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Han Y, Chen S, Yang Q, Xie M, Liang Y, Li J, Zhang LZ. Non-peptide orphanin receptor antagonist activity in rat myocardial ischemia-induced cardiac arrhythmias. Biochem Biophys Res Commun 2023; 685:149160. [PMID: 37922788 DOI: 10.1016/j.bbrc.2023.149160] [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: 07/30/2023] [Revised: 10/19/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023]
Abstract
One of the causes of sudden cardiac death is arrhythmia after acute myocardial ischemia. After ischemia, endogenous orphanin (N/OFQ) plays a role in the development of arrhythmias. It is discussed in this paper how nonpeptide orphanin receptor (ORL1) antagonists such as J-113397, SB-612111 and compound-24 (C-24) affect arrhythmia in rats following acute myocardial ischemia and what the optimal concentrations for these antagonists are. The electrocardiogram of the rat was recorded as part of the experiment. The concentrations of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the myocardium were measured following euthanasia. Following the use of three antagonists, we found the lowest inflammatory factor concentrations and the smallest number of ischemic arrhythmia episodes. All of them had a small impact on cardiac function. LF/HF values were significantly reduced in all three antagonist groups, suggesting that they are involved in the regulation of sympathetic nerves. In conclusion, pretreatment with the three antagonist groups can effectively reduce the concentration of TNF-α and IL-1β, and the occurrence of arrhythmias after ischemia can also be significantly reduced. Inflammation and sympathetic activity may be related to the mechanism of action of antagonists.
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Affiliation(s)
- Yi Han
- Department of Anesthesiology, Second Hospital of Shanxi Medical University, Taiyuan, 030000, China; College of Anesthesiology, Shanxi Medical University, Taiyuan, 030000, China.
| | - Sikun Chen
- Department of Anesthesiology, Linfen People's Hospital, Linfen, 041000, China
| | - Qixing Yang
- Department of Anesthesiology, Linfen People's Hospital, Linfen, 041000, China
| | - Mengli Xie
- Department of Anesthesiology, Xi 'an Honghui Hospital, Xian, 710000, China
| | - Yuzhang Liang
- School of Physics, Dalian University of Technology, Dalian, 116024, China
| | - Jing Li
- Department of Endocrine, Central Hospital of China Railway 12th Bureau Group, 182 Yingze Road, Taiyuan, 030001, Shanxi, China
| | - Lin-Zhong Zhang
- Department of Anesthesiology, Second Hospital of Shanxi Medical University, Taiyuan, 030000, China; College of Anesthesiology, Shanxi Medical University, Taiyuan, 030000, China
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Al Yacoub ON, Tarantini S, Zhang Y, Csiszar A, Standifer KM. The Nociceptin/Orphanin FQ peptide receptor antagonist, SB-612111, improves cerebral blood flow in a rat model of traumatic brain injury. Front Pharmacol 2023; 14:1272969. [PMID: 37920208 PMCID: PMC10618424 DOI: 10.3389/fphar.2023.1272969] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/05/2023] [Indexed: 11/04/2023] Open
Abstract
Traumatic brain injury (TBI) affects more than 2.5 million people in the U.S. each year and is the leading cause of death and disability in children and adults ages 1 to 44. Approximately 90% of TBI cases are classified as mild but may still lead to acute detrimental effects such as impaired cerebral blood flow (CBF) that result in prolonged impacts on brain function and quality of life in up to 15% of patients. We previously reported that nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor antagonism reversed mild blast TBI-induced vestibulomotor deficits and prevented hypoxia. To explore mechanisms by which the NOP receptor-N/OFQ pathway modulates hypoxia and other TBI sequelae, the ability of the NOP antagonist, SB-612111 (SB), to reverse TBI-induced CBF and associated injury marker changes were tested in this study. Male Wistar rats randomly received sham craniotomy or craniotomy + TBI via controlled cortical impact. Injury severity was assessed after 1 h (modified neurological severity score (mNSS). Changes in CBF were assessed 2 h post-injury above the exposed cortex using laser speckle contrast imaging in response to the direct application of increasing concentrations of vehicle or SB (1, 10, and 100 µM) to the brain surface. TBI increased mNSS scores compared to baseline and confirmed mild TBI (mTBI) severity. CBF was significantly impaired on the ipsilateral side of the brain following mTBI, compared to contralateral side and to sham rats. SB dose-dependently improved CBF on the ipsilateral side after mTBI compared to SB effects on the respective ipsilateral side of sham rats but had no effect on contralateral CBF or in uninjured rats. N/OFQ levels increased in the cerebral spinal fluid (CSF) following mTBI, which correlated with the percent decrease in ipsilateral CBF. TBI also activated ERK and cofilin within 3 h post-TBI; ERK activation correlated with increased CSF N/OFQ. In conclusion, this study reveals a significant contribution of the N/OFQ-NOP receptor system to TBI-induced dysregulation of cerebral vasculature and suggests that the NOP receptor should be considered as a potential therapeutic target for TBI.
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Affiliation(s)
- Omar N. Al Yacoub
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Stefano Tarantini
- Department of Neurosurgery, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Stephenson Cancer Center, Oklahoma City, OK, United States
| | - Yong Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Anna Csiszar
- Department of Neurosurgery, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Kelly M. Standifer
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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Li H, Hu B, Zhang HP, Boyle CA, Lei S. Roles of K + and cation channels in ORL-1 receptor-mediated depression of neuronal excitability and epileptic activities in the medial entorhinal cortex. Neuropharmacology 2019; 151:144-158. [PMID: 30998945 PMCID: PMC6500758 DOI: 10.1016/j.neuropharm.2019.04.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/24/2019] [Accepted: 04/13/2019] [Indexed: 02/05/2023]
Abstract
Nociceptin (NOP) is an endogenous opioid-like peptide that selectively activates the opioid receptor-like (ORL-1) receptors. The entorhinal cortex (EC) is closely related to temporal lobe epilepsy and expresses high densities of ORL-1 receptors. However, the functions of NOP in the EC, especially in modulating the epileptiform activity in the EC, have not been determined. We demonstrated that activation of ORL-1 receptors remarkably inhibited the epileptiform activity in entorhinal slices induced by application of picrotoxin or by deprivation of extracellular Mg2+. NOP-mediated depression of epileptiform activity was independent of synaptic transmission in the EC, but mediated by inhibition of neuronal excitability in the EC. NOP hyperpolarized entorhinal neurons via activation of K+ channels and inhibition of cation channels. Whereas application of Ba2+ at 300 μM which is effective for the inward rectifier K+ (Kir) channels slightly inhibited NOP-induced hyperpolarization, the current-voltage (I-V) curve of the net currents induced by NOP was linear without showing inward rectification. However, a role of NOP-induced inhibition of cation channels was revealed after inhibition of Kir channels by Ba2+. Furthermore, NOP-mediated augmentation of membrane currents was differently affected by application of the blockers selective for distinct subfamilies of Kir channels. Whereas SCH23390 or ML133 blocked NOP-induced augmentation of membrane currents at negative potentials, application of tertiapin-Q exerted no actions on NOP-induced alteration of membrane currents. Our results demonstrated a novel cellular and molecular mechanism whereby activation of ORL-1 receptors depresses epilepsy.
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Affiliation(s)
- Huiming Li
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA
| | - Binqi Hu
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA
| | - Hao-Peng Zhang
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA
| | - Cody A Boyle
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA
| | - Saobo Lei
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA.
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Toll L, Bruchas MR, Calo' G, Cox BM, Zaveri NT. Nociceptin/Orphanin FQ Receptor Structure, Signaling, Ligands, Functions, and Interactions with Opioid Systems. Pharmacol Rev 2016; 68:419-57. [PMID: 26956246 PMCID: PMC4813427 DOI: 10.1124/pr.114.009209] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The NOP receptor (nociceptin/orphanin FQ opioid peptide receptor) is the most recently discovered member of the opioid receptor family and, together with its endogenous ligand, N/OFQ, make up the fourth members of the opioid receptor and opioid peptide family. Because of its more recent discovery, an understanding of the cellular and behavioral actions induced by NOP receptor activation are less well developed than for the other members of the opioid receptor family. All of these factors are important because NOP receptor activation has a clear modulatory role on mu opioid receptor-mediated actions and thereby affects opioid analgesia, tolerance development, and reward. In addition to opioid modulatory actions, NOP receptor activation has important effects on motor function and other physiologic processes. This review discusses how NOP pharmacology intersects, contrasts, and interacts with the mu opioid receptor in terms of tertiary structure and mechanism of receptor activation; location of receptors in the central nervous system; mechanisms of desensitization and downregulation; cellular actions; intracellular signal transduction pathways; and behavioral actions with respect to analgesia, tolerance, dependence, and reward. This is followed by a discussion of the agonists and antagonists that have most contributed to our current knowledge. Because NOP receptors are highly expressed in brain and spinal cord and NOP receptor activation sometimes synergizes with mu receptor-mediated actions and sometimes opposes them, an understanding of NOP receptor pharmacology in the context of these interactions with the opioid receptors will be crucial to the development of novel therapeutics that engage the NOP receptor.
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Affiliation(s)
- Lawrence Toll
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (L.T.); Departments of Anesthesiology, and Neuroscience, Washington University School of Medicine, St. Louis, Missouri (M.R.B.); Section of Pharmacology, Department of Medical Science, and National Institute of Neurosciences, University of Ferrara, Ferrara, Italy (G.C.); Professor of Pharmacology & Neuroscience, Uniformed Services University, Bethesda, Maryland (B.M.C.); and Astraea Therapeutics, LLC, Mountain View, California (N.T.Z.)
| | - Michael R Bruchas
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (L.T.); Departments of Anesthesiology, and Neuroscience, Washington University School of Medicine, St. Louis, Missouri (M.R.B.); Section of Pharmacology, Department of Medical Science, and National Institute of Neurosciences, University of Ferrara, Ferrara, Italy (G.C.); Professor of Pharmacology & Neuroscience, Uniformed Services University, Bethesda, Maryland (B.M.C.); and Astraea Therapeutics, LLC, Mountain View, California (N.T.Z.)
| | - Girolamo Calo'
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (L.T.); Departments of Anesthesiology, and Neuroscience, Washington University School of Medicine, St. Louis, Missouri (M.R.B.); Section of Pharmacology, Department of Medical Science, and National Institute of Neurosciences, University of Ferrara, Ferrara, Italy (G.C.); Professor of Pharmacology & Neuroscience, Uniformed Services University, Bethesda, Maryland (B.M.C.); and Astraea Therapeutics, LLC, Mountain View, California (N.T.Z.)
| | - Brian M Cox
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (L.T.); Departments of Anesthesiology, and Neuroscience, Washington University School of Medicine, St. Louis, Missouri (M.R.B.); Section of Pharmacology, Department of Medical Science, and National Institute of Neurosciences, University of Ferrara, Ferrara, Italy (G.C.); Professor of Pharmacology & Neuroscience, Uniformed Services University, Bethesda, Maryland (B.M.C.); and Astraea Therapeutics, LLC, Mountain View, California (N.T.Z.)
| | - Nurulain T Zaveri
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (L.T.); Departments of Anesthesiology, and Neuroscience, Washington University School of Medicine, St. Louis, Missouri (M.R.B.); Section of Pharmacology, Department of Medical Science, and National Institute of Neurosciences, University of Ferrara, Ferrara, Italy (G.C.); Professor of Pharmacology & Neuroscience, Uniformed Services University, Bethesda, Maryland (B.M.C.); and Astraea Therapeutics, LLC, Mountain View, California (N.T.Z.)
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Guerrini R, Marzola E, Trapella C, Pela' M, Molinari S, Cerlesi MC, Malfacini D, Rizzi A, Salvadori S, Calo' G. A novel and facile synthesis of tetra branched derivatives of nociceptin/orphanin FQ. Bioorg Med Chem 2014; 22:3703-12. [PMID: 24878361 DOI: 10.1016/j.bmc.2014.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/29/2014] [Accepted: 05/05/2014] [Indexed: 01/08/2023]
Abstract
Branched peptides have been found to be useful in several research fields however their synthesis and purification is complicated. Here we present a novel and facile synthesis of tetra branched derivatives of nociceptin/orphanin FQ (N/OFQ). Three N/OFQ tetra branched derivatives were prepared using novel cores (PWT1, PWT2 and PWT3) containing a maleimido moiety. [Cys(18)]N/OFQ-NH2 was linked to the cores via thiol-Michael reaction characterized by high yield and purity of the desired final product. In the electrically stimulated mouse vas deferens PWT-N/OFQ derivatives mimicked the inhibitory action of the natural sequence showing similar maximal effects and 3 fold higher potencies. The NOP selective antagonist SB-612111 antagonized the effects of N/OFQ and PWT derivatives with similar pKB values (8.02-8.48). In vivo after supraspinal administration PWT2-N/OFQ stimulated food intake in mice mimicking the action of N/OFQ. Compared to the natural peptide PWT2-N/OFQ was 40 fold more potent and elicited larger effects. These findings suggest that the PWT chemical strategy can be successfully applied to biologically active peptides to generate, with unprecedented high purity and yield, tetra branched derivatives displaying an in vitro pharmacological profile similar to that of the natural sequence associated, in vivo, to increased potency and effectiveness.
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Affiliation(s)
- Remo Guerrini
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121 Ferrara, Italy; Laboratorio per le tecnologie delle terapie avanzate (LTTA), University of Ferrara, 44121 Ferrara, Italy.
| | - Erika Marzola
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121 Ferrara, Italy; Laboratorio per le tecnologie delle terapie avanzate (LTTA), University of Ferrara, 44121 Ferrara, Italy
| | - Claudio Trapella
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121 Ferrara, Italy
| | - Michela Pela'
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121 Ferrara, Italy
| | - Stefano Molinari
- Department of Medical Science, Section of Pharmacology and National Institute of Neuroscience, University of Ferrara, 44121 Ferrara, Italy
| | - Maria Camilla Cerlesi
- Department of Medical Science, Section of Pharmacology and National Institute of Neuroscience, University of Ferrara, 44121 Ferrara, Italy
| | - Davide Malfacini
- Department of Medical Science, Section of Pharmacology and National Institute of Neuroscience, University of Ferrara, 44121 Ferrara, Italy
| | - Anna Rizzi
- Department of Medical Science, Section of Pharmacology and National Institute of Neuroscience, University of Ferrara, 44121 Ferrara, Italy
| | - Severo Salvadori
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121 Ferrara, Italy; Laboratorio per le tecnologie delle terapie avanzate (LTTA), University of Ferrara, 44121 Ferrara, Italy
| | - Girolamo Calo'
- Department of Medical Science, Section of Pharmacology and National Institute of Neuroscience, University of Ferrara, 44121 Ferrara, Italy
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Abstract
This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Liao YY, Lee CWS, Ho IK, Chiou LC. Quantitative study of [Tyr10]nociceptin/orphanin FQ (1-11) at NOP receptors in rat periaqueductal gray and expressed NOP receptors in HEK293 cells. Life Sci 2012; 90:306-12. [PMID: 22213115 DOI: 10.1016/j.lfs.2011.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 11/18/2011] [Accepted: 12/05/2011] [Indexed: 11/25/2022]
Abstract
AIM The nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor was reported to be functionally heterogeneous. We investigated if [Tyr(10)]N/OFQ(1-11), a peptide ligand reported to selectively bind to the high affinity site of (125)I-[Tyr(14)]N/OFQ in rodent brains, can be a tool for revealing the NOP receptor heterogeneity. We have previously founded an NOP receptor subset insensitive to Ro 64-6198 and (+)-5a Compound, two non-peptide NOP agonists, in rat ventrolateral periaqueductal gray (vlPAG) neurons. Here, we examined if [Tyr(10)]N/OFQ(1-11) differentiated (+)-5a Compound-sensitive and -insensitive vlPAG neurons. Certain mu-opioid (MOP) receptor ligands highly competing with [Tyr(10)]N/OFQ(1-11) in binding studies also showed high affinity at expressed heteromeric NOP-MOP receptors. We also examined if [Tyr(10)]N/OFQ(1-11) distinguished heteromeric NOP-MOP receptors from homomeric NOP receptors. MAIN METHODS The NOP receptor activity was evaluated by G-protein coupled inwardly rectifying potassium (GIRK) currents in rat vlPAG slices, and by inhibition of cAMP accumulation in HEK293 cells expressing NOP receptors or co-expressing NOP and MOP receptors. KEY FINDINGS In vlPAG neurons, [Tyr(10)]N/OFQ(1-11), like N/OFQ, induced GIRK currents through NOP receptors. It was less potent (EC(50): 8.98μM) but equi-efficacious as N/OFQ. [Tyr(10)]N/OFQ(1-11) displayed different pharmacological profiles as (+)-5a Compound, and was effective in both (+)-5a Compound-sensitive and -insensitive neurons. In NOP-expressing HEK293 cells and NOP- and MOP-co-expressing cells, [Tyr(10)]N/OFQ(1-11) displayed similar concentration-response curves in decreasing cAMP accumulation. SIGNIFICANCE [Tyr(10)]N/OFQ(1-11) is an NOP full agonist and less potent than N/OFQ. However, it can neither reveal the functional heterogeneity of NOP receptors in vlPAG neurons nor differentiate heteromeric NOP-MOP and homomeric NOP receptors.
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Affiliation(s)
- Yan-Yu Liao
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1 Jen-Ai Road, Taipei, Taiwan
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Kimura Y, Fujita M, Hong J, Lohith TG, Gladding RL, Zoghbi SS, Tauscher JA, Goebl N, Rash KS, Chen Z, Pedregal C, Barth VN, Pike VW, Innis RB. Brain and whole-body imaging in rhesus monkeys of 11C-NOP-1A, a promising PET radioligand for nociceptin/orphanin FQ peptide receptors. J Nucl Med 2011; 52:1638-45. [PMID: 21880575 PMCID: PMC3216483 DOI: 10.2967/jnumed.111.091181] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Our laboratory developed (S)-3-(2'-fluoro-6',7'-dihydrospiro[piperidine-4,4'-thieno[3,2-c]pyran]-1-yl)-2-(2-fluorobenzyl)-N-methylpropanamide ((11)C-NOP-1A), a new radioligand for the nociceptin/orphanin FQ peptide (NOP) receptor, with high affinity (K(i), 0.15 nM) and appropriate lipophilicity (measured logD, 3.4) for PET brain imaging. Here, we assessed the utility of (11)C-NOP-1A for quantifying NOP receptors in the monkey brain and estimated the radiation safety profile of this radioligand based on its biodistribution in monkeys. METHODS Baseline and blocking PET scans were acquired from head to thigh for 3 rhesus monkeys for approximately 120 min after (11)C-NOP-1A injection. These 6 PET scans were used to quantify NOP receptors in the brain and to estimate radiation exposure to organs of the body. In the blocked scans, a selective nonradioactive NOP receptor antagonist (SB-612111; 1 mg/kg intravenously) was administered before (11)C-NOP-1A. In all scans, arterial blood was sampled to measure the parent radioligand (11)C-NOP-1A. Distribution volume (V(T); a measure of receptor density) was calculated with a compartment model using brain and arterial plasma data. Radiation-absorbed doses were calculated using the MIRD Committee scheme. RESULTS After (11)C-NOP-1A injection, peak uptake of radioactivity in the brain had a high concentration (∼5 standardized uptake value), occurred early (∼12 min), and thereafter washed out quickly. V(T) (mL · cm(-3)) was highest in the neocortex (∼20) and lowest in hypothalamus and cerebellum (∼13). SB-612111 blocked approximately 50%-70% of uptake and reduced V(T) in all brain regions to approximately 7 mL · cm(-3). Distribution was well identified within 60 min of injection and stable for the remaining 60 min, consistent with only parent radioligand and not radiometabolites entering the brain. Whole-body scans confirmed that the brain had specific (i.e., displaceable) binding but could not detect specific binding in peripheral organs. The effective dose for humans estimated from the baseline scans in monkeys was 5.0 μSv/MBq. CONCLUSION (11)C-NOP-1A is a useful radioligand for quantifying NOP receptors in the monkey brain, and its radiation dose is similar to that of other (11)C-labeled ligands for neuroreceptors. (11)C-NOP-1A appears to be a promising candidate for measuring NOP receptors in the human brain.
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Affiliation(s)
- Yasuyuki Kimura
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
- Department of Molecular Neuroimaging, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Masahiro Fujita
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Jinsoo Hong
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Talakad G. Lohith
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Robert L. Gladding
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Sami S. Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | | | | | | | | | | | | | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Robert B. Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
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