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Soufsaf S, Robaey P, Nekka F. An exploratory analysis of the performance of methylphenidate regimens based on a PKPD model of dopamine and norepinephrine transporter occupancy. J Pharmacokinet Pharmacodyn 2023:10.1007/s10928-023-09854-y. [PMID: 36930337 DOI: 10.1007/s10928-023-09854-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/23/2023] [Indexed: 03/18/2023]
Abstract
Methylphenidate (MPH) is a psychostimulant which inhibits the uptake of dopamine and norepinephrine transporters, DAT and NET, and is mostly used to treat Attention Deficit/Hyperactivity Disorder. The current dose optimization is done through titration, a cumbersome approach for patients. To assess the therapeutic performance of MPH regimens, we introduce an in silico framework composed of (i) a population pharmacokinetic model of MPH, (ii) a pharmacodynamic (PD) model of DAT and NET occupancy, (iii) a therapeutic box delimited by time and DAT occupancy, and (iv) a performance score computation. DAT occupancy data was digitized (n = 152) and described with Emax models. NET occupancy was described with a KPD model. We used this integrative framework to simulate the performance of extended-release (18-99 mg) and tid MPH regimens (25-40 mg). Early blood samples of MPH seem to lead to higher DAT occupancy, consistent with an acute tolerance observed in clinical rating scales. An Emax model with a time-dependent tolerance was fitted to available data to assess the observed clockwise hysteresis. Peak performance is observed at 63 mg. While our analysis does not deny the existence of an acute tolerance, data precision in terms of formulation and sampling times does not allow a definite confirmation of this phenomenon. This work justifies the need for a more systematic collection of DAT and NET occupancy data to further investigate the presence of acute tolerance and assess the impact of low MPH doses on its efficacy.
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D’Elia A, Schiavi S, Manduca A, Rava A, Buzzelli V, Ascone F, Orsini T, Putti S, Soluri A, Galli F, Soluri A, Mattei M, Cicconi R, Massari R, Trezza V. FMR1 deletion in rats induces hyperactivity with no changes in striatal dopamine transporter availability. Sci Rep 2022; 12:22535. [PMID: 36581671 PMCID: PMC9800572 DOI: 10.1038/s41598-022-26986-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 12/22/2022] [Indexed: 12/30/2022] Open
Abstract
Autism Spectrum Disorder (ASD) is a pervasive neurodevelopmental disorder emerging in early life characterized by impairments in social interaction, poor verbal and non-verbal communication, and repetitive patterns of behaviors. Among the best-known genetic risk factors for ASD, there are mutations causing the loss of the Fragile X Messenger Ribonucleoprotein 1 (FMRP) leading to Fragile X syndrome (FXS), a common form of inherited intellectual disability and the leading monogenic cause of ASD. Being a pivotal regulator of motor activity, motivation, attention, and reward processing, dopaminergic neurotransmission has a key role in several neuropsychiatric disorders, including ASD. Fmr1 Δexon 8 rats have been validated as a genetic model of ASD based on FMR1 deletion, and they are also a rat model of FXS. Here, we performed behavioral, biochemical and in vivo SPECT neuroimaging experiments to investigate whether Fmr1 Δexon 8 rats display ASD-like repetitive behaviors associated with changes in striatal dopamine transporter (DAT) availability assessed through in vivo SPECT neuroimaging. At the behavioral level, Fmr1 Δexon 8 rats displayed hyperactivity in the open field test in the absence of repetitive behaviors in the hole board test. However, these behavioral alterations were not associated with changes in striatal DAT availability as assessed by non-invasive in vivo SPECT and Western blot analyses.
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Affiliation(s)
- Annunziata D’Elia
- grid.5326.20000 0001 1940 4177Institute of Biochemistry and Cell Biology (IBBC), National Research Council of Italy (CNR), c/o International Campus “A. Buzzati-Traverso”, Via E. Ramarini, 32, 00015 Monterotondo Scalo (Rome), Italy ,grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Sara Schiavi
- grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Antonia Manduca
- grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy ,grid.417778.a0000 0001 0692 3437Neuroendocrinology, Metabolism and Neuropharmacology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Alessandro Rava
- grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Valeria Buzzelli
- grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Fabrizio Ascone
- grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Tiziana Orsini
- grid.5326.20000 0001 1940 4177Institute of Biochemistry and Cell Biology (IBBC), National Research Council of Italy (CNR), c/o International Campus “A. Buzzati-Traverso”, Via E. Ramarini, 32, 00015 Monterotondo Scalo (Rome), Italy
| | - Sabrina Putti
- grid.5326.20000 0001 1940 4177Institute of Biochemistry and Cell Biology (IBBC), National Research Council of Italy (CNR), c/o International Campus “A. Buzzati-Traverso”, Via E. Ramarini, 32, 00015 Monterotondo Scalo (Rome), Italy
| | - Andrea Soluri
- grid.5326.20000 0001 1940 4177Institute of Biochemistry and Cell Biology (IBBC), National Research Council of Italy (CNR), c/o International Campus “A. Buzzati-Traverso”, Via E. Ramarini, 32, 00015 Monterotondo Scalo (Rome), Italy ,grid.9657.d0000 0004 1757 5329Unit of Molecular Neurosciences, University Campus Bio-Medico, Rome, Rome, Italy
| | - Filippo Galli
- grid.7841.aNuclear Medicine Unit, Department of Medical-Surgical Sciences and of Translational Medicine, Faculty of Medicine and Psychology, “Sapienza” University of Rome, Rome, Italy
| | - Alessandro Soluri
- grid.5326.20000 0001 1940 4177Institute of Biochemistry and Cell Biology (IBBC), National Research Council of Italy (CNR), c/o International Campus “A. Buzzati-Traverso”, Via E. Ramarini, 32, 00015 Monterotondo Scalo (Rome), Italy
| | - Maurizio Mattei
- grid.6530.00000 0001 2300 0941Department of Biology and Centro di Servizi Interdipartimentale-Stazione per la Tecnologia Animale, “Tor Vergata” University, Rome, Italy
| | - Rosella Cicconi
- grid.6530.00000 0001 2300 0941Department of Biology and Centro di Servizi Interdipartimentale-Stazione per la Tecnologia Animale, “Tor Vergata” University, Rome, Italy
| | - Roberto Massari
- grid.5326.20000 0001 1940 4177Institute of Biochemistry and Cell Biology (IBBC), National Research Council of Italy (CNR), c/o International Campus “A. Buzzati-Traverso”, Via E. Ramarini, 32, 00015 Monterotondo Scalo (Rome), Italy
| | - Viviana Trezza
- grid.8509.40000000121622106Department of Science, Section of Biomedical Sciences and Technologies, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
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D'Elia A, Schiavi S, Soluri A, Massari R, Soluri A, Trezza V. Role of Nuclear Imaging to Understand the Neural Substrates of Brain Disorders in Laboratory Animals: Current Status and Future Prospects. Front Behav Neurosci 2020; 14:596509. [PMID: 33362486 PMCID: PMC7759612 DOI: 10.3389/fnbeh.2020.596509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
Molecular imaging, which allows the real-time visualization, characterization and measurement of biological processes, is becoming increasingly used in neuroscience research. Scintigraphy techniques such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) provide qualitative and quantitative measurement of brain activity in both physiological and pathological states. Laboratory animals, and rodents in particular, are essential in neuroscience research, providing plenty of models of brain disorders. The development of innovative high-resolution small animal imaging systems together with their radiotracers pave the way to the study of brain functioning and neurotransmitter release during behavioral tasks in rodents. The assessment of local changes in the release of neurotransmitters associated with the performance of a given behavioral task is a turning point for the development of new potential drugs for psychiatric and neurological disorders. This review addresses the role of SPECT and PET small animal imaging systems for a better understanding of brain functioning in health and disease states. Brain imaging in rodent models faces a series of challenges since it acts within the boundaries of current imaging in terms of sensitivity and spatial resolution. Several topics are discussed, including technical considerations regarding the strengths and weaknesses of both technologies. Moreover, the application of some of the radioligands developed for small animal nuclear imaging studies is discussed. Then, we examine the changes in metabolic and neurotransmitter activity in various brain areas during task-induced neural activation with special regard to the imaging of opioid, dopaminergic and cannabinoid receptors. Finally, we discuss the current status providing future perspectives on the most innovative imaging techniques in small laboratory animals. The challenges and solutions discussed here might be useful to better understand brain functioning allowing the translation of preclinical results into clinical applications.
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Affiliation(s)
- Annunziata D'Elia
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy.,Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Sara Schiavi
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Andrea Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Roberto Massari
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Alessandro Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Viviana Trezza
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
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Nikolaus S, Beu M, Wittsack HJ, Müller-Lutz A, Antke C, Hautzel H, Mori Y, Mamlins E, Antoch G, Müller HW. GABAergic and glutamatergic effects on nigrostriatal and mesolimbic dopamine release in the rat. Rev Neurosci 2020; 31:569-588. [PMID: 32619197 DOI: 10.1515/revneuro-2019-0112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 02/01/2020] [Indexed: 11/15/2022]
Abstract
In this review, a series of experiments is presented, in which γ-amino butyric acid (GABA)ergic and glutamatergic effects on dopamine function in the rat nigrostriatal and mesolimbic system was systematically assessed after pharmacological challenge with GABAA receptor (R) and and N-methyl d-aspartate (NMDA)R agonists and antagonists. In these studies, [123I]iodobenzamide binding to the D2/3R was mesured in nucleus accumbens (NAC), caudateputamen (CP), substantia nigra/ventral tegmental area (SN/VTA), frontal (FC), motor (MC) and parietal cortex (PC) as well as anterior (aHIPP) and posterior hippocampus (pHIPP) with small animal SPECT in baseline and after injection of either the GABAAR agonist muscimol (1 mg/kg), the GABAAR antagonist bicuculline (1 mg/kg), the NMDAR agonist d-cycloserine (20 mg/kg) or the NMDAR antagonist amantadine (40 mg/kg). Muscimol reduced D2/3R binding in NAC, CP, SN/VTA, THAL and pHIPP, while, after amantadine, decreases were confined to NAC, CP and THAL. In contrast, d-cycloserine elevated D2/3R binding in NAC, SN/VTA, THAL, frontal cortex, motor cortex, PC, aHIPP and pHIPP, while, after bicuculline, increases were confined to CP and THAL. Taken together, similar actions on regional dopamine levels were exterted by the GABAAR agonist and the NMDAR antagonist on the one side and by the GABAAR antagonist and the NMDAR agonist on the other, with agonistic action, however, affecting more brain regions. Thereby, network analysis suggests different roles of GABAARs and NMDARs in the mediation of nigrostriatal, nigrothalamocortical and mesolimbocortical dopamine function.
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Affiliation(s)
- Susanne Nikolaus
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Markus Beu
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Hans-Jörg Wittsack
- Department of Diagnostic and Interventional Radiology, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Anja Müller-Lutz
- Department of Diagnostic and Interventional Radiology, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Christina Antke
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Hubertus Hautzel
- Clinic for Nuclear Medicine, University Hospital Essen, Hufelandstraße 55, D-40225, Essen, Germany
| | - Yuriko Mori
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Eduards Mamlins
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Gerald Antoch
- Department of Diagnostic and Interventional Radiology, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
| | - Hans-Wilhelm Müller
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Moorenstr. 5, D-40225, Düsseldorf, Germany
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Nikolaus S, Wittsack HJ, Beu M, Antke C, De Souza Silva MA, Wickrath F, Müller-Lutz A, Huston JP, Antoch G, Müller HW, Hautzel H. GABAergic Control of Nigrostriatal and Mesolimbic Dopamine in the Rat Brain. Front Behav Neurosci 2018; 12:38. [PMID: 29593508 PMCID: PMC5862131 DOI: 10.3389/fnbeh.2018.00038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/20/2018] [Indexed: 12/21/2022] Open
Abstract
Purpose: The present study assessed the effects of the GABAA receptor (R) agonist muscimol (MUS), and the GABAAR antagonist bicuculline (BIC) on neocortical and subcortical radioligand binding to dopamine D2/3Rs in relation to motor and exploratory behaviors in the rat. Methods: D2/3R binding was measured with small animal SPECT in baseline and after challenge with either 1 mg/kg MUS or 1 mg/kg BIC, using [123I]IBZM as radioligand. Motor/exploratory behaviors were assessed for 30 min in an open field prior to radioligand administration. Anatomical information was gained with a dedicated small animal MRI tomograph. Based on the Paxinos rat brain atlas, regions of interest were defined on SPECT-MRI overlays. Estimations of the binding potentials in baseline and after challenges were obtained by computing ratios of the specifically bound compartments to the cerebellar reference region. Results: After MUS, D2/3R binding was significantly reduced in caudateputamen, nucleus accumbens, thalamus, substania nigra/ventral tegmental area, and posterior hippocampus relative to baseline (0.005 ≤ p ≤ 0.012). In all these areas, except for the thalamus, D2/3R binding was negatively correlated with grooming in the first half and positively correlated with various motor/exploratory behaviors in the second half of the testing session. After BIC, D2/3R binding was significantly elevated in caudateputamen (p = 0.022) and thalamus (p = 0.047) relative to baseline. D2/3R binding in caudateputamen and thalamus was correlated negatively with sitting duration and sitting frequency and positively with motor/exploratory behaviors in the first half of the testing time. Conclusions: Findings indicate direct GABAergic control over nigrostriatal and mesolimbic dopamine levels in relation to behavioral action. This may be of relevance for neuropsychiatric conditions such as anxiety disorder and schizophrenia, which are characterized by both dopaminergic and GABAergic dysfunction.
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Affiliation(s)
- Susanne Nikolaus
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Hans-Jörg Wittsack
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Düsseldorf, Düsseldorf, Germany
| | - Markus Beu
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Christina Antke
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Maria A De Souza Silva
- Center for Behavioural Neuroscience, Institute of Experimental Psychology, Heinrich-Heine University, Düsseldorf, Germany
| | - Frijthof Wickrath
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Düsseldorf, Düsseldorf, Germany
| | - Anja Müller-Lutz
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Düsseldorf, Düsseldorf, Germany
| | - Joseph P Huston
- Center for Behavioural Neuroscience, Institute of Experimental Psychology, Heinrich-Heine University, Düsseldorf, Germany
| | - Gerald Antoch
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Düsseldorf, Düsseldorf, Germany
| | - Hans-Wilhelm Müller
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Hubertus Hautzel
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Düsseldorf, Germany
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Claussen CM, Dafny N. Caudate neuronal recording in freely behaving animals following acute and chronic dose response methylphenidate exposure. Pharmacol Biochem Behav 2015; 136:21-30. [PMID: 26101057 PMCID: PMC4743873 DOI: 10.1016/j.pbb.2015.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 06/01/2015] [Accepted: 06/07/2015] [Indexed: 12/19/2022]
Abstract
The misuse and abuse of the psychostimulant, methylphenidate (MPD) the drug of choice in the treatment of attention deficit hyperactivity disorder (ADHD) has seen a sharp uprising in recent years among both youth and adults for its cognitive enhancing effects and for recreational purposes. This uprise in illicit use has lead to many questions concerning the long-term consequences of MPD exposure. The objective of this study was to record animal behavior concomitantly with the caudate nucleus (CN) neuronal activity following acute and repetitive (chronic) dose response exposure to methylphenidate (MPD). A saline control and three MPD dose (0.6, 2.5, and 10.0mg/kg) groups were used. Behaviorally, the same MPD dose in some animals following chronic MPD exposure elicited behavioral sensitization and other animals elicited behavioral tolerance. Based on this finding, the CN neuronal population recorded from animals expressing behavioral sensitization was also evaluated separately from CN neurons recorded from animals expressing behavioral tolerance to chronic MPD exposure, respectively. Significant differences in CN neuronal population responses between the behaviorally sensitized and the behaviorally tolerant animals were observed for the 2.5 and 10.0mg/kg MPD exposed groups. For 2.5mg/kg MPD, behaviorally sensitized animals responded by decreasing their firing rates while behaviorally tolerant animals showed mainly an increase in their firing rates. The CN neuronal responses recorded from the behaviorally sensitized animals following 10.0mg/kg MPD responded by increasing their firing rates whereas the CN neuronal recordings from the behaviorally tolerant animals showed that approximately half decreased their firing rates in response to 10.0mg/kg MPD exposure. The comparison of percentage change in neuronal firing rates showed that the behaviorally tolerant animals trended to exhibit increases in their neuronal firing rates at ED1 following initial MPD exposure and oppositely at ED10 MPD rechallenge. While the behaviorally sensitized animals in general increased in their percentage change of firing rats were observed following acute 10.0mg/kg MPD and the behaviorally sensitized 10.0mg/kg MPD animals and a robust increase in neuronal firing rates at ED1 and ED10 rechallenge. These results suggest the need to first individually analyze animal behavioral activity, and then to evaluate the neuronal responses to the drug based on the animals behavioral response to chronic MPD exposure.
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Affiliation(s)
- Catherine M Claussen
- University of Texas Health Science Center Medical School at Houston, 6431 Fannin St., MSB 7.208B, Houston, TX 77030, USA
| | - Nachum Dafny
- University of Texas Health Science Center Medical School at Houston, 6431 Fannin St., MSB 7.208B, Houston, TX 77030, USA.
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Bannon D, Landau AM, Doudet DJ. How Relevant Are Imaging Findings in Animal Models of Movement Disorders to Human Disease? Curr Neurol Neurosci Rep 2015; 15:53. [DOI: 10.1007/s11910-015-0571-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Nikolaus S, Beu M, De Souza Silva AM, Huston JP, Hautzel H, Chao OY, Antke C, Müller HW. Relationship between L-DOPA-induced reduction in motor and exploratory activity and degree of DAT binding in the rat. Front Behav Neurosci 2014; 8:431. [PMID: 25566000 PMCID: PMC4269131 DOI: 10.3389/fnbeh.2014.00431] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/26/2014] [Indexed: 11/15/2022] Open
Abstract
Purpose: The present study assessed the influence of L-DOPA administration on neostriatal dopamine (DA) transporter (DAT) binding in relation to motor and exploratory behaviors in the rat. Methods: Rats received injections of 5 mg/kg L-DOPA, 10 mg/kg L-DOPA or vehicle. Motor and exploratory behaviors were assessed for 30 min in an open field prior to administration of [123I]FP-CIT. Dopamine transporter binding was measured with small animal single-photon emission computed tomography (SPECT) 2 h after radioligand administration for 60 min. Results: Both L-DOPA doses significantly reduced DAT binding and led to significantly less head-shoulder motility and more sitting relative to vehicle. Moreover, 10 mg/kg L-DOPA induced less distance traveled and ambulation than 5 mg/kg L-DOPA. Analysis of time-behavior (t-b) curves showed that L-DOPA-treated animals relative to vehicle exhibited (1) a faster rate of increase in duration of sitting; (2) a slower rate of increase in duration of head-shoulder motility; and (3) a slower rate of decrease in frequency of head-shoulder motility. Conclusions: The reductions of striatal DAT binding after L-DOPA challenges reflected elevated concentrations of synaptic DA. L-DOPA-treated animals showed less head-shoulder motility and more sitting than vehicle-treated animals, indicating an association between less behavioral activity and increased availability of striatal DA. The faster increase of sitting duration to a higher final level and the slower increase of head-shoulder motility to a lower final level relative to controls may be interpreted in terms on behavioral habituation to a novel environment.
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Affiliation(s)
- Susanne Nikolaus
- Clinic of Nuclear Medicine, University Hospital Düsseldorf Düsseldorf, Germany
| | - Markus Beu
- Clinic of Nuclear Medicine, University Hospital Düsseldorf Düsseldorf, Germany
| | - Angelica Maria De Souza Silva
- Center for Behavioural Neuroscience, Institute of Experimental Psychology, Heinrich-Heine University Düsseldorf, Germany
| | - Joseph P Huston
- Center for Behavioural Neuroscience, Institute of Experimental Psychology, Heinrich-Heine University Düsseldorf, Germany
| | - Hubertus Hautzel
- Clinic of Nuclear Medicine, University Hospital Düsseldorf Düsseldorf, Germany
| | - Owen Y Chao
- Center for Behavioural Neuroscience, Institute of Experimental Psychology, Heinrich-Heine University Düsseldorf, Germany
| | - Christina Antke
- Clinic of Nuclear Medicine, University Hospital Düsseldorf Düsseldorf, Germany
| | - Hans-Wilhelm Müller
- Clinic of Nuclear Medicine, University Hospital Düsseldorf Düsseldorf, Germany
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Abstract
Purpose The effect of clinical l-3,4-dihydroxyphenylalanine (l-DOPA) doses on the binding of [123I]N-Ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane ([123I]FP-CIT) to the rat dopamine transporter (DAT) was investigated using small animal single-photon emission computed tomography. Materials and methods DAT binding was measured at baseline, after challenge with the aromatic l-amino acid decarboxylase inhibitor benserazide, and after challenge with either 5 or 10 mg/kg l-DOPA plus benserazide. For baseline and challenges, striatal equilibrium ratios (V3′′) were computed as an estimation of the binding potential. Moreover, striatal V3′′ values were correlated with parameters of motor and exploratory behavior. Results V3′′ differed significantly between baseline and either dose of l-DOPA/benserazide. Moreover, V3′′ differed significantly between l-DOPA treatment groups. After 5 mg/kg l-DOPA/benserazide, DAT binding was inversely correlated with sitting duration (1–5 min) and sitting frequency (10–15 min). After 10 mg/kg l-DOPA/benserazide, an inverse correlation was found between DAT binding and sitting duration (1–30 min), whereas DAT binding and duration of ambulatory activity (1–30 min) as well as head and shoulder motility (10–15 min) exhibited a positive correlation. Conclusion Challenge with 5 and 10 mg/kg l-DOPA/benserazide led to mean reductions in DAT binding by 34 and 20%, respectively. Results indicate a biphasic response with a higher effect on DAT after the lower dose of l-DOPA. The reduction in DAT binding may be interpreted in terms of competition between [123I]FP-CIT and endogenous dopamine. Moreover, there is preliminary evidence of an association between striatal DAT and motor and exploratory parameters.
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Niñerola-Baizán A, Rojas S, Bonastre M, Tudela R, Lomeña F, Pavía J, Marin C, Ros D. In vivo evaluation of the dopaminergic neurotransmission system using [123I]FP-CIT SPECT in 6-OHDA lesioned rats. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 10:67-73. [PMID: 24888455 DOI: 10.1002/cmmi.1608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/24/2014] [Accepted: 04/10/2014] [Indexed: 02/04/2023]
Abstract
The 6-hydroxydopamine (6-OHDA) rodent model of Parkinson's disease (PD) has been used to evaluate the nigrostriatal pathway. The aim of this work was to explore the relationship between the degree of 6-OHDA-induced dopaminergic degeneration and [(123)I]FP-CIT binding using single photon emission computed tomography (SPECT). Fourteen rats received a 6-OHDA injection (4 or 8 µg) into the left medial forebrain bundle. After 3 weeks, magnetic resonance imaging and scans with a small-animal SPECT system were performed. Finally, the nigrostriatal lesion was assessed by immunohistochemical analysis. Immunohistochemical analysis confirmed two levels of dopaminergic degeneration. Lesions induced by 6-OHDA diminished the ipsilateral [(123)I]FP-CIT binding by 61 and 76%, respectively. The decrease in tracer uptake between control and lesioned animals was statistically significant, as was the difference between the two 6-OHDA lesioned groups. Results concluded that [(123)I]FP-CIT SPECT is a useful technique to discriminate the degree of dopaminergic degeneration in a rat model of PD.
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Affiliation(s)
- Aida Niñerola-Baizán
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
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Stubbs DJ, Yamamoto AK, Menon DK. Imaging in sepsis-associated encephalopathy--insights and opportunities. Nat Rev Neurol 2013; 9:551-61. [PMID: 23999468 DOI: 10.1038/nrneurol.2013.177] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sepsis-associated encephalopathy (SAE) refers to a clinical spectrum of acute neurological dysfunction that arises in the context of sepsis. Although the pathophysiology of SAE is incompletely understood, it is thought to involve endothelial activation, blood-brain barrier leakage, inflammatory cell migration, and neuronal loss with neurotransmitter imbalance. SAE is associated with a high risk of mortality. Imaging studies using MRI and CT have demonstrated changes in the brains of patients with SAE that are also seen in disorders such as stroke. Next-generation imaging techniques such as magnetic resonance spectroscopy, diffusion tensor imaging and PET, as well as experimental imaging modalities, provide options for early identification of patients with SAE, and could aid in identification of pathophysiological processes that represent possible therapeutic targets. In this Review, we explore the recent literature on imaging in SAE, relating the findings of these studies to pathological data and experimental studies to obtain insights into the pathophysiology of sepsis-associated neurological dysfunction. Furthermore, we suggest how novel imaging technologies can be used for early-stage proof-of-concept and proof-of-mechanism translational studies, which may help to improve diagnosis in SAE.
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Affiliation(s)
- Daniel J Stubbs
- Division of Anaesthesia, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
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Nikolaus S, Hautzel H, Heinzel A, Müller HW. Key players in major and bipolar depression--a retrospective analysis of in vivo imaging studies. Behav Brain Res 2012; 232:358-90. [PMID: 22483788 DOI: 10.1016/j.bbr.2012.03.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 03/13/2012] [Accepted: 03/17/2012] [Indexed: 11/30/2022]
Abstract
In the present study, we evaluated the contribution of the individual synaptic constituents of all assessed neurotransmitter systems by subjecting all available in vivo imaging studies on patients with unipolar major depressive disorder (MDD) and bipolar depression (BD) to a retrospective analysis. In acute MDD, findings revealed significant increases of prefrontal and frontal DA synthesis, decreases of thalamic and midbrain SERT, increases of insular SERT, decreases of midbrain 5-HT(1A) receptors and decreases of prefrontal, frontal, occipital and cingulate 5-HT(2A) receptors, whereas, in remission, decreases of striatal D₂ receptors, midbrain SERT, frontal, parietal, temporal, occipital and cingulate 5-HT(1A) receptors and parietal 5-HT(2A) receptors were observed. In BD, findings indicated a trend towards increased striatal D₂ receptors in depression and mania, decreased striatal DA synthesis in remission and decreased frontal D₁ receptors in all three conditions. Additionally, there is some evidence that ventrostriatal and hippocampal SERT may be decreased in depression, whereas in remission and mania elevations of thalamic and midbrain SERT, respectively, were observed. Moreover, in depression, limbic 5-HT(1A) receptors were elevated, whereas in mania a decrease of both cortical and limbic 5-HT(2A) receptor binding was observed. Furthermore, in depression, prefrontal, frontal, occipital and cingulate M2 receptor binding was found to be reduced. From this, a complex pattern of dysregulations within and between neurotransmitter systems may be derived, which is likely to be causally linked not only with the subtype and duration of disease but also with the predominance of individual symptoms and with the kind and duration of pharmacological treatment(s).
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Affiliation(s)
- Susanne Nikolaus
- Clinic of Nuclear Medicine, University Hospital Düsseldorf, Heinrich-Heine University, Moorenstr. 5, 40225 Düsseldorf, Germany.
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