1
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Kroll T, Miranda A, Drechsel A, Beer S, Lang M, Drzezga A, Rosa-Neto P, Verhaeghe J, Elmenhorst D, Bauer A. Dynamic neuroreceptor positron emission tomography in non-anesthetized rats using point source based motion correction: A feasibility study with [ 11C]ABP688. J Cereb Blood Flow Metab 2024:271678X241239133. [PMID: 38684219 DOI: 10.1177/0271678x241239133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
To prevent motion artifacts in small animal positron emission tomography (PET), animals are routinely scanned under anesthesia or physical restraint. Both may potentially alter metabolism and neurochemistry. This study investigates the feasibility of fully awake acquisition and subsequent absolute quantification of dynamic brain PET data via pharmacokinetic modelling in moving rats using the glutamate 5 receptor radioligand [11C]ABP688 and point source based motion correction. Five male rats underwent three dynamic [11C]ABP688 PET scans: two test-retest awake PET scans and one scan under anesthesia for comparison. Specific radioligand binding was determined via the simplified reference tissue model (reference: cerebellum) and outcome parameters BPND and R1 were evaluated in terms of stability and reproducibility. Test-retest measurements in awake animals gave reliable results with high correlations of BPND (y = 1.08 × -0.2, r = 0.99, p < 0.01) and an acceptable variability (mean over all investigated regions 15.7 ± 2.4%). Regional [11C]ABP688 BPNDs under awake and anesthetized conditions were comparable although in awake scans, absolute radioactive peak uptakes were lower and relative blood flow in terms of R1 was higher. Awake small animal PET with absolute quantification of neuroreceptor availability is technically feasible and reproducible thereby providing a suitable alternative whenever effects of anesthesia are undesirable, e.g. in sleep research.
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Affiliation(s)
- Tina Kroll
- Institute of Neurosciences and Medicine (INM-2), Forschungszentrum Jülich GmbH, Germany
| | - Alan Miranda
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium
| | - Alexandra Drechsel
- Institute of Neurosciences and Medicine (INM-2), Forschungszentrum Jülich GmbH, Germany
| | - Simone Beer
- Institute of Neurosciences and Medicine (INM-2), Forschungszentrum Jülich GmbH, Germany
| | - Markus Lang
- Institute of Neurosciences and Medicine (INM-5), Forschungszentrum Jülich GmbH, Germany
| | - Alexander Drzezga
- Institute of Neurosciences and Medicine (INM-2), Forschungszentrum Jülich GmbH, Germany
- Department of Nuclear Medicine, University Hospital Cologne, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn-Cologne, Germany
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, Alzheimer's Disease Research Unit, Douglas Research Institute, Le Centre intégré universitaire de santé et de services sociaux (CIUSSS) de l'Ouest-de-l'Île-de-Montréal; Department of Neurology and Neurosurgery, Psychiatry and Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium
| | - David Elmenhorst
- Institute of Neurosciences and Medicine (INM-2), Forschungszentrum Jülich GmbH, Germany
- Department of Nuclear Medicine, University Hospital Cologne, Germany
| | - Andreas Bauer
- Institute of Neurosciences and Medicine (INM-2), Forschungszentrum Jülich GmbH, Germany
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2
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Alstrup AKO, Dollerup MR, Simonsen MIT, Vendelbo MH. Preclinical Imaging Studies: Protocols, Preparation, Anesthesia, and Animal Care. Semin Nucl Med 2023; 53:570-576. [PMID: 36858906 DOI: 10.1053/j.semnuclmed.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 02/01/2023] [Indexed: 03/03/2023]
Abstract
Today preclinical PET imaging connects laboratory research with clinical applications. Here PET clearly bridges the gap, as nearly identical imaging protocols can be applied to both animal and humans. However, some hurdles exist and researchers must be careful, partly because the animals are usually anesthetized during the scans, while human volunteers are awake. This review is based on our own experiences of some of the most important pitfalls and how to overcome them. This includes how studies should be designed, how to select the right anesthesia and monitoring. The choice of anesthesia is quite crucial, as it may have a greater influence on the results than the effect of the tested procedures. Monitoring is necessary, as the animals cannot fully maintain homeostasis during anesthesia, and reliable results are dependent on a stable physiology. Additionally, it is important to note that rodents, in particular, are prone to rapidly becoming hypothermic. Thus, the selection of an appropriate anesthetic and monitoring protocol is crucial for both obtaining accurate results and ensuring animal welfare. Prior to imaging, catheters for tracer administration and, if necessary, blood sampling should be implanted. The administration of tracers should be done in a manner that minimizes interference with the scans, and the same applies to any serial blood sampling. The limited blood volume and organ size of rodents should also be taken into consideration when planning experiments. Finally, if the animal needs to be awakened after the scan, proper care must be taken to ensure their welfare.
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Affiliation(s)
- Aage K O Alstrup
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
| | - Mie R Dollerup
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
| | - Mette I T Simonsen
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
| | - Mikkel H Vendelbo
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark; Department of Biomedicine, Aarhus University, Aarhus, Denmark
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3
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Ahmadi-Noorbakhsh S, Farajli Abbasi M, Ghasemi M, Bayat G, Davoodian N, Sharif-Paghaleh E, Poormoosavi SM, Rafizadeh M, Maleki M, Shirzad-Aski H, Kargar Jahromi H, Dadkhah M, Khalvati B, Safari T, Behmanesh MA, Khoshnam SE, Houshmand G, Talaei SA. Anesthesia and analgesia for common research models of adult mice. Lab Anim Res 2022; 38:40. [PMID: 36514128 PMCID: PMC9746144 DOI: 10.1186/s42826-022-00150-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 11/23/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022] Open
Abstract
Anesthesia and analgesia are major components of many interventional studies on laboratory animals. However, various studies have shown improper reporting or use of anesthetics/analgesics in research proposals and published articles. In many cases, it seems "anesthesia" and "analgesia" are used interchangeably, while they are referring to two different concepts. Not only this is an unethical practice, but also it may be one of the reasons for the proven suboptimal quality of many animal researches. This is a widespread problem among investigations on various species of animals. However, it could be imagined that it may be more prevalent for the most common species of laboratory animals, such as the laboratory mice. In this review, proper anesthetic/analgesic methods for routine procedures on laboratory mice are discussed. We considered the available literature and critically reviewed their anesthetic/analgesic methods. Detailed dosing and pharmacological information for the relevant drugs are provided and some of the drugs' side effects are discussed. This paper provides the necessary data for an informed choice of anesthetic/analgesic methods in some routine procedures on laboratory mice.
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Affiliation(s)
- Siavash Ahmadi-Noorbakhsh
- grid.411705.60000 0001 0166 0922Preclinical Core Facility (TPCF), Tehran University of Medical Sciences, Tehran, Iran ,grid.415814.d0000 0004 0612 272XThe National Ethics Committee for Biomedical Research, Floor 13th, Complex A, Ministry of Health and Medical Education, Eyvanak Blvd., Shahrake Gharb, Tehran, Iran
| | - Mohammad Farajli Abbasi
- grid.412105.30000 0001 2092 9755Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran
| | - Maedeh Ghasemi
- grid.411036.10000 0001 1498 685XDepartment of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Gholamreza Bayat
- grid.411705.60000 0001 0166 0922Department of Physiology-Pharmacology-Medical Physic, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Nahid Davoodian
- grid.412237.10000 0004 0385 452XEndocrinology and Metabolism Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Ehsan Sharif-Paghaleh
- grid.411705.60000 0001 0166 0922Preclinical Core Facility (TPCF), Tehran University of Medical Sciences, Tehran, Iran ,grid.411705.60000 0001 0166 0922Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran ,grid.13097.3c0000 0001 2322 6764Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, England
| | - Seyedeh Mahsa Poormoosavi
- grid.512425.50000 0004 4660 6569Department of Histology, School of Medicine, Research and Clinical Center for Infertility, Dezful University of Medical Sciences, Dezful, Iran
| | - Melika Rafizadeh
- grid.411600.2Department of Pharmacology, Medical School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Maleki
- grid.449129.30000 0004 0611 9408Department of Physiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran
| | - Hesamaddin Shirzad-Aski
- grid.411747.00000 0004 0418 0096Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Hossein Kargar Jahromi
- grid.444764.10000 0004 0612 0898Research Center for Non-Communicable Disease, Jahrom University of Medical Sciences, Jahrom, Iran
| | - Masoomeh Dadkhah
- grid.411426.40000 0004 0611 7226Pharmaceutical Sciences Research Center, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Bahman Khalvati
- grid.413020.40000 0004 0384 8939Medicinal Plants Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Tahereh Safari
- grid.488433.00000 0004 0612 8339School of Medicine, Department of Physiology, PhD, Zahedan University of Medical Sciences, Zahedan, Iran ,grid.488433.00000 0004 0612 8339Pharmacology Research Center, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Mohammad Amin Behmanesh
- grid.512425.50000 0004 4660 6569Department of Histology, School of Medicine, Dezful University of Medical Sciences, Dezful, Iran
| | - Seyed Esmaeil Khoshnam
- grid.411230.50000 0000 9296 6873Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Gholamreza Houshmand
- grid.411623.30000 0001 2227 0923Psychiatry and Behavioral Sciences Research Center, Addiction Institute, Department of Pharmacology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Sayyed Alireza Talaei
- grid.444768.d0000 0004 0612 1049Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
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4
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Miranda A, Bertoglio D, Stroobants S, Staelens S, Verhaeghe J. Translation of Preclinical PET Imaging Findings: Challenges and Motion Correction to Overcome the Confounding Effect of Anesthetics. Front Med (Lausanne) 2021; 8:753977. [PMID: 34746189 PMCID: PMC8569248 DOI: 10.3389/fmed.2021.753977] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 09/27/2021] [Indexed: 11/13/2022] Open
Abstract
Preclinical brain positron emission tomography (PET) in animals is performed using anesthesia to avoid movement during the PET scan. In contrast, brain PET scans in humans are typically performed in the awake subject. Anesthesia is therefore one of the principal limitations in the translation of preclinical brain PET to the clinic. This review summarizes the available literature supporting the confounding effect of anesthesia on several PET tracers for neuroscience in preclinical small animal scans. In a second part, we present the state-of-the-art methodologies to circumvent this limitation to increase the translational significance of preclinical research, with an emphasis on motion correction methods. Several motion tracking systems compatible with preclinical scanners have been developed, each one with its advantages and limitations. These systems and the novel experimental setups they can bring to preclinical brain PET research are reviewed here. While technical advances have been made in this field, and practical implementations have been demonstrated, the technique should become more readily available to research centers to allow for a wider adoption of the motion correction technique for brain research.
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Affiliation(s)
- Alan Miranda
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Daniele Bertoglio
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
- University Hospital Antwerp, Antwerp, Belgium
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
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5
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Kyme AZ, Fulton RR. Motion estimation and correction in SPECT, PET and CT. Phys Med Biol 2021; 66. [PMID: 34102630 DOI: 10.1088/1361-6560/ac093b] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 06/08/2021] [Indexed: 11/11/2022]
Abstract
Patient motion impacts single photon emission computed tomography (SPECT), positron emission tomography (PET) and X-ray computed tomography (CT) by giving rise to projection data inconsistencies that can manifest as reconstruction artifacts, thereby degrading image quality and compromising accurate image interpretation and quantification. Methods to estimate and correct for patient motion in SPECT, PET and CT have attracted considerable research effort over several decades. The aims of this effort have been two-fold: to estimate relevant motion fields characterizing the various forms of voluntary and involuntary motion; and to apply these motion fields within a modified reconstruction framework to obtain motion-corrected images. The aims of this review are to outline the motion problem in medical imaging and to critically review published methods for estimating and correcting for the relevant motion fields in clinical and preclinical SPECT, PET and CT. Despite many similarities in how motion is handled between these modalities, utility and applications vary based on differences in temporal and spatial resolution. Technical feasibility has been demonstrated in each modality for both rigid and non-rigid motion, but clinical feasibility remains an important target. There is considerable scope for further developments in motion estimation and correction, and particularly in data-driven methods that will aid clinical utility. State-of-the-art machine learning methods may have a unique role to play in this context.
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Affiliation(s)
- Andre Z Kyme
- School of Biomedical Engineering, The University of Sydney, Sydney, New South Wales, AUSTRALIA
| | - Roger R Fulton
- Sydney School of Health Sciences, The University of Sydney, Sydney, New South Wales, AUSTRALIA
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6
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Conscious rat PET imaging with soft immobilization for quantitation of brain functions: comprehensive assessment of anesthesia effects on cerebral blood flow and metabolism. EJNMMI Res 2021; 11:46. [PMID: 33963948 PMCID: PMC8106566 DOI: 10.1186/s13550-021-00787-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 04/28/2021] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Animal brain functions evaluated by in vivo imaging under anesthesia can be affected by anesthetic agents, resulting in incorrect assessment of physiological brain function. We therefore performed dynamic positron emission tomography (PET) imaging of conscious rats using recently reported soft immobilization to validate the efficacy of the immobilization for brain function assessments. We also determined the effects of six anesthetic agents-a mixed anesthetic agent (MMB), ketamine + xylazine (KX), chloral hydrate (Chloral), pentobarbital (PTB), propofol (PF), and isoflurane (IFL)-on brain function by comparison with conscious rats. RESULTS The immobilization enabled 45-min dynamic [18F]FDG-PET acquisition with arterial blood sampling using conscious rats without the use of special techniques or invasive surgery. The spatial resolution and quantitativity of [18F]FDG-PET were not significantly lower for conscious rats than for anesthetized rats. While MMB, Chloral, PTB, and PF showed ubiquitous reduction in the cerebral metabolic rates of glucose (CMRglu) in brain regions, KX and IFL showed higher reductions in cerebellum and interbrain, and cerebellum, respectively. Cerebral blood flow (CBF) was reduced by MMB, KX, PTB, and PF; increased by IFL; and unaltered by Chloral. The magnitude of decrease in CMRglu and CBF for MMB were not larger than for other five anesthetic agents, although blood glucose levels and body temperature can be easily affected by MMB. CONCLUSION The six anesthetic agents induced various effects on CMRglu and CBF. The immobilization technique presented here is a promising tool for noninvasive brain functional imaging using conscious rats to avoid the effects of anesthetic agents.
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7
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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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8
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Shin S, Kim K, Pak K, Nam HY, Im HJ, Lee MJ, Kim SJ, Kim IJ. Effects of animal handling on striatal DAT availability in rats. Ann Nucl Med 2020; 34:496-501. [PMID: 32424547 DOI: 10.1007/s12149-020-01476-5] [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: 03/26/2020] [Accepted: 05/07/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Positron emission tomography (PET) is a non-invasive technique measuring quantification of physiological and biochemical processes in the living organism. However, there are many considerations including anesthesia and fasting to acquire small animal imaging. We aimed to evaluate the effects of anesthesia and fasting of rats in dopamine transporter (DAT) imaging acquisition. METHODS Male Sprague Dawley (SD) rats aged 7 weeks and weighing 180-260 g were used in this study. Rats were randomly divided by 4 groups. Group A was kept under anesthesia for 40 min and fasted over 12 h. Group B was only fasted over 12 h. Group C was only kept under anesthesia for 40 min. Group D was neither kept under anesthesia nor fasted over 12 h. PET scans were started at 40 min after 18F-FP-CIT injection and obtained for 20 min. Volumes-of-interest for striatum and extrastriatal area were used for 18F-FP-CIT PET analysis. Cerebellum was considered as a reference region. Specific binding ratio (SBR) was calculated as follows: [(uptake of target-uptake of cerebellum)]/(uptake of cerebellum). RESULTS SBR without fasting and anesthesia (group D) was significantly lower than those of other groups (vs group A, p = 0.0004; vs group B, p = 0.0377; vs group C, p = 0.0134). However, SBRs of extrastriatal area (p = 0.5120) were not affected by fasting and anesthesia. CONCLUSIONS In conclusion, the SBR of striatum was increased after anesthesia by isoflurane and fasting. When designing an experiment using DAT imaging, the effects of isoflurane and fasting should be considered.
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Affiliation(s)
- Seunghyeon Shin
- Department of Nuclear Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Republic of Korea
| | - Keunyoung Kim
- Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241, Republic of Korea
| | - Kyoungjune Pak
- Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241, Republic of Korea.
| | - Hyun-Yeol Nam
- Department of Nuclear Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Republic of Korea.
| | - Hyung-Jun Im
- Graduate School of Convergence Science and Technology, Seoul National University, Suwon, Republic of Korea
| | - Myung Jun Lee
- Department of Neurology and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Seong-Jang Kim
- Department of Nuclear Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - In Joo Kim
- Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241, Republic of Korea.
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Digital autoradiography for efficient functional imaging without anesthesia in experimental animals: Reversing phencyclidine-induced functional alterations using clozapine. Prog Neuropsychopharmacol Biol Psychiatry 2020; 100:109887. [PMID: 32061743 DOI: 10.1016/j.pnpbp.2020.109887] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 01/27/2020] [Accepted: 02/11/2020] [Indexed: 11/20/2022]
Abstract
Autoradiography (ARG) is a high-resolution imaging method for localization of radiolabeled biomarkers in ex vivo specimen. ARG using 2-deoxy-d-glucose (2-DG) method is used in to study drug actions on brain functional activity, as it provides results comparable to clinically used functional positron-emission tomography (PET). The requirement of slow analog detection methods and emerging advances in small animal PET imaging have, however, reduced the interest in ARG. In contrast to ARG, experimental animals need to be restrained or sedated/anesthetized for PET imaging, which strongly influence functional activity and thus complicate the interpretation of the results. Digital direct particle-counting ARG systems have gained attraction during the last decade to overcome the caveats of conventional ARG methods. Here we demonstrate that the well-established 2-DG imaging method can be adapted into use with contemporary digital detectors. This method readily and rapidly captures the characteristic effects of phencyclidine (5 mg/kg, i.p.), a dissociative agent targeting the NMDAR (N-methyl-d-aspartate receptor), on regional glucose utilization in the adult mouse brain. Pretreatment with antipsychotic drug clozapine (6 mg/kg, i.p.) essentially abolishes these effects of phencyclidine on brain functional activity. Digital ARG produces viable data for the regional analysis of functional activity in a fraction of time required for film development. These results support the use of digital ARG in preclinical drug research, where high throughput and response linearity are preferred and use of sedation/anesthesia has to be avoided.
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10
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García-Varela L, Vállez García D, Rodríguez-Pérez M, van Waarde A, Sijbesma JWA, Schildt A, Kwizera C, Aguiar P, Sobrino T, Dierckx RAJO, Elsinga PH, Luurtsema G. Test-Retest Repeatability of [ 18F]MC225-PET in Rodents: A Tracer for Imaging of P-gp Function. ACS Chem Neurosci 2020; 11:648-658. [PMID: 31961646 PMCID: PMC7034080 DOI: 10.1021/acschemneuro.9b00682] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
![]()
In
longitudinal PET studies, animals are repeatedly anesthetized
which may affect the repeatability of PET measurements. The aim of
this study was to assess the effect of anesthesia on the P-gp function
as well as the reproducibility of [18F]MC225 PET scans.
Thus, dynamic PET scans with blood sampling were conducted in 13 Wistar
rats. Seven animals were exposed to isoflurane anesthesia 1 week before
the PET scan (“Anesthesia-exposed” PET). A second group
of six animals was used to evaluate the reproducibility of measurements
of P-gp function at the blood–brain barrier (BBB) with [18F]MC225. In this group, two PET scans were made with a 1
week interval (“Test” and “Retest” PET).
Pharmacokinetic parameters were calculated using compartmental models
and metabolite-corrected plasma as an input function. “Anesthesia-exposed”
animals showed a 28% decrease in whole-brain volume of distribution
(VT) (p < 0.001) compared
to “Test”, where the animals were not previously anesthetized.
The VT at “Retest” also
decreased (19%) compared to “Test” (p < 0.001). The k2 values in whole-brain
were significantly increased by 18% in “Anesthesia-exposed”
(p = 0.005) and by 15% in “Retest”
(p = 0.008) compared to “Test”. However,
no significant differences were found in the influx rate constant K1, which is considered as the best parameter
to measure the P-gp function. Moreover, Western Blot analysis did
not find significant differences in the P-gp expression of animals
not pre-exposed to anesthesia (“Test”) or pre-exposed
animals (“Retest”). To conclude, anesthesia may affect
the brain distribution of [18F]MC225 but it does not affect
the P-gp expression or function.
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Affiliation(s)
- Lara García-Varela
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - David Vállez García
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Manuel Rodríguez-Pérez
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Jürgen W. A. Sijbesma
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Anna Schildt
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Chantal Kwizera
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Pablo Aguiar
- Department of Nuclear Medicine and Molecular Imaging Group, Clinical University Hospital, IDIS Health Research Institute, Santiago de Compostela 15706, Spain
| | - Tomás Sobrino
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Rudi A. J. O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Philip H. Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
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Miranda A, Staelens S, Stroobants S, Verhaeghe J. Fast and Accurate Rat Head Motion Tracking With Point Sources for Awake Brain PET. IEEE TRANSACTIONS ON MEDICAL IMAGING 2017; 36:1573-1582. [PMID: 28207390 DOI: 10.1109/tmi.2017.2667889] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
To avoid the confounding effects of anesthesia and immobilization stress in rat brain positron emission tomography (PET), motion tracking-based unrestrained awake rat brain imaging is being developed. In this paper, we propose a fast and accurate rat headmotion tracking method based on small PET point sources. PET point sources (3-4) attached to the rat's head are tracked in image space using 15-32-ms time frames. Our point source tracking (PST) method was validated using a manually moved microDerenzo phantom that was simultaneously tracked with an optical tracker (OT) for comparison. The PST method was further validated in three awake [18F]FDG rat brain scans. Compared with the OT, the PST-based correction at the same frame rate (31.2 Hz) reduced the reconstructed FWHM by 0.39-0.66 mm for the different tested rod sizes of the microDerenzo phantom. The FWHM could be further reduced by another 0.07-0.13 mm when increasing the PST frame rate (66.7 Hz). Regional brain [18F]FDG uptake in the motion corrected scan was strongly correlated ( ) with that of the anesthetized reference scan for all three cases ( ). The proposed PST method allowed excellent and reproducible motion correction in awake in vivo experiments. In addition, there is no need of specialized tracking equipment or additional calibrations to be performed, the point sources are practically imperceptible to the rat, and PST is ideally suitable for small bore scanners, where optical tracking might be challenging.
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Miranda A, Staelens S, Stroobants S, Verhaeghe J. Markerless rat head motion tracking using structured light for brain PET imaging of unrestrained awake small animals. Phys Med Biol 2017; 62:1744-1758. [PMID: 28102175 DOI: 10.1088/1361-6560/aa5a46] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Preclinical positron emission tomography (PET) imaging in small animals is generally performed under anesthesia to immobilize the animal during scanning. More recently, for rat brain PET studies, methods to perform scans of unrestrained awake rats are being developed in order to avoid the unwanted effects of anesthesia on the brain response. Here, we investigate the use of a projected structure stereo camera to track the motion of the rat head during the PET scan. The motion information is then used to correct the PET data. The stereo camera calculates a 3D point cloud representation of the scene and the tracking is performed by point cloud matching using the iterative closest point algorithm. The main advantage of the proposed motion tracking is that no intervention, e.g. for marker attachment, is needed. A manually moved microDerenzo phantom experiment and 3 awake rat [18F]FDG experiments were performed to evaluate the proposed tracking method. The tracking accuracy was 0.33 mm rms. After motion correction image reconstruction, the microDerenzo phantom was recovered albeit with some loss of resolution. The reconstructed FWHM of the 2.5 and 3 mm rods increased with 0.94 and 0.51 mm respectively in comparison with the motion-free case. In the rat experiments, the average tracking success rate was 64.7%. The correlation of relative brain regional [18F]FDG uptake between the anesthesia and awake scan reconstructions was increased from on average 0.291 (not significant) before correction to 0.909 (p < 0.0001) after motion correction. Markerless motion tracking using structured light can be successfully used for tracking of the rat head for motion correction in awake rat PET scans.
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Affiliation(s)
- Alan Miranda
- Molecular Imaging Center Antwerp, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
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Lever SZ, Fan KH, Lever JR. Tactics for preclinical validation of receptor-binding radiotracers. Nucl Med Biol 2017; 44:4-30. [PMID: 27755986 PMCID: PMC5161541 DOI: 10.1016/j.nucmedbio.2016.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 08/24/2016] [Accepted: 08/24/2016] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Aspects of radiopharmaceutical development are illustrated through preclinical studies of [125I]-(E)-1-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-4-(iodoallyl)piperazine ([125I]-E-IA-BF-PE-PIPZE), a radioligand for sigma-1 (σ1) receptors, coupled with examples from the recent literature. Findings are compared to those previously observed for [125I]-(E)-1-(2-(2,3-dimethoxy-5-yl)ethyl)-4-(iodoallyl)piperazine ([125I]-E-IA-DM-PE-PIPZE). METHODS Syntheses of E-IA-BF-PE-PIPZE and [125I]-E-IA-BF-PE-PIPZE were accomplished by standard methods. In vitro receptor binding studies and autoradiography were performed, and binding potential was predicted. Measurements of lipophilicity and protein binding were obtained. In vivo studies were conducted in mice to evaluate radioligand stability, as well as specific binding to σ1 sites in brain, brain regions and peripheral organs in the presence and absence of potential blockers. RESULTS E-IA-BF-PE-PIPZE exhibited high affinity and selectivity for σ1 receptors (Ki = 0.43 ± 0.03 nM, σ2/σ1 = 173). [125I]-E-IA-BF-PE-PIPZE was prepared in good yield and purity, with high specific activity. Radioligand binding provided dissociation (koff) and association (kon) rate constants, along with a measured Kd of 0.24 ± 0.01 nM and Bmax of 472 ± 13 fmol/mg protein. The radioligand proved suitable for quantitative autoradiography in vitro using brain sections. Moderate lipophilicity, Log D7.4 2.69 ± 0.28, was determined, and protein binding was 71 ± 0.3%. In vivo, high initial whole brain uptake, >6% injected dose/g, cleared slowly over 24 h. Specific binding represented 75% to 93% of total binding from 15 min to 24 h. Findings were confirmed and extended by regional brain biodistribution. Radiometabolites were not observed in brain (1%). CONCLUSIONS Substitution of dihydrobenzofuranylethyl for dimethoxyphenethyl increased radioligand affinity for σ1 receptors by 16-fold. While high specific binding to σ1 receptors was observed for both radioligands in vivo, [125I]-E-IA-BF-PE-PIPZE displayed much slower clearance kinetics than [125I]-E-IA-DM-PE-PIPZE. Thus, minor structural modifications of σ1 receptor radioligands lead to major differences in binding properties in vitro and in vivo.
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Affiliation(s)
- Susan Z Lever
- Department of Chemistry, University of Missouri, Columbia, MO, USA; University of Missouri Research Reactor Center, Columbia, MO, USA.
| | - Kuo-Hsien Fan
- Department of Chemistry, University of Missouri, Columbia, MO, USA
| | - John R Lever
- Department of Radiology, University of Missouri, Columbia, MO, USA; Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA.
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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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Vanhove C, Bankstahl JP, Krämer SD, Visser E, Belcari N, Vandenberghe S. Accurate molecular imaging of small animals taking into account animal models, handling, anaesthesia, quality control and imaging system performance. EJNMMI Phys 2015; 2:31. [PMID: 26560138 PMCID: PMC4642455 DOI: 10.1186/s40658-015-0135-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/05/2015] [Indexed: 11/22/2022] Open
Abstract
Small-animal imaging has become an important technique for the development of new radiotracers, drugs and therapies. Many laboratories have now a combination of different small-animal imaging systems, which are being used by biologists, pharmacists, medical doctors and physicists. The aim of this paper is to give an overview of the important factors in the design of a small animal, nuclear medicine and imaging experiment. Different experts summarize one specific aspect important for a good design of a small-animal experiment.
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Affiliation(s)
- Christian Vanhove
- Department of Electronics and Information Systems, MEDISIP, Ghent University-iMinds Medical IT-IBiTech, De Pintelaan 185 block B, B-9000, Ghent, Belgium.
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Preclinical Molecular Imaging, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Stefanie D Krämer
- Radiopharmaceutical Sciences/Biopharmacy, ETH Zurich, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, CH-8093, Zurich, Switzerland
| | - Eric Visser
- Department of Radiology and Nuclear Medicine, Radboudumc, 6525 GA Nijmegen, the Netherlands
| | - Nicola Belcari
- Department of Physics, University of Pisa and INFN sezione di Pisa, 56127 Pisa, Italy
| | - Stefaan Vandenberghe
- Department of Electronics and Information Systems, MEDISIP, Ghent University-iMinds Medical IT-IBiTech, De Pintelaan 185 block B, B-9000, Ghent, Belgium
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Chen Z, Tang J, Liu C, Li X, Huang H, Xu X, Yu H. Effects of anesthetics on vesicular monoamine transporter type 2 binding to ¹⁸F-FP-(+)-DTBZ: a biodistribution study in rat brain. Nucl Med Biol 2015; 43:124-129. [PMID: 26526872 DOI: 10.1016/j.nucmedbio.2015.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/14/2015] [Accepted: 09/28/2015] [Indexed: 11/30/2022]
Abstract
OBJECTIVES The in vivo binding analysis of vesicular monoamine transporter type 2 (VMAT2) to radioligand has provided a means of investigating related disorders. Anesthesia is often inevitable when the investigations are performed in animals. In the present study, we tested effects of four commonly-used anesthetics: isoflurane, pentobarbital, chloral hydrate and ketamine, on in vivo VMAT2 binding to (18)F-FP-(+)-DTBZ, a specific VMAT2 radioligand, in rat brain. METHODS The transient equilibrium time window for in vivo binding of (18)F-FP-(+)-DTBZ after a bolus injection was firstly determined. The brain biodistribution studies under anesthetized and awake rats were then performed at the equilibrium time. Standard uptake values (SUVs) of the interest brain regions: the striatum (ST), hippocampus (HP), cortex (CX) and cerebellum (CB) were obtained; and ratios of tissue to cerebellum were calculated. RESULTS Isoflurane and pentobarbital did not alter distribution of (18)F-FP-(+)-DTBZ in the brain relative to the awake group; neither SUVs nor ratios of ST/CB and HP/CB were altered significantly. Chloral hydrate significantly increased SUVs of all the brain regions, but did not significantly alter ratios of ST/CB and HP/CB. Ketamine significantly increased SUVs of the striatum, hippocampus and cortex, and insignificantly increased the SUV of the cerebellum; consequently, ketamine significantly increased ratios of ST/CB and HP/CB. CONCLUSIONS It is concluded that in vivo VMAT2 binding to (18)F-FP-(+)-DTBZ are not altered by isoflurane and pentobarbital, but altered by chloral hydrate and ketamine. Isoflurane and pentobarbital may be promising anesthetic compounds for investigating in vivo VMAT2 binding. Further studies are warranted to investigate the interactions of anesthetics with VMAT2 binding potential with in vivo PET studies.
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Affiliation(s)
- Zhengping Chen
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063.
| | - Jie Tang
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063
| | - Chunyi Liu
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063
| | - Xiaomin Li
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063
| | - Hongbo Huang
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063
| | - Xijie Xu
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063
| | - Huixin Yu
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China, 214063
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Li YQ, Liao XX, Lu JH, Liu R, Hu CL, Dai G, Zhang XS, Shi XC, Li X. Assessing the early changes of cerebral glucose metabolism via dynamic (18)FDG-PET/CT during cardiac arrest. Metab Brain Dis 2015; 30:969-77. [PMID: 25703241 DOI: 10.1007/s11011-015-9658-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 02/10/2015] [Indexed: 12/31/2022]
Abstract
To study the changes of cerebral glucose metabolism (CGM) during the phase of return of spontaneous circulation (ROSC) after cardiac arrest (CA), we used 18-fluorodeoxyglucose-positron emission tomography/computed tomography ((18)FDG-PET/CT) to measure the CGM changes in six beagle canine models. After the baseline (18)FDG-PET/CT was recorded, ventricular fibrillation (VF) was induced for 6 min, followed by close-chest cardiopulmonary resuscitation (CPR) in conjunction with intravenous (IV) administration of epinephrine and external defibrillator shocks until ROSC was achieved, within 30 min. The (18)FDG was recorded prior to intravenous administration at 0 h (baseline), and at 4, 24, and 48 h after CA with ROSC. We evaluated the expression of two key control factors in canine CGM, hexokinase I (HXK I) and HXK II, by immunohistochemistry at the four above mentioned time points. Electrically induced VF of 6 min duration was successfully induced in the dogs. Resuscitation was then performed to maintain blood pressure stability. Serial (18)FDG-PET/CT scans found that the CGM decreased at 4 h after ROSC and remained lower than the baseline even at 48 h. The expression of HXK I and II levels were consistent with the changes in CGM. These data from our present work showed that (18)FDG-PET/CT imaging can be used to detect decreased CGM during CA and was consistent with the results of CMRgl. Furthermore, there were also concomitant changes in the expression of HXK I and HXK II. The decrease in CGM may be an early sign of hyperacute global cerebral ischemia.
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Affiliation(s)
- Ying-Qing Li
- Emergency Department of Guangzhou First People's Hospital, Guangzhou Medical University, Panfu Road 1, Guangzhou, People's Republic of China
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Tang J, Xi L, Zhou J, Huang H, Zhang T, Carney PR, Jiang H. Noninvasive high-speed photoacoustic tomography of cerebral hemodynamics in awake-moving rats. J Cereb Blood Flow Metab 2015; 35:1224-32. [PMID: 26082016 PMCID: PMC4527999 DOI: 10.1038/jcbfm.2015.138] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/10/2015] [Accepted: 05/06/2015] [Indexed: 11/09/2022]
Abstract
We present a noninvasive method of photoacoustic tomography (PAT) for imaging cerebral hemodynamics in awake-moving rats. The wearable PAT (wPAT) system has a size of 15 mm in height and 33 mm in diameter, and a weight of ~8 g (excluding cabling). The wPAT achieved an imaging rate of 3.33 frames/s with a lateral resolution of 243 μm. Animal experiments were designed to show wPAT feasibility for imaging cerebral hemodynamics on awake-moving animals. Results showed that the cerebral oxy-hemoglobin and deoxy-hemoglobin changed significantly in response to hyperoxia; and, after the injection of pentylenetetrazol (PTZ), cerebral blood volume changed faster over time and larger in amplitude for rats in awake-moving state compared with rats under anesthesia. By providing a light-weight, high-resolution technology for in vivo monitoring of cerebral hemodynamics in awake-behaving animals, it will be possible to develop a comprehensive understanding on how activity alters hemodynamics in normal and diseased states.
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Affiliation(s)
- Jianbo Tang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Lei Xi
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Junli Zhou
- Department of Pediatrics, University of Florida, Gainesville, Florida, USA
| | - Hua Huang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Tao Zhang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Paul R Carney
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
- Department of Pediatrics, University of Florida, Gainesville, Florida, USA
- Department of Neurology, University of Florida, Gainesville, Florida, USA
- Department of Neuroscience, University of Florida, Gainesville, Florida, USA
| | - Huabei Jiang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
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An investigation of the challenges in reconstructing PET images of a freely moving animal. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 36:405-15. [PMID: 24122172 DOI: 10.1007/s13246-013-0222-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
Abstract
Imaging the brain of a freely moving small animal using positron emission tomography (PET) while simultaneously observing its behaviour is an important goal for neuroscience. While we have successfully demonstrated the use of line-of-response (LOR) rebinning to correct the head motion of confined animals, a large proportion of events may need to be discarded because they either 'miss' the detector array after transformation or fall out of the acceptance range of a sinogram. The proportion of events that would have been measured had motion not occurred, so-called 'lost events', is expected to be even larger for freely moving animals. Moreover, the data acquisition in the case of a freely moving animal is further complicated by a complex attenuation field. The aims of this study were (a) to characterise the severity of the 'lostevents' problem for the freely moving animal scenario, and(b) to investigate the relative impact of attenuation correction errors on quantitative accuracy of reconstructed images. A phantom study was performed to simulate the uncorrelated motion of a target and non-target sourcevolume. A small animal PET scanner was used to acquirelist-mode data for different sets of phantom positions. The list-mode data were processed using the standard LOR rebinning approach, and multiple frame variants of this designed to reduce discarded events. We found that LOR rebinning caused up to 86 % 'lost events', and artifacts that we attribute to incomplete projections, when applied to a freely moving target. This fraction was reduced by up to 18 % using the variant approaches, resulting in slightly reduced image artifacts. The effect of the non-target compartment on attenuation correction of the target volume was surprisingly small. However, for certain poses where the target and non-target volumes are aligned transaxially in the field-of-view, the attenuation problem becomes more complex and sophisticated correction methods will be required. We conclude that there are limitations with the LOR rebinning approach and simplified attenuation correction for freely moving animals requiring the development and validation of more sophisticated approaches.
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Nalin L, Selvaraju RK, Velikyan I, Berglund M, Andréasson S, Wikstrand A, Rydén A, Lubberink M, Kandeel F, Nyman G, Korsgren O, Eriksson O, Jensen-Waern M. Positron emission tomography imaging of the glucagon-like peptide-1 receptor in healthy and streptozotocin-induced diabetic pigs. Eur J Nucl Med Mol Imaging 2014; 41:1800-10. [PMID: 24643781 DOI: 10.1007/s00259-014-2745-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 02/21/2014] [Indexed: 01/13/2023]
Abstract
PURPOSE The glucagon-like peptide-1 receptor (GLP-1R) has been proposed as a target for molecular imaging of beta cells. The feasibility of non-invasive imaging and quantification of GLP-1R in pancreas using the positron emission tomography (PET) tracer [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in non-diabetic and streptozotocin (STZ)-induced diabetic pigs treated with insulin was investigated. METHODS Non-diabetic (n = 4) and STZ-induced diabetic pigs (n = 3) from the same litter were examined. Development of diabetes was confirmed by blood glucose values, clinical examinations and insulin staining of pancreatic sections post mortem. Tissue perfusion in the pancreas and kidneys was evaluated by [(15)O]water PET/computed tomography (CT) scans. The in vivo receptor specificity of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 was assessed by administration of either tracer alone or by competition with 3-6.5 μg/kg of Exendin-4. Volume of distribution and occupancy in the pancreas were quantified with a single tissue compartment model. RESULTS [(15)O]water PET/CT examinations showed reduced perfusion in the pancreas and kidneys in diabetic pigs. [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 uptake in the pancreas of both non-diabetic and diabetic pigs was almost completely abolished by co-injection of unlabeled Exendin-4 peptide. [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 uptake did not differ between non-diabetic and diabetic pigs. In all animals, administration of the tracer resulted in an immediate increase in the heart rate (HR). CONCLUSION Pancreatic uptake of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 was not reduced by destruction of beta cells in STZ-induced diabetic pigs.
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Affiliation(s)
- Lovisa Nalin
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Effects of anesthesia and species on the uptake or binding of radioligands in vivo in the Göttingen minipig. BIOMED RESEARCH INTERNATIONAL 2013; 2013:808713. [PMID: 24083242 PMCID: PMC3780537 DOI: 10.1155/2013/808713] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/15/2013] [Accepted: 07/15/2013] [Indexed: 01/22/2023]
Abstract
Progress in neuroscience research often involves animals, as no adequate alternatives exist to animal models of living systems. However, both the physiological characteristics of the species used and the effects of anesthesia raise questions of common concern. Here, we demonstrate the confounding influences of these effects on tracer binding in positron emission tomography (PET). We determined the effects of two routinely used anesthetics (isoflurane and propofol) on the binding of two tracers of monoamine function, [11C]SCH23390, a tracer of the dopamine D1 and D5 receptors, and the alpha2-adrenoceptor antagonist, [11C]yohimbine, in Göttingen minipigs. The kinetics of SCH23390 in the pigs differed from those of our earlier studies in primates. With two different graphical analyses of uptake of SCH23390, the initial clearance values of this tracer were higher with isoflurane than with propofol anesthesia, indicative of differences in blood flow, whereas no significant differences were observed for the volumes of distribution of yohimbine. The study underscores the importance of differences of anesthesia and species when the properties of radioligands are evaluated under different circumstances that may affect blood flow and tracer uptake. These differences must be considered in the choice of a particular animal species and mode of anesthesia for a particular application.
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Matthews PM, Coatney R, Alsaid H, Jucker B, Ashworth S, Parker C, Changani K. Technologies: preclinical imaging for drug development. DRUG DISCOVERY TODAY. TECHNOLOGIES 2013; 10:e343-e350. [PMID: 24050130 DOI: 10.1016/j.ddtec.2012.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Preclinical imaging with magnetic resonance imaging (MRI), computerised tomography (CT), ultrasound (US), positron emission tomography (PET) or single-photon emission computed tomography (SPECT) enable non-invasive measures of tissue structure, function or metabolism in vivo. The technologies can add value to preclinical studies by enabling dynamic pharmacological observations on the same animal and because of possibilities for relatively direct clinical translation. Potential benefits from the application of preclinical imaging should be considered routinely in drug development.
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Acutely administered antipsychotic drugs are highly selective for dopamine D2 over D3 receptors. Pharmacol Res 2013; 70:66-71. [DOI: 10.1016/j.phrs.2013.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 01/04/2013] [Accepted: 01/06/2013] [Indexed: 11/20/2022]
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Alstrup AKO, Smith DF. Anaesthesia for positron emission tomography scanning of animal brains. Lab Anim 2013; 47:12-8. [PMID: 23349451 DOI: 10.1258/la.2012.011173] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Positron emission tomography (PET) provides a means of studying physiological and pharmacological processes as they occur in the living brain. Mice, rats, dogs, cats, pigs and non-human primates are often used in studies using PET. They are commonly anaesthetized with ketamine, propofol or isoflurane in order to prevent them from moving during the imaging procedure. The use of anaesthesia in PET studies suffers, however, from the drawback of possibly altering central neuromolecular mechanisms. As a result, PET findings obtained in anaesthetized animals may fail to correctly represent normal properties of the awake brain. Here, we review findings of PET studies carried out either in both awake and anaesthetized animals or in animals given at least two different anaesthetics. Such studies provide a means of estimating the extent to which anaesthesia affects the outcome of PET neuroimaging in animals. While no final conclusion can be drawn concerning the 'best' general anaesthetic for PET neuroimaging in laboratory animals, such studies provide findings that can enhance an understanding of neurobiological mechanisms in the living brain.
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Affiliation(s)
- Aage Kristian Olsen Alstrup
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospitals, Nørrebrogade 44, 10G, DK-8000 Aarhus C, Denmark.
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Mathew SJ, Shah A, Lapidus K, Clark C, Jarun N, Ostermeyer B, Murrough JW. Ketamine for treatment-resistant unipolar depression: current evidence. CNS Drugs 2012; 26:189-204. [PMID: 22303887 PMCID: PMC3677048 DOI: 10.2165/11599770-000000000-00000] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Currently available drugs for unipolar major depressive disorder (MDD), which target monoaminergic systems, have a delayed onset of action and significant limitations in efficacy. Antidepressants with primary pharmacological targets outside the monoamine system may offer the potential for more rapid activity with improved therapeutic benefit. The glutamate system has been scrutinized as a target for antidepressant drug discovery. The purpose of this article is to review emerging literature on the potential rapid-onset antidepressant properties of the glutamate NMDA receptor antagonist ketamine, an established anaesthetic agent. The pharmacology of ketamine and its enantiomer S-ketamine is reviewed, followed by examples of its clinical application in chronic, refractory pain conditions, which are commonly co-morbid with depression. The first generation of studies in patients with treatment-resistant depression (TRD) reported the safety and acute efficacy of a single subanaesthetic dose (0.5 mg/kg) of intravenous ketamine. A second generation of ketamine studies is focused on testing alternate routes of drug delivery, identifying methods to prevent relapse following resolution of depressive symptoms and understanding the neural basis for the putative antidepressant actions of ketamine. In addition to traditional depression rating endpoints, ongoing research is examining the impact of ketamine on neurocognition. Although the first clinical report in MDD was published in 2000, there is a paucity of adequately controlled double-blind trials, and limited clinical experience outside of research settings. Given the potential risks of ketamine, safety considerations will ultimately determine whether this old drug is successfully repositioned as a new therapy for TRD.
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Affiliation(s)
- Sanjay J. Mathew
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
,Michael E. Debakey VA Medical Center, Houston, TX, USA
,Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA
| | - Asim Shah
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
| | - Kyle Lapidus
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA
| | - Crystal Clark
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
,Michael E. Debakey VA Medical Center, Houston, TX, USA
| | - Noor Jarun
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
| | - Britta Ostermeyer
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
| | - James W. Murrough
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA
,Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
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McCormick PN, Ginovart N, Wilson AA. Isoflurane anaesthesia differentially affects the amphetamine sensitivity of agonist and antagonist D2/D3 positron emission tomography radiotracers: implications for in vivo imaging of dopamine release. Mol Imaging Biol 2011; 13:737-46. [PMID: 20680481 DOI: 10.1007/s11307-010-0380-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
PURPOSE Using positron emission tomography in isoflurane-anaesthetised cat, we recently demonstrated that the effect of D-amphetamine (AMPH) was greater on the binding potential (BP(ND)) of the agonist dopamine D2/D3 radiotracer (+)-4-[(11)C]propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1, 4]oxazin-9-ol ([(11)C]-(+)-PHNO) than on that of the antagonist [(11)C]-raclopride, a finding that we were unable to replicate in conscious rat. Herein we tested whether isoflurane differentially affects the AMPH sensitivity of [(11)C]-(+)-PHNO and [(3)H]-raclopride. PROCEDURES Conscious or isoflurane-anaesthetised rats pretreated intravenously (i.v.) with saline or 4 mg/kg AMPH were co-injected i.v. with [(11)C]-(+)-PHNO/[(3)H]-raclopride or [(3)H]-(+)-PHNO/[(11)C]-(-)-N-propyl-norapomorphine ([(11)C]-(-)-NPA) and euthanised 2, 10, 20, 30, 40 or 60 min following [(11)C]-(+)-PHNO/[(3)H]-raclopride or 60 min following [(3)H]-(+)-PHNO/[(11)C]-(-)-NPA. Striatal binding at 60 min, estimated by the specific binding ratio (SBR) and the binding potential with respect to non-displaceable binding (BP(ND)) for pseudodynamic data, was calculated using the simplified reference tissue model. RESULTS Isoflurane increased [(11)C]-(+)-PHNO, [(3)H]-(+)-PHNO and [(11)C]-(-)-NPA SBR (mean ± SD) by 80 ± 30%, 170 ± 50% and 120 ± 40%, and doubled the effect of AMPH on the SBR of these radiotracers to -61 ± 9%, -69 ± 12% and -60 ± 12%, respectively. Neither effect was seen for [(3)H]-raclopride SBR. Similar results were observed for [(11)C]-(+)-PHNO and [(3)H]-raclopride BP(ND). CONCLUSIONS Isoflurane differentially increases the binding and AMPH sensitivity of [(11)C]-(+)-PHNO and [(11)C]-(-)-NPA relative to [(3)H]-raclopride, suggesting that agonist radiotracers will prove no more effective for imaging dopaminergic activity in human than antagonist radiotracers.
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Kiryu S, Inoue Y, Watanabe M, Ohtomo K. Effect of isoflurane anesthesia and hypothermia on the hepatic kinetics of Gd-EOB-DTPA: evaluation using MRI of conscious mice. J Magn Reson Imaging 2011; 34:354-60. [PMID: 21692139 DOI: 10.1002/jmri.22650] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 04/14/2011] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To develop a method for body magnetic resonance imaging (MRI) of conscious mice and investigate the effect of isoflurane anesthesia and hypothermia on the hepatic kinetics of gadoxetate disodium (Gd-EOB-DTPA). MATERIALS AND METHODS Conscious or anesthetized mice were restrained on a holder and the rectal temperature was measured serially. Serial MRI of the liver was performed after intravenous injection of Gd-EOB-DTPA with or without temperature control. Three mice were studied for each condition. RESULTS The temperature dropped rapidly in anesthetized mice beside the MR unit. The decline was less prominent in conscious mice. The temperature decreased less in anesthetized mice and remained constant in conscious mice in the radiofrequency (RF) coil. The washout of Gd-EOB-DTPA was slower in anesthetized hypothermic mice than in conscious normothermic mice. Warmed anesthetized mice showed faster washout, and cooled conscious mice showed delayed washout. Severer hypothermia in anesthetized mice resulted in weaker initial enhancement and slower washout. CONCLUSION By separately manipulating the presence or absence of anesthesia and hypothermia, we demonstrated that washout of Gd-EOB-DTPA was delayed under hypothermia, regardless of anesthesia. Serial body MRI of conscious mice was feasible and allowed the evaluation of kinetics of a contrast agent, while excluding the possible effects of anesthesia.
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Affiliation(s)
- Shigeru Kiryu
- Department of Radiology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
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Tantawy MN, Peterson TE, Jones CK, Johnson K, Rook JM, Conn PJ, Baldwin RM, Ansari MS, Kessler RM. Impact of isoflurane anesthesia on D2 receptor occupancy by [18F]fallypride measured by microPET with a modified Logan plot. Synapse 2011; 65:1173-80. [PMID: 21584868 DOI: 10.1002/syn.20955] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 05/11/2011] [Indexed: 11/11/2022]
Abstract
UNLABELLED In the previous work, we reported a method that utilized imaging data collected from 60 to 120 min following [(18) F]fallypride administration to estimate the distribution volume ratio DVR' (DVR' ∝ DVR; DVR = 1 + BP(ND) , where BP(ND) is a measure of receptor density, DA D2 in this case). In this work, we use this method to assess the effects of isoflurane anesthesia on [(18) F]fallypride DVR'. METHODS Rats were injected with [(18) F]fallypride either unconsciously under ∼1.5% isoflurane via the tail vein (Group 1) or consciously via a catheter inserted either in the jugular vein (Group 2) or the tail vein (Group 3). After about 1 h of free access to food and water the rats were anesthetized with 1.5% isoflurane and imaged in a microPET for 60 min. The rats that were injected consciously (Groups 2 and 3) were placed in a rat restrainer during [(18) F]fallypride injection. They were habituated in that restrainer for 3 days prior to the experiment day to minimize restraint-related stress. For comparison, a control group of rats was imaged for 120 min simultaneously with the administration of [(18) F]fallypride i.v. while under 1.5% isoflurane. The DVR' estimates from the 60 min acquisitions were compared with the DVR' from the last 60 min of the 120 min acquisitions (after neglecting the first 60 min). In addition, the striatal time-activity curves were fit with a 2-tissue + plasma compartment model using an arbitrary simulated plasma input function to obtain k(3) /k(4) (≈ BP(ND) ) for the 60 and 120 min acquisitions. RESULTS Isoflurane anesthesia caused a significant reduction, up to 22%, in the DVR' estimates, which were 15.7 ± 0.3 (mean ± SE) for the controls, 17.7 ± 0.3 for Group 1, 19.2 ± 0.4 for Group 2, and 18.8 ± 0.7 for Group 3. The compartmental model fit produced similar results, ∼30% reduction in k(3) /k(4) for the 120-min acquisitions compared with the 60-min acquisitions (initial conscious uptake of the radiotracer). CONCLUSION The results of this study demonstrate that isoflurane anesthesia significantly decreases striatal [(18) F]fallypride BP(ND) in rats. Of similar importance, this work demonstrates the effectiveness of delayed scans following radiotracer injection and the implication that different types of studies can be conducted simultaneously with this method, including studies of behavioral and environmental impact on brain receptors.
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Affiliation(s)
- Mohammed N Tantawy
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
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Schulz D, Southekal S, Junnarkar SS, Pratte JF, Purschke ML, Stoll SP, Ravindranath B, Maramraju SH, Krishnamoorthy S, Henn FA, O'Connor P, Woody CL, Schlyer DJ, Vaska P. Simultaneous assessment of rodent behavior and neurochemistry using a miniature positron emission tomograph. Nat Methods 2011; 8:347-52. [DOI: 10.1038/nmeth.1582] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 02/02/2011] [Indexed: 12/12/2022]
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Xi W, Tian M, Zhang H. Molecular imaging in neuroscience research with small-animal PET in rodents. Neurosci Res 2011; 70:133-43. [PMID: 21241748 DOI: 10.1016/j.neures.2010.12.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 12/21/2010] [Accepted: 12/24/2010] [Indexed: 10/18/2022]
Abstract
Cognitive neuroscience, which studies the biological basis of mental processes, widely uses neuroimaging technologies like functional magnetic resonance imaging and positron emission tomography (PET) to study the human brain. Small laboratory animals, like rodents, are commonly used in brain research and provide abundant models of human brain diseases. The development of high-resolution small-animal PET and various radiotracers together with sophisticated methods for analyzing functional brain imaging data have accelerated research on brain function and neurotransmitter release during behavioral tasks in rodents. In this review, we first summarize advances in the methodology of cognitive research brought about by the development of sophisticated methods for whole-brain imaging analysis and improvements in neuroimaging protocols. Then, we discuss basic mechanisms related to metabolic changes and the expression of neurotransmitters in various brain areas during task-induced neural activity. In particular, we discuss glucose metabolism imaging and brain receptor imaging for various receptor systems. Finally, we discuss the current status and future perspectives. Mechanisms of neurotransmitter expression will probably become an increasingly important field of study in the future, leading to more collaboration between investigators in fields such as computational and theoretical neuroscience.
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Affiliation(s)
- Wang Xi
- Department of Nuclear Medicine, Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
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Landau AM, Chakravarty MM, Clark CM, Zis AP, Doudet DJ. Electroconvulsive therapy alters dopamine signaling in the striatum of non-human primates. Neuropsychopharmacology 2011; 36:511-8. [PMID: 20944554 PMCID: PMC3055667 DOI: 10.1038/npp.2010.182] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electroconvulsive therapy (ECT) is one of the most effective therapies for depression and has beneficial motor effects in parkinsonian patients. However, little is known about the mechanisms of therapeutic action of ECT for either condition. The aim of this work was to explore the impact of ECT on dopaminergic function in the striatum of non-human primates. Rhesus monkeys underwent a course of six ECT treatments under a human clinical protocol. Longitudinal effects on the dopaminergic nigrostriatal system were studied over 6 weeks using the in vivo capabilities of positron emission tomography (PET). PET scans were performed prior to the onset of ECT treatments and at 24-48 h, 8-10 days, and 6 weeks after the final ECT treatment. Early increases in dopamine transporter and vesicular monoamine transporter 2 binding returned to baseline levels by 6 weeks post-ECT. Transient increases in D1 receptor binding were also observed, whereas the binding potential to D2 receptors was unaltered. The increase in dopaminergic neurotransmission suggested by our results may account in part for the therapeutic effect of ECT in mood disorders and Parkinson's disease.
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Affiliation(s)
- Anne M Landau
- Aarhus PET Center and Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark,Department of Medicine/Neurology, University of British Columbia, Vancouver, BC, Canada
| | - M Mallar Chakravarty
- Aarhus PET Center and Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark,Rotman Research Institute, Baycrest Hospital and Mouse Imaging Centre, Sick Children's Hospital, Toronto, ON, Canada
| | - Campbell M Clark
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Athanasios P Zis
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Doris J Doudet
- Aarhus PET Center and Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark,Department of Medicine/Neurology, University of British Columbia, Vancouver, BC, Canada,Department of Medicine/Neurology, University of British Columbia, 2221 Wesbrook Mall, Purdy Pavilion M36, Vancouver, BC, V6T 2B5, Canada. Tel: +6 04 822 7163; Fax: +6 04 822 7866; E-mail:
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Lee MS, Ko J, Lee AR, Lee IH, Jung MA, Austin B, Chung H, Nahm S, Eom K. Effects of anesthetic protocol on normal canine brain uptake of 18F-FDG assessed by PET/CT. Vet Radiol Ultrasound 2010; 51:130-5. [PMID: 20402395 DOI: 10.1111/j.1740-8261.2009.01636.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The purpose of this study was to assess the effects of four anesthetic protocols on normal canine brain uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) using positron emission tomography/computed tomography (PET/CT). Five clinically normal beagle dogs were anesthetized with (1) propofol/isoflurane, (2) medetomidine/pentobarbital, (3) xylazine/ketamine, and (4) medetomidine/tiletamine-zolazepam in a randomized cross-over design. The standard uptake value (SUV) of FDG was obtained in the frontal, parietal, temporal and occipital lobes, cerebellum, brainstem and whole brain, and compared within and between anesthetic protocols using the Friedman test with significance set at P < 0.05. Significant differences in SUVs were observed in various part of the brain associated with each anesthetic protocol. The SUV for the frontal and occipital lobes was significantly higher than in the brainstem in all dogs. Dogs receiving medetomidine/tiletamine-zolazepam also had significantly higher whole brain SUVs than the propofol/isoflurane group. We concluded that each anesthetic protocol exerted a different regional brain glucose uptake pattern. As a result, when comparing brain glucose uptake using PET/CT, one should consider the effects of anesthetic protocols on different regions of the glucose uptake in the dog's brain.
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Affiliation(s)
- Min Su Lee
- Department of Veterinary Diagnostic Imaging, the College of Veterinary Medicine, Konkuk University, Seoul, Korea
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Casteels C, Bormans G, Van Laere K. The effect of anaesthesia on [(18)F]MK-9470 binding to the type 1 cannabinoid receptor in the rat brain. Eur J Nucl Med Mol Imaging 2010; 37:1164-73. [PMID: 20182714 DOI: 10.1007/s00259-010-1383-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 01/05/2010] [Indexed: 11/27/2022]
Abstract
PURPOSE Small animal PET can be applied to study molecular processes in animal models of a variety of human diseases. In order to keep the animals in a restricted position during imaging, anaesthesia is in many instances inevitable. Using small animal PET and ex vivo autoradiography, we examined the influence of pentobarbital and isoflurane anaesthesia on the rat brain uptake of [(18)F]MK-9470, a radioligand for the type 1 cannabinoid receptor. METHODS PET imaging was performed on adult Wistar rats under pentobarbital (n = 6) and isoflurane anaesthesia (n = 7), and under control conditions (free moving during tracer uptake, n = 8). Parametric PET images were generated, anatomically standardized and analysed by voxel-based Statistical Parametric Mapping and a predefined volume of interest approach. Immediately after in vivo PET, brains were processed for ex vivo autoradiography using manually placed regions of interest. An extra group (n = 6) was included ex vivo, in which animals were intravenously injected without the use of anaesthetics. RESULTS Using in vivo and ex vivo molecular imaging techniques, no significant changes in absolute [(18)F]MK-9470 uptake were present in the brain of pentobarbital and isoflurane rats as compared to control conditions. Relative [(18)F]MK-9470 uptake PET values obtained applying global scaling were, however, decreased in the cortex under both anaesthetics (pentobarbital: -13.3+/-1.4%; isoflurane -8.7 +/- 3.1%), while an increase was seen in the cerebellum by 13.5 +/- 4.0% and 13.9 +/- 4.1% under pentobarbital and isoflurane, respectively. Ex vivo results were in agreement with in vivo findings. CONCLUSION These findings suggest a similar, regionally specific interference of pentobarbital and isoflurane anaesthesia with in vivo CB1 receptor imaging using [(18)F]MK-9470.
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Affiliation(s)
- Cindy Casteels
- Division of Nuclear Medicine, KU Leuven and University Hospital Gasthuisberg, Herestraat 49 bus 7003, 3000, Leuven, Belgium.
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Planas AM. Noninvasive Brain Imaging in Small Animal Stroke Models: MRI and PET. NEUROMETHODS 2010. [DOI: 10.1007/978-1-60761-750-1_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Yu M, Guaraldi MT, Bozek J, Kagan M, Azure M, Radeke H, Cdebaca M, Robinson SP. Effects of food intake and anesthetic on cardiac imaging and uptake of BMS747158-02 in comparison with FDG. J Nucl Cardiol 2009; 16:763-8. [PMID: 19548049 DOI: 10.1007/s12350-009-9088-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 03/20/2009] [Accepted: 04/19/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND BMS747158-02 is an (18)F-labeled agent being developed for PET myocardial perfusion imaging. This study examined impacts of feeding state and anesthetic on cardiac imaging and uptake of this agent in rats in comparison with (18)F-fluorodeoxyglucose (FDG). METHODS AND RESULTS Studies were performed in rats either nonfasted or food deprived for 20 hours and anesthetized with either sodium pentobarbital (Pentob) or ketamine and xylazine (Ket/Xyl). Influences of the feeding state and anesthesia were examined by measurement of blood glucose levels, and tissue biodistribution and cardiac imaging of BMS747158-02 and FDG. The blood glucose levels were lower in fasted than nonfasted rats before anesthesia (91 +/- 11 vs 122 +/- 10 mg/dL) and the levels did not significantly change when anesthetized with Pentob. However, the levels increased markedly by 262 +/- 64 mg/dL in nonfasted rats anesthetized with Ket/Xyl. At 60 minutes post-injection, the heart uptake of FDG was significantly lower in fasted than nonfasted rats (0.2 +/- 0.1 vs 2.8 +/- 1.5%ID/g). However, the heart uptake of BMS747158-02 did not differ under these conditions (3.3 +/- 0.9 vs 3.6 +/- 0.9%ID/g, respectively). In nonfasted rats, the heart uptake of FDG was markedly lower when anesthetized with Ket/Xyl than with Pentobl (0.2 +/- 0.1 vs 2.8 +/- 1.5%ID/g). In contrast, the heart uptake of BMS747158-02 was similar with both anesthetics (3.6 +/- 0.5 vs 3.6 +/- 0.9%ID/g). Consistent with the biodistribution studies, the myocardium was not visible following FDG imaging in fasted rats, but clearly seen with BMS747158-02 in both fasted and nonfasted rats anesthetized with either anesthetic. CONCLUSIONS Unlike FDG, BMS747158-02 cardiac images are clear and not affected by the feeding state and anesthetics.
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Affiliation(s)
- Ming Yu
- Discovery Biology Research, Lantheus Medical Imaging, 331 Treble Cove Rd, North Billerica, MA 01862, USA.
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Itoh T, Abe K, Zoghbi SS, Inoue O, Hong J, Imaizumi M, Pike VW, Innis RB, Fujita M. PET measurement of the in vivo affinity of 11C-(R)-rolipram and the density of its target, phosphodiesterase-4, in the brains of conscious and anesthetized rats. J Nucl Med 2009; 50:749-56. [PMID: 19372471 DOI: 10.2967/jnumed.108.058305] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED A variety of phosphodiesterases hydrolyze and terminate the effects of the intracellular second messenger 3',5'-cyclic adenosine monophosphate (cAMP). Phosphodiesterase subtype 4 (PDE4) is particularly abundant in the brain and has been imaged with (11)C-(R)-rolipram, a selective inhibitor of PDE4. We sought to measure in vivo both the binding site density (B(max)) and the radioligand affinity (1/K(D)) of (11)C-(R)-rolipram in the rat brain. We also studied 2 critical factors in small-animal PET scans: the influence of anesthesia and the difference in binding under in vivo and in vitro conditions. METHODS In vivo, B(max) and K(D) were measured in PET saturation experiments by the administration of (11)C-(R)-rolipram and various doses of carrier (R)-rolipram in conscious and isoflurane-anesthetized rats. The metabolite-corrected arterial input function was measured in each scan. To image conscious rats, the head of the rat was fixed in a holder and the animals were trained to comply with this apparatus. Bound and free (R)-rolipram levels were calculated under transient equilibrium conditions (i.e., at the time of peak specific binding). RESULTS The B(max) and K(D) of conscious rats were significantly greater than those of anesthetized rats, by 29% and 59%, respectively. In addition, the in vitro K(D) was 3-7 times greater than was the in vivo K(D), although the B(max) was similar in both conditions. CONCLUSION The in vivo B(max) and K(D) of (R)-rolipram were successfully measured in both conscious and anesthetized rats. K(D) was affected to a greater extent than was B(max) by the 2 conditions. That is, K(D) was increased in the conscious rat, compared with in the anesthetized rat, and K(D) was increased in vitro, compared with in vivo. The current study shows that the rat, a readily available species for research, can be used to measure in vivo both affinity and density of radioligand targets, which can later be directly assessed with standard in vitro techniques.
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Affiliation(s)
- Tetsuji Itoh
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
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Tokunaga M, Seneca N, Shin RM, Maeda J, Obayashi S, Okauchi T, Nagai Y, Zhang MR, Nakao R, Ito H, Innis RB, Halldin C, Suzuki K, Higuchi M, Suhara T. Neuroimaging and physiological evidence for involvement of glutamatergic transmission in regulation of the striatal dopaminergic system. J Neurosci 2009; 29:1887-96. [PMID: 19211895 PMCID: PMC2746446 DOI: 10.1523/jneurosci.2559-08.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 11/30/2008] [Accepted: 12/27/2008] [Indexed: 11/21/2022] Open
Abstract
Aberrant neurotransmissions via glutamate and dopamine receptors have been the focus of biomedical research on the molecular basis of psychiatric disorders, but the mode of their interaction is yet to be uncovered. In this study, we demonstrated the pharmacological reversal of methamphetamine-stimulated dopaminergic overflow by suppression of group I metabotropic glutamate (mGlu) receptor in living primates and rodents. In vivo positron emission tomography (PET) was conducted on cynomolgus monkeys and rats using a full agonistic tracer for dopamine D(2/3) receptor, [(11)C]MNPA [(R)-2-(11)CH(3)O-N-n-propylnorapomorphine], and fluctuation of kinetic data resulting from anesthesia was avoided by scanning awake subjects. Excessive release of dopamine induced by methamphetamine and abolishment of this alteration by treatment with an antagonist of group I mGlu receptors, 2-methyl-6-(phenylethynyl)pyridine (MPEP), were measured in both species as decreased binding potential because of increased dopamine and its recovery to baseline levels, respectively. Counteraction of MPEP to the methamphetamine-induced dopamine spillover was also supported neurochemically by microdialysis of unanesthetized rat striatum. Moreover, patch-clamp electrophysiological assays using acute brain slices prepared from rats indicated that direct targets of MPEP mechanistically involved in the effects of methamphetamine are present locally within the striatum. Because MPEP alone did not markedly alter the baseline dopaminergic neurotransmission according to our PET and electrophysiological data, the present findings collectively extend the insights on dopamine-glutamate cross talk from extrastriatal localization of responsible mGlu receptors to intrastriatal synergy and support therapeutic interventions in case of disordered striatal dopaminergic status using group I mGlu receptor antagonists assessable by in vivo imaging techniques.
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Affiliation(s)
- Masaki Tokunaga
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Nicholas Seneca
- Molecular Imaging Branch, National Institute of Mental Health–National Institutes of Health, Bethesda, Maryland 20892, and
| | - Ryong-Moon Shin
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Jun Maeda
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Shigeru Obayashi
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Takashi Okauchi
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Yuji Nagai
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Ming-Rong Zhang
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Ryuji Nakao
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Hiroshi Ito
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Robert B. Innis
- Molecular Imaging Branch, National Institute of Mental Health–National Institutes of Health, Bethesda, Maryland 20892, and
| | - Christer Halldin
- Department of Clinical Neuroscience, Psychiatry Section, Kalorinska Institute, S-17176 Stockholm, Sweden
| | - Kazutoshi Suzuki
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Makoto Higuchi
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Tetsuya Suhara
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
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Metabotropic glutamate receptor modulation, translational methods, and biomarkers: relationships with anxiety. Psychopharmacology (Berl) 2008; 199:389-402. [PMID: 18322676 DOI: 10.1007/s00213-008-1096-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 01/28/2008] [Indexed: 01/31/2023]
Abstract
RATIONALE The increasing awareness of the need to align clinical and preclinical research to facilitate rapid development of new drug therapies is reflected in the recent introduction of the term "translational medicine". This review examines the implications of translational medicine for psychiatric disorders, focusing on metabotropic glutamate (mGlu) receptor biology in anxiety disorders and on anxiety-related biomarkers. OBJECTIVES This review aims to (1) examine recent progress in translational medicine, emphasizing the role that translational research has played in understanding of the potential of mGlu receptor agonists and antagonists as anxiolytics, (2) identify lacunas where animal and human research have yet to be connected, and (3) suggest areas where translational research can be further developed. RESULTS Current data show that animal and human mGlu(5) binding can be directly compared in experiments using the PET ligand (11)C-ABP688. Testing of the mGlu(2/3) receptor agonist LY354740 in the fear-potentiated startle paradigm allows direct functional comparisons between animals and humans. LY354740 has been tested in panic models, but in different models in rats and humans, hindering efforts at translation. Other potentially translatable methods, such as stress-induced hyperthermia and HPA-axis measures, either have been underexploited or are associated with technical difficulties. New techniques such as quantitative trait loci (QTL) analysis may be useful for generating novel biomarkers of anxiety. CONCLUSIONS Translational medicine approaches can be valuable to the development of anxiolytics, but the amount of cross-fertilization between clinical and pre-clinical departments will need to be expanded to realize the full potential of these approaches.
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Toyama H, Hatano K, Suzuki H, Ichise M, Momosaki S, Kudo G, Ito F, Kato T, Yamaguchi H, Katada K, Sawada M, Ito K. In vivo imaging of microglial activation using a peripheral benzodiazepine receptor ligand: [11C]PK-11195 and animal PET following ethanol injury in rat striatum. Ann Nucl Med 2008; 22:417-24. [PMID: 18600420 DOI: 10.1007/s12149-008-0136-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Accepted: 02/19/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To investigate whether [(11)C]PK-11195, a specific peripheral benzodiazepine receptors (PBRs) ligand for positron emission tomography (PET), can show activated microglia in a rat brain injury model. METHODS On day 1, ethanol was injected into the rat's right striatum (ST) using a stereotaxic operative procedure. On day 3, head magnetic resonance imaging (MRI) scans for surgically treated rats were performed to evaluate ethanol injury morphologically. On day 4, dynamic PET scans (17 injured rats and 7 non-injured controls) were performed for 60 min with an animal PET scanner under chloral hydrate anesthesia following a bolus injection of [(11)C]PK-11195 through tail vein. Because PBRs are present throughout the brain, there is no suitable receptor-free reference region. The reference tissue model may not be applicable because of low target to background ratio for low affinity of [(11)C]PK-11195 to PBRs. We evaluated the PBRs binding with regions of interest (ROIs)-based approach to estimate total distribution volume (V). We used an integral from 0 min to 60 min (V (60)) as an estimate of V. On the coronal PET image, ROIs were placed on bilateral ST. Differences in right/left ST V (60) ratios between lesioned and unlesioned control rats were compared using unpaired t tests. Immunohistochemical staining was performed for confirming the presence of activated microglia following decapitation on the PET experiment day. RESULTS The right/left ST V (60) ratios in lesioned rats (1.07 +/- 0.08) were significantly higher than those in unlesioned control rats (1.00 +/- 0.06, P < 0.05). On immunohistochemical staining, activated microglia were exclusively observed in the injured right ST but not in the noninjured left ST of the injury rats and the bilateral ST of the non-injured control rats. CONCLUSIONS These results suggest that [(11)C]PK-11195 PET imaging would be a useful tool for evaluating microglial activation in a rat brain injury model.
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Affiliation(s)
- Hiroshi Toyama
- Department of Radiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, Japan.
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Imaging dopamine release with Positron Emission Tomography (PET) and 11C-raclopride in freely moving animals. Neuroimage 2008; 41:1051-66. [DOI: 10.1016/j.neuroimage.2008.02.065] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 02/16/2008] [Accepted: 02/29/2008] [Indexed: 11/19/2022] Open
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Affiliation(s)
- Simon M Ametamey
- Center for Radiopharmaceutical Science of ETH, PSI and USZ, Department of Chemistry and Applied Biosciences of ETH, CH-8093 Zurich, Switzerland.
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Hildebrandt IJ, Su H, Weber WA. Anesthesia and Other Considerations for in Vivo Imaging of Small Animals. ILAR J 2008; 49:17-26. [DOI: 10.1093/ilar.49.1.17] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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44
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Sakiyama Y, Hatano K, Tajima T, Kato T, Kawasumi Y, Suzuki M, Ito K. An atlas-based image registration method for dopamine receptor imaging with PET in rats. Ann Nucl Med 2007; 21:455-62. [PMID: 17952554 DOI: 10.1007/s12149-007-0049-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 06/11/2007] [Indexed: 10/22/2022]
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Kilbourn MR, Ma B, Butch ER, Quesada C, Sherman PS. Anesthesia increases in vivo N-([18F]fluoroethyl)piperidinyl benzilate binding to the muscarinic cholinergic receptor. Nucl Med Biol 2007; 34:479-82. [PMID: 17591547 DOI: 10.1016/j.nucmedbio.2007.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 04/14/2007] [Indexed: 11/30/2022]
Abstract
The in vivo binding of N-[18F]fluoroethyl-piperidinyl benzilate ([18F]FEPB) to the muscarinic cholinergic receptor was measured in awake and anesthetized rats. Studies were done using an equilibrium infusion technique to provide estimates of specific binding as distribution volume ratios. Anesthesia with either isoflurane or sodium pentobarbital produced a significant (65-90%) increase of radiotracer binding in receptor-rich brain regions (striatum, cortex, hippocampus) relative to awake controls. Pretreatment of anesthetized animals with the acetylcholinesterase inhibitor phenserine produced no further increases in radioligand binding, in contrast to the large (>70%) increases previously observed in awake animals following drug treatment. These studies demonstrate that anesthesia can produce significant changes in baseline biochemical measures that can obscure even very large effects of pharmacological challenges.
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Affiliation(s)
- Michael R Kilbourn
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48109-0552, USA.
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Strome EM, Cepeda IL, Sossi V, Doudet DJ. Evaluation of the integrity of the dopamine system in a rodent model of Parkinson's disease: small animal positron emission tomography compared to behavioral assessment and autoradiography. Mol Imaging Biol 2007; 8:292-9. [PMID: 16897319 DOI: 10.1007/s11307-006-0051-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE In the 6-hydroxydopamine (6-OHDA) rat model of Parkinson's disease (PD), it is important to determine lesion severity. This evaluation can be performed in vivo, through evaluation of dopamine (DA)-dependent motor function or with small animal positron emission tomography (microPET), or at postmortem, by examining markers for DA neurons. PROCEDURES Rats were given mild or severe unilateral 6-OHDA lesions, scanned with the tracer [(11)C](+/-)dihydrotetrabenazine ([(11)C]DTBZ), and tested on a tapered/ledged beam-walking task. At postmortem, autoradiography was performed with [(11)C]DTBZ. RESULTS Autoradiography was significantly correlated with microPET and behavioral scores, whereas the microPET and behavioral data were not significantly correlated. CONCLUSIONS This study shows that behavioral analysis, microPET, and autoradiography are all good tools for measuring the integrity of the DA system, and demonstrates the utility of the tapered/ledged beam-walking test to screen for lesion severity, as well as the importance of including postmortem analysis after in vivo imaging studies.
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Affiliation(s)
- Elissa M Strome
- Pacific Parkinson's Research Centre, University of British Columbia, Purdy Pavilion M36, 2221 Wesbrook Mall, Vancouver, BC, V6T 2B5, Canada.
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Schubiger PA. Molecular imaging with PET--open questions? ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2007:1-13. [PMID: 17172150 DOI: 10.1007/978-3-540-49527-7_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Molecular imaging has become a very popular term in medicine and can be interpreted in many different ways. It is argued that a correct definition should be 'in vivo imaging of biological processes with appropriate molecular probes'. The real challenge in molecular imaging therefore is the search for the 'optimal' molecular imaging probes. It is discussed that nuclear, optical and magnetic probes can be used. However, only PET probes have the high sensitivity to be applied generally. To develop PET probes efficiently, methods for the in vitro and in vivo characterization are discussed and alternatives compared. Some open questions with respect to the reliability of animal imaging and evaluation of the imaging data will be elucidated.
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Affiliation(s)
- P A Schubiger
- Animal Imaging Center-PET, Center for Radiopharmaceutical Science of ETH, PSI and USZ, Zürich, Switzerland.
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Ametamey SM, Honer M. Pharmacological prerequisites for PET ligands and practical issues in preclinical PET research. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2006:317-27. [PMID: 17172161 DOI: 10.1007/978-3-540-49527-7_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The development of PET radiopharmaceuticals for the non-invasive imaging of cancerous lesions, brain receptors, transporters and enzymes started more than 25 years ago. But till today no established algorithms exist to predict the success of a PET radiopharmaceutical. PET radioligand development is a challenging endeavor and predicting the success of PET ligand can be an elusive undertaking. A large number of PET radiopharmaceuticals have been developed for imaging, but so far only a few have found application as imaging agents in vivo in humans. Typically, the potential compound selected for development usually has the desired in vitro characteristics but unknown in vivo properties. The purpose of this chapter is to highlight some of the pharmacological constraints and prerequisites. Interspecies difference in metabolism and mass effects are discussed with examples. Finally, some of the practical issues related to laboratory animal imaging using anesthetic agents are also presented.
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Affiliation(s)
- S M Ametamey
- Animal Imaging Center-PET, Center for Radiopharmaceutical Science of ETH, PSI and USZ, Zürich, Switzerland.
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Udo de Haes JI, Harada N, Elsinga PH, Maguire RP, Tsukada H. Effect of fenfluramine-induced increases in serotonin release on [18F]MPPF binding: a continuous infusion PET study in conscious monkeys. Synapse 2006; 59:18-26. [PMID: 16237679 DOI: 10.1002/syn.20209] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
[(18)F]MPPF is a selective and reversible antagonist to the serotonin-1A (5-HT(1A)) receptor. The aim of the present study was to investigate whether the binding of [(18)F]MPPF is sensitive to increases in 5-HT levels. We used the 5-HT releasing agent and reuptake inhibitor fenfluramine (FEN) to increase the concentration of 5-HT. [(18)F]MPPF binding was assessed using positron emission tomography (PET) in conscious monkeys. Possible effects of blood flow on ligand binding were excluded by using a bolus-infusion paradigm. Control scans were obtained to assess the state of ligand equilibrium. FEN (5 or 10 mg/kg, i.v.) was administered between 90 and 130 min after the start of the [(18)F]MPPF infusion. The binding potential (BP) was calculated for an early interval (30 min preceding FEN administration) and late interval (20-50 min after administration of FEN). Microdialyses results showed a 20- and 35-fold increase in extracellular 5-HT levels in the prefrontal cortex after injection of FEN at a dose of 5 mg/kg and 10 mg/kg respectively. However, despite these large increases in 5-HT levels, no differences in BP were found between the control and FEN scans. These results may imply that the majority of 5-HT(1A) receptors is in the low affinity state in the living brain.
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Affiliation(s)
- Joanna I Udo de Haes
- Department of Biological Psychiatry, University Medical Center Groningen, The Netherlands.
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Kung MP, Kung HF. Mass effect of injected dose in small rodent imaging by SPECT and PET. Nucl Med Biol 2006; 32:673-8. [PMID: 16243641 DOI: 10.1016/j.nucmedbio.2005.04.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 04/02/2005] [Accepted: 04/02/2005] [Indexed: 10/25/2022]
Abstract
This paper discusses the effect of mass (chemical quantity) of injected dose on positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Commonly, PET or SPECT imaging study uses a "no-carrier added" dose, which contains a small amount of radioactive imaging agent (in picogram to microgram). For small animal (rodent) imaging studies, specifically targeting binding sites or biological processes, the mass (chemical quantity) in the dose may significantly modify the binding, pharmacokinetics and, ultimately, the imaging outcome. Due to differences in size and other physiological factors between humans and rodents, there is a dramatic divergence of mass effect between small animal and human imaging study. In small animal imaging studies, the mass, or effective dose (ED(50)), a dose required for 50% of receptor or binding site occupancy, is usually not directly related to binding potential (B(max)/K(d)) (measured by in vitro binding assay). It is likely that dynamic interplays between specific and nonspecific binding in blood circulation, transient lung retention, kidney excretion, liver-gallbladder flow, soft tissue retention as well as metabolism could each play a significant role in determining the concentration of the tracer in the target regions. When using small animal imaging for studying drug occupancy (either by a pretreatment, coinjection or chasing dose), the mass effects on imaging outcome are important factors for consideration.
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Affiliation(s)
- Mei-Ping Kung
- Department of Radiology, University of Pennsylvania, Philadelphia, 19104, USA
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