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Valizadeh P, Momtazmanesh S, Plazzi G, Rezaei N. Connecting the dots: An updated review of the role of autoimmunity in narcolepsy and emerging immunotherapeutic approaches. Sleep Med 2024; 113:378-396. [PMID: 38128432 DOI: 10.1016/j.sleep.2023.12.005] [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: 08/24/2023] [Revised: 12/08/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023]
Abstract
BACKGROUND Narcolepsy type 1 (NT1) is a chronic disorder characterized by pathological daytime sleepiness and cataplexy due to the disappearance of orexin immunoreactive neurons in the hypothalamus. Genetic and environmental factors point towards a potential role for inflammation and autoimmunity in the pathogenesis of the disease. This study aims to comprehensively review the latest evidence on the autoinflammatory mechanisms and immunomodulatory treatments aimed at suspected autoimmune pathways in NT1. METHODS Recent relevant literature in the field of narcolepsy, its autoimmune hypothesis, and purposed immunomodulatory treatments were reviewed. RESULTS Narcolepsy is strongly linked to specific HLA alleles and T-cell receptor polymorphisms. Furthermore, animal studies and autopsies have found infiltration of T cells in the hypothalamus, supporting T cell-mediated immunity. However, the role of autoantibodies has yet to be definitively established. Increased risk of NT1 after H1N1 infection and vaccination supports the autoimmune hypothesis, and the potential role of coronavirus disease 2019 and vaccination in triggering autoimmune neurodegeneration is a recent finding. Alterations in cytokine levels, gut microbiota, and microglial activation indicate a potential role for inflammation in the disease's development. Reports of using immunotherapies in NT1 patients are limited and inconsistent. Early treatment with IVIg, corticosteroids, plasmapheresis, and monoclonal antibodies has seldomly shown some potential benefits in some studies. CONCLUSION The current body of literature supports that narcolepsy is an autoimmune disorder most likely caused by T-cell involvement. However, the potential for immunomodulatory treatments to reverse the autoinflammatory process remains understudied. Further clinical controlled trials may provide valuable insights into this area.
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Affiliation(s)
- Parya Valizadeh
- School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Sara Momtazmanesh
- School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Giuseppe Plazzi
- IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy; Department of Biomedical, Metabolic, and Neural Sciences, Università Degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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2
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Kolmos MG, Arribas AP, Kornum BR, Justinussen JL. Experimental sickness reduces hypocretin receptor 1 expression in the lateral hypothalamus and ventral tegmental area of female mice. Eur J Neurosci 2023; 58:4002-4010. [PMID: 37818927 DOI: 10.1111/ejn.16151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/23/2023] [Accepted: 09/11/2023] [Indexed: 10/13/2023]
Abstract
Recent studies have focused on how sickness behaviours, including lethargy, are coordinated in the brain in response to peripheral infections. Decreased hypocretin (orexin) signalling is associated with lethargy and previous research suggests that hypocretin signalling is downregulated during sickness. However, there are studies that find increases or no change in hypocretin signalling during sickness. It is further unknown whether hypocretin receptor expression changes during sickness. Using lipopolysaccharide (LPS) to induce sickness in female mice, we investigated how LPS-injection affects gene expression of hypocretin receptors and prepro-hypocretin as well as hypocretin-1 peptide concentrations in brain tissue. We found that hypocretin receptor 1 gene expression was downregulated during sickness in the lateral hypothalamus and ventral tegmental area, but not in the dorsal raphe nucleus or locus coeruleus. We found no changes in hypocretin receptor 2 expression. Using a gene expression calculation that accounts for primer efficiencies and multiple endogenous controls, we were unable to detect changes in prepro-hypocretin expression. Using radioimmunoassay, we found no change in hypocretin-1 peptide in rostral brain tissue. Our results indicate that hypocretin receptor expression can fluctuate during sickness, adding an additional level of complexity to understanding hypocretin signalling during sickness.
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Affiliation(s)
- Mie Gunni Kolmos
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alba Pérez Arribas
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte Rahbek Kornum
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jessica Lauren Justinussen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Akaishi M, Hashiba E, Takekawa D, Kushikata T, Hirota K. Plasma orexin A does not reflect severity of illness in the intensive care units patients with systemic inflammation. JA Clin Rep 2022; 8:7. [PMID: 35064847 PMCID: PMC8783934 DOI: 10.1186/s40981-022-00498-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Systemic inflammatory response occurs by sepsis and invasive surgery. Recent articles suggest that not only CRP but also procalcitonin, presepsin, and neutrophil gelatinase-associated lipocalin may reflect the severity of systemic inflammation. In addition, as systemic inflammation could degenerate orexin neurons, plasma orexin A might also be a good biomarker to predict the severity. Thus, we have determined relation between plasma biomarker and severity of illness score in patients with systemic inflammation.
Methods
Previous database (UMIN000018427) was used to secondly determine which plasma biomarkers may predict the severity of illness in the ICU patients with systemic inflammation (n = 57, 31 non-sepsis surgical patients and 26 sepsis patients). We measured plasma levels of orexin A, CRP, procalcitonin, presepsin, and neutrophil gelatinase-associated lipocalin were measured, and APACHE II score was assessed in these patients at their admission to the ICU. Data are shown as mean ± SD. Statistical analyses were done with unpaired t test. The correlation between APACHE II score and plasma biomarkers were examined using Pearson’s correlation coefficient and a least squares linear regression line.
Results
Demographic data did not differ between sepsis and non-sepsis groups. However, APACHE-II score was significantly higher in sepsis group than those in non-sepsis group (20.9 ± 6.6 vs 15.8 ± 3.2, p < 0.01). There were significant correlations between APACHE II score and plasma CRP (r = 0.532, p < 0.01), procalcitonin (r = 0.551, p < 0.01), presepsin (r = 0.510, p < 0.01), and neutrophil gelatinase-associated lipocalin (r = 0.466, P < 0.01) except orexin A.
Conclusion
All plasma biomarkers tested except orexin A may reflect the severity of illness in patients with systemic inflammation.
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4
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Melzi S, Morel AL, Scoté-Blachon C, Liblau R, Dauvilliers Y, Peyron C. Histamine in murine narcolepsy: What do genetic and immune models tell us? Brain Pathol 2021; 32:e13027. [PMID: 34672414 PMCID: PMC8877734 DOI: 10.1111/bpa.13027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/14/2021] [Accepted: 09/27/2021] [Indexed: 12/20/2022] Open
Abstract
An increased number of histaminergic neurons, identified by labeling histidine‐decarboxylase (HDC) its synthesis enzyme, was unexpectedly found in patients with narcolepsy type 1 (NT1). In quest for enlightenment, we evaluate whether an increase in HDC cell number and expression level would be detected in mouse models of the disease, in order to provide proof of concepts reveling possible mechanisms of compensation for the loss of orexin neurons, and/or of induced expression as a consequence of local neuroinflammation, a state that likely accompanies NT1. To further explore the compensatory hypothesis, we also study the noradrenergic wake‐promoting system. Immunohistochemistry for HDC, orexin, and melanin‐concentrating hormone (MCH) was used to count neurons. Quantitative‐PCR of HDC, orexin, MCH, and tyrosine‐hydroxylase was performed to evaluate levels of mRNA expression in the hypothalamus or the dorsal pons. Both quantifications were achieved in genetic and neuroinflammatory models of narcolepsy with major orexin impairment, namely the orexin‐deficient (Orex‐KO) and orexin‐hemagglutinin (Orex‐HA) mice respectively. The number of HDC neurons and mRNA expression level were unchanged in Orex‐KO mice compared to controls. Similarly, we found no change in tyrosine‐hydroxylase mRNA expression in the dorsal pons between groups. Further, despite the presence of protracted local neuroinflammation as witnessed by the presence of reactive microglia, we found no change in the number of neurons nor the expression of HDC in Orex‐HA mice compared to controls. Importantly, no correlation was found in all conditions between HDC and orexin. Our findings indicate that, in mice, the expression of histamine and noradrenalin, two wake‐promoting systems, are not modulated by orexin level whether the lack of orexin is constitutive or induced at adult age, showing thus no compensation. They also show no recruitment of histamine by local neuroinflammation. Further studies will be needed to further define the role of histamine in the pathophysiology of NT1.
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Affiliation(s)
- Silvia Melzi
- Sleep Team, Center for Research in Neuroscience of LYON, CNRS UMR5292, INSERM U1028, University of Lyon1, Bron, France
| | - Anne-Laure Morel
- Sleep Team, Center for Research in Neuroscience of LYON, CNRS UMR5292, INSERM U1028, University of Lyon1, Bron, France
| | - Céline Scoté-Blachon
- Functional Neurogenetics platform, Center for Research in Neuroscience of LYON, CNRS UMR5292, INSERM U1028, University of Lyon1, Bron, France
| | - Roland Liblau
- Toulouse Institute for Infectious and Inflammatory diseases, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, UPS, University of Toulouse, Toulouse, France
| | - Yves Dauvilliers
- National Reference Centre for Orphan Diseases, Narcolepsy - Rare hypersomnia, Sleep Unit, Department of Neurology, CHU Montpellier, Institute for Neuroscience of Montpellier INM, INSERM U1298, University of Montpellier, Montpellier, France
| | - Christelle Peyron
- Sleep Team, Center for Research in Neuroscience of LYON, CNRS UMR5292, INSERM U1028, University of Lyon1, Bron, France
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5
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Bazyar H, Zare Javid A, Bavi Behbahani H, Shivappa N, Hebert JR, Khodaramhpour S, Khaje Zadeh S, Aghamohammadi V. The association between dietary inflammatory index with sleep quality and obesity amongst iranian female students: A cross-sectional study. Int J Clin Pract 2021; 75:e14061. [PMID: 33523533 DOI: 10.1111/ijcp.14061] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/21/2021] [Accepted: 01/25/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Overweight, obesity and lack of sleep quality as inflammatory states are the common problems amongst college students and the Association of Dietary Inflammatory Index (DII) with these problems amongst this population is unknown. We aimed to evaluate the relationship of the DII with obesity and sleep quality amongst Iranian female students. METHODS The present cross-sectional study was conducted on 249 female college students. The Dietary Inflammatory Index (DII) was calculated using a valid and reliable 147-item food frequency questionnaire (FFQ). To assess sleep quality, Pittsburgh Sleep Quality Index (PSQI) was used. Odds Ratio (OR) and 95% Confidence Intervals (CIs) were estimated for anthropometric indices and sleep quality according to the DII score. Linear regression was used to estimate the relationship between DII score with sleep and anthropometric indices. RESULTS There was a significant association evident between DII and sleep quality (>5 is considered as poor quality of sleep); ie, the odds ratios between DII quartile 2 vs 1 (unadjusted model: OR = 0.33 (CI: 0.14-0.74), P for trend = .002; model 1: the fully adjusted OR = 0.31(CI: 0.12-0.78), P for trend = .005; model 2:OR = 0.30 (CI: 0.12-0.78), P for trend = .005) to quartile 4(unadjusted model: OR = 1.13(CI: 0.45-2.80); model 1: OR = 1.11(CI: 0.44-2.79); model 2:OR = 1.13(CI: 0.44-2.87), P for trend = .005). Also, odds ratios increased significantly from quartile 2 to quartile 4 in all models for DII and sleep quality. According to the continuous score of DII, there was a significant positive association between DII and sleep quality in all three models: unadjusted, model 1, and model 2 (OR = 1.21 (CI: 1.05-1.40), OR = 1.21 (CI: 1.03-1.43), and OR = 1.22 (CI: 1.03-1.44), respectively. CONCLUSIONS In this study, after removing the effect of confounding factors, participants in the highest quartile of DII score had significantly higher PSQI global score.
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Affiliation(s)
- Hadi Bazyar
- Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Nutrition, School of Allied Medical Sciences, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Ahmad Zare Javid
- Department of Nutrition, School of Allied Medical Sciences, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Hossein Bavi Behbahani
- Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Nutrition, School of Allied Medical Sciences, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Nitin Shivappa
- Cancer Prevention and Control Program, University of South Carolina, Columbia, SC, USA
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
- Department of Nutrition, Connecting Health Innovations LLC, Columbia, SC, USA
| | - James R Hebert
- Cancer Prevention and Control Program, University of South Carolina, Columbia, SC, USA
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
- Department of Nutrition, Connecting Health Innovations LLC, Columbia, SC, USA
| | - Sara Khodaramhpour
- Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Sara Khaje Zadeh
- Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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6
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Igarashi S, Nozu T, Ishioh M, Kumei S, Saito T, Toki Y, Hatayama M, Yamamoto M, Shindo M, Tanabe H, Okumura T. Centrally administered orexin prevents lipopolysaccharide and colchicine induced lethality via the vagal cholinergic pathway in a sepsis model in rats. Biochem Pharmacol 2020; 182:114262. [DOI: 10.1016/j.bcp.2020.114262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/02/2020] [Accepted: 10/02/2020] [Indexed: 12/15/2022]
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7
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Laperchia C, Xu YZ, Mumba Ngoyi D, Cotrufo T, Bentivoglio M. Neural Damage in Experimental Trypanosoma brucei gambiense Infection: Hypothalamic Peptidergic Sleep and Wake-Regulatory Neurons. Front Neuroanat 2018. [PMID: 29535612 PMCID: PMC5835115 DOI: 10.3389/fnana.2018.00013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Neuron populations of the lateral hypothalamus which synthesize the orexin (OX)/hypocretin or melanin-concentrating hormone (MCH) peptides play crucial, reciprocal roles in regulating wake stability and sleep. The disease human African trypanosomiasis (HAT), also called sleeping sickness, caused by extracellular Trypanosoma brucei (T. b.) parasites, leads to characteristic sleep-wake cycle disruption and narcoleptic-like alterations of the sleep structure. Previous studies have revealed damage of OX and MCH neurons during systemic infection of laboratory rodents with the non-human pathogenic T. b. brucei subspecies. No information is available, however, on these peptidergic neurons after systemic infection with T. b. gambiense, the etiological agent of 97% of HAT cases. The present study was aimed at the investigation of immunohistochemically characterized OX and MCH neurons after T. b. gambiense or T. b. brucei infection of a susceptible rodent, the multimammate mouse, Mastomysnatalensis. Cell counts and evaluation of OX fiber density were performed at 4 and 8 weeks post-infection, when parasites had entered the brain parenchyma from the periphery. A significant decrease of OX neurons (about 44% reduction) and MCH neurons (about 54% reduction) was found in the lateral hypothalamus and perifornical area at 8 weeks in T. b. gambiense-infected M. natalensis. A moderate decrease (21% and 24% reduction, respectively), which did not reach statistical significance, was found after T. b. brucei infection. In two key targets of diencephalic orexinergic innervation, the peri-suprachiasmatic nucleus (SCN) region and the thalamic paraventricular nucleus (PVT), densitometric analyses showed a significant progressive decrease in the density of orexinergic fibers in both infection paradigms, and especially during T. b. gambiense infection. Altogether the findings provide novel information showing that OX and MCH neurons are highly vulnerable to chronic neuroinflammatory signaling caused by the infection of human-pathogenic African trypanosomes.
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Affiliation(s)
- Claudia Laperchia
- Department of Neuroscience Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Yuan-Zhong Xu
- Department of Neuroscience Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Dieudonné Mumba Ngoyi
- Institut National de Recherche Biomédicale (INRB), Kinshasa, Democratic Republic of Congo
| | - Tiziana Cotrufo
- Department of Neuroscience Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Marina Bentivoglio
- Department of Neuroscience Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,National Institute of Neuroscience (INN), Verona Unit, Verona, Italy
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8
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Nadjar A, Wigren HKM, Tremblay ME. Roles of Microglial Phagocytosis and Inflammatory Mediators in the Pathophysiology of Sleep Disorders. Front Cell Neurosci 2017; 11:250. [PMID: 28912686 PMCID: PMC5582207 DOI: 10.3389/fncel.2017.00250] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/07/2017] [Indexed: 11/13/2022] Open
Abstract
Sleep serves crucial learning and memory functions in both nervous and immune systems. Microglia are brain immune cells that actively maintain health through their crucial physiological roles exerted across the lifespan, including phagocytosis of cellular debris and orchestration of neuroinflammation. The past decade has witnessed an explosive growth of microglial research. Considering the recent developments in the field of microglia and sleep, we examine their possible impact on various pathological conditions associated with a gain, disruption, or loss of sleep in this focused mini-review. While there are extensive studies of microglial implication in a variety of neuropsychiatric and neurodegenerative diseases, less is known regarding their roles in sleep disorders. It is timely to stimulate new research in this emergent and rapidly growing field of investigation.
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Affiliation(s)
- Agnes Nadjar
- Nutrition et Neurobiologie Intégrée, UMR 1286, Institut National de la Recherche AgronomiqueBordeaux, France.,Nutrition et Neurobiologie Intégrée, UMR 1286, Bordeaux UniversityBordeaux, France.,OptiNutriBrain International Associated Laboratory (NutriNeuro France-INAF Canada)Québec, QC, Canada
| | | | - Marie-Eve Tremblay
- Axe Neurosciences, CRCHU de Québec-Université LavalQuébec, QC, Canada.,Département de médecine moléculaire, Université LavalQuébec, QC, Canada
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9
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Pace M, Adamantidis A, Facchin L, Bassetti C. Role of REM Sleep, Melanin Concentrating Hormone and Orexin/Hypocretin Systems in the Sleep Deprivation Pre-Ischemia. PLoS One 2017; 12:e0168430. [PMID: 28061506 PMCID: PMC5218733 DOI: 10.1371/journal.pone.0168430] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 12/01/2016] [Indexed: 12/19/2022] Open
Abstract
STUDY OBJECTIVES Sleep reduction after stroke is linked to poor recovery in patients. Conversely, a neuroprotective effect is observed in animals subjected to acute sleep deprivation (SD) before ischemia. This neuroprotection is associated with an increase of the sleep, melanin concentrating hormone (MCH) and orexin/hypocretin (OX) systems. This study aims to 1) assess the relationship between sleep and recovery; 2) test the association between MCH and OX systems with the pathological mechanisms of stroke. METHODS Sprague-Dawley rats were assigned to four experimental groups: (i) SD_IS: SD performed before ischemia; (ii) IS: ischemia; (iii) SD_Sham: SD performed before sham surgery; (iv) Sham: sham surgery. EEG and EMG were recorded. The time-course of the MCH and OX gene expression was measured at 4, 12, 24 hours and 3, 4, 7 days following ischemic surgery by qRT-PCR. RESULTS A reduction of infarct volume was observed in the SD_IS group, which correlated with an increase of REM sleep observed during the acute phase of stroke. Conversely, the IS group showed a reduction of REM sleep. Furthermore, ischemia induces an increase of MCH and OX systems during the acute phase of stroke, although, both systems were still increased for a long period of time only in the SD_IS group. CONCLUSIONS Our data indicates that REM sleep may be involved in the neuroprotective effect of SD pre-ischemia, and that both MCH and OX systems were increased during the acute phase of stroke. Future studies should assess the role of REM sleep as a prognostic marker, and test MCH and OXA agonists as new treatment options in the acute phase of stroke.
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Affiliation(s)
- Marta Pace
- Center for Experimental Neurology (ZEN), Department of Neurology, Bern University Hospital, Bern, Switzerland
- Department of Neuroscience and Brain Technologies, Italian Institute of Technology (IIT), Genova, Italy
- * E-mail:
| | - Antoine Adamantidis
- Center for Experimental Neurology (ZEN), Department of Neurology, Bern University Hospital, Bern, Switzerland
| | - Laura Facchin
- Center for Experimental Neurology (ZEN), Department of Neurology, Bern University Hospital, Bern, Switzerland
| | - Claudio Bassetti
- Center for Experimental Neurology (ZEN), Department of Neurology, Bern University Hospital, Bern, Switzerland
- Sleep-Wake-Epilepsy-Center, Department of Neurology, Bern University Hospital, Bern, Switzerland
- Division of Cognitive and Restorative Neurology, Department of Neurology, Bern University Hospital, Bern, Switzerland
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10
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Hirota K. Sepsis and the orexin system. J Anesth 2016; 30:919-922. [PMID: 27580992 DOI: 10.1007/s00540-016-2246-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/24/2016] [Indexed: 01/15/2023]
Affiliation(s)
- Kazuyoshi Hirota
- Department of Anesthesiology, Hirosaki University Graduate School of Medicine, Hirosaki, 036-8562, Japan.
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11
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Song J, Kim E, Kim CH, Song HT, Lee JE. The role of orexin in post-stroke inflammation, cognitive decline, and depression. Mol Brain 2015; 8:16. [PMID: 25884812 PMCID: PMC4357085 DOI: 10.1186/s13041-015-0106-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 02/23/2015] [Indexed: 01/02/2023] Open
Abstract
Ischemic stroke results in diverse pathophysiologies, including cerebral inflammation, neuronal loss, cognitive dysfunction, and depression. Studies aimed at identifying therapeutic solutions to alleviate these outcomes are important due to the increase in the number of stroke patients annually. Recently, many studies have reported that orexin, commonly known as a neuropeptide regulator of sleep/wakefulness and appetite, is associated with neuronal cell apoptosis, memory function, and depressive symptoms. Here, we briefly summarize recent studies regarding the role and future perspectives of orexin in post-ischemic stroke. This review advances our understanding of the role of orexin in post-stroke pathologies, focusing on its possible function as a therapeutic regulator in the post-ischemic brain. Ultimately, we suggest the clinical potential of orexin to regulate post-stroke pathologies.
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Affiliation(s)
- Juhyun Song
- Department of Anatomy, Yonsei University College of Medicine, Seoul, 120-752, South Korea.
| | - Eosu Kim
- Department of Pharmacology, Yonsei University College of Medicine, 120-752, Seoul, South Korea.
| | - Chul-Hoon Kim
- Department of Psychiatry, Yonsei University College of Medicine, 120-752, Seoul, South Korea.
| | - Ho-Taek Song
- Department of Diagnostic Radiology, Yonsei University College of Medicine, 120-752, Seoul, South Korea.
| | - Jong Eun Lee
- Department of Anatomy, Yonsei University College of Medicine, Seoul, 120-752, South Korea. .,BK21 Plus Project for Medical Sciences, and Brain Research Institute, Yonsei University, College of Medicine, Seoul, 120-752, South Korea.
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12
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Sundvik M, Panula P. Interactions of the orexin/hypocretin neurones and the histaminergic system. Acta Physiol (Oxf) 2015; 213:321-33. [PMID: 25484194 DOI: 10.1111/apha.12432] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/26/2014] [Accepted: 12/01/2014] [Indexed: 12/28/2022]
Abstract
Histaminergic and orexin/hypocretin systems are components in the brain wake-promoting system. Both are affected in the sleep disorder narcolepsy, but the role of histamine in narcolepsy is unclear. The histaminergic neurones are activated by the orexin/hypocretin system in rodents, and the development of the orexin/hypocretin neurones is bidirectionally regulated by the histaminergic system in zebrafish. This review summarizes the current knowledge of the interactions of these two systems in normal and pathological conditions in humans and different animal models.
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Affiliation(s)
- M. Sundvik
- Institute of Biomedicine, Anatomy, and Neuroscience center; University of Helsinki; Helsinki Finland
| | - P. Panula
- Institute of Biomedicine, Anatomy, and Neuroscience center; University of Helsinki; Helsinki Finland
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13
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Palomba M, Seke-Etet PF, Laperchia C, Tiberio L, Xu YZ, Colavito V, Grassi-Zucconi G, Bentivoglio M. Alterations of orexinergic and melanin-concentrating hormone neurons in experimental sleeping sickness. Neuroscience 2015; 290:185-95. [PMID: 25595977 DOI: 10.1016/j.neuroscience.2014.12.066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 12/12/2014] [Accepted: 12/23/2014] [Indexed: 01/24/2023]
Abstract
Human African trypanosomiasis or sleeping sickness is a severe, neglected tropical disease caused by the extracellular parasite Trypanosoma brucei. The disease, which leads to chronic neuroinflammation, is characterized by sleep and wake disturbances, documented also in rodent models. In rats and mice infected with Trypanosoma brucei brucei, we here tested the hypothesis that the disease could target neurons of the lateral hypothalamus (LH) containing orexin (OX)-A or melanin-concentrating hormone (MCH), implicated in sleep/wake regulation. In the cerebrospinal fluid of infected rats, the OX-A level was significantly decreased early after parasite neuroinvasion, and returned to the control level at an advanced disease stage. The number of immunohistochemically characterized OX-A and MCH neurons decreased significantly in infected rats during disease progression and in infected mice at an advanced disease stage. A marked reduction of the complexity of dendritic arborizations of OX-A neurons was documented in infected mice. The evaluation of NeuN-immunoreactive neurons did not reveal significant neuronal loss in the LH of infected mice, thus suggesting a potential selective vulnerability of OX-A and MCH neurons. Immunophenotyping and quantitative analysis showed in infected mice marked activation of microglial cells surrounding OX-A neurons. Day/night oscillation of c-Fos baseline expression was used as marker of OX-A neuron activity in mice. In control animals Fos was expressed in a higher proportion of OX-A neurons in the night (activity) phase than in the day (rest) phase. Interestingly, in infected mice the diurnal spontaneous Fos oscillation was reversed, with a proportion of OX-A/Fos neurons significantly higher at daytime than at nighttime. Altogether the findings reveal a progressive decrease of OX-A and MCH neurons and dysregulation of OX-A neuron diurnal activity in rodent models of sleeping sickness. The data point to the involvement of these peptidergic neurons in the pathogenesis of sleep/wake alterations in the disease and to their vulnerability to inflammatory signaling.
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Affiliation(s)
- M Palomba
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - P F Seke-Etet
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - C Laperchia
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - L Tiberio
- Department of Molecular and Translational Medicine, University of Brescia, Italy
| | - Y-Z Xu
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - V Colavito
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - G Grassi-Zucconi
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - M Bentivoglio
- Department of Neurological and Movement Sciences, University of Verona, Italy.
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Palomba M, Seke Etet PF, Veronesi C. Effect of inflammatory challenge on hypothalamic neurons expressing orexinergic and melanin-concentrating hormone. Neurosci Lett 2014; 570:47-52. [DOI: 10.1016/j.neulet.2014.03.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/12/2014] [Accepted: 03/27/2014] [Indexed: 01/10/2023]
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15
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Guyon A. CXCL12 chemokine and its receptors as major players in the interactions between immune and nervous systems. Front Cell Neurosci 2014; 8:65. [PMID: 24639628 PMCID: PMC3944789 DOI: 10.3389/fncel.2014.00065] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/13/2014] [Indexed: 11/13/2022] Open
Abstract
The chemokine CXCL12/stromal cell-derived factor 1 alpha has first been described in the immune system where it functions include chemotaxis for lymphocytes and macrophages, migration of hematopoietic cells from fetal liver to bone marrow and the formation of large blood vessels. Among other chemokines, CXCL12 has recently attracted much attention in the brain as it has been shown that it can be produced not only by glial cells but also by neurons. In addition, its receptors CXCR4 and CXCR7, which are belonging to the G protein-coupled receptors family, are abundantly expressed in diverse brain area, CXCR4 being a major co-receptor for human immunodeficiency virus 1 entry. This chemokine system has been shown to play important roles in brain plasticity processes occurring during development but also in the physiology of the brain in normal and pathological conditions. For example, in neurons, CXCR4 stimulation has been shown regulate the synaptic release of glutamate and γ-aminobutyric acid (GABA). It can also act post-synaptically by activating a G protein activated inward rectifier K+ (GIRK), a voltage-gated K channel Kv2.1 associated to neuronal survival, and by increasing high voltage activated Ca2+ currents. In addition, it has been recently evidenced that there are several cross-talks between the CXCL12/CXCR4–7 system and other neurotransmitter systems in the brain (such as GABA, glutamate, opioids, and cannabinoids). Overall, this chemokine system could be one of the key players of the neuro-immune interface that participates in shaping the brain in response to changes in the environment.
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Affiliation(s)
- Alice Guyon
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275 Centre National de la Recherche Scientifique/Université Nice Sophia Antipolis Valbonne, France
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16
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Weymann KB, Wood LJ, Zhu X, Marks DL. A role for orexin in cytotoxic chemotherapy-induced fatigue. Brain Behav Immun 2014; 37:84-94. [PMID: 24216337 PMCID: PMC3951615 DOI: 10.1016/j.bbi.2013.11.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/16/2013] [Accepted: 11/01/2013] [Indexed: 02/08/2023] Open
Abstract
Fatigue is the most common symptom related to cytotoxic chemotherapeutic treatment of cancer. Peripheral inflammation associated with cytotoxic chemotherapy is likely a causal factor of fatigue. The neural mechanisms by which cytotoxic chemotherapy associated inflammation induces fatigue behavior are not known. This lack of knowledge hinders development of interventions to reduce or prevent this disabling symptom. Infection induced fatigue/lethargy in rodents is mediated by suppression of hypothalamic orexin activity. Orexin is critical for maintaining wakefulness and motivated behavior. Though there are differences between infection and cytotoxic chemotherapy in some symptoms, both induce peripheral inflammation and fatigue. Based on these similarities we hypothesized that cytotoxic chemotherapy induces fatigue by disrupting orexin neuron activity. We found that a single dose of a cytotoxic chemotherapy cocktail (cyclophosphamide, adriamycin, 5-fluorouracil - CAF) induced fatigue/lethargy in mice and rats as evidenced by a significant decline in voluntary locomotor activity measured by telemetry. CAF induced inflammatory gene expression - IL-1R1 (p<0.001), IL-6 (p<0.01), TNFα (p<0.01), and MCP-1 (p<0.05) - in the rodent hypothalamus 6-24h after treatment during maximum fatigue/lethargy. CAF decreased orexin neuron activity as reflected by decreased nuclear cFos localization in orexin neurons 24h after treatment (p<0.05) and by decreased orexin-A in cerebrospinal fluid 16 h after treatment (p<0.001). Most importantly, we found that central administration of 1 μg orexin-A restored activity in CAF-treated rats (p<0.05). These results demonstrate that cytotoxic chemotherapy induces hypothalamic inflammation and that suppression of hypothalamic orexin neuron activity has a causal role in cytotoxic chemotherapy-induced fatigue in rodents.
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Affiliation(s)
- K B Weymann
- Oregon Health & Science University, Portland, OR 97239, United States.
| | - L J Wood
- Oregon Health & Science University, Portland, OR 97239, United States; School of Nursing, MGH Institute of Health Professions, Boston, MA 02129, United States.
| | - X Zhu
- Oregon Health & Science University, Portland, OR 97239, United States.
| | - D L Marks
- Oregon Health & Science University, Portland, OR 97239, United States.
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17
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Tsujino N, Sakurai T. Role of orexin in modulating arousal, feeding, and motivation. Front Behav Neurosci 2013; 7:28. [PMID: 23616752 PMCID: PMC3629303 DOI: 10.3389/fnbeh.2013.00028] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/25/2013] [Indexed: 01/15/2023] Open
Abstract
Orexin deficiency results in narcolepsy in humans, dogs, and rodents, suggesting that the orexin system is particularly important for maintenance of wakefulness. However, orexin neurons are “multi-tasking” neurons that regulate sleep/wake states as well as feeding behavior, emotion, and reward processes. Orexin deficiency causes abnormalities in energy homeostasis, stress-related behavior, and reward systems. Orexin excites waking-active monoaminergic and cholinergic neurons in the hypothalamus and brain stem regions to maintain a long, consolidated waking period. Orexin neurons also have reciprocal links with the hypothalamic nuclei, which regulates feeding. Moreover, the responsiveness of orexin neurons to peripheral metabolic cues suggests that these neurons have an important role as a link between energy homeostasis and vigilance states. The link between orexin and the ventral tegmental nucleus serves to motivate an animal to engage in goal-directed behavior. This review focuses on the interaction of orexin neurons with emotion, reward, and energy homeostasis systems. These connectivities are likely to be highly important to maintain proper vigilance states.
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Affiliation(s)
- Natsuko Tsujino
- Department of Molecular Neuroscience and Integrative Physiology, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
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18
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Obukuro K, Takigawa M, Hisatsune A, Isohama Y, Katsuki H. Quinolinate induces selective loss of melanin-concentrating hormone neurons, rather than orexin neurons, in the hypothalamus of mice and young rats. Neuroscience 2010; 170:298-307. [DOI: 10.1016/j.neuroscience.2010.06.081] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 06/08/2010] [Accepted: 06/30/2010] [Indexed: 12/30/2022]
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19
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Datta S. Cellular and chemical neuroscience of mammalian sleep. Sleep Med 2010; 11:431-40. [PMID: 20359944 DOI: 10.1016/j.sleep.2010.02.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/05/2010] [Accepted: 02/12/2010] [Indexed: 11/18/2022]
Abstract
Extraordinary strides have been made toward understanding the complexities and regulatory mechanisms of sleep over the past two decades thanks to the help of rapidly evolving technologies. At its most basic level, mammalian sleep is a restorative process of the brain and body. Beyond its primary restorative purpose, sleep is essential for a number of vital functions. Our primary research interest is to understand the cellular and molecular mechanisms underlying the regulation of sleep and its cognitive functions. Here I will reflect on our own research contributions to 50 years of extraordinary advances in the neurobiology of slow-wave sleep (SWS) and rapid eye movement (REM) sleep regulation. I conclude this review by suggesting some potential future directions to further our understanding of the neurobiology of sleep.
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Affiliation(s)
- Subimal Datta
- Laboratory of Sleep and Cognitive Neuroscience, Departments of Psychiatry, Neurology, and Neuroscience, Boston University School of Medicine, 85 East Newton Street, Suite: M-902, Boston, MA 02118, USA.
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20
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Guyon A, Conductier G, Rovere C, Enfissi A, Nahon JL. Melanin-concentrating hormone producing neurons: Activities and modulations. Peptides 2009; 30:2031-9. [PMID: 19524001 DOI: 10.1016/j.peptides.2009.05.028] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 03/25/2009] [Accepted: 05/25/2009] [Indexed: 10/20/2022]
Abstract
Regulation of energy homeostasis in animals involves adaptation of energy intake to its loss, through a perfect regulation of feeding behavior and energy storage/expenditure. Factors from the periphery modulate brain activity in order to adjust food intake as needed. Particularly, "first order" neurons from arcuate nucleus are able to detect modifications in homeostatic parameters and to transmit information to "second order" neurons, partly located in the lateral hypothalamic area. These "second order" neurons have widespread projections throughout the brain and their proper activation leads them to a coordinated response associated to an adapted behavior. Among these neurons, melanin-concentrating hormone (MCH) expressing neurons play an integrative role of the various factors arising from periphery, first order neurons and extra-hypothalamic arousal systems neurons and modulate regulation of feeding, drinking and seeking behaviors. As regulation of MCH release is correlated to regulation of MCH neuronal activity, we focused this review on the electrophysiological properties of MCH neurons from the lateral hypothalamic area. We first reviewed the knowledge on the endogenous electrical properties of MCH neurons identified according to various criteria which are described. Then, we dealt with the modulations of the electrical activity of MCH neurons by different factors such as glucose, glutamate and GABA, peptides and hormones regulating feeding and transmitters of extra-hypothalamic arousal systems. Finally, we described the current knowledge on the modulation of MCH neuronal activity by cytokines and chemokines. Because of such regulation, MCH neurons are some of the best candidate to account for infection-induced anorexia, but also obesity.
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Affiliation(s)
- Alice Guyon
- Institut de Pharmacologie Moléculaire et Cellulaire, Univrsité de Nice-Sophia Antipolis, Centre National de la Recherche Scientifique, Valbonne, France.
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DellaGioia N, Hannestad J. A critical review of human endotoxin administration as an experimental paradigm of depression. Neurosci Biobehav Rev 2009; 34:130-43. [PMID: 19666048 DOI: 10.1016/j.neubiorev.2009.07.014] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 07/22/2009] [Accepted: 07/24/2009] [Indexed: 12/12/2022]
Abstract
The syndrome called depression may represent the common final pathway at which different aetiopathogenic processes converge. One such aetiopathogenic process is innate immune system activation. Some depressed patients have increased levels of inflammatory cytokines and other immunologic abnormalities. It is not known whether immune system activation contributes to the pathogenesis of depressive symptoms. Supporting this possibility is the observation that in both rodents and humans, exogenous immune stimuli such as endotoxin can produce symptoms that resemble depression. A new approach to depression research would be to use immune stimuli to elicit depressive symptoms in humans. Here we review each of the symptoms elicited in humans by endotoxin administration, and compare this model to two other immune depression paradigms: interferon-alpha treatment and typhoid vaccine administration, to assess to what degree endotoxin administration represents a valid model of immune depression. We also review corresponding behavioral changes in rodents and the potential molecular pathways through which immune system activation produces each symptom.
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Affiliation(s)
- Nicole DellaGioia
- Yale Department of Psychiatry, Clinical Neuroscience Research Unit, Yale University School of Medicine, New Haven, CT 06519, USA
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22
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Guyon A, Massa F, Rovère C, Nahon JL. How cytokines can influence the brain: a role for chemokines? J Neuroimmunol 2008; 198:46-55. [PMID: 18547650 DOI: 10.1016/j.jneuroim.2008.04.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 04/10/2008] [Indexed: 11/17/2022]
Abstract
Following inflammation or infection, cytokines are released in the blood. Besides their effect on the immune system, cytokines can also act in the brain to modulate our behaviors, inducing for example anorexia when produced in large amount. This review focuses on our current knowledge on how cytokines can influence the brain and the behaviors through several possible pathways: modulating peripheral neurons which project to the brain through the vagus nerve, modulating the levels of hormones such as leptin which can act to the brain through the humoral pathway and possibly acting directly in the brain, through the local production of cytokines and chemokines such as SDF-1alpha/CXCL12.
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Affiliation(s)
- Alice Guyon
- Institut de Pharmacologie Moléculaire et Cellulaire, UNSA, CNRS, Sophia Antipolis, 660, route des Lucioles, 06560, Valbonne, France.
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23
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Bentivoglio M, Kristensson K. Neural–immune interactions in disorders of sleep-wakefulness organization. Trends Neurosci 2007; 30:645-52. [DOI: 10.1016/j.tins.2007.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 09/21/2007] [Accepted: 09/26/2007] [Indexed: 11/30/2022]
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24
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Datta S, Maclean RR. Neurobiological mechanisms for the regulation of mammalian sleep-wake behavior: reinterpretation of historical evidence and inclusion of contemporary cellular and molecular evidence. Neurosci Biobehav Rev 2007; 31:775-824. [PMID: 17445891 PMCID: PMC1955686 DOI: 10.1016/j.neubiorev.2007.02.004] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 01/17/2007] [Accepted: 02/26/2007] [Indexed: 11/17/2022]
Abstract
At its most basic level, the function of mammalian sleep can be described as a restorative process of the brain and body; recently, however, progressive research has revealed a host of vital functions to which sleep is essential. Although many excellent reviews on sleep behavior have been published, none have incorporated contemporary studies examining the molecular mechanisms that govern the various stages of sleep. Utilizing a holistic approach, this review is focused on the basic mechanisms involved in the transition from wakefulness, initiation of sleep and the subsequent generation of slow-wave sleep and rapid eye movement (REM) sleep. Additionally, using recent molecular studies and experimental evidence that provides a direct link to sleep as a behavior, we have developed a new model, the cellular-molecular-network model, explaining the mechanisms responsible for regulating REM sleep. By analyzing the fundamental neurobiological mechanisms responsible for the generation and maintenance of sleep-wake behavior in mammals, we intend to provide a broader understanding of our present knowledge in the field of sleep research.
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Affiliation(s)
- Subimal Datta
- Sleep and Cognitive Neuroscience Laboratory, Department of Psychiatry and Behavioral Neuroscience, Boston University School of Medicine, Boston, MA 02118, USA.
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25
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Wollmann G, Acuna-Goycolea C, van den Pol AN. Direct Excitation of Hypocretin/Orexin Cells by Extracellular ATP at P2X Receptors. J Neurophysiol 2005; 94:2195-206. [PMID: 15958604 DOI: 10.1152/jn.00035.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypocretin/orexin (hcrt) neurons play an important role in hypothalamic arousal and energy homeostasis. ATP may be released by neurons or glia or by pathological conditions. Here we studied the effect of extracellular ATP on hypocretin cells using whole cell patch-clamp recording in hypothalamic slices of transgenic mice expressing green fluorescent protein (GFP) exclusively in hcrt-producing cells. Local application of ATP induced a dose-dependent increase in spike frequency. In the presence of TTX, ATP (100 μM) depolarized the cells by 7.8 ± 1.2 mV. In voltage clamp under blockade of synaptic activity with the GABAA receptor antagonist bicuculline, and ionotropic glutamate receptor antagonists dl-2-amino-5-phosphonopentanoic acid (AP-5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), ATP (100 μM) evoked an 18 pA inward current. The inward current was blocked by extracellular choline substitution for Na+, had a reversal potential of −27 mV, and was not affected by nominally Ca2+-free external buffer, suggesting that ATP activated a nonselective cation current. All excitatory effects of ATP showed rapid attenuation. ATP-induced excitatory actions were mimicked by nonhydrolyzable ATP-γ-S but not by α,β-MeATP and inhibited by the purinoceptor antagonists suramin and pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (PPADS). The current was potentiated by a decrease in bath pH, suggesting P2X2 subunit involvement. Frequency and amplitude of spontaneous and miniature synaptic events were not altered by ATP. Suramin, but not PPADS, caused a small suppression of evoked excitatory synaptic potentials. Together, these results show a depolarizing response to extracellular ATP that would lead to an increased activity of the hypocretin arousal system.
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Affiliation(s)
- Guido Wollmann
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar St., New Haven, Connecticut 06520, USA
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Affiliation(s)
- Merrill S Wise
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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