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Lagard C, Vodovar D, Chevillard L, Callebert J, Caillé F, Pottier G, Liang H, Risède P, Tournier N, Mégarbane B. Investigation of the Mechanisms of Tramadol-Induced Seizures in Overdose in the Rat. Pharmaceuticals (Basel) 2022; 15:ph15101254. [PMID: 36297366 PMCID: PMC9607071 DOI: 10.3390/ph15101254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/09/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022] Open
Abstract
Tramadol overdose is frequently associated with the onset of seizures, usually considered as serotonin syndrome manifestations. Recently, the serotoninergic mechanism of tramadol-attributed seizures has been questioned. This study’s aim was to identify the mechanisms involved in tramadol-induced seizures in overdose in rats. The investigations included (1) the effects of specific pretreatments on tramadol-induced seizure onset and brain monoamine concentrations, (2) the interaction between tramadol and γ-aminobutyric acid (GABA)A receptors in vivo in the brain using positron emission tomography (PET) imaging and 11C-flumazenil. Diazepam abolished tramadol-induced seizures, in contrast to naloxone, cyproheptadine and fexofenadine pretreatments. Despite seizure abolishment, diazepam significantly enhanced tramadol-induced increase in the brain serotonin (p < 0.01), histamine (p < 0.01), dopamine (p < 0.05) and norepinephrine (p < 0.05). No displacement of 11C-flumazenil brain kinetics was observed following tramadol administration in contrast to diazepam, suggesting that the observed interaction was not related to a competitive mechanism between tramadol and flumazenil at the benzodiazepine-binding site. Our findings do not support the involvement of serotoninergic, histaminergic, dopaminergic, norepinephrine or opioidergic pathways in tramadol-induced seizures in overdose, but they strongly suggest a tramadol-induced allosteric change of the benzodiazepine-binding site of GABAA receptors. Management of tramadol-poisoned patients should take into account that tramadol-induced seizures are mainly related to a GABAergic pathway.
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Affiliation(s)
- Camille Lagard
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
| | - Dominique Vodovar
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
- Department of Medical and Toxicological Critical Care, AP-HP, Lariboisière Hospital, 75010 Paris, France
- Imagerie Moléculaire In Vivo, IMIV, CEA, INSERM, CNRS, Universités Paris-Sud et Paris-Saclay, 91471 Orsay, France
| | - Lucie Chevillard
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
| | - Jacques Callebert
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
- Laboratory of Biochemistry and Molecular Biology, AP-HP, Lariboisière Hospital, 75010 Paris, France
| | - Fabien Caillé
- Imagerie Moléculaire In Vivo, IMIV, CEA, INSERM, CNRS, Universités Paris-Sud et Paris-Saclay, 91471 Orsay, France
| | - Géraldine Pottier
- Imagerie Moléculaire In Vivo, IMIV, CEA, INSERM, CNRS, Universités Paris-Sud et Paris-Saclay, 91471 Orsay, France
| | - Hao Liang
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
| | - Patricia Risède
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
| | - Nicolas Tournier
- Imagerie Moléculaire In Vivo, IMIV, CEA, INSERM, CNRS, Universités Paris-Sud et Paris-Saclay, 91471 Orsay, France
| | - Bruno Mégarbane
- Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, Université Paris Cité, F-75006 Paris, France
- Department of Medical and Toxicological Critical Care, AP-HP, Lariboisière Hospital, 75010 Paris, France
- Correspondence: ; Tel.: +33-149-958-961; Fax: +33-149-956-578
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Chen G, Zhang Z, Wang M, Geng Y, Jin B, Aung T. Update on the Neuroimaging and Electroencephalographic Biomarkers of Epileptogenesis: A Literature Review. Front Neurol 2021; 12:738658. [PMID: 34512540 PMCID: PMC8429485 DOI: 10.3389/fneur.2021.738658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/09/2021] [Indexed: 11/13/2022] Open
Abstract
Epilepsy is one of the most common debilitating neurological disorders that lead to severe socio-cognitive dysfunction. While there are currently more than 30 antiseizure medications available for the treatment and prevention of seizures, none address the prevention of epileptogenesis that leading to the development of epilepsy following a potential brain insult. Hence, there is a growing need for the identification of accurate biomarkers of epileptogenesis that enable the prediction of epilepsy following a known brain insult. Although recent studies using various neuroimages and electroencephalography have found promising biomarkers of epileptogenesis, their utility needs to be further validated in larger clinical trials. In this literature review, we searched the Medline, Pubmed, and Embase databases using the following search algorithm: "epileptogenesis" and "biomarker" and "EEG" or "electroencephalography" or "neuroimaging" limited to publications in English. We presented a comprehensive overview of recent innovations in the role of neuroimaging and EEG in identifying reliable biomarkers of epileptogenesis.
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Affiliation(s)
- Guihua Chen
- Department of Neurology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Zheyu Zhang
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Meiping Wang
- Department of Neurology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Yu Geng
- Department of Neurology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Bo Jin
- Department of Neurology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Thandar Aung
- Epilepsy Center, University of Pittsburgh, Pittsburgh, PA, United States
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Stefanits H, Milenkovic I, Mahr N, Pataraia E, Baumgartner C, Hainfellner JA, Kovacs GG, Kasprian G, Sieghart W, Yilmazer-Hanke D, Czech T. Alterations in GABAA Receptor Subunit Expression in the Amygdala and Entorhinal Cortex in Human Temporal Lobe Epilepsy. J Neuropathol Exp Neurol 2020; 78:1022-1048. [PMID: 31631219 DOI: 10.1093/jnen/nlz085] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 07/06/2019] [Indexed: 12/14/2022] Open
Abstract
The amygdala has long been implicated in the pathophysiology of human temporal lobe epilepsy (TLE). The different nuclei of this complex structure are interconnected and share reciprocal connections with the hippocampus and other brain structures, partly via the entorhinal cortex. Expression of GABAA receptor subunits α1, α2, α3, α5, β2, β2/3, and γ2 was evaluated by immunohistochemistry in amygdala specimens and the entorhinal cortex of 12 TLE patients and 12 autopsy controls. A substantial decrease in the expression of α1, α2, α3, and β2/3 subunits was found in TLE cases, accompanied by an increase of γ2 subunit expression in many nuclei. In the entorhinal cortex, the expression of all GABAA receptor subunits was decreased except for the α1 subunit, which was increased on cellular somata. The overall reduction in α subunit expression may lead to decreased sensitivity to GABA and its ligands and compromise phasic inhibition, whereas upregulation of the γ2 subunit might influence clustering and kinetics of receptors and impair tonic inhibition. The description of these alterations in the human amygdala is important for the understanding of network changes in TLE as well as the development of subunit-specific therapeutic agents for the treatment of this disease.
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Affiliation(s)
- Harald Stefanits
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Ivan Milenkovic
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Nina Mahr
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Ekaterina Pataraia
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Christoph Baumgartner
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Johannes A Hainfellner
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Gabor G Kovacs
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Gregor Kasprian
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Werner Sieghart
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Deniz Yilmazer-Hanke
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
| | - Thomas Czech
- Department of Neurosurgery, Institute of Neurology, Department of Neurology, Department of Biomedical Imaging and Image Guided Therapy, Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria; Second Neurological Department, General Hospital Hietzing, Vienna, Austria; and Clinical Neuroanatomy, Neurology Department, Medical Faculty, Ulm University, Ulm, Germany
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Increase in P-glycoprotein levels in the blood-brain barrier of partial portal vein ligation /chronic hyperammonemia rats is medicated by ammonia/reactive oxygen species/ERK1/2 activation: In vitro and in vivo studies. Eur J Pharmacol 2019; 846:119-127. [PMID: 30639310 DOI: 10.1016/j.ejphar.2019.01.005] [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: 08/29/2018] [Revised: 12/19/2018] [Accepted: 01/08/2019] [Indexed: 12/15/2022]
Abstract
Liver failure altered P-glycoprotein (P-gp) function and expression at blood-brain barrier (BBB), partly owing to hyperammonemia. We aimed to examine the effects of partial portal vein ligation (PVL) plus chronic hyperammonemia (CHA) on P-gp function and expression at rat BBB. Experimental rats included sham-operation (SH), PVL, CHA and PVL+CHA. The PVL+CHA rats were developed by ammonia-containing diet for 2 weeks after operation. The brain-to-plasma concentration ratios (Kp) and apparent unidirectional influx constants (Kin) of rhodamine123 and sodium fluorescein were measured to assess function of P-gp and BBB integrity, respectively. Human cerebral microvascular endothelial cells (HCMEC/D3) were used to assess effects of ammonia on P-gp expression and function. It was found that PVL+CHA significantly decreased Kp and Kin of rhodamine123 without affecting brain distribution of fluorescein. The P-gp expressions in membrane protein in cortex and hippocampus were significantly increased in CHA and PVL +CHA rats, especially in PVL + CHA rats, while remarkably increased phosphorylated ERK1/2 was only found in PVL +CHA rats. Expressions of tight junction proteins claudin-5 and occluding in rat brain remained unchanged. In vitro data showed that NH4Cl increased reactive oxygen species, membrane expression and function of P-gp as well as phosphorylated ERK1/2 levels in HCMEC/D3. The NH4Cl-induced alterations were reversed by reactive oxygen species scavenger N-acetylcysteine and ERK1/2 inhibitor U0126. In conclusion, PVL+CHA increased function and membrane translocation of P-gp at rat BBB partly via ammonia. Reactive oxygen species/ERK1/2 pathway activation may be one of the reasons that ammonia upregulated P-gp expression and function at BBB.
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Neuroimaging Biomarkers of Experimental Epileptogenesis and Refractory Epilepsy. Int J Mol Sci 2019; 20:ijms20010220. [PMID: 30626103 PMCID: PMC6337422 DOI: 10.3390/ijms20010220] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 12/31/2018] [Accepted: 01/03/2019] [Indexed: 11/17/2022] Open
Abstract
This article provides an overview of neuroimaging biomarkers in experimental epileptogenesis and refractory epilepsy. Neuroimaging represents a gold standard and clinically translatable technique to identify neuropathological changes in epileptogenesis and longitudinally monitor its progression after a precipitating injury. Neuroimaging studies, along with molecular studies from animal models, have greatly improved our understanding of the neuropathology of epilepsy, such as the hallmark hippocampus sclerosis. Animal models are effective for differentiating the different stages of epileptogenesis. Neuroimaging in experimental epilepsy provides unique information about anatomic, functional, and metabolic alterations linked to epileptogenesis. Recently, several in vivo biomarkers for epileptogenesis have been investigated for characterizing neuronal loss, inflammation, blood-brain barrier alterations, changes in neurotransmitter density, neurovascular coupling, cerebral blood flow and volume, network connectivity, and metabolic activity in the brain. Magnetic resonance imaging (MRI) is a sensitive method for detecting structural and functional changes in the brain, especially to identify region-specific neuronal damage patterns in epilepsy. Positron emission tomography (PET) and single-photon emission computerized tomography are helpful to elucidate key functional alterations, especially in areas of brain metabolism and molecular patterns, and can help monitor pathology of epileptic disorders. Multimodal procedures such as PET-MRI integrated systems are desired for refractory epilepsy. Validated biomarkers are warranted for early identification of people at risk for epilepsy and monitoring of the progression of medical interventions.
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De Lange E, vd Berg D, Bellanti F, Voskuyl R, Syvänen S. P-glycoprotein protein expression versus functionality at the blood-brain barrier using immunohistochemistry, microdialysis and mathematical modeling. Eur J Pharm Sci 2018; 124:61-70. [DOI: 10.1016/j.ejps.2018.08.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 08/14/2018] [Accepted: 08/15/2018] [Indexed: 10/28/2022]
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Neuroimaging in animal models of epilepsy. Neuroscience 2017; 358:277-299. [DOI: 10.1016/j.neuroscience.2017.06.062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 02/06/2023]
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Pitkänen A, Löscher W, Vezzani A, Becker AJ, Simonato M, Lukasiuk K, Gröhn O, Bankstahl JP, Friedman A, Aronica E, Gorter JA, Ravizza T, Sisodiya SM, Kokaia M, Beck H. Advances in the development of biomarkers for epilepsy. Lancet Neurol 2017; 15:843-856. [PMID: 27302363 DOI: 10.1016/s1474-4422(16)00112-5] [Citation(s) in RCA: 229] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 02/16/2016] [Accepted: 03/02/2016] [Indexed: 12/13/2022]
Abstract
Over 50 million people worldwide have epilepsy. In nearly 30% of these cases, epilepsy remains unsatisfactorily controlled despite the availability of over 20 antiepileptic drugs. Moreover, no treatments exist to prevent the development of epilepsy in those at risk, despite an increasing understanding of the underlying molecular and cellular pathways. One of the major factors that have impeded rapid progress in these areas is the complex and multifactorial nature of epilepsy, and its heterogeneity. Therefore, the vision of developing targeted treatments for epilepsy relies upon the development of biomarkers that allow individually tailored treatment. Biomarkers for epilepsy typically fall into two broad categories: diagnostic biomarkers, which provide information on the clinical status of, and potentially the sensitivity to, specific treatments, and prognostic biomarkers, which allow prediction of future clinical features, such as the speed of progression, severity of epilepsy, development of comorbidities, or prediction of remission or cure. Prognostic biomarkers are of particular importance because they could be used to identify which patients will develop epilepsy and which might benefit from preventive treatments. Biomarker research faces several challenges; however, biomarkers could substantially improve the management of people with epilepsy and could lead to prevention in the right person at the right time, rather than just symptomatic treatment.
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Affiliation(s)
- Asla Pitkänen
- Department of Neurobiology, A I Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine, Hannover, Germany; Center for Systems Neuroscience, Hannover, Germany
| | - Annamaria Vezzani
- Department of Neuroscience, Experimental Neurology, IRCCS-Istituto di Recerche Farmacologiche "Mario Negri", Milan, Italy
| | - Albert J Becker
- Section for Translational Epilepsy Research, Department of Neuropathology, University of Bonn Medical Center, University of Bonn, Bonn, Germany
| | - Michele Simonato
- Department of Medical Sciences, Section of Pharmacology, University of Ferrara, Ferrara, Italy; Unit of Gene Therapy of Neurodegenerative Diseases, Division of Neuroscience, University Vita-Salute San Raffaele, Milan, Italy
| | - Katarzyna Lukasiuk
- The Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Olli Gröhn
- Department of Neurobiology, A I Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Jens P Bankstahl
- Preclinical Molecular Imaging, Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Alon Friedman
- Department of Brain and Cognitive Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Israel; Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Eleonora Aronica
- Department of Neuropathology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands; Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Jan A Gorter
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Teresa Ravizza
- Department of Neuroscience, Experimental Neurology, IRCCS-Istituto di Recerche Farmacologiche "Mario Negri", Milan, Italy
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK; Epilepsy Society, Chalfont St Peter, Buckinghamshire, UK
| | - Merab Kokaia
- Epilepsy Center, Experimental Epilepsy Group, Division of Neurology, Department of Clinical Sciences, Lund University Hospital, Lund, Sweden
| | - Heinz Beck
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn, Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
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Froklage FE, Postnov A, Yaqub MM, Bakker E, Boellaard R, Hendrikse NH, Comans EF, Schuit RC, Schober P, Velis DN, Zwemmer J, Heimans JJ, Lammertsma AA, Voskuyl RA, Reijneveld JC. Altered GABAA receptor density and unaltered blood-brain barrier [11C]flumazenil transport in drug-resistant epilepsy patients with mesial temporal sclerosis. J Cereb Blood Flow Metab 2017; 37:97-105. [PMID: 26661244 PMCID: PMC5167109 DOI: 10.1177/0271678x15618219] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 09/06/2015] [Accepted: 10/06/2015] [Indexed: 01/16/2023]
Abstract
Studies in rodents suggest that flumazenil is a P-glycoprotein substrate at the blood-brain barrier. This study aimed to assess whether [11C]flumazenil is a P-glycoprotein substrate in humans and to what extent increased P-glycoprotein function in epilepsy may confound interpretation of clinical [11C]flumazenil studies used to assess gamma-aminobutyric acid A receptors. Nine drug-resistant patients with epilepsy and mesial temporal sclerosis were scanned twice using [11C]flumazenil before and after partial P-glycoprotein blockade with tariquidar. Volume of distribution, nondisplaceable binding potential, and the ratio of rate constants of [11C]flumazenil transport across the blood-brain barrier (K1/k2) were derived for whole brain and several regions. All parameters were compared between pre- and post-tariquidar scans. Regional results were compared between mesial temporal sclerosis and contralateral sides. Tariquidar significantly increased global K1/k2 (+23%) and volume of distribution (+10%), but not nondisplaceable binding potential. At the mesial temporal sclerosis side volume of distribution and nondisplaceable binding potential were lower in hippocampus (both ∼-19%) and amygdala (both ∼-16%), but K1/k2 did not differ, suggesting that only regional gamma-aminobutyric acid A receptor density is altered in epilepsy. In conclusion, although [11C]flumazenil appears to be a (weak) P-glycoprotein substrate in humans, this does not seem to affect its role as a tracer for assessing gamma-aminobutyric acid A receptor density.
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Affiliation(s)
- Femke E Froklage
- Department of Neurology, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, the Netherlands .,Department of Neurology, VU University Medical Center, Amsterdam, the Netherlands
| | - Andrey Postnov
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Maqsood M Yaqub
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Esther Bakker
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Ronald Boellaard
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - N Harry Hendrikse
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands.,Department of Clinical Pharmacology & Pharmacy, VU University Medical Center, Amsterdam, the Netherlands
| | - Emile Fi Comans
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Robert C Schuit
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Patrick Schober
- Department of Anesthesiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Demetrios N Velis
- Department of Neurology, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, the Netherlands.,Department of Neurosurgery, VU University Medical Center, Amsterdam, the Netherlands
| | - Jack Zwemmer
- Department of Neurology, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, the Netherlands
| | - Jan J Heimans
- Department of Neurology, VU University Medical Center, Amsterdam, the Netherlands
| | - Adriaan A Lammertsma
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Rob A Voskuyl
- Department of Neurology, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, the Netherlands
| | - Jaap C Reijneveld
- Department of Neurology, VU University Medical Center, Amsterdam, the Netherlands
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Effects of common anesthetic agents on [ 18F]flumazenil binding to the GABA A receptor. EJNMMI Res 2016; 6:80. [PMID: 27826950 PMCID: PMC5101239 DOI: 10.1186/s13550-016-0235-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/29/2016] [Indexed: 12/25/2022] Open
Abstract
Background The availability of GABAA receptor binding sites in the brain can be assessed by positron emission tomography (PET) using the radioligand, [18F]flumazenil. However, the brain uptake and binding of this PET radioligand are influenced by anesthetic drugs, which are typically needed in preclinical imaging studies and clinical imaging studies involving patient populations that do not tolerate relatively longer scan times. The objective of this study was to examine the effects of anesthesia on the binding of [18F]flumazenil to GABAA receptors in mice. Methods Brain and whole blood radioactivity concentrations were measured ex vivo by scintillation counting or in vivo by PET in four groups of mice following administration of [18F]flumazenil: awake mice and mice anesthetized with isoflurane, dexmedetomidine, or ketamine/dexmedetomidine. Dynamic PET recordings were obtained for 60 min in mice anesthetized by either isoflurane or ketamine/dexmedetomidine. Static PET recordings were obtained at 25 or 55 min after [18F]flumazenil injection in awake or dexmedetomidine-treated mice acutely anesthetized with isoflurane. The apparent distribution volume (VT*) was calculated for the hippocampus and frontal cortex from either the full dynamic PET scans using an image-derived input function or from a series of ex vivo experiments using whole blood as the input function. Results PET images showed persistence of high [18F]flumazenil uptake (up to 20 % ID/g) in the brains of mice scanned under isoflurane or ketamine/dexmedetomidine anesthesia, whereas uptake was almost indiscernible in late samples or static scans from awake or dexmedetomidine-treated animals. The steady-state VT* was twofold higher in hippocampus of isoflurane-treated mice and dexmedetomidine-treated mice than in awake mice. Conclusions Anesthesia has pronounced effects on the binding and blood-brain distribution of [18F]flumazenil. Consequently, considerable caution must be exercised in the interpretation of preclinical and clinical PET studies of GABAA receptors involving the use of anesthesia.
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A microPET comparison of the effects of etifoxine and diazepam on [ 11 C]flumazenil uptake in rat brains. Neurosci Lett 2016; 612:74-79. [DOI: 10.1016/j.neulet.2015.11.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 11/03/2015] [Accepted: 11/24/2015] [Indexed: 11/19/2022]
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Pike VW. Considerations in the Development of Reversibly Binding PET Radioligands for Brain Imaging. Curr Med Chem 2016; 23:1818-69. [PMID: 27087244 PMCID: PMC5579844 DOI: 10.2174/0929867323666160418114826] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/04/2016] [Accepted: 04/15/2016] [Indexed: 12/17/2022]
Abstract
The development of reversibly binding radioligands for imaging brain proteins in vivo, such as enzymes, neurotransmitter transporters, receptors and ion channels, with positron emission tomography (PET) is keenly sought for biomedical studies of neuropsychiatric disorders and for drug discovery and development, but is recognized as being highly challenging at the medicinal chemistry level. This article aims to compile and discuss the main considerations to be taken into account by chemists embarking on programs of radioligand development for PET imaging of brain protein targets.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Rm. B3C346A, 10 Center Drive, Bethesda, MD 20892, USA.
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Efectos de los inductores antiepilépticos en la neuropsicofarmacología: una cuestión ignorada. Parte II: cuestiones farmacológicas y comprensión adicional. REVISTA DE PSIQUIATRIA Y SALUD MENTAL 2015; 8:167-88. [DOI: 10.1016/j.rpsm.2014.10.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/23/2014] [Indexed: 12/19/2022]
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Abstract
PURPOSE OF REVIEW Drug resistance is an important clinical problem: it is associated with higher rates of somatic and psychiatric comorbidities and cognitive/memory decline, with seizures being just the 'tip of the iceberg'. This review summarizes recent developments in imaging research, focusing specifically on the functional consequence of chronic epilepsies and mechanisms of drug resistance, restricted to work published in 2013. RECENT FINDINGS Functional imaging approaches reliably identify underlying specific networks in patients with different epileptic syndromes, show specific responses to certain antiepileptic drugs and differentiate between responder and nonresponder. Functional MRI (fMRI) and the intracarotid amobarbital test (IAT) are generally congruent, but fMRI may be more sensitive than IAT to right hemisphere language processing. In addition, memory fMRI supports the functional adequacy of ipsilateral structures rather than functional reserve of the contralateral hemisphere. There is further evidence from group analysis of fMRI data for a node within the ipsilateral piriform cortex to be important for seizure modulation in focal refractory epilepsies of different cortical origin. Molecular imaging with verapamil-PET identifies P-glycprotein overexpression as a mechanism contributing to drug resistance in individual patients. SUMMARY Neuroimaging in epilepsy has progressed from correlations with demographic, semiologic, neuropsychological and other observational data primarily in patients undergoing presurgical investigations to imaging network connectivity changes in epilepsy syndromes, and testing specific mechanisms underlying drug-resistant epilepsy.
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Development of (18)F-labeled radiotracers for neuroreceptor imaging with positron emission tomography. Neurosci Bull 2014; 30:777-811. [PMID: 25172118 DOI: 10.1007/s12264-014-1460-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/02/2014] [Indexed: 12/14/2022] Open
Abstract
Positron emission tomography (PET) is an in vivo molecular imaging tool which is widely used in nuclear medicine for early diagnosis and treatment follow-up of many brain diseases. PET uses biomolecules as probes which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiotracers. Fluorine-18 is a radionuclide routinely used in the radiolabeling of neuroreceptor ligands for PET because of its favorable half-life of 109.8 min. The delivery of such radiotracers into the brain provides images of transport, metabolic, and neurotransmission processes on the molecular level. After a short introduction into the principles of PET, this review mainly focuses on the strategy of radiotracer development bridging from basic science to biomedical application. Successful radiotracer design as described here provides molecular probes which not only are useful for imaging of human brain diseases, but also allow molecular neuroreceptor imaging studies in various small-animal models of disease, including genetically-engineered animals. Furthermore, they provide a powerful tool for in vivo pharmacology during the process of pre-clinical drug development to identify new drug targets, to investigate pathophysiology, to discover potential drug candidates, and to evaluate the pharmacokinetics and pharmacodynamics of drugs in vivo.
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Bankstahl JP. What does a picture tell? In vivo imaging of ABC transporter function. DRUG DISCOVERY TODAY. TECHNOLOGIES 2014; 12:e113-9. [PMID: 25027369 DOI: 10.1016/j.ddtec.2014.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Activity of ABC transporters in tumor tissue or at the blood–brain barrier is believed to be responsible for treatment failure of substrate drugs. As this mechanism will not be present in every single patient, diagnostic tools to study transporter function are urgently needed. Many efforts were made over the past years to improve in vivo quantification of ABC transporter function by molecular imaging techniques. This includes development of new positron emitting tracers, but also the evaluation of modified experimental protocols using already existing tracers. In addition to imaging of transporter function in healthy animals or volunteers, results from disease models or human patients are covered in this review.
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Dedeurwaerdere S, Shultz SR, Federico P, Engel J. Workshop on Neurobiology of Epilepsy appraisal: new systemic imaging technologies to study the brain in experimental models of epilepsy. Epilepsia 2014; 55:819-28. [PMID: 24836499 DOI: 10.1111/epi.12642] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2014] [Indexed: 12/14/2022]
Abstract
Modern functional neuroimaging provides opportunities to visualize activity of the entire brain, making it an indispensable diagnostic tool for epilepsy. Various forms of noninvasive functional neuroimaging are now also being performed as research tools in animal models of epilepsy and provide opportunities for parallel animal/human investigations into fundamental mechanisms of epilepsy and identification of epilepsy biomarkers. Recent animal studies of epilepsy using positron emission tomography, tractography, and functional magnetic resonance imaging were reviewed. Epilepsy is an abnormal emergent property of disturbances in neuronal networks which, even for epilepsies characterized by focal seizures, involve widely distributed systems, often in both hemispheres. Functional neuroimaging in animal models now provides opportunities to examine neuronal disturbances in the whole brain that underlie generalized and focal seizure generation as well as various types of epileptogenesis. Tremendous advances in understanding the contribution of specific properties of widely distributed neuronal networks to both normal and abnormal human behavior have been provided by current functional neuroimaging methodologies. Successful application of functional neuroimaging of the whole brain in the animal laboratory now permits investigations during epileptogenesis and correlation with deep brain electroencephalography (EEG) activity. With the continuing development of these techniques and analytical methods, the potential for future translational research on epilepsy is enormous. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.
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Idazoxan reduces blood-brain barrier damage during experimental autoimmune encephalomyelitis in mouse. Eur J Pharmacol 2014; 736:70-6. [PMID: 24797785 DOI: 10.1016/j.ejphar.2014.04.034] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 11/21/2022]
Abstract
We have previously shown that Idazoxan (IDA), an imidazoline 2 receptor ligand, is neuroprotective against spinal cord injury caused by experimental autoimmune encephalomyelitis (EAE) in mouse, an animal modal of multiple sclerosis (MS). However, the protective mechanism remains unclear. Here, we provided evidence to show that IDA confers neuroprotection through reduction in blood-brain barrier (BBB) damage. EAE was induced by immunizing C57 BL/6 mice with myelin oligodendrocyte glycoprotein35-55 amino acid peptide (MOG35-55). IDA was administrated for 14 days after MOG immunization at 2 mg/kg (i.p., bid). Significant reduction in BBB damage occurred in the IDA-treated group of mice compared with the saline-treated group, as evidenced by the reduction in Evan׳s blue content in the brain tissue and the reduced BBB tight junction damage viewed under a transmission electron microscope. Moreover, EAE-induced reductions in tight junction proteins (JAM-1, Occludin, Claudin-5 and ZO-1) were also significantly ameliorated in IDA-treated mice, all of which supported the notion that IDA reduced BBB damage. Interestingly, the expression levels of extracellular matrix metalloproteinase-9 (MMP-9) and the ratio of MMP-9 against tissue inhibitor of metalloproteinase-1 (TIMP-1), which is known to be associated with MS-induced BBB damage, were significantly reduced in IDA-treated group, lending further support to the hypothesis that IDA confers brain protection through reducing BBB damage. This study raised a possibility that IDA is a promising pro-drug for development against MS.
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Vivash L, Gregoire MC, Bouilleret V, Berard A, Wimberley C, Binns D, Roselt P, Katsifis A, Myers DE, Hicks RJ, O'Brien TJ, Dedeurwaerdere S. In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy. PLoS One 2014; 9:e86722. [PMID: 24466212 PMCID: PMC3897736 DOI: 10.1371/journal.pone.0086722] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Purpose Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. Methods Dynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data. Key Findings The PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding. Significance Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.
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Affiliation(s)
- Lucy Vivash
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Marie-Claude Gregoire
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Viviane Bouilleret
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Alexis Berard
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Catriona Wimberley
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - David Binns
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Peter Roselt
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew Katsifis
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Damian E. Myers
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Rodney J. Hicks
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Stefanie Dedeurwaerdere
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Translational Neurosciences, University of Antwerp, Wilrijk, Belgium
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Syvänen S, Eriksson J. Advances in PET imaging of P-glycoprotein function at the blood-brain barrier. ACS Chem Neurosci 2013; 4:225-37. [PMID: 23421673 DOI: 10.1021/cn3001729] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Efflux transporter P-glycoprotein (P-gp) at the blood-brain barrier (BBB) restricts substrate compounds from entering the brain and may thus contribute to pharmacoresistance observed in patient groups with refractory epilepsy and HIV. Altered P-gp function has also been implicated in neurodegenerative diseases such as Alzheimer's and Parkinson's disease. Positron emission tomography (PET), a molecular imaging modality, has become a promising method to study the role of P-gp at the BBB. The first PET study of P-gp function was conducted in 1998, and during the past 15 years two main categories of P-gp PET tracers have been investigated: tracers that are substrates of P-gp efflux and tracers that are inhibitors of P-gp function. PET, as a noninvasive imaging technique, allows translational research. Examples of this are preclinical investigations of P-gp function before and after administering P-gp modulating drugs, investigations in various animal and disease models, and clinical investigations regarding disease and aging. The objective of the present review is to give an overview of available PET radiotracers for studies of P-gp and to discuss how such studies can be designed. Further, the review summarizes results from PET studies of P-gp function in different central nervous system disorders.
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Affiliation(s)
- Stina Syvänen
- Department of Public Health and Caring Sciences, Uppsala University, Rudbecklaboratoriet, 751 85 Uppsala, Sweden
| | - Jonas Eriksson
- PET Centre, Uppsala University Hospital, 751 85 Uppsala, Sweden
- Preclinical PET Platform, Department
of Medicinal Chemistry, Uppsala University, Dag Hammarskjöldsv 14C, 751 83 Uppsala, Sweden
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