARTICIPANTS Hypocretin knockout (n = 17) and wild-type mice (n = 21). INTERVENTIONS Cataplexy, sleep attacks and sleep-wake behavior were identified using electroencephalogram, electromyogram and videography. These behaviors were monitored for 4 hours after an i.p. injection of saline, amphetamine and specific dopamine receptor modulators (D1- and D2-like receptor modulators). MEASUREMENTS AND RESULTS Amphetamine (2 mg/kg), which increases brain dopamine levels, decreased sleep attacks and cataplexy by 61% and 67%, suggesting that dopamine transmission modulates such behaviors. Dopamine receptor modulation also had powerful effects on sleep attacks and cataplexy. Activation (SKF 38393; 20 mg/kg) and blockade (SCH 23390; 1 mg/kg) of D1-like receptors decreased and increased sleep attacks by 77% and 88%, without affecting cataplexy. Pharmacological activation of D2-like receptors (quinpirole; 0.5 mg/kg) increased cataplectic attacks by 172% and blockade of these receptors (eticlopride; 1 mg/kg) potently suppressed them by 97%. Manipulation of D2-like receptors did not affect sleep attacks. CONCLUSIONS We show that the dopaminergic system plays a role in regulating both cataplexy and sleep attacks in narcoleptic mice. We found that cataplexy is modulated by a D2-like receptor mechanism, whereas dopamine modulates sleep attacks by a D1-like receptor mechanism. These results support a role for the dopamine system in regulating sleep attacks and cataplexy in a murine model of narcolepsy.
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Affiliation(s)
| | - Gavin Tse
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Lauren Gillis
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - John H. Peever
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
- Department of Physiology, University of Toronto, Toronto, Canada
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Eguibar JR, Cortés MDC, Lara-Lozano M. Presynaptic dopaminergic agonists increased gripping-generated immobility episodes in the myelin-mutant taiep rat. Neurosci Lett 2010; 483:189-92. [DOI: 10.1016/j.neulet.2010.07.086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 07/29/2010] [Accepted: 07/31/2010] [Indexed: 11/26/2022]
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Knudsen S, Gammeltoft S, Jennum PJ. Rapid eye movement sleep behaviour disorder in patients with narcolepsy is associated with hypocretin-1 deficiency. Brain 2010; 133:568-79. [DOI: 10.1093/brain/awp320] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Chen L, Brown RE, McKenna JT, McCarley RW. Animal models of narcolepsy. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2009; 8:296-308. [PMID: 19689311 DOI: 10.2174/187152709788921717] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Narcolepsy is a debilitating sleep disorder with excessive daytime sleepiness and cataplexy as its two major symptoms. Although this disease was first described about one century ago, an animal model was not available until the 1970s. With the establishment of the Stanford canine narcolepsy colony, researchers were able to conduct multiple neurochemical studies to explore the pathophysiology of this disease. It was concluded that there was an imbalance between monoaminergic and cholinergic systems in canine narcolepsy. In 1999, two independent studies revealed that orexin neurotransmission deficiency was pivotal to the development of narcolepsy with cataplexy. This scientific leap fueled the generation of several genetically engineered mouse and rat models of narcolepsy. To facilitate further research, it is imperative that researchers reach a consensus concerning the evaluation of narcoleptic behavioral and EEG phenomenology in these models.
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Affiliation(s)
- Lichao Chen
- Research Service, VA Boston Healthcare System, Department of Psychiatry, Harvard Medical School, Brockton, MA 02301, USA.
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15
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Abstract
Intensive care subjects the critically ill patient to a multitude of stressors caused by the severity of illness and the use of invasive treatment modalities and medications. The ICU environment contributes significant stress of its own related to noise, light, 24-hour patient care, and other factors that disturb sleep. Consequently, various sleep pathologies may emerge or worsen in the ICU patient. Some sleep disorder symptomatology may be confused with serious neurologic complications of critical illness and lead to inappropriate testing or treatment, particularly in the patient who has narcolepsy. Given the high prevalence of sleep disorders in the general population, it is essential that the ICU practitioner attain an adequate knowledge of sleep and its disorders.
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Affiliation(s)
- Lee K Brown
- Program in Sleep Medicine, University of New Mexico Health Sciences Center, 1101 Medical Arts Avenue NE, Building #2, Albuquerque, NM 87102, USA.
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Abstract
Narcolepsy is characterized by excessive daytime sleepiness (EDS), cataplexy and/or other dissociated manifestations of rapid eye movement (REM) sleep (hypnagogic hallucinations and sleep paralysis). Narcolepsy is currently treated with amphetamine-like central nervous system (CNS) stimulants (for EDS) and antidepressants (for cataplexy). Some other classes of compounds such as modafinil (a non-amphetamine wake-promoting compound for EDS) and gamma-hydroxybutyrate (GHB, a short-acting sedative for EDS/fragmented nighttime sleep and cataplexy) given at night are also employed. The major pathophysiology of human narcolepsy has been recently elucidated based on the discovery of narcolepsy genes in animals. Using forward (i.e., positional cloning in canine narcolepsy) and reverse (i.e., mouse gene knockout) genetics, the genes involved in the pathogenesis of narcolepsy (hypocretin/orexin ligand and its receptor) in animals have been identified. Hypocretins/orexins are novel hypothalamic neuropeptides also involved in various hypothalamic functions such as energy homeostasis and neuroendocrine functions. Mutations in hypocretin-related genes are rare in humans, but hypocretin-ligand deficiency is found in many narcolepsy-cataplexy cases. In this review, the clinical, pathophysiological and pharmacological aspects of narcolepsy are discussed.
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Affiliation(s)
- Seiji Nishino
- Stanford University School of Medicine, Department of Psychiatry and Behavioral Sciences, Sleep and Circadian, Neurobiology Laboratory, Center for Narcolepsy, 1201 Welch Road, P213, Palo Alto, CA 94304, USA.
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17
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Kita I, Yoshida Y, Nishino S. An activation of parvocellular oxytocinergic neurons in the paraventricular nucleus in oxytocin-induced yawning and penile erection. Neurosci Res 2006; 54:269-75. [PMID: 16427151 DOI: 10.1016/j.neures.2005.12.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2005] [Revised: 12/08/2005] [Accepted: 12/14/2005] [Indexed: 11/26/2022]
Abstract
Intracerebroventricular (ICV) or PVN local injections of oxytocin induce yawning and penile erection, for which a positive feedback mechanism for the PVN oxytocinergic activation is suggested, but this had not been directly substantiated in vivo. We have assessed the behavioral effects and activity of oxytocinergic neurons with double-staining for c-Fos and oxytocin in the PVN after ICV administration of oxytocin in adult male rats. ICV oxytocin injections (50 and 200 ng) dose-dependently induced yawning and penile erection and significantly increased the percentage of c-Fos positive oxytocin neurons in the medial, dorsal and lateral parvocellular subdivision of the PVN. However, increases in the magnocellular portion were not significant. We also found that lithium chloride (LiCl, 0.5 and l.0 mEq), a compound known to activate oxytocinergic neurons, also significantly increased the percentage of c-Fos positive oxytocin neurons in all PVN portions. However, LiCl did not induce yawning and penile erection, but counteracted the oxytocin-induced yawning and penile erection. These results suggest that if the activation of oxytocinergic neurons in the PVN is important for mediating oxytocin-induced yawning and penile erection, a selective activation of parvocellular oxytocinergic neurons in the PVN is likely to be involved.
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Affiliation(s)
- Ichiro Kita
- Sleep and Circadian Neurobiology Laboratory, Center for Narcolepsy, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94304-5489, USA
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