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Satpati A, Pereira FL, Soloviev AV, Mladinov M, Larsen E, Hua SL, Tu CL, Leite REP, Suemoto CK, Rodriguez RD, Paes VR, Walsh C, Spina S, Seeley WW, Pasqualucci CA, Filho WJ, Chang W, Neylan TC, Grinberg LT. The wake- and sleep-modulating neurons of the lateral hypothalamic area demonstrate a differential pattern of degeneration in Alzheimers disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.06.583765. [PMID: 38559184 PMCID: PMC10979907 DOI: 10.1101/2024.03.06.583765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
BACKGROUND Sleep-wake dysfunction is an early and common event in Alzheimer's disease (AD). The lateral hypothalamic area (LHA) regulates the sleep and wake cycle through wake-promoting orexinergic neurons (OrxN) and sleep-promoting melanin-concentrating hormone or MCHergic neurons (MCHN). These neurons share close anatomical proximity with functional reciprocity. This study investigated LHA OrxN and MCHN loss patterns in AD individuals. Understanding the degeneration pattern of these neurons will be instrumental in designing potential therapeutics to slow down the disease progression and remediate the sleep-wake dysfunction in AD. METHODS Postmortem human brain tissue from donors with AD (across progressive stages) and controls were examined using unbiased stereology. Formalin-fixed, celloidin-embedded hypothalamic sections were stained with Orx-A/MCH, p-tau (CP13), and counterstained with gallocyanin. Orx or MCH-positive neurons with or without CP13 inclusions and gallocyanin-stained neurons were considered for stereology counting. Additionally, we extracted RNA from the LHA using conventional techniques. We used customized Neuropathology and Glia nCounter (Nanostring) panels to study gene expression. Wald statistical test was used to compare the groups, and the genes were considered differentially expressed when the p-value was <.05. RESULTS We observed a progressive decline in OrxN alongside a relative preservation of MCHN. OrxN decreased by 58% (p=0.03) by Braak stages (BB) 1-2 and further declined to 81% (p=0.03) by BB 5-6. Conversely, MCHN demonstrated a non-statistical significant decline (27%, p=0.1088) by BB 6. We observed a progressive increase in differentially expressed genes (DEGs), starting with glial profile changes in BB2. While OrxN loss was observed, Orx-related genes showed upregulation in BB 3-4 compared to BB 0-1. GO and KEGG terms related to neuroinflammatory pathways were mainly enriched. CONCLUSIONS To date, OrxN loss in the LHA represents the first neuronal population to die preceding the loss of LC neurons. Conversely, MCHN shows resilience to AD p-tau accumulation across Braak stages. The initial loss of OrxN correlates with specific neuroinflammation, glial profile changes, and an overexpression of HCRT, possibly due to hyperexcitation following compensation mechanisms. Interventions preventing OrxN loss and inhibiting p-tau accumulation in the LHA could prevent neuronal loss in AD and, perhaps, the progression of the disease.
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Devère M, Takhlidjt S, Prévost G, Chartrel N, Leprince J, Picot M. The 26RFa (QRFP)/GPR103 Neuropeptidergic System: A Key Regulator of Energy and Glucose Metabolism. Neuroendocrinology 2024:1-17. [PMID: 38599200 DOI: 10.1159/000538629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/28/2024] [Indexed: 04/12/2024]
Abstract
BACKGROUND Obesity and type 2 diabetes are strongly associated pathologies, currently considered as a worldwide epidemic problem. Understanding the mechanisms that drive the development of these diseases would enable to develop new therapeutic strategies for their prevention and treatment. Particularly, the role of the brain in energy and glucose homeostasis has been studied for 2 decades. In specific, the hypothalamus contains well-identified neural networks that regulate appetite and potentially also glucose homeostasis. A new concept has thus emerged, suggesting that obesity and diabetes could be due to a dysfunction of the same, still poorly understood, neural networks. SUMMARY The neuropeptide 26RFa (also termed QRFP) belongs to the family of RFamide regulatory peptides and has been identified as the endogenous ligand of the human G protein-coupled receptor GPR103 (QRFPR). The primary structure of 26RFa is strongly conserved during vertebrate evolution, suggesting its crucial roles in the control of vital functions. Indeed, the 26RFa/GPR103 peptidergic system is reported to be involved in the control of various neuroendocrine functions, notably the control of energy metabolism in which it plays an important role, both centrally and peripherally, since 26RFa regulates feeding behavior, thermogenesis and lipogenesis. Moreover, 26RFa is reported to control glucose homeostasis both peripherally, where it acts as an incretin, and centrally, where the 26RFa/GPR103 system relays insulin signaling in the brain to control glucose metabolism. KEY MESSAGES This review gives a comprehensive overview of the role of the 26RFa/GPR103 system as a key player in the control of energy and glucose metabolism. In a pathophysiological context, this neuropeptidergic system represents a prime therapeutic target whose mechanisms are highly relevant to decipher.
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Affiliation(s)
- Mélodie Devère
- University Rouen Normandie, Inserm, NorDiC UMR 1239, Normandie University, Rouen, France
| | - Saloua Takhlidjt
- University Rouen Normandie, Inserm, NorDiC UMR 1239, Normandie University, Rouen, France
| | - Gaëtan Prévost
- University Rouen Normandie, Inserm, NorDiC UMR 1239, Normandie University, Rouen, France
- Department of Endocrinology, Diabetes and Metabolic Diseases, University Rouen Normandie, Inserm, Normandie University, NorDiC UMR 1239, CHU Rouen, Rouen, France
| | - Nicolas Chartrel
- University Rouen Normandie, Inserm, NorDiC UMR 1239, Normandie University, Rouen, France
| | - Jérôme Leprince
- University Rouen Normandie, Inserm, NorDiC UMR 1239, Normandie University, Rouen, France
- University Rouen Normandie, Normandie University, INSERM US 51, CNRS UAR 2026, HeRacLeS, Rouen, France
| | - Marie Picot
- University Rouen Normandie, Inserm, NorDiC UMR 1239, Normandie University, Rouen, France
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Farajzadeh-Dehkordi M, Mafakher L, Harifi A, Haghdoost-Yazdi H, Piri H, Rahmani B. Unraveling the function and structure impact of deleterious missense SNPs in the human OX1R receptor by computational analysis. Sci Rep 2024; 14:833. [PMID: 38191899 PMCID: PMC10774445 DOI: 10.1038/s41598-023-49809-4] [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: 08/24/2023] [Accepted: 12/12/2023] [Indexed: 01/10/2024] Open
Abstract
The orexin/hypocretin receptor type 1 (OX1R) plays a crucial role in regulating various physiological functions, especially feeding behavior, addiction, and reward. Genetic variations in the OX1R have been associated with several neurological disorders. In this study, we utilized a combination of sequence and structure-based computational tools to identify the most deleterious missense single nucleotide polymorphisms (SNPs) in the OX1R gene. Our findings revealed four highly conserved and structurally destabilizing missense SNPs, namely R144C, I148N, S172W, and A297D, located in the GTP-binding domain. Molecular dynamics simulations analysis demonstrated that all four most detrimental mutant proteins altered the overall structural flexibility and dynamics of OX1R protein, resulting in significant changes in the structural organization and motion of the protein. These findings provide valuable insights into the impact of missense SNPs on OX1R function loss and their potential contribution to the development of neurological disorders, thereby guiding future research in this field.
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Affiliation(s)
- Mahvash Farajzadeh-Dehkordi
- Student Research Committee, Qazvin University of Medical Sciences, Qazvin, Iran
- Department of Molecular Medicine, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Ladan Mafakher
- Thalassemia & Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Abbas Harifi
- Department of Electrical and Computer Engineering, University of Hormozgan, Bandar Abbas, Hormozgan, Iran
| | - Hashem Haghdoost-Yazdi
- Cellular and Molecular Research Center, Research Institute for Prevention of Non-Communicable Disease, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Hossein Piri
- Cellular and Molecular Research Center, Research Institute for Prevention of Non-Communicable Disease, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Babak Rahmani
- Student Research Committee, Qazvin University of Medical Sciences, Qazvin, Iran.
- Department of Molecular Medicine, Qazvin University of Medical Sciences, Qazvin, Iran.
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Tang M, Wu L, Shen Z, Chen J, Yang Y, Zhang M, Zhao P, Jiang G. Association between Sleep and Alzheimer's Disease: A Bibliometric Analysis from 2003 to 2022. Neuroepidemiology 2023; 57:377-390. [PMID: 37699365 DOI: 10.1159/000533700] [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: 05/17/2023] [Accepted: 07/26/2023] [Indexed: 09/14/2023] Open
Abstract
INTRODUCTION Alzheimer's disease (AD) often presents with sleep disorders, which are also an important risk factor for AD, affecting cognitive function to a certain extent. This study aimed to reveal the current global status, present hotspots, and discuss emerging trends of sleep and AD using a bibliometric approach. METHODS Research and review articles related to sleep and AD from 2003 to 2022 were extracted from the Web of Science Core Collection. VOSviewer 1.6.18.0, Scimago Graphica, and CiteSpace 6.2.R2 were used to map the productive and highly cited countries, institutions, journals, authors, references, and keywords in the field. RESULTS Overall, 4,008 publications were included in this bibliometric analysis. The number of publications and citations showed an increasing trend over the past two decades. The USA and China had the largest and second largest, respectively, number of publications and citations and cooperated with other countries more closely. Ancoli-Israel Sonia published the most papers, and Holtzman David M was co-cited most frequently. The most productive journal was Journal of Alzheimer's Disease, and Neurology was the most frequently cited journal. The risk factors, β-amyloid (Aβ), tau, neuroinflammation, astrocytes, glymphatic system, orexin, functional connectivity, and management have been the main research directions of researchers over the past few years and may be the future trend of valuable research. CONCLUSION We identified hotspots and emerging trends including risk factors, Aβ, tau, neuroinflammation, the glymphatic system, orexin, and management, which may help identify new therapeutic targets and improve clinical efficacy of sleep and AD.
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Affiliation(s)
- Ming Tang
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Li Wu
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Ziyi Shen
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Junwen Chen
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Yang Yang
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Ming Zhang
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Peilin Zhao
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
| | - Guohui Jiang
- Department of Neurology, Affiliated Hospital of North Sichuan Medical College; Institute of Neurological Diseases, North Sichuan Medical College, Nanchong, China
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Edwards GA, Wood CA, Nguyen Q, Kim PJ, Gomez-Gutierrez R, Park KW, Zurhellen C, Al-Ramahi I, Jankowsky JL. TMEM106B coding variant is protective and deletion detrimental in a mouse model of tauopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.533978. [PMID: 36993574 PMCID: PMC10055407 DOI: 10.1101/2023.03.23.533978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
TMEM106B is a risk modifier for a growing list of age-associated dementias including Alzheimer’s and frontotemporal dementia, yet its function remains elusive. Two key questions that emerge from past work are whether the conservative T185S coding variant found in the minor haplotype contributes to protection, and whether the presence of TMEM106B is helpful or harmful in the context of disease. Here we address both issues while extending the testbed for study of TMEM106B from models of TDP to tauopathy. We show that TMEM106B deletion accelerates cognitive decline, hindlimb paralysis, neuropathology, and neurodegeneration. TMEM106B deletion also increases transcriptional overlap with human AD, making it a better model of disease than tau alone. In contrast, the coding variant protects against tau-associated cognitive decline, neurodegeneration, and paralysis without affecting tau pathology. Our findings show that the coding variant contributes to neuroprotection and suggest that TMEM106B is a critical safeguard against tau aggregation.
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Lozano-Tovar S, Rodríguez-Agudelo Y, Dávila-Ortiz de Montellano DJ, Pérez-Aldana BE, Ortega-Vázquez A, Monroy-Jaramillo N. Relationship between APOE, PER2, PER3 and OX2R Genetic Variants and Neuropsychiatric Symptoms in Patients with Alzheimer's Disease. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4412. [PMID: 36901420 PMCID: PMC10001852 DOI: 10.3390/ijerph20054412] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
Alzheimer's disease (AD) is characterized by the presence of neuropsychiatric or behavioral and psychological symptoms of dementia (BPSD). BPSD have been associated with the APOE_ε4 allele, which is also the major genetic AD risk factor. Although the involvement of some circadian genes and orexin receptors in sleep and behavioral disorders has been studied in some psychiatric pathologies, including AD, there are no studies considering gene-gene interactions. The associations of one variant in PER2, two in PER3, two in OX2R and two in APOE were evaluated in 31 AD patients and 31 cognitively healthy subjects. Genotyping was performed using real-time PCR and capillary electrophoresis from blood samples. The allelic-genotypic frequencies of variants were calculated for the sample study. We explored associations between allelic variants with BPSD in AD patients based on the NPI, PHQ-9 and sleeping disorders questionnaires. Our results showed that the APOE_ε4 allele is an AD risk variant (p = 0.03). The remaining genetic variants did not reveal significant differences between patients and controls. The PER3_rs228697 variant showed a nine-fold increased risk for circadian rhythm sleep-wake disorders in Mexican AD patients, and our gene-gene interaction analysis identified a novel interaction between PERIOD and APOE gene variants. These findings need to be further confirmed in larger samples.
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Affiliation(s)
- Susana Lozano-Tovar
- Facultad de Psicología, Universidad Nacional Autónoma de México (UNAM), Circuito Ciudad Universitaria Avenida, C.U., Mexico City 04510, Mexico
| | - Yaneth Rodríguez-Agudelo
- Laboratorio de Neuropsicología Clínica, Instituto Nacional de Neurología y Neurocirugía, “Manuel Velasco Suárez”, Mexico City 14269, Mexico
| | | | - Blanca Estela Pérez-Aldana
- Doctorado en Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Mexico City 04960, Mexico
| | - Alberto Ortega-Vázquez
- Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana, Unidad Xochimilco, Mexico City 04960, Mexico
| | - Nancy Monroy-Jaramillo
- Departamento de Genética, Instituto Nacional de Neurología y Neurocirugía, “Manuel Velasco Suárez”, Mexico City 14269, Mexico
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Ball HL, Said H, Chapman K, Fu R, Xiong Y, Burk JA, Rosenbaum D, Veneziano R, Cotten ML. Orexin A, an amphipathic α-helical neuropeptide involved in pleiotropic functions in the nervous and immune systems: Synthetic approach and biophysical studies of the membrane-bound state. Biophys Chem 2023; 297:107007. [PMID: 37037119 DOI: 10.1016/j.bpc.2023.107007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/11/2023] [Accepted: 03/12/2023] [Indexed: 03/16/2023]
Abstract
This research reports on the membrane interactions of orexin A (OXA), an α-helical and amphipathic neuropeptide that contains 33 residues and two disulfide bonds in the N-terminal region. OXA, which activates the orexins 1 and 2 receptors in neural and immune cell membranes, has essential pleiotropic physiological effects, including at the levels of arousal, sleep/wakefulness, energy balance, neuroprotection, lipid signaling, the inflammatory response, and pain. As a result, the orexin system has become a prominent target to treat diseases such as sleep disorders, drug addiction, and inflammation. While the high-resolution structure of OXA has been investigated in water and bound to micelles, there is a lack of information about its conformation bound to phospholipid membranes and its receptors. NMR is a powerful method to investigate peptide structures in a membrane environment. To facilitate the NMR structural studies of OXA exposed to membranes, we present a novel synthetic scheme, leading to the production of isotopically-labeled material at high purity. A receptor activation assay shows that the 15N-labeled peptide is biologically active. Biophysical studies are performed using surface plasmon resonance, circular dichroism, and NMR to investigate the interactions of OXA with phospholipid bilayers. The results demonstrate a strong interaction between the peptide and phospholipids, an increase in α-helical content upon membrane binding, and an in-plane orientation of the C-terminal region critical to function. This new knowledge about structure-activity relationships in OXA could inspire the design of novel therapeutics that leverage the anti-inflammatory and neuro-protective functions of OXA, and therefore could help address neuroinflammation, a major issue associated with neurological disorders such as Alzheimer's disease.
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Affiliation(s)
- Haydn L Ball
- Department of Chemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hooda Said
- Department of Bioengineering, College of Engineering and Computing, George Mason University, Fairfax, VA 22030, USA
| | - Karen Chapman
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Riqiang Fu
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Yawei Xiong
- Department of Applied Science, William & Mary, Williamsburg, VA 23185, USA
| | - Joshua A Burk
- Department of Psychological Sciences, William & Mary, Williamsburg, VA 23185, USA
| | - Daniel Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Remi Veneziano
- Department of Bioengineering, College of Engineering and Computing, George Mason University, Fairfax, VA 22030, USA
| | - Myriam L Cotten
- Department of Applied Science, William & Mary, Williamsburg, VA 23185, USA.
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Haddad M, Khazali H, Janahmadi M, Ghanbarian H. Inhibition of the retinal orexin receptors affects the hypothalamic-pituitary-gonadal axis through retinal pituitary adenylate cyclase activating polypeptide (PACAP) in male Wistar rats. Gen Comp Endocrinol 2023; 337:114242. [PMID: 36801394 DOI: 10.1016/j.ygcen.2023.114242] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023]
Abstract
Orexins A and B (OXA and OXB) and their receptors are expressed in the retina of both human and rodents and play a vital role in regulating signal transmission circuits in the retina. There is an anatomical-physiological relationship between the retinal ganglion cells and suprachiasmatic nucleus (SCN) through glutamate as a neurotransmitter and retinal pituitary adenylate cyclase-activating polypeptide (PACAP) as a co-transmitter. SCN is the main brain center for regulating the circadian rhythm, which governs the reproductive axis. The impact of retinal orexin receptors on the hypothalamic-pituitary-gonadal axis has not been investigated. Retinal OX1R or/and OX2R in adult male rats by 3 µl of SB-334867 (1 µg) or/and 3 µl of JNJ-10397049 (2 µg) were antagonized via intravitreal injection (IVI). Four time-periods were considered (3, 6, 12, and 24 h) for the controls without any treatment, SB-334867, JNJ-10397049, and SB-334867 + JNJ-10397049 groups. Antagonizing retinal OX1R or/and OX2R resulted in a significant elevation of retinal PACAP expression compared to control animals. In addition, expression of GnRH increased non-significantly in the hypothalamus over the 6 h of the study, and the serum concentration of LH decreased significantly in the SB-334867 group after 3 h of injection. Furthermore, testosterone serum levels declined significantly, especially within 3 h of injection; serum levels of progesterone were also exposed to a significant rise at least within 3 h of injection. However, the retinal PACAP expression changes were mediated by OX1R more effectively than by OX2R. In this study, we report the retinal orexins and their receptors as light-independent factors by which the retina affects the hypothalamic-pituitary-gonadal axis.
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Affiliation(s)
- Muhammad Haddad
- Department of Animal Sciences and Marine Biology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
| | - Homayoun Khazali
- Department of Animal Sciences and Marine Biology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran.
| | - Mahyar Janahmadi
- Neuroscience Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Hossein Ghanbarian
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Ishioh M, Nozu T, Miyagishi S, Igarashi S, Funayama T, Ohhira M, Okumura T. Activation of basal forebrain cholinergic neurons improves colonic hyperpermeability through the vagus nerve and adenosine A2B receptors in rats. Biochem Pharmacol 2022; 206:115331. [PMID: 36330948 DOI: 10.1016/j.bcp.2022.115331] [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: 07/08/2022] [Revised: 10/20/2022] [Accepted: 10/24/2022] [Indexed: 12/14/2022]
Abstract
Intestinal barrier dysfunction, a leaky gut, contributes to the pathophysiology of various diseases such as dementia and irritable bowel syndrome (IBS). We recently clarified that orexin, ghrelin, or adenosine A2B signaling in the brain improved leaky gut through the vagus nerve. The present study was performed to clarify whether basal forebrain cholinergic neurons (BFCNs) are implicated in the central regulation of intestinal barrier function. We activated BFCNs using benzyl quinolone carboxylic acid (BQCA), a positive muscarinic M1 allosteric modulator, and evaluated colonic permeability by quantifying the absorbed Evans blue in rat colonic tissue. Intracisternal (not intraperitoneal) injection of BQCA blocked the increased colonic permeability in response to lipopolysaccharide. Vagotomy blocked BQCA-induced improvement of colonic hyperpermeability. Intracisternally administered pirenzepine, a muscarinic M1 selective antagonist, prevented intestinal barrier function improvement by intravenously administered 2-deoxy-d-glucose, central vagal stimulant. Adenosine A2B receptor antagonist but not dopamine or opioid receptor antagonist prevented BQCA-induced blockade of colonic hyperpermeability. Additionally, intracisternal injection of pirenzepine blocked orexin- or butyrate-induced intestinal barrier function improvement. These results suggest that BFCNs improve leaky gut through adenosine A2B signaling and the vagal pathway. Furthermore, BFCNs mediate orexin- or butyrate-induced intestinal barrier function improvement. Since BFCNs play a role in cognitive function and a leaky gut is associated with dementia, the present finding may lead us to speculate that BFCNs are involved in the development of dementia by regulating intestinal barrier function.
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Affiliation(s)
- Masatomo Ishioh
- Division of Metabolism, Biosystemic Science, Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, Japan; Department of General Medicine, Asahikawa Medical University, Japan.
| | - Tsukasa Nozu
- Department of Regional Medicine and Education, Asahikawa Medical University, Japan
| | - Saori Miyagishi
- Department of General Medicine, Asahikawa Medical University, Japan
| | - Sho Igarashi
- Division of Metabolism, Biosystemic Science, Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, Japan
| | - Takuya Funayama
- Division of Metabolism, Biosystemic Science, Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, Japan
| | - Masumi Ohhira
- Department of General Medicine, Asahikawa Medical University, Japan
| | - Toshikatsu Okumura
- Division of Metabolism, Biosystemic Science, Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, Japan; Department of General Medicine, Asahikawa Medical University, Japan; Center for Medical Education, Asahikawa Medical University, Japan
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Cook C, Nunn N, Worth AA, Bechtold DA, Suter T, Gackeheimer S, Foltz L, Emmerson PJ, Statnick MA, Luckman SM. The hypothalamic RFamide, QRFP, increases feeding and locomotor activity: The role of Gpr103 and orexin receptors. PLoS One 2022; 17:e0275604. [PMID: 36251705 PMCID: PMC9576062 DOI: 10.1371/journal.pone.0275604] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/20/2022] [Indexed: 11/08/2022] Open
Abstract
Here we show that central administration of pyroglutamylated arginine-phenylamine-amide peptide (QRFP/26RFa) increases both food intake and locomotor activity, without any significant effect on energy expenditure, thermogenesis or reward. Germline knock out of either of the mouse QRFP receptor orthologs, Gpr103a and Gpr103b, did not produce a metabolic phenotype. However, both receptors are required for the effect of centrally administered QRFP to increase feeding and locomotor activity. As central injection of QRFP activated orexin/hypocretin neurons in the lateral hypothalamus, we compared the action of QRFP and orexin on behaviour. Both peptides increased arousal and locomotor activity. However, while orexin increased consummatory behaviour, QRFP also affected other appetitive behaviours. Furthermore, the feeding but not the locomotor response to QRFP, was blocked by co-administration of an orexin receptor 1 antagonist. These results suggest that QRFP agonism induces both appetitive and consummatory behaviour, but only the latter is dependent on orexin/hypocretin receptor signalling.
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Affiliation(s)
- Chris Cook
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, University of Manchester, Manchester, United Kingdom
| | - Nicolas Nunn
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, University of Manchester, Manchester, United Kingdom
| | - Amy A. Worth
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, University of Manchester, Manchester, United Kingdom
| | - David A. Bechtold
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, University of Manchester, Manchester, United Kingdom
| | - Todd Suter
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States of America
| | - Susan Gackeheimer
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States of America
| | - Lisa Foltz
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States of America
| | - Paul J. Emmerson
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States of America
| | - Michael A. Statnick
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States of America
- Recursion Pharmaceuticals, Salt Lake City, UT, United States of America
| | - Simon M. Luckman
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medicine, University of Manchester, Manchester, United Kingdom
- * E-mail:
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Huang L, Kang J, Chen G, Ye W, Meng X, Du Q, Feng Z. Low-intensity focused ultrasound attenuates early traumatic brain injury by OX-A/NF-κB/NLRP3 signaling pathway. Aging (Albany NY) 2022; 14:7455-7469. [PMID: 36126193 PMCID: PMC9550253 DOI: 10.18632/aging.204290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/03/2022] [Indexed: 11/25/2022]
Abstract
Background: Traumatic brain injury (TBI) is a serious hazard to human health and is characterized by high rates of disability and mortality. It is necessary to explore new effective treatment methods to reduce the impact of TBI on individuals and society. As an emerging neuromodulation technique, ultrasound is used to treat some neurological diseases, but the neuroprotective mechanism of low-intensity focused ultrasound (LIFUS) in TBI remains unclear. We aimed to investigate the protective effects and potential mechanisms of LIFUS in TBI. Methods: A rat model of TBI was established using the free-fall method. After establishing the TBI model, the hypothalamus region was covered with LIFUS radiation, and an orexin receptor 1 (OXR1) antagonist (SB334867) was injected intraperitoneally. Neurobehavioral examination, Nissl staining, hematoxylin and eosin staining of the brain tissue, and brain water content, were performed 3 days later. Western blotting, quantitative real-time polymerase chain reaction, immunofluorescence staining, and immunohistochemical staining, were used to evaluate the neuroprotective mechanisms of LIFUS. Results: LIFUS improved tissue damage, neurological deficits, and brain edema. LIFUS can increase the expression of orexin-A (OX-A) and OXR1, significantly inhibit the activation of nuclear factor-κB (NF-κB) protein and nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome after TBI, and reduce the release of pro-inflammatory factors after TBI; however, SB334867 can reverse this effect. Conclusions: This study suggests that LIFUS may play a neuroprotective role by promoting the release of OX-A from the hypothalamus and inhibiting the inflammatory response after TBI through the OX-A /NF-κB/NLRP3 pathway.
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Affiliation(s)
- Lianghua Huang
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
| | - Junwei Kang
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
| | - Gengfa Chen
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
| | - Wen Ye
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
| | - Xiangqiang Meng
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
| | - Qing Du
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
| | - Zhen Feng
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, P.R. China
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12
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Luo Y, Shan L, Xu L, Patnala S, Kanfer I, Li J, Yu P, Jun X. A network pharmacology-based approach to explore the therapeutic potential of Sceletium tortuosum in the treatment of neurodegenerative disorders. PLoS One 2022; 17:e0273583. [PMID: 36006974 PMCID: PMC9409587 DOI: 10.1371/journal.pone.0273583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 08/10/2022] [Indexed: 11/24/2022] Open
Abstract
Sceletium tortuosum (SCT) has been utilized medicinally by indigenous Koi-San people purportedly for mood elevation. SCT extracts are reported to be neuroprotective and have efficacy in improving cognition. However, it is still unclear which of the pharmacological mechanisms of SCT contribute to the therapeutic potential for neurodegenerative disorders. Hence, this study investigated two aspects–firstly, the abilities of neuroprotective sub-fractions from SCT on scavenging radicals, inhibiting some usual targets relevant to Alzheimer’s disease (AD) or Parkinson’s disease (PD), and secondly utilizing the network pharmacology related methods to search probable mechanisms using Surflex-Dock program to show the key targets and corresponding SCT constituents. The results indicated sub-fractions from SCT could scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, inhibit acetylcholinesterase (AChE), monoamine oxidase type B (MAO-B) and N-methyl-D-aspartic acid receptor (NMDAR). Furthermore, the results of gene ontology and docking analyses indicated the key targets involved in the probable treatment of AD or PD might be AChE, MAO-B, NMDAR subunit2B (GluN2B-NMDAR), adenosine A2A receptor and cannabinoid receptor 2, and the corresponding constituents in Sceletium tortuosum might be N-trans-feruloyl-3-methyldopamine, dihydrojoubertiamine and other mesembrine type alkaloids. In summary, this study has provided new evidence for the therapeutic potential of SCT in the treatment of AD or PD, as well as the key targets and notable constituents in SCT. Therefore, we propose SCT could be a natural chemical resource for lead compounds in the treatment of neurodegenerative disorders.
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Affiliation(s)
- Yangwen Luo
- College of Pharmacy, Jinan University, Guangzhou, China
| | - Luchen Shan
- College of Pharmacy, Jinan University, Guangzhou, China
| | - Lipeng Xu
- College of Pharmacy, Jinan University, Guangzhou, China
| | - Srinivas Patnala
- Faculty of Pharmacy, Rhodes University, Grahamstown, South Africa
| | - Isadore Kanfer
- Faculty of Pharmacy, Rhodes University, Grahamstown, South Africa
| | - Jiahao Li
- College of Pharmacy, Jinan University, Guangzhou, China
| | - Pei Yu
- College of Pharmacy, Jinan University, Guangzhou, China
- * E-mail: (PY); (JX)
| | - Xu Jun
- College of Pharmacy, Jinan University, Guangzhou, China
- * E-mail: (PY); (JX)
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13
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Sun YY, Wang Z, Zhou HY, Huang HC. Sleep-Wake Disorders in Alzheimer's Disease: A Review. ACS Chem Neurosci 2022; 13:1467-1478. [PMID: 35507669 DOI: 10.1021/acschemneuro.2c00097] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Alzheimer's disease (AD) is a multifactorial disease, and it has become a serious health problem in the world. Senile plaques (SPs) and neurofibrillary tangles (NFTs) are two main pathological characters of AD. SP mainly consists of aggregated β-amyloid (Aβ), and NFT is formed by hyperphosphorylated tau protein. Sleep-wake disorders are prevalent in AD patients; however, the links and mechanisms of sleep-wake disorders on the AD pathogenesis remain to be investigated. Here, we referred to the sleep-wake disorders and reviewed some evidence to demonstrate the relationship between sleep-wake disorders and the pathogenesis of AD. On one hand, the sleep-wake disorders may lead to the increase of Aβ production and the decrease of Aβ clearance, the spreading of tau pathology, as well as oxidative stress and inflammation. On the other hand, the ApoE4 allele, a risk gene for AD, was reported to participate in sleep-wake disorders. Furthermore, some neurotransmitters, such as acetylcholine, glutamate, serotonin, melatonin, and orexins, and their receptors were suggested to be involved in AD development and sleep-wake disorders. We discussed and suggested some possible therapeutic strategies for AD treatment based on the view of sleep regulation. In general, this review explored different views to find novel targets of diagnosis and therapy for AD.
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Affiliation(s)
- Yu-Ying Sun
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, , Beijing 100191, China
- Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing 100023, China
| | - Zhun Wang
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, , Beijing 100191, China
- Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing 100023, China
| | - He-Yan Zhou
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, , Beijing 100191, China
- Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing 100023, China
| | - Han-Chang Huang
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, , Beijing 100191, China
- Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing 100023, China
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14
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Elahdadi Salmani M, Sarfi M, Goudarzi I. Hippocampal orexin receptors: Localization and function. VITAMINS AND HORMONES 2022; 118:393-421. [PMID: 35180935 DOI: 10.1016/bs.vh.2021.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Orexin (hypocretin) is secreted from the perifornical/lateral hypothalamus and is well known for sleep regulation. Orexin has two, orexin A and B, transcripts and two receptors, type 1 and 2 (OX1R and OX2R), located in the plasma membrane of neurons in different brain areas, including the hippocampus involved in learning, memory, seizures, and epilepsy, as physiologic and pathologic phenomena. OX1R is expressed in the dentate gyrus and CA1 and the OX2R in the CA3 areas. Orexin enhances learning and memory as well as reward, stress, seizures, and epilepsy, partly through OX1Rs, while either aggravating or alleviating those phenomena via OX2Rs. OX1Rs activation induces long-term changes of synaptic responses in the hippocampus, an age and concentration-dependent manner. Briefly, we will review the localization and functions of hippocampal orexin receptors, their role in learning, memory, stress, reward, seizures, epilepsy, and hippocampal synaptic plasticity.
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Affiliation(s)
| | | | - Iran Goudarzi
- School of Biology, Damghan University, Damghan, Iran
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15
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Patel SK, Singh SK. Pyroglutamylated RFamide peptide (QRFP): Role in early testicular development in relation to Sertoli cell maturation in prepubertal mice. Neuropeptides 2022; 91:102215. [PMID: 34883413 DOI: 10.1016/j.npep.2021.102215] [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: 06/17/2021] [Revised: 11/30/2021] [Accepted: 11/30/2021] [Indexed: 11/18/2022]
Abstract
QRFP, an orexigenic neuropeptide, binds to its cognate receptor GPR103 and regulates various biological functions. We have recently shown that QRFP and its receptor are present in mice testes and that their expression is high during early postnatal period. The present study aimed to investigate the effect of sustained high level of QRFP on Sertoli cells proliferation and differentiation and to relate these events with germ cell differentiation and lumen formation in the seminiferous tubules in mice testes during prepubertal period. QRFP was injected intraperitoneally to male mice from postnatal day 5 to 16. Morphometric analysis and various markers related to Sertoli cell maturation (WT1, p27kip1, AMH, AR and CYP19A1) and germ cell proliferation and differentiation (PCNA, GDNF and c-Kit) were evaluated. QRFP administration caused an early lumen formation in the seminiferous tubules in testis of treated mice. Further, there was a significant increase in p27kip1 expression and a marked decrease in AMH expression in QRFP-treated mice compared to controls. However, no appreciable change was noted in AR expression in treated mice. QRFP treatment also caused an increase in c-Kit expression in treated mice compared to controls, suggesting an accelerated spermatogonial differentiation in testis of QRFP-treated mice. Taken together, the present results suggest that the prolonged high level of QRFP increases Sertoli cell maturation, which, in turn, plays a contributory role in increasing the pace of germ cell differentiation and formation of lumen in the seminiferous tubules.
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Affiliation(s)
- Shishir Kumar Patel
- Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Shio Kumar Singh
- Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
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16
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Kondo T, Hara N, Koyama S, Yada Y, Tsukita K, Nagahashi A, Ikeuchi T, Ishii K, Asada T, Arai T, Yamada R, Inoue H. Dissection of the polygenic architecture of neuronal Aβ production using a large sample of individual iPSC lines derived from Alzheimer's disease patients. NATURE AGING 2022; 2:125-139. [PMID: 37117761 DOI: 10.1038/s43587-021-00158-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 11/23/2021] [Indexed: 04/30/2023]
Abstract
Genome-wide association studies have demonstrated that polygenic risks shape Alzheimer's disease (AD). To elucidate the polygenic architecture of AD phenotypes at a cellular level, we established induced pluripotent stem cells from 102 patients with AD, differentiated them into cortical neurons and conducted a genome-wide analysis of the neuronal production of amyloid β (Aβ). Using such a cellular dissection of polygenicity (CDiP) approach, we identified 24 significant genome-wide loci associated with alterations in Aβ production, including some loci not previously associated with AD, and confirmed the influence of some of the corresponding genes on Aβ levels by the use of small interfering RNA. CDiP genotype sets improved the predictions of amyloid positivity in the brains and cerebrospinal fluid of patients in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Secondary analyses of exome sequencing data from the Japanese ADNI and the ADNI cohorts focused on the 24 CDiP-derived loci associated with alterations in Aβ led to the identification of rare AD variants in KCNMA1.
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Affiliation(s)
- Takayuki Kondo
- Medical-risk Avoidance based on iPS Cells Team, RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- iPSC-based Drug Discovery and Development Team, RIKEN BioResource Research Center (BRC), Kyoto, Japan
| | - Norikazu Hara
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata, Japan
| | - Satoshi Koyama
- Unit of Statistical Genetics, Center for Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuichiro Yada
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- iPSC-based Drug Discovery and Development Team, RIKEN BioResource Research Center (BRC), Kyoto, Japan
| | - Kayoko Tsukita
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- iPSC-based Drug Discovery and Development Team, RIKEN BioResource Research Center (BRC), Kyoto, Japan
| | - Ayako Nagahashi
- Medical-risk Avoidance based on iPS Cells Team, RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Takeshi Ikeuchi
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata, Japan
| | - Kenji Ishii
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Takashi Asada
- Department of Psychiatry, Division of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Tetsuaki Arai
- Department of Psychiatry, Division of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Ryo Yamada
- Unit of Statistical Genetics, Center for Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Haruhisa Inoue
- Medical-risk Avoidance based on iPS Cells Team, RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan.
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan.
- iPSC-based Drug Discovery and Development Team, RIKEN BioResource Research Center (BRC), Kyoto, Japan.
- Institute for Advancement of Clinical and Translational Science (iACT), Kyoto University Hospital, Kyoto, Japan.
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17
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Madaan P, Behl T, Sehgal A, Singh S, Sharma N, Yadav S, Kaur S, Bhatia S, Al-Harrasi A, Abdellatif AAH, Ashraf GM, Abdel-Daim MM, Dailah HG, Anwer MK, Bungau S. Exploring the Therapeutic Potential of Targeting Purinergic and Orexinergic Receptors in Alcoholic Neuropathy. Neurotox Res 2022; 40:646-669. [DOI: 10.1007/s12640-022-00477-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/13/2022] [Accepted: 01/19/2022] [Indexed: 12/11/2022]
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18
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Couvineau A, Voisin T, Nicole P, Gratio V, Blais A. Orexins: A promising target to digestive cancers, inflammation, obesity and metabolism dysfunctions. World J Gastroenterol 2021; 27:7582-7596. [PMID: 34908800 PMCID: PMC8641057 DOI: 10.3748/wjg.v27.i44.7582] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/22/2021] [Accepted: 11/18/2021] [Indexed: 02/06/2023] Open
Abstract
Hypothalamic neuropeptides named hypocretin/orexins which were identified in 1998 regulate critical functions such as wakefulness in the central nervous system. These past 20 years had revealed that orexins/receptors system was also present in the peripheral nervous system where they participated to the regulation of multiple functions including blood pressure regulation, intestinal motility, hormone secretion, lipolyze and reproduction functions. Associated to these peripheral functions, it was found that orexins and their receptors were involved in various diseases such as acute/chronic inflammation, metabolic syndrome and cancers. The present review suggests that orexins or the orexin neural circuitry represent potential therapeutic targets for the treatment of multiple pathologies related to inflammation including intestinal bowel disease, multiple sclerosis and septic shock, obesity and digestive cancers.
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Affiliation(s)
- Alain Couvineau
- INSERM UMR1149/Inflammation Research Center, Team “From inflammation to cancer in digestive diseases” labeled by “la Ligue Nationale contre le Cancer”, University of Paris, DHU UNITY, Paris 75018, France
| | - Thierry Voisin
- INSERM UMR1149/Inflammation Research Center, Team “From inflammation to cancer in digestive diseases” labeled by “la Ligue Nationale contre le Cancer”, University of Paris, DHU UNITY, Paris 75018, France
| | - Pascal Nicole
- INSERM UMR1149/Inflammation Research Center, Team “From inflammation to cancer in digestive diseases” labeled by “la Ligue Nationale contre le Cancer”, University of Paris, DHU UNITY, Paris 75018, France
| | - Valerie Gratio
- INSERM UMR1149/Inflammation Research Center, Team “From inflammation to cancer in digestive diseases” labeled by “la Ligue Nationale contre le Cancer”, University of Paris, DHU UNITY, Paris 75018, France
| | - Anne Blais
- UMR PNCA, AgroParisTech, INRA, Université Paris-Saclay, Paris 75005, France
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19
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Gao F, Liu T, Tuo M, Chi S. The role of orexin in Alzheimer disease: From sleep-wake disturbance to therapeutic target. Neurosci Lett 2021; 765:136247. [PMID: 34530113 DOI: 10.1016/j.neulet.2021.136247] [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: 04/23/2021] [Revised: 08/01/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
Accumulating evidence has shown that sleep disturbance is a common symptom in Alzheimer's disease (AD), which is regarded as a modifiable risk factor for AD. Orexin is a key modulator of the sleep-wake cycle and has been found to be dysregulated in AD patients. The increased orexin in cerebrospinal fluid (CSF) is associated with decreased sleep efficiency and REM sleep, as well as cognitive impairment in AD patients. The orexin system has profuse projections to brain regions that are implicated in arousal and cognition and has been found to participate in the progression of AD pathology. Conversely the orexin receptor antagonists are able to consolidate sleep and reduce AD pathology. Therefore, improved understanding of the mechanisms linking orexin system, sleep disturbance and AD could make orexin receptor antagonists a promising target for the prevention or treatment of AD.
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Affiliation(s)
- Fan Gao
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, China
| | - Tao Liu
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, China
| | - Miao Tuo
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, China
| | - Song Chi
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, China.
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20
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Zhang D, Perrey DA, Decker AM, Langston TL, Mavanji V, Harris DL, Kotz CM, Zhang Y. Discovery of Arylsulfonamides as Dual Orexin Receptor Agonists. J Med Chem 2021; 64:8806-8825. [PMID: 34101446 DOI: 10.1021/acs.jmedchem.1c00841] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Loss of orexin-producing neurons results in narcolepsy with cataplexy, and orexin agonists have been shown to increase wakefulness and alleviate narcolepsy symptoms in animal models. Several OX2R agonists have been reported but with little or no activity at OX1R. We conducted structure-activity relationship studies on the OX2R agonist YNT-185 (2) and discovered dual agonists such as RTOXA-43 (40) with EC50's of 24 nM at both OX2R and OX1R. Computational modeling studies based on the agonist-bound OX2R cryogenic electron microscopy structures showed that 40 bound in the same binding pocket and interactions of the pyridylmethyl group of 40 with OX1R may have contributed to its high OX1R potency. Intraperitoneal injection of 40 increased time awake, decreased time asleep, and increased sleep/wake consolidation in 12-month old mice. This work provides a promising dual small molecule agonist and supports development of orexin agonists as potential treatments for orexin-deficient disorders such as narcolepsy.
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Affiliation(s)
- Dehui Zhang
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, United States
| | - David A Perrey
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, United States
| | - Ann M Decker
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, United States
| | - Tiffany L Langston
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, United States
| | - Vijayakumar Mavanji
- Research Service, Veterans Affairs Health Care System, Minneapolis, Minnesota 55417, United States
| | - Danni L Harris
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, United States
| | - Catherine M Kotz
- Research Service, Veterans Affairs Health Care System, Minneapolis, Minnesota 55417, United States.,Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Geriatric, Research, Education and Clinical Center, Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota 55417, United States
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, United States
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21
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Intranasal insulin and orexins to treat age-related cognitive decline. Physiol Behav 2021; 234:113370. [PMID: 33621561 DOI: 10.1016/j.physbeh.2021.113370] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 02/19/2021] [Indexed: 02/06/2023]
Abstract
The intranasal (IN) administration of neuropeptides, such as insulin and orexins, has been suggested as a treatment strategy for age-related cognitive decline (ARCD). Because dysfunctional neuropeptide signaling is an observed characteristic of ARCD, it has been suggested that IN delivery of insulin and/or orexins may restore endogenous peptide signaling and thereby preserve cognition. IN administration is particularly alluring as it is a relatively non-invasive method that directly targets peptides to the brain. Several laboratories have examined the behavioral effects of IN insulin in young, aged, and cognitively impaired rodents and humans. These studies demonstrated improved performance on various cognitive tasks following IN insulin administration. Fewer laboratories have assessed the effects of IN orexins; however, this peptide also holds promise as an effective treatment for ARCD through the activation of the cholinergic system and/or the reduction of neuroinflammation. Here, we provide a brief overview of the advantages of IN administration and the delivery pathway, then summarize the current literature on IN insulin and orexins. Additional preclinical studies will be useful to ultimately uncover the mechanisms underlying the pro-cognitive effects of IN insulin and orexins, whereas future clinical studies will aid in the determination of the most efficacious dose and dosing paradigm. Eventually, IN insulin and/or orexin administration may be a widely used treatment strategy in the clinic for ARCD.
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22
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Siddappaji KK, Gopal S. Molecular mechanisms in Alzheimer's disease and the impact of physical exercise with advancements in therapeutic approaches. AIMS Neurosci 2021; 8:357-389. [PMID: 34183987 PMCID: PMC8222772 DOI: 10.3934/neuroscience.2021020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/16/2021] [Indexed: 11/18/2022] Open
Abstract
Alzheimer's disease (AD) is one of the most common, severe neurodegenerative brain disorder characterized by the accumulation of amyloid-beta plaques, neurofibrillary tangles in the brain causing neural disintegration, synaptic dysfunction, and neuronal death leading to dementia. Although many US-FDA-approved drugs like Donepezil, Rivastigmine, Galantamine are available in the market, their consumption reduces only the symptoms of the disease but fails in potency to cure the disease. This disease affects many individuals with aging. Combating the disease tends to be very expensive. This review focuses on biochemical mechanisms in the neuron both at normal and AD state with relevance to the tau hypothesis, amyloid hypothesis, the risk factors influencing dementia, oxidative stress, and neuroinflammation altogether integrated with neurodegeneration. A brief survey is carried out on available biomarkers in the diagnosis of the disease, drugs used for the treatment, and the challenges in approaching therapeutic targets in inhibiting the disease pathologies. This review conjointly assesses the demerits with the inefficiency of drugs to reach targets, their side effects, and toxicity. Optimistically, this review directs on the advantageous strategies in using nanotechnology-based drug delivery systems to cross the blood-brain barrier for improving the efficacy of drugs combined with a novel neuronal stem cell therapy approach. Determinately, this review aims at the natural, non-therapeutic healing impact of physical exercise on different model organisms and the effect of safe neuromodulation treatments using repetitive Transcranial Magnetic Stimulation (rTMS), transcranial Electrical Stimulation (tES) in humans to control the disease pathologies prominent in enhancing the synaptic function.
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Affiliation(s)
| | - Shubha Gopal
- Department of Studies in Microbiology, University of Mysore, Mysuru, 570006, Karnataka, India
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23
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Wang W, Tian Y, Shi X, Ma Q, Xu Y, Yang G, Yi W, Shi Y, Zhou N. N-glycosylation of the human neuropeptide QRFP receptor (QRFPR) is essential for ligand binding and receptor activation. J Neurochem 2021; 158:138-152. [PMID: 33655503 DOI: 10.1111/jnc.15337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 11/29/2022]
Abstract
The newly identified pyroglutamylated RFamide peptide (QRFP) signaling system has been shown to be implicated in regulating a variety of physiological processes. G-protein-coupled receptors (GPCRs) are preferentially N-glycosylated on extracellular domains. The human QRFP receptor QRFPR (GPR103) possesses three N-glycosylation consensus sites, two located on the N-terminal domain (N5 and N19) and one on the first extracellular loop (ECL1) (N106); however, to date, their role in QRFPR expression and signaling has not been established. Here, we combined mutants with glutamine substitution of the critical asparagines of the consensus sites with glycosidase PNGase F and N-glycosylation inhibitor tunicamycin to study the effect of N-glycosylation in the regulation of QRFPR cell surface expression and signaling. Western blot analysis performed with site-directed mutagenesis revealed that two asparagines at N19 in the N-terminus and N106 in ECL1, but not N5 in the N-terminus, served as sites for N-glycosylation. Treatment with PNGase F and tunicamycin resulted in a reduction in both two-protein species, ~43 kDa and ~85 kDa in size, by 2-4 kDa. Analysis with confocal microscopy and quantitative ELISA showed that N-glycosylation of QRFPR is not essentially required for targeting the cell membrane. However, further binding assay and functional assays demonstrated that removal of N-glycosylation sequons or treatment with tunicamycin led to significant impairments in the interaction of receptor with QRFP26 and downstream signaling. Thus, our findings suggest that for the human QRFP receptor (QRFPR), N-glycosylation is not important for cell surface expression but is a pre-requisite for ligand binding and receptor activation.
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Affiliation(s)
- Weiwei Wang
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yanan Tian
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaoliu Shi
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qiang Ma
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yue Xu
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Gangjie Yang
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wen Yi
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ying Shi
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Naiming Zhou
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
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24
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Keenan RJ, Oberrauch S, Bron R, Nowell CJ, Challis LM, Hoyer D, Jacobson LH. Decreased Orexin Receptor 1 mRNA Expression in the Locus Coeruleus in Both Tau Transgenic rTg4510 and Tau Knockout Mice and Accompanying Ascending Arousal System Tau Invasion in rTg4510. J Alzheimers Dis 2021; 79:693-708. [PMID: 33361602 DOI: 10.3233/jad-201177] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Sleep/wake disturbances (e.g., insomnia and sleep fragmentation) are common in neurodegenerative disorders, especially Alzheimer's disease (AD) and frontotemporal dementia (FTD). These symptoms are somewhat reminiscent of narcolepsy with cataplexy, caused by the loss of orexin-producing neurons. A bidirectional relationship between sleep disturbance and disease pathology suggests a detrimental cycle that accelerates disease progression and cognitive decline. The accumulation of brain tau fibrils is a core pathology of AD and FTD-tau and clinical evidence supports that tau may impair the orexin system in AD/FTD. This hypothesis was investigated using tau mutant mice. OBJECTIVE To characterize orexin receptor mRNA expression in sleep/wake regulatory brain centers and quantify noradrenergic locus coeruleus (LC) and orexinergic lateral hypothalamus (LH) neurons, in tau transgenic rTg4510 and tau-/- mice. METHODS We used i n situ hybridization and immunohistochemistry (IHC) in rTg4510 and tau-/- mice. RESULTS rTg4510 and tau-/- mice exhibited a similar decrease in orexin receptor 1 (OX1R) mRNA expression in the LC compared with wildtype controls. IHC data indicated this was not due to decreased numbers of LC tyrosine hydroxylase-positive (TH) or orexin neurons and demonstrated that tau invades TH LC and orexinergic LH neurons in rTg4510 mice. In contrast, orexin receptor 2 (OX2R) mRNA levels were unaffected in either model. CONCLUSION The LC is strongly implicated in the regulation of sleep/wakefulness and expresses high levels of OX1R. These findings raise interesting questions regarding the effects of altered tau on the orexin system, specifically LC OX1Rs, and emphasize a potential mechanism which may help explain sleep/wake disturbances in AD and FTD.
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Affiliation(s)
- Ryan J Keenan
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Sara Oberrauch
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Romke Bron
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Cameron J Nowell
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Leesa M Challis
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Daniel Hoyer
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia.,Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Laura H Jacobson
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia.,Melbourne Dementia Research Centre, University of Melbourne, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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25
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Abstract
Twenty-two years after their discovery, the hypocretins (Hcrts), also known as orexins, are two of the most studied peptidergic systems, involved in myriad physiological systems that range from sleep, arousal, motivation, homeostatic regulation, fear, anxiety and learning. A causal relationship between activity of Hcrt and arousal stability was established shortly after their discovery and have led to the development of a new class of drugs to treat insomnia. In this review we discuss the many faces of the Hcrt system and examine recent findings that implicate decreased Hcrt function in the pathogenesis of a number of neuropsychiatric conditions. We also discuss future therapeutic strategies to replace or enhance Hcrt function as a treatment option for these neuropsychiatric conditions.
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Affiliation(s)
- Erica Seigneur
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA
| | - Luis de Lecea
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA
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26
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Yaeger JD, Krupp KT, Gale JJ, Summers CH. Counterbalanced microcircuits for Orx1 and Orx2 regulation of stress reactivity. MEDICINE IN DRUG DISCOVERY 2020. [DOI: 10.1016/j.medidd.2020.100059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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27
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Orexin-A protects against cerebral ischemia-reperfusion injury by inhibiting excessive autophagy through OX1R-mediated MAPK/ERK/mTOR pathway. Cell Signal 2020; 79:109839. [PMID: 33212156 DOI: 10.1016/j.cellsig.2020.109839] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 02/06/2023]
Abstract
Orexin A (OXA) is a neuroprotective peptide that exerts protective effects on multiple physiological and pathological processes. Activation of autophagy is linked to the occurrence of cerebral ischemia-reperfusion injury (CIRI); however, its function remains incompletely understood. In this study, OXA was sought to exert its neuroprotective role by regulating autophagy in oxygen and glucose deprivation and reoxygenation (OGD/R) model and middle cerebral artery occlusion (MCAO) model of rats, and to elucidate the underlying molecular mechanisms. Acridine orange (AO) staining was used to evaluate autophagic vacuoles. Cell viability was measured by CCK8. The levels of p-ERK1/2, t-ERK1/2, p-mTOR, LC3B, Beclin 1, and p62 were evaluated by western blotting. Apoptosis rate was detected by Hoechst 33342 staining and Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL). OXA treatment alleviated neuronal apoptosis and significantly inhibited autophagy activity. Mechanistically, OXA exerted its neuroprotective effects in vivo and in vitro by suppressing over-activated autophagy by modulating OX1R-mediated MAPK/ERK/mTOR pathway. The results of this study elucidate the roles of autophagy in CIRI and the mechanisms underlying the neuroprotective action of OXA. Our findings could facilitate the development of novel therapeutics for ischemic stroke.
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28
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Wang W, Jiang C, Xu Y, Ma Q, Yang J, Shi Y, Zhou N. Functional characterization of neuropeptide 26RFa receptors GPR103A and GPR103B in zebrafish, Danio rerio. Cell Signal 2020; 73:109677. [DOI: 10.1016/j.cellsig.2020.109677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 05/10/2020] [Accepted: 05/23/2020] [Indexed: 11/25/2022]
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29
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Sharma A, Lee S, Kim H, Yoon H, Ha S, Kang SU. Molecular Crosstalk Between Circadian Rhythmicity and the Development of Neurodegenerative Disorders. Front Neurosci 2020; 14:844. [PMID: 32848588 PMCID: PMC7424028 DOI: 10.3389/fnins.2020.00844] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/20/2020] [Indexed: 12/17/2022] Open
Abstract
Neurodegenerative disorders have been shown to exhibit substantial interconnectedness with circadian rhythmicity. Alzheimer's patients exhibit high degradation of the suprachiasmatic nucleus (SCN), the central endogenous circadian timekeeper, and Parkinson's patients have highly disrupted peripheral clock gene expression. Disrupted sleep patterns are highly evident in patients with neurodegenerative diseases; fragmented sleep has been shown to affect tau-protein accumulation in Alzheimer's patients, and rapid eye movement (REM) behavioral disorder is observed in a significant amount of Parkinson's patients. Although numerous studies exist analyzing the mechanisms of neurodegeneration and circadian rhythm function independently, molecular mechanisms establishing specific links between the two must be explored further. Thus, in this review, we explore the possible intersecting molecular mechanisms between circadian rhythm and neurodegeneration, with a particular focus on Parkinson's disease. We provide evidence for potential influences of E3 ligase and poly adenosine diphosphate (ADP-ribose) polymerase 1 (PARP1) activity on neurodegenerative pathology. The cellular stress and subsequent DNA damage signaling imposed by hyperactivity of these multiple molecular systems in addition to aberrant circadian rhythmicity lead to extensive protein aggregation such as α-synuclein pre-formed fibrils (α-Syn PFFs), suggesting a specific molecular pathway linking circadian rhythmicity, PARP1/E3 ligase activity, and Parkinson's disease.
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Affiliation(s)
- Arastu Sharma
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sehyun Lee
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Hoonseo Kim
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Hargsoon Yoon
- Neural Engineering and Nano Electronics Laboratory, Department of Engineering, Norfolk State University, Norfolk, VA, United States
| | - Shinwon Ha
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sung Ung Kang
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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30
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Orexins role in neurodegenerative diseases: From pathogenesis to treatment. Pharmacol Biochem Behav 2020; 194:172929. [PMID: 32315694 DOI: 10.1016/j.pbb.2020.172929] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 12/12/2022]
Abstract
Orexin is a neurotransmitter that mainly regulates sleep/wake cycle. In addition to its sleep cycle regulatory role, it is involved in regulation of attention, energy homeostasis, neurogenesis and cognition. Several evidences has shown the involvement of orexin in narcolepsy, but there are also growing evidences that shows the disturbance in orexin system in neurodegenerative diseases including Alzheimer's, Parkinson's, Epilepsy, Huntington's diseases and Amyotrophic lateral sclerosis. Pathogenesis and clinical symptoms of these disorders can be partly attributed from orexin system imbalance. However, there are controversial reports on the exact relationship between orexin and these neurodegenerative diseases. Therefore, the aim of this review is to summarize the current evidences regarding the role of orexin in these neurodegenerative diseases.
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31
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Pallais JP, Kotz CM, Stanojlovic M. Orexin/hypocretinin in multiple sclerosis and experimental autoimmune encephalomyelitis. Neural Regen Res 2020; 15:1039-1040. [PMID: 31823881 PMCID: PMC7034266 DOI: 10.4103/1673-5374.270310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Jean Pierre Pallais
- Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Catherine M Kotz
- Integrative Biology and Physiology, University of Minnesota; Minneapolis VA Health Care System, Geriatric Research, Education and Clinical Center, Minneapolis, MN, USA
| | - Milos Stanojlovic
- Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
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32
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Zagorácz O, Ollmann T, Péczely L, László K, Kovács A, Berta B, Kállai V, Kertes E, Lénárd L. QRFP administration into the medial hypothalamic nuclei improves memory in rats. Brain Res 2019; 1727:146563. [PMID: 31765630 DOI: 10.1016/j.brainres.2019.146563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/31/2019] [Accepted: 11/19/2019] [Indexed: 10/25/2022]
Abstract
Even though several of RFamide peptides have been shown to modify memory and learning processes in different species, almost nothing is known regarding cognitive effects of recently discovered neuropeptide QRFP. Considering multiple physiological functions of QRFP, localization of QRFP-synthesizing neurons in the hypothalamus and its' widely spread binding sites within the CNS, the present study was designed to investigate the possible role of QRFP in the consolidation of spatial memory. As target area for microinjection, the medial hypothalamic area, including dorsomedial (DMN) and ventromedial (VMN) nuclei, has been chosen. At first, the effects of two doses (200 ng and 400 ng) of QRFP were investigated in Morris water maze. After that receptor antagonist BIBP3226 (equimolar amount to the effective dose of neuropeptide) was applied to elucidate whether it can prevent effects of QRFP. To reveal possible changes in anxiety level, animals were tested in Elevated plus maze. The higher dose of QRFP (400 ng) improved short-term memory consolidation in Morris water maze. Pretreatment with antagonist BIBP3226 abolished cognitive effects of QRFP. The neuropeptide did not affect anxiety level of rats. This study provides unique evidence regarding the role of QRFP in the consolidation of memory and gives the basis for further investigations of neuropeptide's cognitive effects.
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Affiliation(s)
- Olga Zagorácz
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - Tamás Ollmann
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - László Péczely
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - Kristóf László
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - Anita Kovács
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - Beáta Berta
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - Veronika Kállai
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - Erika Kertes
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
| | - László Lénárd
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary; Molecular Neurophysiology Research Group, Pécs University, Szentágothai Research Center, Pécs, Hungary.
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33
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Molecular codes and in vitro generation of hypocretin and melanin concentrating hormone neurons. Proc Natl Acad Sci U S A 2019; 116:17061-17070. [PMID: 31375626 PMCID: PMC6708384 DOI: 10.1073/pnas.1902148116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hypocretin/orexin (HCRT) and melanin concentrating hormone (MCH) neuropeptides are exclusively produced by the lateral hypothalamus and play important roles in sleep, metabolism, reward, and motivation. Loss of HCRT (ligands or receptors) causes the sleep disorder narcolepsy with cataplexy in humans and in animal models. How these neuropeptides are produced and involved in diverse functions remain unknown. Here, we developed methods to sort and purify HCRT and MCH neurons from the mouse late embryonic hypothalamus. RNA sequencing revealed key factors of fate determination for HCRT (Peg3, Ahr1, Six6, Nr2f2, and Prrx1) and MCH (Lmx1, Gbx2, and Peg3) neurons. Loss of Peg3 in mice significantly reduces HCRT and MCH cell numbers, while knock-down of a Peg3 ortholog in zebrafish completely abolishes their expression, resulting in a 2-fold increase in sleep amount. We also found that loss of HCRT neurons in Hcrt-ataxin-3 mice results in a specific 50% decrease in another orexigenic neuropeptide, QRFP, that might explain the metabolic syndrome in narcolepsy. The transcriptome results were used to develop protocols for the production of HCRT and MCH neurons from induced pluripotent stem cells and ascorbic acid was found necessary for HCRT and BMP7 for MCH cell differentiation. Our results provide a platform to understand the development and expression of HCRT and MCH and their multiple functions in health and disease.
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34
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Kumar J, Murugaiah V, Sotiriadis G, Kaur A, Jeyaneethi J, Sturniolo I, Alhamlan FS, Chatterjee J, Hall M, Kishore U, Karteris E. Surfactant Protein D as a Potential Biomarker and Therapeutic Target in Ovarian Cancer. Front Oncol 2019; 9:542. [PMID: 31338320 PMCID: PMC6629871 DOI: 10.3389/fonc.2019.00542] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/04/2019] [Indexed: 12/11/2022] Open
Abstract
Surfactant protein D (SP-D) is an important innate immune molecule that is involved in clearing pathogens and regulating inflammation at pulmonary as well as extra-pulmonary sites. Recent studies have established the role of SP-D as an innate immune surveillance molecule against lung and pancreatic cancer, but little is known about its involvement in signaling pathways it can potentially activate in ovarian cancer. We focused our study on ovarian cancer by performing bioinformatics analysis (Oncomine) of datasets and survival analysis (Kaplan-Meier plotter), followed by immunohistochemistry using ovarian cancer tissue microarrays. SP-D mRNA was found to be expressed widely in different types of ovarian cancer irrespective of stage or grade. These in silico data were further validated by immunohistochemistry of clinical tissues. High transcriptional levels of SP-D were associated with unfavorable prognosis (overall and progression-free survival). We also detected SP-D protein in Circulating Tumor Cells of three ovarian cancer patients, suggesting that SP-D can also be used as a potential biomarker. Previous studies have shown that a recombinant fragment of human SP-D (rfhSP-D) induced apoptosis in pancreatic cancer cells via Fas-mediated pathway. In this study, we report that treatment of SKOV3 cells (an ovarian cancer cell line) with rfhSP-D led to a decrease in cell motility and cell proliferation. This was followed by an inhibition of the mTOR pathway activity, increase in caspase 3 cleavage, and induction of pro-apoptotic genes Fas and TNF-α. These data, suggesting a likely protective role of rfhSP-D against ovarian cancer, together with the observation that the ovarian cancer microenvironment overexperesses SP-D leading to poor prognosis, seems to suggest that the tumor microenvironment components manipulate the protective effect of SP-D in vivo.
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Affiliation(s)
- Juhi Kumar
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Valamarthy Murugaiah
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Georgios Sotiriadis
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Anuvinder Kaur
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Jeyarooban Jeyaneethi
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Isotta Sturniolo
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Fatimah S Alhamlan
- Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Jayanta Chatterjee
- Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
| | - Marcia Hall
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom.,Mount Vernon Cancer Centre, Northwood, United Kingdom
| | - Uday Kishore
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Emmanouil Karteris
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom.,Institute of Environment, Health and Societies, Brunel University London, Uxbridge, United Kingdom
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35
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Niknia S, Kaeidi A, Hajizadeh MR, Mirzaei MR, Khoshdel A, Hajializadeh Z, Fahmidehkar MA, Mahmoodi M. Neuroprotective and antihyperalgesic effects of orexin-A in rats with painful diabetic neuropathy. Neuropeptides 2019; 73:34-40. [PMID: 30447858 DOI: 10.1016/j.npep.2018.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 11/06/2018] [Accepted: 11/06/2018] [Indexed: 01/19/2023]
Abstract
AIM OF STUDY Diabetes mellitus is related to the development of neuronal tissue injury in different peripheral and central nervous system regions. A common complication of diabetes is painful diabetic peripheral neuropathy (PDN). We have studied the neuroprotective and anti-nociceptive properties of neuropeptide orexin-A in an animal experimental model of diabetic neuropathy. METHODS All experiments were carried out on male Wistar rats (220-250 g). Diabetes was induced by a single intraperitoneal injection of 55 mg/kg (i.p.) streptozotocin (STZ). Orexin-A was chronically administrated into the implanted intrathecal catheter (0.6, 2.5 and 5 nM/L, daily, 4 weeks). The tail-flick and rotarod treadmill tests were used to evaluate the nociceptive threshold and motor coordination of these diabetic rats, respectively. Cleaved caspase-3, Bax, Bcl2 and the Bax/Bcl-2 ratio, as the biochemical indicators of apoptosis, were investigated in the dorsal half of the lumbar spinal cord tissue by western blotting method. RESULTS Treatment of the diabetic rats with orexin-A (5 nM/L) significantly attenuated the hyperalgesia and motor deficit in diabetic animals. Furthermore, orexin-A (5 nM/L) administration suppressed pro-apoptotic cleaved caspase-3 and Bax proteins. Also, orexin-A (5 nM/L) reduced the expression of Bax/Bcl-2 ratio in spinal cord dorsal half of rats with PDN. CONCLUSIONS Altogether our data suggest that the orexin-A has anti-hyperalgesic and neuroprotective effects in rats with PDN. Cellular mechanisms underlying the observed effects may, at least partially, be related to reducing the neuronal apoptosis.
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Affiliation(s)
- Seddigheh Niknia
- Department of Clinical Biochemistry, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Molecular Medicine Research Center, Research Institute of Basic Medical Sciences, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Ayat Kaeidi
- Physiology-Pharmacology Research Center, Research Institute of Basic Medical Sciences, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Mohammad Reza Hajizadeh
- Department of Clinical Biochemistry, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Molecular Medicine Research Center, Research Institute of Basic Medical Sciences, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Mohammad Reza Mirzaei
- Department of Clinical Biochemistry, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Molecular Medicine Research Center, Research Institute of Basic Medical Sciences, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Alireza Khoshdel
- Department of Clinical Biochemistry, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Pistachio Safety Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Zahra Hajializadeh
- Endocrinology and Metabolism Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Ali Fahmidehkar
- Department of Clinical Biochemistry, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Department of Laboratory Science, School of Paramedical Sciences, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran
| | - Mehdi Mahmoodi
- Department of Clinical Biochemistry, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Molecular Medicine Research Center, Research Institute of Basic Medical Sciences, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Department of Clinical Biochemistry, Afzalipoor Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran.
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36
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Chen XY, Du YF, Chen L. Neuropeptides Exert Neuroprotective Effects in Alzheimer's Disease. Front Mol Neurosci 2019; 11:493. [PMID: 30687008 PMCID: PMC6336706 DOI: 10.3389/fnmol.2018.00493] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 12/21/2018] [Indexed: 01/03/2023] Open
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by cognitive deficits and neuronal loss. Deposition of beta-amyloid peptide (Aβ) causes neurotoxicity through the formation of plaques in brains of Alzheimer's disease. Numerous studies have indicated that the neuropeptides including ghrelin, neurotensin, pituitary adenylate cyclase-activating polypeptide (PACAP), neuropeptide Y, substance P and orexin are closely related to the pathophysiology of Alzheimer's disease. The levels of neuropeptides and their receptors change in Alzheimer's disease. These neuropeptides exert neuroprotective roles mainly through preventing Aβ accumulation, increasing neuronal glucose transport, increasing the production of neurotrophins, inhibiting endoplasmic reticulum stress and autophagy, modulating potassium channel activity and hippocampal long-term potentiation. Therefore, the neuropeptides may function as potential drug targets in the prevention and cure of Alzheimer's disease.
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Affiliation(s)
- Xin-Yi Chen
- Department of Physiology and Pathophysiology, Qingdao University, Qingdao, China.,Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Yi-Feng Du
- Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Lei Chen
- Department of Physiology and Pathophysiology, Qingdao University, Qingdao, China
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37
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Couvineau A, Voisin T, Nicole P, Gratio V, Abad C, Tan YV. Orexins as Novel Therapeutic Targets in Inflammatory and Neurodegenerative Diseases. Front Endocrinol (Lausanne) 2019; 10:709. [PMID: 31695678 PMCID: PMC6817618 DOI: 10.3389/fendo.2019.00709] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/02/2019] [Indexed: 02/05/2023] Open
Abstract
Orexins [orexin-A (OXA) and orexin-B (OXB)] are two isoforms of neuropeptides produced by the hypothalamus. The main biological actions of orexins, focused on the central nervous system, are to control the sleep/wake process, appetite and feeding, energy homeostasis, drug addiction, and cognitive processes. These effects are mediated by two G protein-coupled receptor (GPCR) subtypes named OX1R and OX2R. In accordance with the synergic and dynamic relationship between the nervous and immune systems, orexins also have neuroprotective and immuno-regulatory (i.e., anti-inflammatory) properties. The present review gathers recent data demonstrating that orexins may have a therapeutic potential in several pathologies with an immune component including multiple sclerosis, Alzheimer's disease, narcolepsy, obesity, intestinal bowel diseases, septic shock, and cancers.
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Affiliation(s)
- Alain Couvineau
- INSERM UMR1149/Inflammation Research Center (CRI), Team “From Inflammation to Cancer in Digestive Diseases” Labeled by “la Ligue Nationale Contre le Cancer”, University of Paris, Paris, France
- *Correspondence: Alain Couvineau
| | - Thierry Voisin
- INSERM UMR1149/Inflammation Research Center (CRI), Team “From Inflammation to Cancer in Digestive Diseases” Labeled by “la Ligue Nationale Contre le Cancer”, University of Paris, Paris, France
| | - Pascal Nicole
- INSERM UMR1149/Inflammation Research Center (CRI), Team “From Inflammation to Cancer in Digestive Diseases” Labeled by “la Ligue Nationale Contre le Cancer”, University of Paris, Paris, France
| | - Valérie Gratio
- INSERM UMR1149/Inflammation Research Center (CRI), Team “From Inflammation to Cancer in Digestive Diseases” Labeled by “la Ligue Nationale Contre le Cancer”, University of Paris, Paris, France
| | - Catalina Abad
- University of Rouen Normandy, INSERM U1234 PANTHER, IRIB, Rouen, France
| | - Yossan-Var Tan
- University of Rouen Normandy, INSERM U1234 PANTHER, IRIB, Rouen, France
- Yossan-Var Tan
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Calva CB, Fadel JR. Intranasal administration of orexin peptides: Mechanisms and therapeutic potential for age-related cognitive dysfunction. Brain Res 2018; 1731:145921. [PMID: 30148983 DOI: 10.1016/j.brainres.2018.08.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/03/2018] [Accepted: 08/23/2018] [Indexed: 12/11/2022]
Abstract
Cognitive impairment is a core feature of several neuropsychiatric and neurological disorders, including narcolepsy and age-related dementias. Current pharmacotherapeutic approaches to cognitive enhancement are few in number and limited in efficacy. Thus, novel treatment strategies are needed. The hypothalamic orexin (hypocretin) system, a central integrator of physiological function, plays an important role in modulating cognition. Several single- and dual-orexin receptor antagonists are available for various clinical and preclinical applications, but the paucity of orexin agonists has limited the ability to research their therapeutic potential. To circumvent this hurdle, direct intranasal administration of orexin peptides is being investigated as a prospective treatment for cognitive dysfunction, narcolepsy or other disorders in which deficient orexin signaling has been implicated. Here, we describe the possible mechanisms and therapeutic potential of intranasal orexin delivery. Combined with the behavioral evidence that intranasal orexin-A administration improves cognitive function in narcoleptic and sleep-deprived subjects, our neurochemical studies in young and aged animals highlights the capacity for intranasal orexin administration to improve age-related deficits in neurotransmission. In summary, we highlight prior and original work from our lab and from others that provides a framework for the use of intranasal orexin peptides in treating cognitive dysfunction, especially as it relates to age-related cognitive disorders.
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Affiliation(s)
- Coleman B Calva
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, 6311 Garners Ferry Road, Columbia, SC 29209, USA
| | - Jim R Fadel
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, 6311 Garners Ferry Road, Columbia, SC 29209, USA.
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Appetite, Metabolism and Hormonal Regulation in Normal Ageing and Dementia. Diseases 2018; 6:diseases6030066. [PMID: 30036957 PMCID: PMC6164971 DOI: 10.3390/diseases6030066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 07/17/2018] [Accepted: 07/19/2018] [Indexed: 12/12/2022] Open
Abstract
Feeding and nutrition follow the growth trajectory of the course of life. The profound physiological changes that human body experiences during ageing affect separate aspects of food intake, from tastant perception to satiety. Concurrent morbidities, such as neurodegeneration, as seen in dementia, and metabolic syndrome, may further shape nutritional behaviours, status and adequacy. In an effort to fill the gap between the exhausting basic research and the actual needs of professionals caring for the exponentially expanding ageing population, the current review addresses major factors relevant to appetite and eating disturbances. Does age alter the perception of food modalities? Is food generally still perceived as alluring and delicious with age? Is there an interplay between ageing, cognitive decline, and malnutrition? What tools can we adopt for proper and timely monitoring? Finally, what anatomical and pathophysiological evidence exists to support a hypothesis of central regulation of metabolic perturbations in normal and accelerated cognitive impairment, and how can we benefit from it in health practice?
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40
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Xue Q, Bai B, Ji B, Chen X, Wang C, Wang P, Yang C, Zhang R, Jiang Y, Pan Y, Cheng B, Chen J. Ghrelin Through GHSR1a and OX1R Heterodimers Reveals a Gαs-cAMP-cAMP Response Element Binding Protein Signaling Pathway in Vitro. Front Mol Neurosci 2018; 11:245. [PMID: 30065627 PMCID: PMC6056640 DOI: 10.3389/fnmol.2018.00245] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 06/25/2018] [Indexed: 01/19/2023] Open
Abstract
Growth hormone secretagogue receptor 1α (GHSR1a) and Orexin 1 receptor (OX1R) are involved in various important physiological processes, and have many similar characteristics in function and distribution in peripheral tissues and the central nervous system. We explored the possibility of heterodimerization between GHSR1a and OX1R and revealed a signal transduction pathway mechanism. In this study, bioluminescence and fluorescence resonance energy transfer and co-immunoprecipitation (Co-IP) analyses were performed to demonstrate the formation of functional GHSR1a/OX1R heterodimers. This showed that a peptide corresponding to the 5-transmembrane domain of OX1R impaired heterodimer construction. We found that ghrelin stimulated GHSR1a/OX1R heterodimer cells to increase the activation of Gαs protein, compared to the cells that express GHSR1a. Stimulation of GHSR1a/OX1R heterodimers with orexin-A did not alter GPCR interactions with Gα protein subunits. GHSR1a/OX1R heterodimers induced Gαs and downstream signaling pathway activity, including increase of cAMP-response element luciferase reporter activity and cAMP levels. In addition, ghrelin induced a higher proliferation rate in SH-SY5Y cells than in controls. This suggests that ghrelin GHSR1a/OX1R heterodimers promotes an upregulation of a Gαs-cAMP-cAMP-responsive element signaling pathway in vitro and an increase in neuroblastoma cell proliferation.
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Affiliation(s)
- Qingjie Xue
- Neurobiology Institute, Jining Medical University, Jining, China.,Department of Pathogenic Biology, Jining Medical University, Jining, China
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Bingyuan Ji
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Xiaoyu Chen
- Department of Physiology, Taishan Medical University, Taian, China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Peixiang Wang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Chunqing Yang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Yanyou Pan
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Baohua Cheng
- Neurobiology Institute, Jining Medical University, Jining, China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, China.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
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41
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Sil’kis IG. A Neurochemical Approach to the Search for Drugs for the Treatment of Symptoms of Alzheimer’s Disease. NEUROCHEM J+ 2018. [DOI: 10.1134/s1819712418010130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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42
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Peineau S, Rabiant K, Pierrefiche O, Potier B. Synaptic plasticity modulation by circulating peptides and metaplasticity: Involvement in Alzheimer's disease. Pharmacol Res 2018; 130:385-401. [PMID: 29425728 DOI: 10.1016/j.phrs.2018.01.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 01/23/2018] [Accepted: 01/26/2018] [Indexed: 10/18/2022]
Abstract
Synaptic plasticity is a cellular process involved in learning and memory whose alteration in its two main forms (Long Term Depression (LTD) and Long Term Potentiation (LTP)), is observed in most brain pathologies, including neurodegenerative disorders such as Alzheimer's disease (AD). In humans, AD is associated at the cellular level with neuropathological lesions composed of extracellular deposits of β-amyloid (Aβ) protein aggregates and intracellular neurofibrillary tangles, cellular loss, neuroinflammation and a general brain homeostasis dysregulation. Thus, a dramatic synaptic environment perturbation is observed in AD patients, involving changes in brain neuropeptides, cytokines, growth factors or chemokines concentration and diffusion. Studies performed in animal models demonstrate that these circulating peptides strongly affect synaptic functions and in particular synaptic plasticity. Besides this neuromodulatory action of circulating peptides, other synaptic plasticity regulation mechanisms such as metaplasticity are altered in AD animal models. Here, we will review new insights into the study of synaptic plasticity regulatory/modulatory mechanisms which could influence the process of synaptic plasticity in the context of AD with a particular attention to the role of metaplasticity and peptide dependent neuromodulation.
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Affiliation(s)
- Stéphane Peineau
- GRAP UMR1247, INSERM, Centre Universitaire de Recherche en Santé, Université de Picardie Jules Verne, Amiens, France; Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK.
| | - Kevin Rabiant
- GRAP UMR1247, INSERM, Centre Universitaire de Recherche en Santé, Université de Picardie Jules Verne, Amiens, France
| | - Olivier Pierrefiche
- GRAP UMR1247, INSERM, Centre Universitaire de Recherche en Santé, Université de Picardie Jules Verne, Amiens, France.
| | - Brigitte Potier
- Laboratoire Aimé Cotton, CNRS-ENS UMR9188, Université Paris-Sud, Orsay, France.
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Vinzant N, Scholl JL, Wu CM, Kindle T, Koodali R, Forster GL. Iron Oxide Nanoparticle Delivery of Peptides to the Brain: Reversal of Anxiety during Drug Withdrawal. Front Neurosci 2017; 11:608. [PMID: 29163012 PMCID: PMC5672019 DOI: 10.3389/fnins.2017.00608] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 10/18/2017] [Indexed: 01/19/2023] Open
Abstract
Targeting neuropeptide systems is important for future advancements in treatment of neurological and psychiatric illnesses. However, many of the peptides and their analogs do not cross the blood-brain barrier (BBB) efficiently. Nanoparticles such as iron oxide can cross the BBB, and here we describe a novel method for the conjugation of a peptide antisauvagine-30 (ASV-30) to iron oxide nanoparticles. Previous research has shown that direct infusion of ASV-30 into the brain reduces anxiety-like behavior in animal models via actions on corticotropin releasing factor type 2 (CRF2) receptors. Therefore, we tested whether iron oxide+ASV-30 complexes cross the BBB of rats and then determined whether iron oxide+ASV-30 nanoparticles are localized with CRF2-expressing neurons. Finally we tested the hypothesis that systemic infusion of iron oxide+ASV-30 can reduce anxiety-like behavior. First we describe the synthesis and demonstrate the stability of iron oxide-peptide nanoparticle complexes. Next, nanoparticles (87.7 μg/kg Fe2O3) with or without ASV-30 (200 μg/kg, ip) were injected into male rats 30 min prior to transcardial perfusion and brain fixation for immunohistochemical analysis, or before testing on the elevated plus maze (EPM) in an amphetamine withdrawal model of anxiety. Systemically administered iron oxide+ASV-30 particles were present in the brain and associated with neurons, including those that express CRF2 receptors, but did not localize with the iron storage protein ferritin. Furthermore, systemic administration of ironoxide+ASV-30 reduced amphetamine withdrawal-induced anxiety without affecting locomotion, suggesting that the anxiolytic effects of ASV-30 were preserved and the bioavailability of ASV-30 was sufficient. The findings demonstrate a novel approach to peptide delivery across the BBB and provide insight as to the neural distribution and efficacy of this nanotechnology.
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Affiliation(s)
- Nathan Vinzant
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Jamie L Scholl
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Chia-Ming Wu
- Department of Chemistry, University of South Dakota, Vermillion, SD, United States
| | - Trevor Kindle
- Department of Chemistry, University of South Dakota, Vermillion, SD, United States
| | - Ranjit Koodali
- Department of Chemistry, University of South Dakota, Vermillion, SD, United States
| | - Gina L Forster
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
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44
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Leprince J, Bagnol D, Bureau R, Fukusumi S, Granata R, Hinuma S, Larhammar D, Primeaux S, Sopkova-de Oliveiras Santos J, Tsutsui K, Ukena K, Vaudry H. The Arg-Phe-amide peptide 26RFa/glutamine RF-amide peptide and its receptor: IUPHAR Review 24. Br J Pharmacol 2017; 174:3573-3607. [PMID: 28613414 DOI: 10.1111/bph.13907] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 05/30/2017] [Accepted: 06/05/2017] [Indexed: 12/21/2022] Open
Abstract
The RFamide neuropeptide 26RFa was first isolated from the brain of the European green frog on the basis of cross-reactivity with antibodies raised against bovine neuropeptide FF (NPFF). 26RFa and its N-terminally extended form glutamine RF-amide peptide (QRFP) have been identified as cognate ligands of the former orphan receptor GPR103, now renamed glutamine RF-amide peptide receptor (QRFP receptor). The 26RFa/QRFP precursor has been characterized in various mammalian and non-mammalian species. In the brain of mammals, including humans, 26RFa/QRFP mRNA is almost exclusively expressed in hypothalamic nuclei. The 26RFa/QRFP transcript is also present in various organs especially in endocrine glands. While humans express only one QRFP receptor, two isoforms are present in rodents. The QRFP receptor genes are widely expressed in the CNS and in peripheral tissues, notably in bone, heart, kidney, pancreas and testis. Structure-activity relationship studies have led to the identification of low MW peptidergic agonists and antagonists of QRFP receptor. Concurrently, several selective non-peptidic antagonists have been designed from high-throughput screening hit optimization. Consistent with the widespread distribution of QRFP receptor mRNA and 26RFa binding sites, 26RFa/QRFP exerts a large range of biological activities, notably in the control of energy homeostasis, bone formation and nociception that are mediated by QRFP receptor or NPFF2. The present report reviews the current knowledge concerning the 26RFa/QRFP-QRFP receptor system and discusses the potential use of selective QRFP receptor ligands for therapeutic applications.
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Affiliation(s)
- Jérôme Leprince
- INSERM U1239, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Normandy University, Rouen, France
| | - Didier Bagnol
- CNS Drug Discovery, Arena Pharmaceuticals Inc., San Diego, CA, USA
| | - Ronan Bureau
- Normandy Centre for Studies and Research on Medicines (CERMN), Normandy University, Caen, France
| | - Shoji Fukusumi
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Riccarda Granata
- Laboratory of Molecular and Cellular Endocrinology, Division of Endocrinology, Diabetes and Metabolism, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Shuji Hinuma
- Department of Food and Nutrition, Faculty of Human Life Science, Senri Kinran University, Suita-City, Osaka, Japan
| | - Dan Larhammar
- Department of Neuroscience, Unit of Pharmacology, Uppsala University, Uppsala, Sweden
| | - Stefany Primeaux
- Department of Physiology, Joint Diabetes, Endocrinology & Metabolism Center, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | | | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, Center for Medical Life Science, Tokyo, Japan
| | - Kazuyoshi Ukena
- Section of Behavioral Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Japan
| | - Hubert Vaudry
- INSERM U1239, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Normandy University, Rouen, France
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Abstract
Alzheimer's disease (AD) is the most frequent age-related dementia. It prevalently causes cognitive decline, although it is frequently associated with secondary behavioral disturbances. AD neurodegeneration characteristically produces a remarkable destruction of the sleep-wake cycle, with diurnal napping, nighttime arousals, sleep fragmentation, and REM sleep impairment. It was recently hypothesized that the orexinergic system was involved in AD pathology. Accordingly, recent papers showed the association between orexinergic neurotransmission dysfunction, sleep impairment, and cognitive decline in AD. Orexin is a hypothalamic neurotransmitter which physiologically produces wakefulness and reduces REM sleep and may alter the sleep-wake cycle in AD patients. Furthermore, the orexinergic system seems to interact with CSF AD biomarkers, such as beta-amyloid and tau proteins. Beta-amyloid accumulation is the main hallmark of AD pathology, while tau proteins mark brain neuronal injury due to AD pathology. Investigations so far suggest that orexinergic signaling overexpression alters the sleep-wake cycle and secondarily induces beta-amyloid accumulation and tau-mediated neurodegeneration. Therefore, considering that orexinergic system dysregulation impairs sleep-wake rhythms and may influence AD pathology, it is hypothesized that orexin receptor antagonists are likely potential preventive/therapeutic options in AD patients.
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Affiliation(s)
- Claudio Liguori
- Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy.
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46
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Abstract
Orexin/hypocretin peptide (orexin-A and orexin-B) signaling is believed to take place via the two G-protein-coupled receptors (GPCRs), named OX1 and OX2 orexin receptors, as described in the previous chapters. Signaling of orexin peptides has been investigated in diverse endogenously orexin receptor-expressing cells - mainly neurons but also other types of cells - and in recombinant cells expressing the receptors in a heterologous manner. Findings in the different systems are partially convergent but also indicate cellular background-specific signaling. The general picture suggests an inherently high degree of diversity in orexin receptor signaling.In the current chapter, I present orexin signaling on the cellular and molecular levels. Discussion of the connection to (potential) physiological orexin responses is only brief since these are in focus of other chapters in this book. The same goes for the post-synaptic signaling mechanisms, which are dealt with in Burdakov: Postsynaptic actions of orexin. The current chapter is organized according to the tissue type, starting from the central nervous system. Finally, receptor signaling pathways are discussed across tissues, cell types, and even species.
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Affiliation(s)
- Jyrki P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki, POB 66, FIN-00014, Helsinki, Finland.
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47
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Sullan MJ, Asken BM, Jaffee MS, DeKosky ST, Bauer RM. Glymphatic system disruption as a mediator of brain trauma and chronic traumatic encephalopathy. Neurosci Biobehav Rev 2017; 84:316-324. [PMID: 28859995 DOI: 10.1016/j.neubiorev.2017.08.016] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 08/17/2017] [Accepted: 08/21/2017] [Indexed: 12/14/2022]
Abstract
Traumatic brain injury (TBI) is an increasingly important issue among veterans, athletes and the general public. Difficulties with sleep onset and maintenance are among the most commonly reported symptoms following injury, and sleep debt is associated with increased accumulation of beta amyloid (Aβ) and phosphorylated tau (p-tau) in the interstitial space. Recent research into the glymphatic system, a lymphatic-like metabolic clearance mechanism in the central nervous system (CNS) which relies on cerebrospinal fluid (CSF), interstitial fluid (ISF), and astrocytic processes, shows that clearance is potentiated during sleep. This system is damaged in the acute phase following mTBI, in part due to re-localization of aquaporin-4 channels away from astrocytic end feet, resulting in reduced potential for waste removal. Long-term consequences of chronic dysfunction within this system in the context of repetitive brain trauma and insomnia have not been established, but potentially provide one link in the explanatory chain connecting repetitive TBI with later neurodegeneration. Current research has shown p-tau deposition in perivascular spaces and along interstitial pathways in chronic traumatic encephalopathy (CTE), pathways related to glymphatic flow; these are the main channels by which metabolic waste is cleared. This review addresses possible links between mTBI-related damage to glymphatic functioning and physiological changes found in CTE, and proposes a model for the mediating role of sleep disruption in increasing the risk for developing CTE-related pathology and subsequent clinical symptoms following repetitive brain trauma.
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Affiliation(s)
- Molly J Sullan
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, PO Box 100165, Gainesville, FL 32610, USA.
| | - Breton M Asken
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, PO Box 100165, Gainesville, FL 32610, USA.
| | - Michael S Jaffee
- Department of Neurology, School of Medicine, University of Florida, 2000 SW Archer Rd, Gainesville, FL 32610, USA.
| | - Steven T DeKosky
- Department of Neurology, McKnight Brain Institute, University of Florida, PO Box 100236, Gainesville, FL 32610, USA.
| | - Russell M Bauer
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, PO Box 100165, Gainesville, FL 32610, USA; Brain Rehabilitation Research Center, North Florida/South Georgia Health System (NF/SG VHS), USA.
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48
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Dual-agonist occupancy of orexin receptor 1 and cholecystokinin A receptor heterodimers decreases G-protein–dependent signaling and migration in the human colon cancer cell line HT-29. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1153-1164. [DOI: 10.1016/j.bbamcr.2017.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/03/2017] [Accepted: 03/06/2017] [Indexed: 01/14/2023]
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49
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Chartrel N, Picot M, El Medhi M, Arabo A, Berrahmoune H, Alexandre D, Maucotel J, Anouar Y, Prévost G. The Neuropeptide 26RFa (QRFP) and Its Role in the Regulation of Energy Homeostasis: A Mini-Review. Front Neurosci 2016; 10:549. [PMID: 27965532 PMCID: PMC5126098 DOI: 10.3389/fnins.2016.00549] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/15/2016] [Indexed: 01/09/2023] Open
Abstract
This mini-review deals with the neuropeptide 26RFa (or QRFP) which is a member of the RFamide peptide family discovered simultaneously by three groups in 2003. 26RFa (or its N-extended form 43RFa) was subsequently shown to be the endogenous ligand of the human orphan receptor GPR103. In the brain, 26RFa and GPR103mRNA are primarily expressed in hypothalamic nuclei involved in the control of feeding behavior, and at the periphery, the neuropeptide and its receptor are present in abundance in the gut and the pancreatic islets, suggesting that 26RFa is involved in the regulation of energy metabolism. Indeed, 26RFa stimulates food intake when injected centrally, and its orexigenic effect is even more pronounced in obese animals. The expression of 26RFa is up-regulated in the hypothalamus of obese animals, supporting that the 26RFa/GPR103 system may play a role in the development and/or maintenance of the obese status. Recent data indicate that 26RFa is also involved in the regulation of glucose homeostasis. 26RFa reduces glucose-induced hyperglycemia, increases insulin sensitivity and insulinemia. Furthermore, an oral ingestion of glucose strongly stimulates 26RFa release by the gut, indicating that 26RFa is a novel incretin. Finally, 26RFa is able to prevent pancreatic β cell death and apoptosis. This brief overview reveals that 26RFa is a key neuropeptide in the regulation of energy metabolism. Further fields of research are suggested including the pathophysiological implication of the 26RFa/GPR103 system.
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Affiliation(s)
- Nicolas Chartrel
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Marie Picot
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Mouna El Medhi
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Arnaud Arabo
- University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Hind Berrahmoune
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy UniversityMont-Saint-Aignan, France; Department of Endocrinology, Diabetes and Metabolic Diseases, Institute for Research and Innovation in Biomedecine, University Hospital of Rouen, University of Rouen, Normandy UniversityRouen, France
| | - David Alexandre
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Julie Maucotel
- University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Youssef Anouar
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Gaëtan Prévost
- INSERM U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, University of Rouen, Normandy UniversityMont-Saint-Aignan, France; Department of Endocrinology, Diabetes and Metabolic Diseases, Institute for Research and Innovation in Biomedecine, University Hospital of Rouen, University of Rouen, Normandy UniversityRouen, France
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50
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Orexin signaling regulates both the hippocampal clock and the circadian oscillation of Alzheimer's disease-risk genes. Sci Rep 2016; 6:36035. [PMID: 27796320 PMCID: PMC5086843 DOI: 10.1038/srep36035] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 10/10/2016] [Indexed: 01/08/2023] Open
Abstract
Alzheimer’s disease (AD) is a circadian clock-related disease. However, it is not very clear whether pre-symptomatic AD leads to circadian disruption or whether malfunction of circadian rhythms exerts influence on development of AD. Here, we report a functional clock that exists in the hippocampus. This oscillator both receives input signals and maintains the cycling of the hippocampal Per2 gene. One of the potential inputs to the oscillator is orexin signaling, which can shorten the hippocampal clock period and thereby regulate the expression of clock-controlled-genes (CCGs). A 24-h time course qPCR analysis followed by a JTK_CYCLE algorithm analysis indicated that a number of AD-risk genes are potential CCGs in the hippocampus. Specifically, we found that Bace1 and Bace2, which are related to the production of the amyloid-beta peptide, are CCGs. BACE1 is inhibited by E4BP4, a repressor of D-box genes, while BACE2 is activated by CLOCK:BMAL1. Finally, we observed alterations in the rhythmic expression patterns of Bace2 and ApoE in the hippocampus of aged APP/PS1dE9 mice. Our results therefore indicate that there is a circadian oscillator in the hippocampus whose oscillation could be regulated by orexins. Hence, orexin signaling regulates both the hippocampal clock and the circadian oscillation of AD-risk genes.
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