1
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Imamura K, Akagi KI, Miyanoiri Y, Tsujimoto H, Hirokawa T, Ashida H, Murakami K, Inoue A, Suno R, Ikegami T, Sekiyama N, Iwata S, Kobayashi T, Tochio H. Interaction modes of human orexin 2 receptor with selective and nonselective antagonists studied by NMR spectroscopy. Structure 2024; 32:352-361.e5. [PMID: 38194963 DOI: 10.1016/j.str.2023.12.008] [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: 02/24/2023] [Revised: 08/17/2023] [Accepted: 12/13/2023] [Indexed: 01/11/2024]
Abstract
Orexin neuropeptides have many physiological roles in the sleep-wake cycle, feeding behavior, reward demands, and stress responses by activating cognitive receptors, the orexin receptors (OX1R and OX2R), distributed in the brain. There are only subtle differences between OX1R and OX2R in the orthosteric site, which has hindered the rational development of subtype-selective antagonists. In this study, we utilized solution-state NMR to capture the structural plasticity of OX2R labeled with 13CH3-ε-methionine in complex with antagonists. Mutations in the orthosteric site allosterically affected the intracellular tip of TM6. Ligand exchange experiments with the subtype-selective EMPA and the nonselective suvorexant identified three methionine residues that were substantially perturbed. The NMR spectra suggested that the suvorexant-bound state exhibited more structural plasticity than the EMPA-bound state, which has not been foreseen from the close similarity of their crystal structures, providing insights into dynamic features to be considered in understanding the ligand recognition mode.
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Affiliation(s)
- Kayo Imamura
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Ken-Ichi Akagi
- Section of Laboratory Equipment, National Institute of Biomedical Innovation, Health, and Nutrition, Osaka 567-0085, Japan
| | - Yohei Miyanoiri
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hirokazu Tsujimoto
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takatsugu Hirokawa
- Division of Biomedical Science, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan; Transborder Medical Research Center, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Hideo Ashida
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kaori Murakami
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Ryoji Suno
- Department of Medical Chemistry, Kansai Medical University, Hirakata 573-1010, Japan
| | - Takahisa Ikegami
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro, Yokohama, Kanagawa 230-0045, Japan
| | - Naotaka Sekiyama
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - So Iwata
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takuya Kobayashi
- Department of Medical Chemistry, Kansai Medical University, Hirakata 573-1010, Japan
| | - Hidehito Tochio
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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2
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Brotschi C, Bolli MH, Gatfield J, Roch C, Sifferlen T, Treiber A, Williams JT, Boss C. Pyrazole derivatives as selective orexin-2 receptor antagonists (2-SORA): synthesis, structure-activity-relationship, and sleep-promoting properties in rats. RSC Med Chem 2024; 15:344-354. [PMID: 38283232 PMCID: PMC10809354 DOI: 10.1039/d3md00573a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 11/20/2023] [Indexed: 01/30/2024] Open
Abstract
Selective orexin 2 receptor antagonists (2-SORA) such as seltorexant (15) are in clinical development for the treatment of insomnia and other conditions such as depression. Herein, we report our structure-activity-relationship (SAR) optimization efforts starting from an HTS hit (1) (N-(1-((5-acetylfuran-2-yl)methyl)-1H-pyrazol-4-yl)-5-(m-tolyl)oxazole-4-carboxamide) that was derived from an unrelated in-house GPCR-agonist program. Medicinal chemistry efforts focused on the optimization of orexin 2 receptor (OX2R) antagonistic activity, stability in liver microsomes, time dependent CYP3A4 inhibition, and aqueous solubility. Compounds were assessed for their brain-penetrating potential in in vivo experiments to select the most promising compounds for our in vivo sleep model. Our lead optimization efforts led to the discovery of the potent, brain penetrating and orally active, 2-SORA (N-(1-(2-(5-methoxy-1H-pyrrolo[3,2-b]pyridin-3-yl)ethyl)-1H-pyrazol-4-yl)-5-(m-tolyl)oxazole-4-carboxamide) 43 with efficacy in a sleep model in rats comparable to 15.
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Affiliation(s)
- Christine Brotschi
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - Martin H Bolli
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - John Gatfield
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - Catherine Roch
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - Thierry Sifferlen
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - Alexander Treiber
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - Jodi T Williams
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
| | - Christoph Boss
- Idorsia Pharmaceuticals Ltd, Drug Discovery and Preclinical Development Hegenheimermattweg 91 4123 Allschwil Basel-Landschaft Switzerland
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3
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Rong J, Yamasaki T, Li Y, Kumata K, Zhao C, Haider A, Chen J, Xiao Z, Fujinaga M, Hu K, Mori W, Zhang Y, Xie L, Zhou X, Collier TL, Zhang MR, Liang S. Development of Novel 11C-Labeled Selective Orexin-2 Receptor Radioligands for Positron Emission Tomography Imaging. ACS Med Chem Lett 2023; 14:1419-1426. [PMID: 37849554 PMCID: PMC10577698 DOI: 10.1021/acsmedchemlett.3c00320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/19/2023] [Indexed: 10/19/2023] Open
Abstract
Orexin 2 receptors (OX2R) represent a vital subtype of orexin receptors intricately involved in the regulation of wakefulness, arousal, and sleep-wake cycles. Despite their importance, there are currently no positron emission tomography (PET) tracers available for imaging the OX2R in vivo. Herein, we report [11C]1 ([11C]OX2-2201) and [11C]2 ([11C]OX2-2202) as novel PET ligands. Both compounds 1 (Ki = 3.6 nM) and 2 (Ki = 2.2 nM) have excellent binding affinity activities toward OX2R and target selectivity (OX2/OX1 > 600 folds). In vitro autoradiography in the rat brain suggested good to excellent in vitro binding specificity for [11C]1 and [11C]2. PET imaging in rat brains indicated that the low brain uptake of [11C]2 may be due to P-glycoprotein and/or breast cancer resistance protein efflux interaction and/or low passive permeability. Continuous effort in medicinal chemistry optimization is necessary to improve the brain permeability of this scaffold.
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Affiliation(s)
- Jian Rong
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Tomoteru Yamasaki
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Yinlong Li
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Katsushi Kumata
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Chunyu Zhao
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Ahmed Haider
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Jiahui Chen
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Zhiwei Xiao
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Masayuki Fujinaga
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Kuan Hu
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Wakana Mori
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Yiding Zhang
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Lin Xie
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Xin Zhou
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
| | - Thomas L. Collier
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Ming-Rong Zhang
- Department
of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical
Sciences, National Institutes for Quantum
Science and Technology, Chiba 263-8555, Japan
| | - Steven Liang
- Department
of Radiology and Imaging Sciences, Emory
University, Atlanta, Georgia 30322, United States
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
and Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
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4
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Kostansek JA, Latona GJ, Heruye SH, Matthews S, Bockman CS, Simeone KA, Simeone TA. Orexin receptors regulate hippocampal sharp wave-ripple complexes in ex vivo slices. Eur J Pharmacol 2023; 950:175763. [PMID: 37146705 PMCID: PMC10311575 DOI: 10.1016/j.ejphar.2023.175763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 04/13/2023] [Accepted: 05/02/2023] [Indexed: 05/07/2023]
Abstract
Orexin is a neuromodulatory peptide produced by lateral hypothalamic orexin neurons and binds to G-protein-coupled orexin-1 receptor and orexin-2 receptors. Whether orexin modulates learning and memory is not fully understood. Orexin has biphasic effects on learning and memory: promoting learning and memory at homeostatic levels and inhibiting at supra- and sub-homeostatic levels. Hippocampal sharp wave-ripples encode memory information and are essential for memory consolidation and retrieval. The role of orexin on sharp wave-ripples in hippocampal CA1 remains unknown. Here, we used multi-electrode array recordings in acute ex vivo hippocampal slices to determine the effects of orexin receptor antagonists on sharp wave-ripples. Bath-application of either the orexin-1 receptor antagonist N-(2-Methyl-6-benzoxazolyl)-N'-1,5-naphthyridin-4-yl urea (SB-334867) or the orexin-2 receptor antagonist N-Ethyl-2-[(6-methoxy-3-pyridinyl)[(2-methylphenyl)sulfonyl]amino]-N-(3-pyridinylmethyl)-acetamide (EMPA) reduced sharp wave and ripple incidence, sharp wave amplitude, and sharp wave duration. SB-334867 and EMPA effects on sharp wave amplitude and duration were equivalent, whereas EMPA exhibited a greater reduction of sharp wave and ripple incidence. EMPA also increased ripple duration, whereas SB-334867 had no effect. Inhibition of both orexin receptors with a dual orexin receptor antagonist N-[1,1'-Biphenyl]-2-yl-1-[2-[(1-methyl-1H-benzimidazol-2-yl)thio]acetyl-2-pyrrolidinedicarboxamide (TCS-1102) had effects similar to EMPA, however, sharp wave amplitude and duration were unaffected. Region-specific expression of orexin receptors suggests orexin may regulate sharp wave generation in CA3, dentate gyrus-mediated sharp wave modification, sharp wave propagation to CA1, and local ripple emergence in CA1. Our study indicates an orexin contribution to hippocampal sharp wave-ripple complexes and suggests a mechanism by which sub-homeostatic concentrations of orexin may inhibit learning and memory function.
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Affiliation(s)
- Joseph A Kostansek
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA.
| | - Gavin J Latona
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA
| | - Segewkal H Heruye
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA
| | - Stephanie Matthews
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA
| | - Charles S Bockman
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA
| | - Kristina A Simeone
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA
| | - Timothy A Simeone
- Creighton University, School of Medicine, Department of Pharmacology & Neuroscience, Omaha, NE, 68174, USA.
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5
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Luo F, Deng JY, Sun X, Zhen J, Luo XD. Anterior cingulate cortex orexin signaling mediates early-life stress-induced social impairment in females. Proc Natl Acad Sci U S A 2023; 120:e2220353120. [PMID: 37155875 PMCID: PMC10193930 DOI: 10.1073/pnas.2220353120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 03/30/2023] [Indexed: 05/10/2023] Open
Abstract
Early-life stress has long-term impacts on the structure and function of the anterior cingulate cortex (ACC), and raises the risk of adult neuropsychiatric disorders including social dysfunction. The underlying neural mechanisms, however, are still uncertain. Here, we show that, in female mice, maternal separation (MS) during the first three postnatal weeks results in social impairment accompanied with hypoactivity in pyramidal neurons (PNs) of the ACC. Activation of ACC PNs ameliorates MS-induced social impairment. Neuropeptide Hcrt, which encodes hypocretin (orexin), is the top down-regulated gene in the ACC of MS females. Activating ACC orexin terminals enhances the activity of ACC PNs and rescues the diminished sociability observed in MS females via an orexin receptor 2 (OxR2)-dependent mechanism. Our results suggest orexin signaling in the ACC is critical in mediating early-life stress-induced social impairment in females.
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Affiliation(s)
- Fei Luo
- Center for Neuropsychiatric Diseases, Institute of Life Science, Nanchang University, Nanchang330031, China
- Department of Psychiatry, Yichun First municipal People’s Hospital, YiChun336000, China
| | - Jun-yang Deng
- Department of Psychiatry, Yichun First municipal People’s Hospital, YiChun336000, China
| | - Xuan Sun
- Center for Neuropsychiatric Diseases, Institute of Life Science, Nanchang University, Nanchang330031, China
| | - Jian Zhen
- Center for Neuropsychiatric Diseases, Institute of Life Science, Nanchang University, Nanchang330031, China
| | - Xiao-dan Luo
- Department of Psychiatry, Yichun First municipal People’s Hospital, YiChun336000, China
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6
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Watanabe H, Ide T, Ono M. Synthesis and Characterization of Novel Radioiodinated Triazole-Pyrolidine Derivative to Detect Orexin 2 Receptor in the Brain. Chem Pharm Bull (Tokyo) 2023; 71:234-239. [PMID: 36858529 DOI: 10.1248/cpb.c22-00770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
It is generally accepted that the orexin 2 receptor (OX2R) plays a critical role in the arousal-promoting function, and in vivo imaging of OX2R is expected to contribute to elucidation of orexin systems and the development of drugs to treat sleep disorder. In this study, we newly synthesized and characterized a radioiodinated triazole-pyrolidine derivative ([125I]TPI) to detect OX2R in the brain. In vitro studies using OX1R or OX2R expression cells showed selective binding of [125I]TPI to OX2R. In addition, in vitro autoradiography using rat brain sections showed high accumulation of radioactivity in the OX2R expression region. However, [125I]TPI showed low brain uptake in normal mice. These results suggest that [125I]TPI has a fundamental character to detect OX2R in vitro, but further structural modification to improve brain pharmacokinetics is required to use it for in vivo detection of OX2R.
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Affiliation(s)
- Hiroyuki Watanabe
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Takuji Ide
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Masahiro Ono
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University
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7
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Orexin 2 receptor (OX2R) protein distribution measured by autoradiography using radiolabeled OX2R-selective antagonist EMPA in rodent brain and peripheral tissues. Sci Rep 2022; 12:8473. [PMID: 35589803 PMCID: PMC9120030 DOI: 10.1038/s41598-022-12601-x] [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: 12/06/2021] [Accepted: 05/13/2022] [Indexed: 11/18/2022] Open
Abstract
Orexin, a neuropeptide, performs various physiological functions, including the regulation of emotion, feeding, metabolism, respiration, and sleep/wakefulness, by activating the orexin 1 receptor and orexin 2 receptor (OX2R). Owing to the pivotal role of OX2R in wakefulness and other biological functions, OX2R agonists are being developed. A detailed understanding of OX2R protein distribution is essential for determining the mechanisms of action of OX2R agonists; however, this has been hindered by the lack of selective antibodies. In this study, we first confirmed the OX2R-selective binding of [3H]-EMPA in in vitro autoradiography studies, using brain slices from OX2R knockout mice and their wild-type littermates. Subsequently, OX2R protein distribution in rats was comprehensively assessed in 51 brain regions and 10 peripheral tissues using in vitro autoradiography with [3H]-EMPA. The widespread distribution of OX2R protein, including that in previously unrecognized regions of the retrosplenial cortex, was identified. In contrast, OX2R protein expression was negligible/very low in peripheral tissues, suggesting that orexin exerts OX2R-dependent physiological functions primarily through activation of the central nervous system. These findings will be useful for understanding the wide range of biological functions of OX2R and the application of OX2R agonists in various disorders.
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8
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Bai P, Liu Y, Xu Y, Striar R, Yuan G, Afshar S, Langan AG, Rattray AK, Wang C. Synthesis and characterization of a new Positron emission tomography probe for orexin 2 receptors neuroimaging. Bioorg Chem 2022; 123:105779. [PMID: 35397430 PMCID: PMC9050936 DOI: 10.1016/j.bioorg.2022.105779] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 03/16/2022] [Accepted: 03/29/2022] [Indexed: 11/28/2022]
Abstract
The orexin receptors (OXRs) have been involved in multiple physiological and neuropsychiatric functions. Identification of PET imaging probes specifically targeting OXRs enables us to better understand the OX system. Seltorexant (JNJ-42847922) is a potent OX2R antagonist with the potential to be an OX2R PET imaging probe. Here, we describe the synthesis and characterization of [18F]Seltorexant as an OX2R PET probe. The ex vivo autoradiography studies indicated the good binding specificity of [18F]Seltorexant. In vivo PET imaging of [18F]Seltorexant in rodents showed suitable BBB penetration with the highest brain uptake of %ID/cc = 3.4 at 2 min post-injection in mice. The regional brain biodistribution analysis and blocking studies showed that [18F]Seltorexant had good binding selectivity and specificity. However, pretreatment with unlabelled Seltorexant and P-gp competitor CsA observed significantly increased brain uptake of [18F]Seltorexant, indicating [18F]Seltorexant could interact P-gp at the blood-brain barrier. Our findings demonstrated that [18F]Seltorexant is a potential brain OX2R PET imaging probe, which paves the way for new OX2R PET probes development and OX system investigation.
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Affiliation(s)
- Ping Bai
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Yan Liu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Yulong Xu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Robin Striar
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Gengyang Yuan
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Sepideh Afshar
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Amelia G Langan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Anna K Rattray
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States
| | - Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States.
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9
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Kawashima H, Aono Y, Watanabe Y, Waddington JL, Saigusa T. In vivo microdialysis reveals that blockade of accumbal orexin OX 2 but not OX 1 receptors enhances dopamine efflux in the nucleus accumbens of freely moving rats. Eur J Neurosci 2022; 55:733-745. [PMID: 34989064 DOI: 10.1111/ejn.15593] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 12/15/2021] [Accepted: 12/31/2021] [Indexed: 11/27/2022]
Abstract
The nucleus accumbens contains orexinergic neural inputs and orexin OX1 -and OX2 -receptors. Behavioural studies suggest that accumbal orexin receptors modulate accumbal dopaminergic activity-dependent locomotion in rats. We studied the effects of intra-accumbal injection of orexin receptor ligands on accumbal extracellular dopamine levels in freely moving rats, using in vivo microdialysis, and analysed the roles of OX1 - and OX2 -receptors in the regulation of basal accumbal dopamine efflux. The orexin receptor ligands were applied intra-accumbally though a microinjection needle attached with a dialysis probe. Neither the non-selective OX1 - and OX2 -receptor agonist orexin-A nor the preferential OX2 -receptor agonist orexin-B (500.0 pg and 5.0 ng) altered accumbal dopamine levels. The non-selective OX1 - and OX2 -receptor antagonist MK-4305 (suvorexant, 500.0 pg, 2.5 and 5.0 ng) enhanced dopamine efflux. A 2-h tetrodotoxin infusion into nucleus accumbens through the probe or co-administration of orexin-A (500.0 pg) strongly inhibited MK-4305 (5.0 ng)-induced accumbal dopamine efflux. The selective OX2 -receptor antagonist EMPA (90.0 and 900.0 pg, 9.0 ng) increased dopamine efflux. Intra-accumbal infusion of tetrodotoxin abolished EMPA (9.0 ng)-induced dopamine efflux. The selective OX1 -receptor antagonist SB-334867 (10.0 and 20.0 ng) failed to alter dopamine efflux. Co-administration of orexin-B (500.0 pg) inhibited both EMPA (9.0 ng)- and MK-4305 (5.0 ng)-induced dopamine efflux. Intraperitoneal injection of MK-4305 (10.0 mg/kg) did not affect accumbal dopamine efflux. The present study provides in vivo neuropharmacological evidence that accumbal OX2 - but not OX1 -receptors exert inhibitory regulation of basal accumbal dopamine efflux and that blockade of accumbal OX2 -receptors enhances dopamine efflux in nucleus accumbens of freely moving rats.
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Affiliation(s)
- Hiroki Kawashima
- Nihon University Graduate School of Dentistry at Matsudo, Oral Molecular Pharmacology, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba, Japan
| | - Yuri Aono
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, Chiba, Japan
| | - Yuriko Watanabe
- Department of Oral surgery, Nihon University School of Dentistry at Matsudo, Chiba, Japan
| | - John L Waddington
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, St. Stephen's Green, Dublin 2, Ireland
| | - Tadashi Saigusa
- Nihon University Graduate School of Dentistry at Matsudo, Oral Molecular Pharmacology, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba, Japan.,Department of Pharmacology, Nihon University School of Dentistry at Matsudo, Chiba, Japan
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10
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Lessel U, Ferrara M, Heine N, Marelli C, Carrettoni L, Pfau R, Schmidt E, Riether D. Identification of Highly Selective Orexin 1 Receptor Antagonists Driven by Structure-Based Design. J Chem Inf Model 2021; 61:5893-5905. [PMID: 34817173 DOI: 10.1021/acs.jcim.1c01055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OX1 receptor antagonists are of interest to treat, for example, substance abuse disorders, personality disorders, eating disorders, or anxiety-related disorders. However, known dual OX1/OX2 receptor antagonists are not suitable due to their sleep-inducing effects; therefore, we were interested in identifying a highly OX1 selective antagonist with a sufficient window to OX2-mediated effects. Herein, we describe the design of highly selective OX1 receptor antagonists driven by the X-ray structure of OX1 with suvorexant, a dual OX1/OX2 receptor antagonist. Moderately selective OX1 antagonists comprising a [2.2.1]-bicyclic scaffold served as our starting point. Based on our binding mode hypothesis, we postulated which part of the scaffold points toward one of the regions where the two binding pockets differ. Structural changes in this part resulted in a modified core with higher inherent selectivity compared to the [2.2.1]-bicyclic template. The structure-based design, synthesis, and hit-to-lead evaluation of this novel OX1 receptor-selective scaffold are discussed herein.
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Affiliation(s)
- Uta Lessel
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany
| | - Marco Ferrara
- Boehringer Ingelheim Research Italia S.a.s. di BI IT S.r.l., Via Giovanni Lorenzini 8, 20139 Milano, MI, Italy
| | - Niklas Heine
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany
| | - Chiara Marelli
- Boehringer Ingelheim Research Italia S.a.s. di BI IT S.r.l., Via Giovanni Lorenzini 8, 20139 Milano, MI, Italy
| | - Laura Carrettoni
- Boehringer Ingelheim Research Italia S.a.s. di BI IT S.r.l., Via Giovanni Lorenzini 8, 20139 Milano, MI, Italy
| | - Roland Pfau
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany
| | - Esther Schmidt
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany
| | - Doris Riether
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany
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11
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Coleman P, de Lecea L, Gotter A, Hagan J, Hoyer D, Kilduff T, Kukkonen JP, Porter R, Renger J, Siegel JM, Sutcliffe G, Upton N, Winrow CJ. Orexin receptors in GtoPdb v.2021.3. IUPHAR/BPS GUIDE TO PHARMACOLOGY CITE 2021; 2021. [PMID: 34927075 DOI: 10.2218/gtopdb/f51/2021.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Orexin receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Orexin receptors [42]) are activated by the endogenous polypeptides orexin-A and orexin-B (also known as hypocretin-1 and -2; 33 and 28 aa) derived from a common precursor, preproorexin or orexin precursor, by proteolytic cleavage and some typical peptide modifications [109]. Currently the only orexin receptor ligands in clinical use are suvorexant and lemborexant, which are used as hypnotics. Orexin receptor crystal structures have been solved [134, 133, 54, 117, 46].
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12
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Elam HB, Perez SM, Donegan JJ, Lodge DJ. Orexin receptor antagonists reverse aberrant dopamine neuron activity and related behaviors in a rodent model of stress-induced psychosis. Transl Psychiatry 2021; 11:114. [PMID: 33558469 PMCID: PMC7870676 DOI: 10.1038/s41398-021-01235-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/08/2021] [Accepted: 01/18/2021] [Indexed: 12/15/2022] Open
Abstract
Post-traumatic stress disorder (PTSD) is a prevalent condition affecting approximately 8% of the United States population and 20% of United States combat veterans. In addition to core symptoms of the disorder, up to 64% of individuals diagnosed with PTSD experience comorbid psychosis. Previous research has demonstrated a positive correlation between symptoms of psychosis and increases in dopamine transmission. We have recently demonstrated projections from the paraventricular nucleus of the thalamus (PVT) to the nucleus accumbens (NAc) can regulate dopamine neuron activity in the ventral tegmental area (VTA). Specifically, inactivation of the PVT leads to a reversal of aberrant dopamine system function and psychosis-like behavior. The PVT receives dense innervation from orexin containing neurons, therefore, targeting orexin receptors may be a novel approach to restore dopamine neuron activity and alleviate PTSD-associated psychosis. In this study, we induced stress-related pathophysiology in male Sprague Dawley rats using an inescapable foot-shock procedure. We observed a significant increase in VTA dopamine neuron population activity, deficits in sensorimotor gating, and hyperresponsivity to psychomotor stimulants. Administration of selective orexin 1 receptor (OX1R) and orexin 2 receptor (OX2R) antagonists (SB334867 and EMPA, respectively) or the FDA-approved, dual-orexin receptor antagonist, Suvorexant, were found to reverse stress-induced increases in dopamine neuron population activity. However, only Suvorexant and SB334867 were able to reverse deficits in behavioral corelates of psychosis. These results suggest that the orexin system may be a novel pharmacological target for the treatment of comorbid psychosis related to PTSD.
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Affiliation(s)
- Hannah B Elam
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
| | - Stephanie M Perez
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Jennifer J Donegan
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Daniel J Lodge
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA
- South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, USA
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13
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Gunera J, Baker JG, van Hilten N, Rosenbaum DM, Kolb P. Structure-Based Discovery of Novel Ligands for the Orexin 2 Receptor. J Med Chem 2020; 63:11045-11053. [PMID: 32977721 DOI: 10.1021/acs.jmedchem.0c00964] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The orexin receptors are peptide-sensing G protein-coupled receptors that are intimately linked with regulation of the sleep/wake cycle. We used a recently solved X-ray structure of the orexin receptor subtype 2 in computational docking calculations with the aim to identify additional ligands with unprecedented chemotypes. We found validated ligands with a high hit rate of 29% out of those tested, none of them showing selectivity with respect to the orexin receptor subtype 1. Furthermore, of the higher-affinity compounds examined, none showed any agonist activity. While novel chemical structures can thus be found, selectivity is a challenge owing to the largely identical binding pockets.
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Affiliation(s)
- Jakub Gunera
- Department of Pharmaceutical Chemistry, Philipps-University, Marburg, Hesse 35032, Germany
| | - Jillian G Baker
- Cell Signalling, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
| | - Niek van Hilten
- Department of Pharmaceutical Chemistry, Philipps-University, Marburg, Hesse 35032, Germany
| | - Daniel M Rosenbaum
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, Texas 75390-8816, United States
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps-University, Marburg, Hesse 35032, Germany
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14
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Guo B, Xiu J, Shen Y, Li Q. Synthesis and biological activity evaluation of azacycloheptane sulfonamide derivatives as potential orexin receptor antagonists. RSC Adv 2020; 10:30683-30691. [PMID: 35516053 PMCID: PMC9056352 DOI: 10.1039/d0ra05068g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/12/2020] [Indexed: 01/09/2023] Open
Abstract
As the orexin signaling system is crucial for the regulation of the sleep/wake cycle, inhibitors of orexin-1 and orexin-2 receptors are of significant interest in the treatment of insomnia. Herein, a series of novel azacycloheptane sulfonamide derivatives were designed and synthesized, and all the compounds were evaluated as potential orexin receptor inhibitors by FLIPR Tetra calcium assay. A majority of the tested azacycloheptane sulfonamide derivatives showed OX1R and OX2R inhibitory activity. Chloro-substituted derivatives functionalized at the C5 or C6 position of the benzoxazole group exhibited better inhibitory activity for OX1R and OX2R than unsubstituted derivatives functionalized at C5 or C6. In addition, phenyl group modification had positive effects on the inhibitory activities, and an electron-withdrawing fluorine group at the ortho or meta position of the phenyl ring improved the OX2R inhibitory activity of the derivatives. This suggests that azacycloheptane sulfonamide derivatives are promising scaffolds for the development of OX1R and OX2R antagonists. Azacycloheptane sulfonamide derivatives are promising scaffolds for the development of OX1R and OX2R antagonists.![]()
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Affiliation(s)
- Bin Guo
- School of Pharmaceutical Science, Chongqing Medical University Chongqing 400016 China
| | - Jingya Xiu
- Jiangsu Nhwaluokang Pharmaceutical Research and Development Co., Ltd. Chongqing 400016 China
| | - Yi Shen
- Jiangsu Nhwaluokang Pharmaceutical Research and Development Co., Ltd. Chongqing 400016 China
| | - Qingeng Li
- School of Pharmaceutical Science, Chongqing Medical University Chongqing 400016 China
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15
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Flanigan ME, Aleyasin H, Li L, Burnett CJ, Chan KL, LeClair KB, Lucas EK, Matikainen-Ankney B, Durand-de Cuttoli R, Takahashi A, Menard C, Pfau ML, Golden SA, Bouchard S, Calipari ES, Nestler EJ, DiLeone RJ, Yamanaka A, Huntley GW, Clem RL, Russo SJ. Orexin signaling in GABAergic lateral habenula neurons modulates aggressive behavior in male mice. Nat Neurosci 2020; 23:638-650. [PMID: 32284606 PMCID: PMC7195257 DOI: 10.1038/s41593-020-0617-7] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 03/02/2020] [Indexed: 11/30/2022]
Abstract
Heightened aggression is characteristic of multiple neuropsychiatric disorders and can have various negative effects on patients, their families and the public. Recent studies in humans and animals have implicated brain reward circuits in aggression and suggest that, in subsets of aggressive individuals, domination of subordinate social targets is reinforcing. In this study, we showed that, in male mice, orexin neurons in the lateral hypothalamus activated a small population of glutamic acid decarboxylase 2 (GAD2)-expressing neurons in the lateral habenula (LHb) via orexin receptor 2 (OxR2) and that activation of these GAD2 neurons promoted male-male aggression and conditioned place preference for aggression-paired contexts. Moreover, LHb GAD2 neurons were inhibitory within the LHb and dampened the activity of the LHb as a whole. These results suggest that the orexin system is important for the regulation of inter-male aggressive behavior and provide the first functional evidence of a local inhibitory circuit within the LHb.
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Affiliation(s)
- Meghan E Flanigan
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Hossein Aleyasin
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Long Li
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - C Joseph Burnett
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kenny L Chan
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Katherine B LeClair
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Elizabeth K Lucas
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Bridget Matikainen-Ankney
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Romain Durand-de Cuttoli
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Aki Takahashi
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Laboratory of Behavioral Neuroendocrinology, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Caroline Menard
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry and Neuroscience, Faculty of Medicine and CERVO Brain Research Center, Université Laval, Ville de Québec, QC, Canada
| | - Madeline L Pfau
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sam A Golden
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Sylvain Bouchard
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Erin S Calipari
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Eric J Nestler
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ralph J DiLeone
- Department of Psychiatry, Yale University, New Haven, CT, USA
| | - Akihiro Yamanaka
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - George W Huntley
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Roger L Clem
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Scott J Russo
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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16
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Rappas M, Ali AAE, Bennett KA, Brown JD, Bucknell SJ, Congreve M, Cooke RM, Cseke G, de Graaf C, Doré AS, Errey JC, Jazayeri A, Marshall FH, Mason JS, Mould R, Patel JC, Tehan BG, Weir M, Christopher JA. Comparison of Orexin 1 and Orexin 2 Ligand Binding Modes Using X-ray Crystallography and Computational Analysis. J Med Chem 2020; 63:1528-1543. [PMID: 31860301 PMCID: PMC7050010 DOI: 10.1021/acs.jmedchem.9b01787] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Indexed: 12/20/2022]
Abstract
The orexin system, which consists of the two G protein-coupled receptors OX1 and OX2, activated by the neuropeptides OX-A and OX-B, is firmly established as a key regulator of behavioral arousal, sleep, and wakefulness and has been an area of intense research effort over the past two decades. X-ray structures of the receptors in complex with 10 new antagonist ligands from diverse chemotypes are presented, which complement the existing structural information for the system and highlight the critical importance of lipophilic hotspots and water molecules for these peptidergic GPCR targets. Learnings from the structural information regarding the utility of pharmacophore models and how selectivity between OX1 and OX2 can be achieved are discussed.
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Affiliation(s)
- Mathieu Rappas
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Ammar A. E. Ali
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Kirstie A. Bennett
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Jason D. Brown
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Sarah J. Bucknell
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Miles Congreve
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Robert M. Cooke
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Gabriella Cseke
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Chris de Graaf
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | - Andrew S. Doré
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | | | | | | | - Jonathan S. Mason
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | | | - Jayesh C. Patel
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
| | | | - Malcolm Weir
- Sosei Heptares, Steinmetz Building, Granta Park, Cambridge CB21 6DG, U.K.
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17
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Yamaguchi M, Ishikawa M, Aono Y, Saigusa T. OX 2 receptors mediate the inhibitory effects of orexin-A on potassium chloride-induced increases in intracellular calcium ion levels in neurons derived from rat dorsal root ganglion in a chronic pain model. Neuropsychopharmacol Rep 2019; 40:30-38. [PMID: 31845549 PMCID: PMC7292216 DOI: 10.1002/npr2.12094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/06/2019] [Accepted: 09/10/2019] [Indexed: 02/06/2023] Open
Abstract
AIMS Orexin-A is known to induce anti-nociceptive effects in animal models of chronic pain. We have found that orexin-A inhibits KCl loading-induced increases in the intracellular calcium ion levels ([Ca2+ ]i ) in C-fiber-like neurons of rats showing inflammatory nociceptive behavior. Here, we examined the effects of orexin-A on the depolarization of C-fiber-like neurons derived from a rat model for another type of chronic pain, namely neuropathic pain. Thus, we analyzed the effects of orexin-A on KCl-induced increases in [Ca2+ ]i in C-fiber-like neurons of rats with sciatic nerve ligation. METHODS Paw withdrawal and threshold force in response to tactile stimuli were evaluated using von Frey filaments. Sham-operated rats served as controls. [Ca2+ ]i in neurons were visualized by calcium fluorescent probe. Changes in [Ca2+ ]i were assessed using relative fluorescence intensity. RESULTS Seven days after sciatic nerve ligation, paw withdrawal and threshold force for tactile stimuli were increased and reduced, respectively. KCl loading to neurons from either sciatic nerve-ligated or control rats increased relative fluorescence intensity. The KCl-induced increase in relative fluorescence intensity in sciatic nerve-ligated, but not that of control, rats was inhibited by orexin-A. The OX1 and OX2 receptor antagonist MK-4305 and OX2 receptor antagonist EMPA, but not the OX1 receptor antagonist SB 334867, each counteracted orexin-A-induced inhibition of KCl-provoked increases in relative fluorescence intensity. CONCLUSION The present findings constitute neuropharmacological evidence that OX2 but not OX1 receptors mediate the inhibitory effects of orexin-A on KCl-induced increases in [Ca2+ ]i in C-fiber-like neurons of rats showing hyperalgesia provoked by sciatic nerve ligation.
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Affiliation(s)
- Masami Yamaguchi
- Department of Anesthesiology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Manabu Ishikawa
- Department of Anesthesiology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Yuri Aono
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Tadashi Saigusa
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
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18
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Turku A, Leino TO, Karhu L, Yli-Kauhaluoma J, Kukkonen JP, Wallén EAA, Xhaard H. Structure-Activity Relationships of 1-Benzoylazulenes at the OX 1 and OX 2 Orexin Receptors. ChemMedChem 2019; 14:965-981. [PMID: 30892823 DOI: 10.1002/cmdc.201900074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/20/2019] [Indexed: 11/08/2022]
Abstract
We previously demonstrated the potential of di- or trisubstituted azulenes as ligands (potentiators, weak agonists, and antagonists) of the orexin receptors. In this study we investigated 27 1-benzoylazulene derivatives, uncovering seven potentiators of the orexin response on OX1 and two weak dual orexin receptor agonists. For potentiators, replacement of the azulene scaffold by indole retained the activity of four out of six compounds. The structure-activity relationships for agonism and potentiation can be summarized into a bicyclic aromatic ring system substituted with two hydrogen-bond acceptors (1-position, benzoyl; 6-position, carboxyl/ester) within 7-8 Å of each other; a third acceptor at the 3-position is also well tolerated. The same pharmacophoric signature is found in the preferred conformations of the orexin receptor agonist Nag26 from molecular dynamics simulations. Subtle changes switch the activity between weak agonism and potentiation, suggesting overlapping binding sites.
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Affiliation(s)
- Ainoleena Turku
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland.,Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, 00014, Helsinki, Finland
| | - Teppo O Leino
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Lasse Karhu
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Jari Yli-Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Jyrki P Kukkonen
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, 00014, Helsinki, Finland.,Department of Physiology, Faculty of Medicine, University of Helsinki, P.O. Box 63, 00014, Helsinki, Finland
| | - Erik A A Wallén
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Henri Xhaard
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
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19
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Jaggard JB, Stahl BA, Lloyd E, Prober DA, Duboue ER, Keene AC. Hypocretin underlies the evolution of sleep loss in the Mexican cavefish. eLife 2018; 7:32637. [PMID: 29405117 PMCID: PMC5800846 DOI: 10.7554/elife.32637] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 11/25/2017] [Indexed: 01/09/2023] Open
Abstract
The duration of sleep varies dramatically between species, yet little is known about the genetic basis or evolutionary factors driving this variation in behavior. The Mexican cavefish, Astyanax mexicanus, exists as surface populations that inhabit rivers, and multiple cave populations with convergent evolution on sleep loss. The number of Hypocretin/Orexin (HCRT)-positive hypothalamic neurons is increased significantly in cavefish, and HCRT is upregulated at both the transcript and protein levels. Pharmacological or genetic inhibition of HCRT signaling increases sleep in cavefish, suggesting enhanced HCRT signaling underlies the evolution of sleep loss. Ablation of the lateral line or starvation, manipulations that selectively promote sleep in cavefish, inhibit hcrt expression in cavefish while having little effect on surface fish. These findings provide the first evidence of genetic and neuronal changes that contribute to the evolution of sleep loss, and support a conserved role for HCRT in sleep regulation.
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Affiliation(s)
- James B Jaggard
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
| | - Bethany A Stahl
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
| | - Evan Lloyd
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
| | - David A Prober
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Erik R Duboue
- Department of Embryology, Carnegie Institution for Science, Baltimore, United States.,Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, United States
| | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
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20
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Cataldi NI, Lux-Lantos VA, Libertun C. Perinatal programming of the orexinergic (hypocretinergic) system in hypothalamus and anterior pituitary by testosterone. Peptides 2018; 99:117-127. [PMID: 28442349 DOI: 10.1016/j.peptides.2017.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 01/12/2023]
Abstract
Orexins A/B derived from hypothalamic prepro-orexin (PPO) are agonists for orexin receptors 1 (OX1) and 2 (OX2). Previously, we showed clear sex differences in the hypothalamic-pituitary-gonadal orexinergic system in adult rodents. Here, we studied the effect of sexual brain differentiation on the orexinergic system in neuroendocrine structures regulating reproduction. We evaluated: a: proestrous and neonatally androgenized female rats; b: adult males, untreated or gonadectomized in adulthood and injected with oil or estradiol and progesterone (E2/P4); c: control and demasculinized males (perinatally treated with flutamide and later castration) injected either with oil or E2/P4 in adulthood. Rats were sacrificed at 12:00 and 18:00h; blood samples and brains were collected. Hormones were measured using radioimmunoassay. PPO, OX1 and OX2 mRNAs were quantified by qPCR in medial basal hypothalamus, anterior hypothalamus, adenohypophysis, and cortex. Western blots for OX1 were done in the same structures. In normal females, gonadotropins surged at 18:00h coinciding with significant elevations of PPO, OX1 and OX2 mRNAs and OX1 protein in hypothalamus and pituitary; no increases were observed at noon. Afternoon changes were absent in masculinized females. Demasculinized males when treated with E2/P4 showed high PPO, OX1 and OX2 mRNAs and OX1 protein expression in hypothalamus and pituitary at 12:00 and 18:00h compared vehicle-treated controls. The same steroid treatment was ineffective in males with normal brain masculinization. Here we show that neonatal testosterone shapes the sexual differences in the hypothalamic-pituitary orexinergic system in synchronicity to establishing the brain sex differences of the reproductive axis. The female brain controls gonadotropin surges and concurrent elevations of all studied components of the orexinergic system, suggesting its participation as a possible link between food intake, behavior and hormonal control of reproduction.
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Affiliation(s)
| | | | - Carlos Libertun
- Instituto de Biología y Medicina Experimental-CONICET, Argentina; Universidad de Buenos Aires, Facultad de Medicina, Departamento de Fisiología y Biofísica, Buenos Aires, Argentina.
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Crystal Structures of Human Orexin 2 Receptor Bound to the Subtype-Selective Antagonist EMPA. Structure 2018; 26:7-19.e5. [DOI: 10.1016/j.str.2017.11.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 09/02/2017] [Accepted: 11/08/2017] [Indexed: 11/16/2022]
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Abstract
The discovery of the orexin system represents the single major progress in the sleep field of the last three to four decades. The two orexin peptides and their two receptors play a major role in arousal and sleep/wake cycles. Defects in the orexin system lead to narcolepsy with cataplexy in humans and dogs and can be experimentally reproduced in rodents. At least six orexin receptor antagonists have reached Phase II or Phase III clinical trials in insomnia, five of which are dual orexin receptor antagonists (DORAs) that target both OX1 and OX2 receptors (OX2Rs). All clinically tested DORAs induce and maintain sleep: suvorexant, recently registered in the USA and Japan for insomnia, represents the first hypnotic principle that acts in a completely different manner from the current standard medications. It is clear, however, that in the clinic, all DORAs promote sleep primarily by increasing rapid eye movement (REM) and are almost devoid of effects on slow-wave (SWS) sleep. At present, there is no consensus on whether the sole promotion of REM sleep has a negative impact in patients suffering from insomnia. However, sleep onset REM (SOREM), which has been documented with DORAs, is clearly an undesirable effect, especially for narcoleptic patients and also in fragile populations (e.g. elderly patients) where REM-associated loss of muscle tone may promote an elevated risk of falls. Debate thus remains as to the ideal orexin agent to achieve a balanced increase in REM and non-rapid eye movement (NREM) sleep. Here, we review the evidence that an OX2R antagonist should be at least equivalent, or perhaps superior, to a DORA for the treatment of insomnia. An OX2R antagonist may produce more balanced sleep than a DORA. Rodent sleep experiments show that the OX2R is the primary target of orexin receptor antagonists in sleep modulation. Furthermore, an OX2R antagonist should, in theory, have a lower narcoleptic/cataplexic potential. In the clinic, the situation remains equivocal, since OX2R antagonists are in early stages: MK-1064 has completed Phase I, and MIN202 is currently in clinical Phase II/III trials. However, data from insomnia patients have not yet been released. Promotional material suggests that balanced sleep is indeed induced by MIN-202, whereas in volunteers MK-1064 has been reported to act similarly to DORAs.
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Affiliation(s)
- Laura H Jacobson
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Sui Chen
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Sanjida Mir
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Daniel Hoyer
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia.
- Department of Chemical Physiology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA.
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Bonaventure P, Dugovic C, Shireman B, Preville C, Yun S, Lord B, Nepomuceno D, Wennerholm M, Lovenberg T, Carruthers N, Fitz SD, Shekhar A, Johnson PL. Evaluation of JNJ-54717793 a Novel Brain Penetrant Selective Orexin 1 Receptor Antagonist in Two Rat Models of Panic Attack Provocation. Front Pharmacol 2017; 8:357. [PMID: 28649201 PMCID: PMC5465257 DOI: 10.3389/fphar.2017.00357] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/24/2017] [Indexed: 11/13/2022] Open
Abstract
Orexin neurons originating in the perifornical and lateral hypothalamic area are highly reactive to anxiogenic stimuli and have strong projections to anxiety and panic-associated circuitry. Recent studies support a role for the orexin system and in particular the orexin 1 receptor (OX1R) in coordinating an integrative stress response. However, no selective OX1R antagonist has been systematically tested in two preclinical models of using panicogenic stimuli that induce panic attack in the majority of people with panic disorder, namely an acute hypercapnia-panic provocation model and a model involving chronic inhibition of GABA synthesis in the perifornical hypothalamic area followed by intravenous sodium lactate infusion. Here we report on a novel brain penetrant, selective and high affinity OX1R antagonist JNJ-54717793 (1S,2R,4R)-7-([(3-fluoro-2-pyrimidin-2-ylphenyl)carbonyl]-N-[5-(trifluoromethyl)pyrazin-2-yl]-7-azabicyclo[2.2.1]heptan-2-amine). JNJ-54717793 is a high affinity/potent OX1R antagonist and has an excellent selectivity profile including 50 fold versus the OX2R. Ex vivo receptor binding studies demonstrated that after oral administration JNJ-54717793 crossed the blood brain barrier and occupied OX1Rs in the rat brain. While JNJ-54717793 had minimal effect on spontaneous sleep in rats and in wild-type mice, its administration in OX2R knockout mice, selectively promoted rapid eye movement sleep, demonstrating target engagement and specific OX1R blockade. JNJ-54717793 attenuated CO2 and sodium lactate induced panic-like behaviors and cardiovascular responses without altering baseline locomotor or autonomic activity. These data confirm that selective OX1R antagonism may represent a novel approach of treating anxiety disorders, with no apparent sedative effects.
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Affiliation(s)
| | | | - Brock Shireman
- Janssen Research & Development, LLC, San DiegoCA, United States
| | - Cathy Preville
- Janssen Research & Development, LLC, San DiegoCA, United States
| | - Sujin Yun
- Janssen Research & Development, LLC, San DiegoCA, United States
| | - Brian Lord
- Janssen Research & Development, LLC, San DiegoCA, United States
| | | | | | | | | | - Stephanie D. Fitz
- Department of Psychiatry, Indiana University School of Medicine, IndianapolisIN, United States
| | - Anantha Shekhar
- Department of Psychiatry, Indiana University School of Medicine, IndianapolisIN, United States
- Stark Neurosciences Research Institute, Indiana University School of Medicine, IndianapolisIN, United States
| | - Philip L. Johnson
- Stark Neurosciences Research Institute, Indiana University School of Medicine, IndianapolisIN, United States
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, IndianapolisIN, United States
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Nonpeptide orexin type-2 receptor agonist ameliorates narcolepsy-cataplexy symptoms in mouse models. Proc Natl Acad Sci U S A 2017; 114:5731-5736. [PMID: 28507129 DOI: 10.1073/pnas.1700499114] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Narcolepsy-cataplexy is a debilitating disorder of sleep/wakefulness caused by a loss of orexin-producing neurons in the lateroposterior hypothalamus. Genetic or pharmacologic orexin replacement ameliorates symptoms in mouse models of narcolepsy-cataplexy. We have recently discovered a potent, nonpeptide OX2R-selective agonist, YNT-185. This study validates the pharmacological activity of this compound in OX2R-transfected cells and in OX2R-expressing neurons in brain slice preparations. Intraperitoneal, and intracerebroventricular, administration of YNT-185 suppressed cataplexy-like episodes in orexin knockout and orexin neuron-ablated mice, but not in orexin receptor-deficient mice. Peripherally administered YNT-185 also promotes wakefulness without affecting body temperature in wild-type mice. Further, there was no immediate rebound sleep after YNT-185 administration in active phase in wild-type and orexin-deficient mice. No desensitization was observed after repeated administration of YNT-185 with respect to the suppression of cataplexy-like episodes. These results provide a proof-of-concept for a mechanistic therapy of narcolepsy-cataplexy by OX2R agonists.
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Carrive P, Kuwaki T. Orexin and Central Modulation of Cardiovascular and Respiratory Function. Curr Top Behav Neurosci 2017; 33:157-196. [PMID: 27909989 DOI: 10.1007/7854_2016_46] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Orexin makes an important contribution to the regulation of cardiorespiratory function. When injected centrally under anesthesia, orexin increases blood pressure, heart rate, sympathetic nerve activity, and the amplitude and frequency of respiration. This is consistent with the location of orexin neurons in the hypothalamus and the distribution of orexin terminals at all levels of the central autonomic and respiratory network. These cardiorespiratory responses are components of arousal and are necessary to allow the expression of motivated behaviors. Thus, orexin contributes to the cardiorespiratory response to acute stressors, especially those of a psychogenic nature. Consequently, upregulation of orexin signaling, whether it is spontaneous or environmentally induced, can increase blood pressure and lead to hypertension, as is the case for the spontaneously hypertensive rat and the hypertensive BPH/2J Schlager mouse. Blockade of orexin receptors will reduce blood pressure in these animals, which could be a new pharmacological approach for the treatment of some forms of hypertension. Orexin can also magnify the respiratory reflex to hypercapnia in order to maintain respiratory homeostasis, and this may be in part why it is upregulated during obstructive sleep apnea. In this pathological condition, blockade of orexin receptors would make the apnea worse. To summarize, orexin is an important modulator of cardiorespiratory function. Acting on orexin signaling may help in the treatment of some cardiovascular and respiratory disorders.
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Affiliation(s)
- Pascal Carrive
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
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26
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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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Orexin, Stress and Central Cardiovascular Control. A Link with Hypertension? Neurosci Biobehav Rev 2016; 74:376-392. [PMID: 27477446 DOI: 10.1016/j.neubiorev.2016.06.044] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/28/2016] [Accepted: 06/13/2016] [Indexed: 01/28/2023]
Abstract
Orexin, the arousal peptide, originates from neurons located in an area of the dorsal hypothalamus well known for integrating defense responses and their cardiovascular component. Orexin neurons, which are driven in large part by the limbic forebrain, send projections to many regions in the brain, including regions involved in cardiovascular control, as far down as sympathetic preganglionic neurons in the spinal cord. Central injections of orexin evoke sympathetically mediated cardiovascular responses. Conversely, blockade of orexin receptors reduce the cardiovascular responses to acute stressors, preferentially of a psychological nature. More importantly, lasting upregulation of orexin signaling can lead to a hypertensive state. This can be observed in rats exposed to chronic stress as well as in strains known to display spontaneous hypertension such as the spontaneously hypertensive rat (SHR) or the hypertensive BPH/2J Schlager mouse. Thus, there is a link between orexin, stress and hypertension, and orexin upregulation could be a factor in the development of essential hypertension. Orexin receptor antagonists have anti-hypertensive effects that could be of clinical use.
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28
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Kumar A, Chanana P, Choudhary S. Emerging role of orexin antagonists in insomnia therapeutics: An update on SORAs and DORAs. Pharmacol Rep 2016; 68:231-42. [DOI: 10.1016/j.pharep.2015.09.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 12/28/2022]
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29
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SB 334867, a selective orexin receptor type 1 antagonist, elevates seizure threshold in mice. Life Sci 2016; 150:81-8. [DOI: 10.1016/j.lfs.2016.02.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/16/2016] [Accepted: 02/20/2016] [Indexed: 11/17/2022]
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30
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Beig MI, Horiuchi J, Dampney RAL, Carrive P. Both Ox1R and Ox2R orexin receptors contribute to the cardiorespiratory response evoked from the perifornical hypothalamus. Clin Exp Pharmacol Physiol 2015; 42:1059-67. [DOI: 10.1111/1440-1681.12461] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/23/2015] [Accepted: 07/09/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Mirza I Beig
- School of Medical Sciences; University of New South Wales; Sydney NSW Australia
| | - Jouji Horiuchi
- Department of Biomedical Engineering; Toyo University; Kawagoe Saitama Japan
| | - Roger AL Dampney
- School of Medical Sciences; University of New South Wales; Sydney NSW Australia
- School of Medical Sciences and Bosch Institute for Biomedical Research; University of Sydney; Sydney NSW Australia
| | - Pascal Carrive
- School of Medical Sciences; University of New South Wales; Sydney NSW Australia
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31
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Bonaventure P, Shelton J, Yun S, Nepomuceno D, Sutton S, Aluisio L, Fraser I, Lord B, Shoblock J, Welty N, Chaplan SR, Aguilar Z, Halter R, Ndifor A, Koudriakova T, Rizzolio M, Letavic M, Carruthers NI, Lovenberg T, Dugovic C. Characterization of JNJ-42847922, a Selective Orexin-2 Receptor Antagonist, as a Clinical Candidate for the Treatment of Insomnia. J Pharmacol Exp Ther 2015; 354:471-82. [PMID: 26177655 DOI: 10.1124/jpet.115.225466] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/14/2015] [Indexed: 11/22/2022] Open
Abstract
Dual orexin receptor antagonists have been shown to promote sleep in various species, including humans. Emerging research indicates that selective orexin-2 receptor (OX2R) antagonists may offer specificity and a more adequate sleep profile by preserving normal sleep architecture. Here, we characterized JNJ-42847922 ([5-(4,6-dimethyl-pyrimidin-2-yl)-hexahydro-pyrrolo[3,4-c]pyrrol-2-yl]-(2-fluoro-6-[1,2,3]triazol-2-yl-phenyl)-methanone), a high-affinity/potent OX2R antagonist. JNJ-42847922 had an approximate 2-log selectivity ratio versus the human orexin-1 receptor. Ex vivo receptor binding studies demonstrated that JNJ-42847922 quickly occupied OX2R binding sites in the rat brain after oral administration and rapidly cleared from the brain. In rats, single oral administration of JNJ-42847922 (3-30 mg/kg) during the light phase dose dependently reduced the latency to non-rapid eye movement (NREM) sleep and prolonged NREM sleep time in the first 2 hours, whereas REM sleep was minimally affected. The reduced sleep onset and increased sleep duration were maintained upon 7-day repeated dosing (30 mg/kg) with JNJ-42847922, then all sleep parameters returned to baseline levels following discontinuation. Although the compound promoted sleep in wild-type mice, it had no effect in OX2R knockout mice, consistent with a specific OX2R-mediated sleep response. JNJ-42847922 did not increase dopamine release in rat nucleus accumbens or produce place preference in mice after subchronic conditioning, indicating that the compound lacks intrinsic motivational properties in contrast to zolpidem. In a single ascending dose study conducted in healthy subjects, JNJ-42847922 increased somnolence and displayed a favorable pharmacokinetic and safety profile for a sedative/hypnotic, thus emerging as a promising candidate for further clinical development for the treatment of insomnia.
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Affiliation(s)
| | | | - Sujin Yun
- Janssen Research & Development, LLC, San Diego, California
| | | | - Steven Sutton
- Janssen Research & Development, LLC, San Diego, California
| | - Leah Aluisio
- Janssen Research & Development, LLC, San Diego, California
| | - Ian Fraser
- Janssen Research & Development, LLC, San Diego, California
| | - Brian Lord
- Janssen Research & Development, LLC, San Diego, California
| | - James Shoblock
- Janssen Research & Development, LLC, San Diego, California
| | - Natalie Welty
- Janssen Research & Development, LLC, San Diego, California
| | | | | | - Robin Halter
- Janssen Research & Development, LLC, San Diego, California
| | - Anthony Ndifor
- Janssen Research & Development, LLC, San Diego, California
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32
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Bonaventure P, Yun S, Johnson PL, Shekhar A, Fitz SD, Shireman BT, Lebold TP, Nepomuceno D, Lord B, Wennerholm M, Shelton J, Carruthers N, Lovenberg T, Dugovic C. A selective orexin-1 receptor antagonist attenuates stress-induced hyperarousal without hypnotic effects. J Pharmacol Exp Ther 2015; 352:590-601. [PMID: 25583879 DOI: 10.1124/jpet.114.220392] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Orexins (OXs) are peptides produced by perifornical (PeF) and lateral hypothalamic neurons that exert a prominent role in arousal-related processes, including stress. A critical role for the orexin-1 receptor (OX1R) in complex emotional behavior is emerging, such as overactivation of the OX1R pathway being associated with panic or anxiety states. Here we characterize a brain-penetrant, selective, and high-affinity OX1R antagonist, compound 56 [N-({3-[(3-ethoxy-6-methylpyridin-2-yl)carbonyl]-3-azabicyclo[4.1.0]hept-4-yl}methyl)-5-(trifluoromethyl)pyrimidin-2-amine]. Ex vivo receptor binding studies demonstrated that, after subcutaneous administration, compound 56 crossed the blood-brain barrier and occupied OX1Rs in the rat brain at lower doses than standard OX1R antagonists GSK-1059865 [5-bromo-N-({1-[(3-fluoro-2-methoxyphenyl)carbonyl]-5-methylpiperidin-2-yl}methyl)pyridin-2-amine], SB-334867 [1-(2-methyl-1,3-benzoxazol-6-yl)-3-(1,5-naphthyridin-4-yl)urea], and SB-408124 [1-(6,8-difluoro-2-methylquinolin-4-yl)-3-[4-(dimethylamino)phenyl]urea]. Although compound 56 did not alter spontaneous sleep in rats and in wild-type mice, its administration in orexin-2 receptor knockout mice selectively promoted rapid eye movement sleep, demonstrating target engagement and specific OX1R blockade. In a rat model of psychological stress induced by cage exchange, the OX1R antagonist prevented the prolongation of sleep onset without affecting sleep duration. In a rat model of panic vulnerability (involving disinhibition of the PeF OX region) to threatening internal state changes (i.e., intravenous sodium lactate infusion), compound 56 attenuated sodium lactate-induced panic-like behaviors and cardiovascular responses without altering baseline locomotor or autonomic activity. In conclusion, OX1R antagonism represents a novel therapeutic strategy for the treatment of various psychiatric disorders associated with stress or hyperarousal states.
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Affiliation(s)
- Pascal Bonaventure
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Sujin Yun
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Philip L Johnson
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Anantha Shekhar
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Stephanie D Fitz
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Brock T Shireman
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Terry P Lebold
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Diane Nepomuceno
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Brian Lord
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Michelle Wennerholm
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Jonathan Shelton
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Nicholas Carruthers
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Timothy Lovenberg
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
| | - Christine Dugovic
- Janssen Research & Development, LLC, San Diego, California (P.B., S.Y., B.T.S., T.P.L., D.N., B.L., M.W., J.S., N.C., T.L., C.D.); and Indiana University School of Medicine, Indianapolis, Indiana (P.L.J., A.S., S.D.F.)
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Christopher JA, Aves SJ, Brown J, Errey JC, Klair SS, Langmead CJ, Mace OJ, Mould R, Patel JC, Tehan BG, Zhukov A, Marshall FH, Congreve M. Discovery of HTL6641, a dual orexin receptor antagonist with differentiated pharmacodynamic properties. MEDCHEMCOMM 2015. [DOI: 10.1039/c5md00027k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A novel series of potent, selective, and orally efficacious dual antagonists of the orexin receptors is described.
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Affiliation(s)
| | | | - Jason Brown
- Heptares Therapeutics Ltd
- Welwyn Garden City
- U.K
| | | | - Suki S. Klair
- Labstract Ltd
- Stevenage Bioscience Catalyst
- Stevenage
- U.K
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Guerreiro S, Florence C, Rousseau E, Hamadat S, Hirsch EC, Michel PP. The Sleep-Modulating Peptide Orexin-B Protects Midbrain Dopamine Neurons from Degeneration, Alone or in Cooperation with Nicotine. Mol Pharmacol 2014; 87:525-32. [DOI: 10.1124/mol.114.095703] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Crystal structure of the human OX2 orexin receptor bound to the insomnia drug suvorexant. Nature 2014; 519:247-50. [DOI: 10.1038/nature14035] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/04/2014] [Indexed: 12/18/2022]
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Both Ox1r and Ox2r orexin receptors contribute to the cardiovascular and locomotor components of the novelty stress response in the rat. Neuropharmacology 2014; 89:146-56. [PMID: 25239810 DOI: 10.1016/j.neuropharm.2014.09.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/06/2014] [Accepted: 09/08/2014] [Indexed: 11/22/2022]
Abstract
Orexin contributes to the expression of the cardiovascular and behavioural response of some forms of stress, including novelty stress. Thus, Almorexant, a dual receptor antagonist that blocks the two known orexin receptors, Ox1R and Ox2R, reduces these responses. However, it is not known if the reduction results from blockade of one receptor only or both. To answer this question, the selective Ox1R antagonist ACT335827 and the selective Ox2R antagonist EMPA were injected intragastrically (300 mg/kg) or intraperitoneally (30 and 100 mg/kg) either alone or as a cocktail and compared to Almorexant in rats exposed to novelty stress. Cardiovascular and locomotor responses were recorded by radio-telemetry. Triple immunolabelling was also conducted to establish the distribution of Ox1R and Ox2R in sympathetic preganglionic neurons and orexin neurons. Intraperitoneal injections of ACT335827 (100 mg/kg) reduced the pressor and tachycardic but not the locomotor response of novelty (by 32% and 48%, respectively). Intraperitoneal injections of EMPA (100 mg/kg) only reduced the pressor response (42%). However when given together, ACT335827 and EMPA reduced all 3 components (65%, 60% and 57% of the tachycardic, pressor and locomotor responses, respectively) as Almorexant (100 mg/kg) did (69%, 87% and 72%, respectively). Triple immunolabelling revealed that sympathetic preganglionic neurons were mainly Ox1R positive only while orexin neurons were both Ox1R and Ox2R positive. This study shows that orexin's contribution to the cardiovascular and locomotor components of the novelty stress response is not mediated by one receptor alone, but by both receptors and at different levels of the neuraxis.
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Winrow CJ, Renger JJ. Discovery and development of orexin receptor antagonists as therapeutics for insomnia. Br J Pharmacol 2014; 171:283-93. [PMID: 23731216 DOI: 10.1111/bph.12261] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 05/13/2013] [Accepted: 05/16/2013] [Indexed: 01/23/2023] Open
Abstract
Insomnia persistently affects the quality and quantity of sleep. Currently approved treatments for insomnia primarily target γ-aminobutyric acid-A (GABA-A) receptor signalling and include benzodiazepines and GABA-A receptor modulators. These drugs are used to address this sleep disorder, but have the potential for side effects such as tolerance and dependence, making them less attractive as maintenance therapy. Forward and reverse genetic approaches in animals have implicated orexin signalling (also referred to as hypocretin signalling) in the control of vigilance and sleep/wake states. Screening for orexin receptor antagonists using in vitro and in vivo methods in animals has identified compounds that block one or other of the orexin receptors (single or dual orexin receptor antagonists [SORAs and DORAs], respectively) in animals and humans. SORAs have primarily been used as probes to further elucidate the roles of the individual orexin receptors, while a number of DORAs have progressed to clinical development as pharmaceutical candidates for insomnia. The DORA almorexant demonstrated significant improvements in a number of clinically relevant sleep parameters in animal models and in patients with insomnia but its development was halted. SB-649868 and suvorexant have demonstrated efficacy and tolerability in Phase II and III trials respectively. Furthermore, suvorexant is currently under review by the Food and Drug Administration for the treatment of insomnia. Based on the publication of recent non-clinical and clinical data, orexin receptor antagonists potentially represent a targeted, effective and well-tolerated new class of medications for insomnia.
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Affiliation(s)
- C J Winrow
- Department of Neuroscience, Merck Research Laboratories, West Point, PA, USA
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Mould R, Brown J, Marshall FH, Langmead CJ. Binding kinetics differentiates functional antagonism of orexin-2 receptor ligands. Br J Pharmacol 2014; 171:351-63. [PMID: 23692283 DOI: 10.1111/bph.12245] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/13/2013] [Accepted: 03/20/2013] [Indexed: 12/13/2022] Open
Abstract
Orexin receptor antagonism represents a novel approach for the treatment of insomnia that directly targets sleep/wake regulation. Several such compounds have entered into clinical development, including the dual orexin receptor antagonists, suvorexant and almorexant. In this study, we have used equilibrium and kinetic binding studies with the orexin-2 (OX₂) selective antagonist radioligand, [³H]-EMPA, to profile several orexin receptor antagonists. Furthermore, selected compounds were studied in cell-based assays of inositol phosphate accumulation and ERK-1/2 phosphorylation in CHO cells stably expressing the OX2 receptor that employ different agonist incubation times (30 and 5 min, respectively). EMPA, suvorexant, almorexant and TCS-OX-29 all bind to the OX₂ receptor with moderate to high affinity (pk(I) values ≥ 7.5), whereas the primarily OX1 selective antagonists SB-334867 and SB-408124 displayed low affinity (pK(I) values ca. 6). Competition kinetic analysis showed that the compounds displayed a range of dissociation rates from very fast (TCS-OX2-29, k(off) = 0.22 min⁻¹) to very slow (almorexant, k(off) = 0.005 min⁻¹). Notably, there was a clear correlation between association rate and affinity. In the cell-based assays, fast-offset antagonists EMPA and TCS-OX2-29 displayed surmountable antagonism of orexin-A agonist activity. However, both suvorexant and particularly almorexant cause concentration-dependent depression in the maximal orexin-A response, a profile that is more evident with a shorter agonist incubation time. Analysis according to a hemi-equilibrium model suggests that antagonist dissociation is slower in a cellular system than in membrane binding; under these conditions, almorexant effectively acts as a pseudo-irreversible antagonist.
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Affiliation(s)
- R Mould
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, Herts, AL7 3AX, UK
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Abstract
Addiction is a chronic relapsing disorder which presents a significant global health burden and unmet medical need. The orexin/hypocretin system is an attractive potential therapeutic target as demonstrated by the successful clinical trials of antagonist medications like Suvorexant for insomnia. It is composed of two neuropeptides, orexin-A and orexin-B and two excitatory and promiscuous G-protein coupled receptors, OX1 and OX2. Orexins are known to have a variety of functions, most notably in regulating arousal, appetite and reward. The orexins have been shown to have a role in mediating the effects of several drugs of abuse, such as cocaine, morphine and alcohol via projections to key brain regions such as the ventral tegmental area, nucleus accumbens and prefrontal cortex. However, it has not yet been demonstrated whether the dual orexin receptor antagonists (DORAs) under development for insomnia are ideal drugs for the treatment of addiction. The question of whether to use a DORA or single orexin receptor antagonist (SORA) for the treatment of addiction is a key question that will need to be answered in order to maximize the clinical utility of orexin receptor antagonists. This review will examine the role of the orexin/hypocretin system in addiction, orexin-based pharmacotherapies under development and factors affecting the selection of one or both orexin receptors as drug targets for the treatment of addiction.
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Chen Q, de Lecea L, Hu Z, Gao D. The hypocretin/orexin system: an increasingly important role in neuropsychiatry. Med Res Rev 2014; 35:152-97. [PMID: 25044006 DOI: 10.1002/med.21326] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Hypocretins, also named as orexins, are excitatory neuropeptides secreted by neurons specifically located in lateral hypothalamus and perifornical areas. Orexinergic fibers are extensively distributed in various brain regions and involved in a number of physiological functions, such as arousal, cognition, stress, appetite, and metabolism. Arousal is the most important function of orexin system as dysfunction of orexin signaling leads to narcolepsy. In addition to narcolepsy, orexin dysfunction is associated with serious neural disorders, including addiction, depression, and anxiety. However, some results linking orexin with these disorders are still contradictory, which may result from differences of detection methods or the precision of tools used in measurements; strategies targeted to orexin system (e.g., antagonists to orexin receptors, gene delivery, and cell transplantation) are promising new tools for treatment of neuropsychiatric disorders, though studies are still in a stage of preclinical or clinical research.
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Affiliation(s)
- Quanhui Chen
- Department of Physiology, Third Military Medical University, Chongqing 400038, China; Department of Sleep and Psychology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400038, China
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Yeoh JW, Campbell EJ, James MH, Graham BA, Dayas CV. Orexin antagonists for neuropsychiatric disease: progress and potential pitfalls. Front Neurosci 2014; 8:36. [PMID: 24616658 PMCID: PMC3934415 DOI: 10.3389/fnins.2014.00036] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 02/10/2014] [Indexed: 11/20/2022] Open
Abstract
The tight regulation of sleep/wake states is critical for mental and physiological wellbeing. For example, dysregulation of sleep/wake systems predisposes individuals to metabolic disorders such as obesity and psychiatric problems, including depression. Contributing to this understanding, the last decade has seen significant advances in our appreciation of the complex interactions between brain systems that control the transition between sleep and wake states. Pivotal to our increased understanding of this pathway was the description of a group of neurons in the lateral hypothalamus (LH) that express the neuropeptides orexin A and B (hypocretin, Hcrt-1 and Hcrt-2). Orexin neurons were quickly placed at center stage with the demonstration that loss of normal orexin function is associated with the development of narcolepsy—a condition in which sufferers fail to maintain normal levels of daytime wakefulness. Since these initial seminal findings, much progress has been made in our understanding of the physiology and function of the orexin system. For example, the orexin system has been identified as a key modulator of autonomic and neuroendocrine function, arousal, reward and attention. Notably, studies in animals suggest that dysregulation of orexin function is associated with neuropsychiatric states such as addiction and mood disorders including depression and anxiety. This review discusses the progress associated with therapeutic attempts to restore orexin system function and treat neuropsychiatric conditions such as addiction, depression and anxiety. We also highlight potential pitfalls and challenges associated with targeting this system to treat these neuropsychiatric states.
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Affiliation(s)
- Jiann Wei Yeoh
- Neurobiology of Addiction Laboratory, The Centre for Translational Neuroscience and Mental Health Research, School of Biomedical Sciences and Pharmacy, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Erin J Campbell
- Neurobiology of Addiction Laboratory, The Centre for Translational Neuroscience and Mental Health Research, School of Biomedical Sciences and Pharmacy, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Morgan H James
- Neurobiology of Addiction Laboratory, The Centre for Translational Neuroscience and Mental Health Research, School of Biomedical Sciences and Pharmacy, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Brett A Graham
- Neurobiology of Addiction Laboratory, The Centre for Translational Neuroscience and Mental Health Research, School of Biomedical Sciences and Pharmacy, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Christopher V Dayas
- Neurobiology of Addiction Laboratory, The Centre for Translational Neuroscience and Mental Health Research, School of Biomedical Sciences and Pharmacy, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
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Fitch TE, Benvenga MJ, Jesudason CD, Zink C, Vandergriff AB, Menezes MM, Schober DA, Rorick-Kehn LM. LSN2424100: a novel, potent orexin-2 receptor antagonist with selectivity over orexin-1 receptors and activity in an animal model predictive of antidepressant-like efficacy. Front Neurosci 2014; 8:5. [PMID: 24478625 PMCID: PMC3904085 DOI: 10.3389/fnins.2014.00005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 01/09/2014] [Indexed: 11/29/2022] Open
Abstract
We describe a novel, potent and selective orexin-2 (OX2)/hypocretin-2 receptor antagonist with in vivo activity in an animal model predictive of antidepressant-like efficacy. N-biphenyl-2-yl-4-fluoro-N-(1H-imidazol-2-ylmethyl) benzenesulfonamide HCl (LSN2424100) binds with high affinity to recombinant human OX2 receptors (Ki = 4.5 nM), and selectivity over OX1 receptors (Ki = 393 nM). LSN2424100 inhibited OXA-stimulated intracellular calcium release in HEK293 cells expressing human and rat OX2 receptors (Kb = 0.44 and 0.83 nM, respectively) preferentially over cells expressing human and rat OX1 (Kb = 90 and 175 nM, respectively). LSN2424100 exhibits good exposure in Sprague–Dawley rats after IP, but not PO, administration of a 30 mg/kg dose (AUC0–6 h = 1300 and 269 ng*h/mL, respectively). After IP administration in rats and mice, LSN2424100 produces dose-dependent antidepressant-like activity in the delayed-reinforcement of low-rate (DRL) assay, a model predictive of antidepressant-like efficacy. Efficacy in the DRL model was lost in mice lacking OX2, but not OX1 receptors, confirming OX2-specific activity. Importantly, antidepressant-like efficacy of the tricyclic antidepressant, imipramine, was maintained in both OX1 and OX2 receptor knock-out mice. In conclusion, the novel OX2 receptor antagonist, LSN2424100, is a valuable tool compound that can be used to explore the role of OX2 receptor-mediated signaling in mood disorders.
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Affiliation(s)
- Thomas E Fitch
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Mark J Benvenga
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Cynthia D Jesudason
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Charity Zink
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Amy B Vandergriff
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Michelle M Menezes
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Douglas A Schober
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
| | - Linda M Rorick-Kehn
- Lilly Research Laboratories, Department of Neuroscience, Eli Lilly and Company Indianapolis, IN, USA
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Roecker AJ, Mercer SP, Schreier JD, Cox CD, Fraley ME, Steen JT, Lemaire W, Bruno JG, Harrell CM, Garson SL, Gotter AL, Fox SV, Stevens J, Tannenbaum PL, Prueksaritanont T, Cabalu TD, Cui D, Stellabott J, Hartman GD, Young SD, Winrow CJ, Renger JJ, Coleman PJ. Discovery of 5''-chloro-N-[(5,6-dimethoxypyridin-2-yl)methyl]-2,2':5',3''-terpyridine-3'-carboxamide (MK-1064): a selective orexin 2 receptor antagonist (2-SORA) for the treatment of insomnia. ChemMedChem 2013; 9:311-22. [PMID: 24376006 DOI: 10.1002/cmdc.201300447] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Indexed: 01/12/2023]
Abstract
The field of small-molecule orexin antagonist research has evolved rapidly in the last 15 years from the discovery of the orexin peptides to clinical proof-of-concept for the treatment of insomnia. Clinical programs have focused on the development of antagonists that reversibly block the action of endogenous peptides at both the orexin 1 and orexin 2 receptors (OX1 R and OX2 R), termed dual orexin receptor antagonists (DORAs), affording late-stage development candidates including Merck's suvorexant (new drug application filed 2012). Full characterization of the pharmacology associated with antagonism of either OX1 R or OX2 R alone has been hampered by the dearth of suitable subtype-selective, orally bioavailable ligands. Herein, we report the development of a selective orexin 2 antagonist (2-SORA) series to afford a potent, orally bioavailable 2-SORA ligand. Several challenging medicinal chemistry issues were identified and overcome during the development of these 2,5-disubstituted nicotinamides, including reversible CYP inhibition, physiochemical properties, P-glycoprotein efflux and bioactivation. This article highlights structural modifications the team utilized to drive compound design, as well as in vivo characterization of our 2-SORA clinical candidate, 5''-chloro-N-[(5,6-dimethoxypyridin-2-yl)methyl]-2,2':5',3''-terpyridine-3'-carboxamide (MK-1064), in mouse, rat, dog, and rhesus sleep models.
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Affiliation(s)
- Anthony J Roecker
- Department of Medicinal Chemistry, Merck Research Laboratories, P.O. Box 4, Sumneytown Pike, West Point, PA 19486 (USA).
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Hoyer D, Jacobson LH. Orexin in sleep, addiction and more: is the perfect insomnia drug at hand? Neuropeptides 2013; 47:477-88. [PMID: 24215799 DOI: 10.1016/j.npep.2013.10.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/13/2013] [Accepted: 10/14/2013] [Indexed: 12/29/2022]
Abstract
Orexins A and B (hypocretins 1 and 2) and their two receptors (OX1R and OX2R) were discovered in 1998 by two different groups. Orexin A and B are derived from the differential processing of a common precursor, the prepro-orexin peptide. The neuropeptides are expressed in a few thousand cells located in the lateral hypothalamus (LH), but their projections and receptor distribution are widespread throughout the brain. Remarkably, prepro peptide and double (OX1R/OX2R) receptor knock out (KO) mice reproduce a sleep phenotype known in humans and dogs as narcolepsy/cataplexy. In humans, this disease is characterized by the absence of orexin producing cells in the LH, and severely depleted levels of orexin the cerebrospinal fluid. Null mutation of the individual OX1R or OX2R in mice substantially ameliorates the narcolepsy/cataplexy phenotype compared to the OX1R/OX2R KO, and highlights specific roles of the individual receptors in sleep architecture, the OX1R KO demonstrating an a attenuated sleep phenotype relative to the OX2R KO. It has therefore been suggested that orexin is a master regulator of the sleep-wake cycle, with high activity of the LH orexin cells during wake and almost none during sleep. Less than 10years later, the first orexin antagonist, almorexant, a dual orexin receptor antagonist (DORA), was reported to be effective in inducing sleep in volunteers and insomnia patients. Although development was stopped for almorexant and for Glaxo's DORA SB-649868, no less than 4 orexin receptor antagonists have reached phase II for insomnia, including Filorexant (MK-6096) and Suvorexant (MK-4305) from Merck. Suvorexant has since progressed to Phase III and dossier submission to the FDA. These four compounds are reported as DORAs, however, they equilibrate very slowly at one and/or the other orexin receptor, and thus at equilibrium may show more or less selectivity for OX1R or OX2R. The appropriate balance of antagonism of the two receptors for sleep is a point of debate, although in rodent models OX2R antagonism alone appears sufficient to induce sleep, whereas OX1R antagonism is largely devoid of this effect. Orexin is involved in a number of other functions including reward and feeding, where OX1R (possibly OX2R) antagonists display anti-addictive properties in rodent models of alcohol, smoking, and drug self-administration. However, despite early findings in feeding and appetite control, orexin receptor antagonists have not produced the anticipated effects in models of increased food intake or obesity in rodents, nor have they shown marked effects on weight in the existing clinical trials. The role of orexin in a number of other domains such as pain, mood, anxiety, migraine and neurodegenerative diseases is an active area of research. The progress of the orexin field is thus extraordinary, and the community awaits the clinical testing of more receptor selective antagonists in sleep and other disorders, as well as that of orexin agonists, with the latter expected to produce positive outcomes in narcolepsy/cataplexy and other conditions.
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Affiliation(s)
- Daniel Hoyer
- Department of Pharmacology & Therapeutics, School of Medicine, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia; The Florey Institute of Neuroscience and Mental Health, Parkville Campus, Kenneth Myer Building, at Genetics Lane, on Royal Parade, University of Melbourne, Parkville 3010, Australia.
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Mercer SP, Roecker AJ, Garson S, Reiss DR, Meacham Harrell C, Murphy KL, Bruno JG, Bednar RA, Lemaire W, Cui D, Cabalu TD, Tang C, Prueksaritanont T, Hartman GD, Young SD, Winrow CJ, Renger JJ, Coleman PJ. Discovery of 2,5-diarylnicotinamides as selective orexin-2 receptor antagonists (2-SORAs). Bioorg Med Chem Lett 2013; 23:6620-4. [PMID: 24215892 DOI: 10.1016/j.bmcl.2013.10.045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 11/24/2022]
Abstract
The orexin (or hypocretin) system has been identified as a novel target for the treatment of insomnia due to the wealth of biological and genetic data discovered over the past decade. Recently, clinical proof-of-concept was achieved for the treatment of primary insomnia using dual (OX1R/OX2R) orexin receptor antagonists. However, elucidation of the pharmacology associated with selective orexin-2 receptor antagonists (2-SORAs) has been hampered by the lack of orally bioavailable, highly selective small molecule probes. Herein, the discovery and optimization of a novel series of 2,5-diarylnicotinamides as potent and orally bioavailable orexin-2 receptor selective antagonists is described. A compound from this series demonstrated potent sleep promotion when dosed orally to EEG telemetrized rats.
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Affiliation(s)
- Swati P Mercer
- Department of Medicinal Chemistry, Merck Research Laboratories, West Point, PA 19486, USA.
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Wang C, Wilson CM, Moseley CK, Carlin SM, Hsu S, Arabasz G, Schroeder FA, Sander CY, Hooker JM. Evaluation of potential PET imaging probes for the orexin 2 receptors. Nucl Med Biol 2013; 40:1000-5. [PMID: 23953751 DOI: 10.1016/j.nucmedbio.2013.07.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 06/10/2013] [Accepted: 07/05/2013] [Indexed: 10/26/2022]
Abstract
A wide range of central nervous system (CNS) disorders, particularly those related to sleep, are associated with the abnormal function of orexin (OX) receptors. Several orexin receptor antagonists have been reported in recent years, but currently there are no imaging tools to probe the density and function of orexin receptors in vivo. To date there are no published data on the pharmacokinetics (PK) and accumulation of some lead orexin receptor antagonists. Evaluation of CNS pharmacokinetics in the pursuit of positron emission tomography (PET) radiotracer development could be used to elucidate the association of orexin receptors with diseases and to facilitate the drug discovery and development. To this end, we designed and evaluated carbon-11 labeled compounds based on diazepane orexin receptor antagonists previously described. One of the synthesized compounds, [(11)C]CW4, showed high brain uptake in rats and further evaluated in non-human primate (NHP) using PET-MR imaging. PET scans performed in a baboon showed appropriate early brain uptake for consideration as a radiotracer. However, [(11)C]CW4 exhibited fast kinetics and high nonspecific binding, as determined after co-administration of [(11)C]CW4 and unlabeled CW4. These properties indicate that [(11)C]CW4 has excellent brain penetrance and could be used as a lead compound for developing new CNS-penetrant PET imaging probes of orexin receptors.
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Affiliation(s)
- Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, United States
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48
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Oi N, Suzuki M, Terauchi T, Tokunaga M, Nakatani Y, Yamamoto N, Fukumura T, Zhang MR, Suhara T, Higuchi M. Synthesis and Evaluation of Novel Radioligands for Positron Emission Tomography Imaging of the Orexin-2 Receptor. J Med Chem 2013; 56:6371-85. [DOI: 10.1021/jm400772t] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Norihito Oi
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki
300-2635, Japan
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
- Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai
980-8574, Japan
| | - Michiyuki Suzuki
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki
300-2635, Japan
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Taro Terauchi
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki
300-2635, Japan
| | - Masaki Tokunaga
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yosuke Nakatani
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki
300-2635, Japan
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
- Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai
980-8574, Japan
| | - Noboru Yamamoto
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki
300-2635, Japan
| | - Toshimitsu Fukumura
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Ming-Rong Zhang
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Tetsuya Suhara
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
- Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai
980-8574, Japan
| | - Makoto Higuchi
- Molecular
Imaging Center, National Institute of Radiological Sciences, 4-9-1
Anagawa, Inage-ku, Chiba 263-8555, Japan
- Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai
980-8574, Japan
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Lebold TP, Bonaventure P, Shireman BT. Selective orexin receptor antagonists. Bioorg Med Chem Lett 2013; 23:4761-9. [PMID: 23891187 DOI: 10.1016/j.bmcl.2013.06.057] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 06/18/2013] [Accepted: 06/20/2013] [Indexed: 01/03/2023]
Abstract
The orexin, or hypocretin, neuropeptides (orexin-A and orexin-B) are produced on neurons in the hypothalamus which project to key areas of the brain that control sleep-wake states, modulation of food intake, panic, anxiety, emotion, reward and addictive behaviors. These neuropeptides exert their effects on a pair of G-protein coupled receptors termed the orexin-1 (OX1) and orexin-2 (OX2) receptors. Emerging biology suggests the involvement of these receptors in psychiatric disorders as they are thought to play a key role in the regulation of multiple systems. This review is intended to highlight key selective OX1 or OX2 small-molecule antagonists.
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Affiliation(s)
- Terry P Lebold
- Janssen Research & Development, 3210 Merryfield Row, San Diego, CA 92121, USA
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50
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Wang C, Moseley CK, Carlin SM, Wilson CM, Neelamegam R, Hooker JM. Radiosynthesis and evaluation of [11C]EMPA as a potential PET tracer for orexin 2 receptors. Bioorg Med Chem Lett 2013; 23:3389-92. [PMID: 23601709 DOI: 10.1016/j.bmcl.2013.03.079] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 10/27/2022]
Abstract
EMPA is a selective antagonist of orexin 2 (OX2) receptors. Previous literature with [(3)H]-EMPA suggest that it may be used as an imaging agent for OX2 receptors; however, brain penetration is known to be modest. To evaluate the potential of EMPA as a PET radiotracer in non-human primate (as a step to imaging in man), we radiolabeled EMPA with carbon-11. Radiosynthesis of [(11)C]N-ethyl-2-(N-(6-methoxypyridin-3-yl)-2-methylphenylsulfonamido)-N-(pyridin-3-ylmethyl)acetamide ([(11)C]EMPA), and evaluation as a potential PET tracer for OX2 receptors is described. Synthesis of an appropriate non-radioactive O-desmethyl precursor was achieved from EMPA with sodium iodide and chlorotrimethylsilane. Selective O-methylation using [(11)C]CH3I in the presence of cesium carbonate in DMSO at room temp afforded [(11)C]EMPA in 1.5-2.5% yield (non-decay corrected relative to trapped [(11)C]CH3I at EOS) with ≥95% chemical and radiochemical purities. The total synthesis time was 34-36min from EOB. Studies in rodent suggested that uptake in tissue was dominated by nonspecific binding. However, [(11)C]EMPA also showed poor uptake in both rats and baboon as measured with PET imaging.
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Affiliation(s)
- Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149, 13th Street, Suite 2301, Charlestown, MA 02129, USA
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