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Lizarraga KJ, Gorgulho A, Chen W, De Salles AA. Molecular imaging of movement disorders. World J Radiol 2016; 8:226-239. [PMID: 27029029 PMCID: PMC4807332 DOI: 10.4329/wjr.v8.i3.226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 11/19/2015] [Accepted: 01/07/2016] [Indexed: 02/06/2023] Open
Abstract
Positron emission tomography measures the activity of radioactively labeled compounds which distribute and accumulate in central nervous system regions in proportion to their metabolic rate or blood flow. Specific circuits such as the dopaminergic nigrostriatal projection can be studied with ligands that bind to the pre-synaptic dopamine transporter or post-synaptic dopamine receptors (D1 and D2). Single photon emission computerized tomography (SPECT) measures the activity of similar tracers labeled with heavy radioactive species such as technetium and iodine. In essential tremor, there is cerebellar hypermetabolism and abnormal GABAergic function in premotor cortices, dentate nuclei and ventral thalami, without significant abnormalities in dopaminergic transmission. In Huntington’s disease, there is hypometabolism in the striatum, frontal and temporal cortices. Disease progression is accompanied by reduction in striatal D1 and D2 binding that correlate with trinucleotide repeat length, disease duration and severity. In dystonia, there is hypermetabolism in the basal ganglia, supplementary motor areas and cerebellum at rest. Thalamic and cerebellar hypermetabolism is seen during dystonic movements, which can be modulated by globus pallidus deep brain stimulation (DBS). Additionally, GABA-A receptor activity is reduced in motor, premotor and somatosensory cortices. In Tourette’s syndrome, there is hypermetabolism in premotor and sensorimotor cortices, as well as hypometabolism in the striatum, thalamus and limbic regions at rest. During tics, multiple areas related to cognitive, sensory and motor functions become hypermetabolic. Also, there is abnormal serotoninergic transmission in prefrontal cortices and bilateral thalami, as well as hyperactivity in the striatal dopaminergic system which can be modulated with thalamic DBS. In Parkinson’s disease (PD), there is asymmetric progressive decline in striatal dopaminergic tracer accumulation, which follows a caudal-to-rostral direction. Uptake declines prior to symptom presentation and progresses from contralateral to the most symptomatic side to bilateral, correlating with symptom severity. In progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), striatal activity is symmetrically and diffusely decreased. The caudal-to-rostral pattern is lost in PSP, but could be present in MSA. In corticobasal degeneration (CBD), there is asymmetric, diffuse reduction of striatal activity, contralateral to the most symptomatic side. Additionally, there is hypometabolism in contralateral parieto-occipital and frontal cortices in PD; bilateral putamen and cerebellum in MSA; caudate, thalamus, midbrain, mesial frontal and prefrontal cortices in PSP; and contralateral cortices in CBD. Finally, cardiac sympathetic SPECT signal is decreased in PD. The capacity of molecular imaging to provide in vivo time courses of gene expression, protein synthesis, receptor and transporter binding, could facilitate the development and evaluation of novel medical, surgical and genetic therapies in movement disorders.
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Mathews WB, Burns HD, Dannals RF, Ravert HT, Naylor EM. Carbon-11 labeling of a potent, nonpeptide, at1-selective angiotensin-II receptor antagonist: MK-996. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580360804] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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3
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Wilson AA, Dasilva JN, Houle S. Facile radiolabelling and purification of 2β-[O-11CH3]-carbomethoxy-3β-aryltropanes: Radiotracers for the dopamine transporter. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580340809] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Shimada Y, Ishiwata K, Kiyosawa M, Nariai T, Oda K, Toyama H, Suzuki F, Ono K, Senda M. Mapping adenosine A(1) receptors in the cat brain by positron emission tomography with [(11)C]MPDX. Nucl Med Biol 2002; 29:29-37. [PMID: 11786273 DOI: 10.1016/s0969-8051(01)00265-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We evaluated the potential of [(11)C]MPDX as a radioligand for mapping adenosine A(1) receptors in comparison with previously proposed [(11)C]KF15372 in cat brain by PET. Two tracers showed the same brain distribution. Brain uptake of [(11)C]MPDX (Ki = 4.2 nM) was much higher and washed out faster than that of [(11)C]KF15372 (Ki = 3.0 nM), and was blocked by carrier-loading or displaced with an A(1) antagonist. The regional A(1) receptor distribution evaluated with kinetic analysis is consistent with that previously measured in vitro. [(11)C]MPDX PET has a potential for mapping adenosine A(1) receptors in brain.
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Affiliation(s)
- Yuhei Shimada
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1 Naka-cho, Itabashi-ku, Tokyo 172-0022, Tokyo, Japan
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Ishiwata K, Ogi N, Shimada J, Wang W, Ishii K, Tanaka A, Suzuki F, Senda M. Search for PET probes for imaging the globus pallidus studied with rat brain ex vivo autoradiography. Ann Nucl Med 2000; 14:461-6. [PMID: 11210099 DOI: 10.1007/bf02988292] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have evaluated the feasibility of using four positron emission tomography (PET) tracers for imaging the globus pallidus by ex vivo autoradiography in rats. The tracers investigated were [11C]KF18446, [11C]SCH 23390 and [11C]raclopride for mapping adenosine A2A, dopamine D1 and dopamine D2 receptors, respectively, and [18F]FDG. The highest uptake by the globus pallidus was found for [11C]SCH 23390, followed by [18F]FDG, [11C]KF18446 and [11C]raclopride. The receptor-specific uptake by the globus pallidus was observed in [11C]KF18446 and [11C]SCH 23390, but not in [11C]raclopride. Uptake ratios of globus pallidus to the striatum for [18F]FDG and [11C]KF18446 were approximately 0.6, which was twice as large as that for [11C]SCH 23390. In a rat model of degeneration of striatopallidal gamma-aminobutyric acid-ergic-enkephalin neurons induced by intrastriatal injection of quinolinic acid, the uptake of [11C]KF18446 by the striatum and globus pallidus was remarkably reduced. To prove the visualization of the globus pallidus by PET with [18F]FDG and [11C]KF18446, PET-MRI registration technique and advances in PET technologies providing high-resolution PET scanner will be required. The metabolic activity of the globus pallidus could then be measured by PET with [18F]FDG, and [11C]KF18446 may be a candidate tracer for imaging the pallidal terminals projecting from the striatum.
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Affiliation(s)
- K Ishiwata
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Itabashi, Japan.
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Chen YI, Brownell AL, Galpern W, Isacson O, Bogdanov M, Beal MF, Livni E, Rosen BR, Jenkins BG. Detection of dopaminergic cell loss and neural transplantation using pharmacological MRI, PET and behavioral assessment. Neuroreport 1999; 10:2881-6. [PMID: 10549790 DOI: 10.1097/00001756-199909290-00001] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We demonstrate the use of magnetic resonance imaging (MRI) for detection of neurotransmitter stimulation using the dopamine transporter ligands amphetamine and CFT (2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane) as pharmacological challenges. We demonstrate that the unilateral loss of a hemodynamic response to either amphetamine or CFT challenge by unilateral 6-hydroxydopamine lesioning is restored by transplantation of fetal dopamine neurons in the striatum. The time course for the hemodynamic changes parallels the time courses for dopamine release, measured by prior microdialysis studies, and also for the rotational behavior in the unilaterally lesioned animals. Transplantation of the fetal cells results in hemodynamic time courses after CFT or amphetamine challenges at the graft site that are identical to those induced both before transplantation and on the intact contralateral side. The transplantation also results in complete behavioral recovery. The spatial extent of the dopaminergic recovery in the lesioned striatum is the same when measured using either PET of tracer levels of [11C]CFT binding or MRI. These results show great promise for the application of pharmacological MRI for application to studies of dopamine cell loss and potential recovery in Parkinson's disease.
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Affiliation(s)
- Y I Chen
- MGH-NMR Center, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown 02129, USA
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Petric A, Barrio JR, Namavari M, Huang SC, Satyamurthy N. Synthesis of 3beta-(4-[18F]fluoromethylphenyl)- and 3beta-(2-[18F] fluoromethylphenyl)tropane-2beta-carboxylic acid methyl esters: new ligands for mapping brain dopamine transporter with positron emission tomography. Nucl Med Biol 1999; 26:529-35. [PMID: 10473191 DOI: 10.1016/s0969-8051(99)00023-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of two new dopamine transporter ligands, 3beta-(4-fluoromethylphenyl)tropane-2beta-carboxylic acid methyl ester and 3beta-(2-fluoromethylphenyl)tropane-2beta-carboxylic acid methyl ester, and their spectral characterization are described. The precursors for these ligands were prepared by TiCl4 catalyzed chloromethylation of 3beta-phenyltropane-2beta-carboxylic acid methyl ester followed by separation of the isomeric product mixture of 2- and 4-chloromethylphenyltropane derivatives. Reaction of the chloromethyl analogs with no-carrier-added [18F]fluoride ion followed by high performance liquid chromatography purification provided the corresponding [18F]fluoromethyltropanes, in good radiochemical yields, useful for imaging the brain dopamine transporter system in vivo with positron emission tomography.
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Affiliation(s)
- A Petric
- Department of Molecular and Medical Pharmacology, UCLA School of Medicine, Los Angeles, California 90095-6948, USA. p6
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8
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Suzuki F, Ishiwata K. Selective adenosine antagonists for mapping central nervous system adenosine receptors with positron emission tomography: Carbon-11 labeled KF15372 (A1) and KF17837 (A2A). Drug Dev Res 1998. [DOI: 10.1002/(sici)1098-2299(199811/12)45:3/4<312::aid-ddr30>3.0.co;2-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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9
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Ball S, Busatto GF, David AS, Jones SH, Hemsley DR, Pilowsky LS, Costa DC, Ell PJ, Kerwin RW. Cognitive functioning and GABAA/benzodiazepine receptor binding in schizophrenia: a 123I-iomazenil SPET study. Biol Psychiatry 1998; 43:107-17. [PMID: 9474443 DOI: 10.1016/s0006-3223(97)00300-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND The role of the inhibitory neurotransmitter gamma aminobutyric acid (GABA) in schizophrenia has previously been investigated using postmortem material. Recently, using single photon emission tomography (SPET) with the selective benzodiazepine antagonist 123I-Iomazenil as the radioligand, we have demonstrated an in vivo relationship between reduced GABAA/benzodiazepine receptor binding and the severity of positive symptomatology in schizophrenia. The present study aimed to build on this using the same in vivo scanning techniques, and relating findings to cognitive functioning. METHODS Ten nonpsychiatric control subjects and 15 schizophrenic patients, matched for age and handedness, were scanned. A battery of neuropsychologic tests was also administered. RESULTS Correlational analysis revealed a pattern of increased correlations between GABAA/benzodiazepine receptor binding and task performance, in the schizophrenic group compared to the control group. CONCLUSIONS Findings are preliminary but suggest a relationship between reduced GABAA/benzodiazepine receptor binding and poorer cognitive functioning, involving memory and visual attention processes, in the schizophrenic group but not in the control group. A role for GABA in the pathophysiology of schizophrenia is suggested. Limitations of the present study and suggestions for future research are discussed.
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Affiliation(s)
- S Ball
- Department of Psychology, University of London, United Kingdom
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10
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Hesslewood SR. Interactions. Clin Nucl Med 1998. [DOI: 10.1007/978-1-4899-3356-0_46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Chessell IP, Pearson RC, Heath PR, Bown DM, Francis PT. Selective loss of cholinergic receptors following unilateral intracortical injection of volkensin. Exp Neurol 1997; 147:183-91. [PMID: 9294415 DOI: 10.1006/exnr.1997.6595] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Experimental lesions and quantitative autoradiography were used to investigate the cellular distribution of neurotransmitter receptors in rats. Lesions were produced by intracortical injections of either volkensin or ricin. However, only the former is retrogradely transported and volkensin treatment causes significant loss of contralateral cortical pyramidal neurones. Binding of [3H]pirenzepine (muscarinic M1 receptors) and [3H]nicotine was reduced in contralateral cortex in volkensin compared with ricin and/or control (uninjected) animals. However, binding of [3H]8-hydroxy-2-(n-dipropylamino)tetralin (5-HT1A receptors), [3H]ketanserin (5-HT2A receptors), and [3H]1,3-dipropylcyclopentylxanthine (adenosine A1 receptors) was unchanged. The most likely explanation for these results is that M1 and nicotinic receptors are present in large numbers on those pyramidal neurones that are lost. The results are discussed in terms of the biology of cortical pyramidal neurones, drugs for Alzheimer's disease, and novel ligands for improving human brain scanning techniques.
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Affiliation(s)
- I P Chessell
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, United Kingdom
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12
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Kämpfer I, Sorger D, Schliebs R, Kärger W, Günther K, Schulze K, Knapp WH. Radioiodination of nicotine with specific activity high enough for mapping nicotinic acetylcholine receptors. EUROPEAN JOURNAL OF NUCLEAR MEDICINE 1996; 23:157-62. [PMID: 8925850 DOI: 10.1007/bf01731839] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A novel radiochemical method is presented to synthesize 5-[123I/125I/131I]-dL-nicotine by radioiodination of 5-bromonicotine. Radioiodination of the precursor 5-dL-bromonicotine was achieved using a copper (I)-assisted nucleophilic exchange reaction in the presence of reducing agent. The reaction conditions were optimized by varying pH, concentration of Sn(II) salt, ascorbic acid, Cu(I)chloride and reaction temperature. After purification by high-performance liquid chromatography the radiochemical purity of the product exceeded 98%, with a radiochemical yield of 55% and a specific activity > or =5 GBq/micromol. Specific binding of the iodinated nicotine was demonstrated in rat brain by autoradiography. The radioactivity from the specific structures was displaced by an excess of non-radioactive nicotine (10(-3)M) with KD and Bmax of 13.1+/-7.8 nM and 22+/-2.7 fmol/mg protein and unspecific binding of about 40%. The in vivo distribution of 5-[131I]iodonicotine was determined in 20 female Wistar rats at various time intervals of 15s to 90 min post injection (p.i.) by well counting and autoradiography. Brain activity peaked within 0.5 min p.i., and then showed a biexponential washout. Initially, activity within the cerebral cortex exceeded that of the cerebellum by a factor of 1.5-2.0. It was also increased in the striatum and thalamus. However, as soon as 15 min p.i. activity was almost homogeneously distributed. In conclusion, synthesis of 5-iodo-dL-nicotine (labelled with 131I, 125I or 123I, respectively) with appropriately high specific activity for receptor studies was achieved and specific binding to nicotine receptors in rat brain was demonstrated; following intravenous injection, however, there is considerable unspecific binding, obviously due to highly flow-dependent tissue retention.
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Affiliation(s)
- I Kämpfer
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 20a, D-04103 Leipzig, Germany
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13
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Abstract
In vivo imaging of neuroreceptor ligand binding in the human brain is a young discipline. In migraine patients only few studies on dopamine D2 receptor binding have been reported. Many potentially useful radiolabeled receptor ligands for SPECT investigations in humans are currently being treated in animal models. There are no reports on development of radiolabeled, specific 5HT1D receptor ligands, which would be of considerable interest in studies of migraine patients. The radiochemistry of receptor ligand development for SPECT is complex and expensive. However, once a suitable radiolabeled ligand has been developed, e.g. labeled with I-123 with a fairly long decay ratio, it can be made widely accessible to nuclear medical units. SPECT might even prove to be as powerful a tool as PET for quantification of neuroreceptor binding profiles. Quantification, though, is not a trivial problem and there is still a need for development of kinetic models that can be applied in the clinical setting, particularly for studies of acute conditions like a migraine attack.
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Affiliation(s)
- L Friberg
- Department of Neurological Surgery, University of Texas, Southwestern Medical School, Dallas 75235-8855, USA
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14
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Volk S, Maul FD, Hör G, Schreiner M, Weppner M, Holzmann T, Pflug B. Dopamine D2 receptor occupancy measured by single photon emission computed tomography with 123I-Iodobenzamide in chronic schizophrenia. Psychiatry Res 1994; 55:111-8. [PMID: 10711799 DOI: 10.1016/0925-4927(94)90005-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Single photon emission computed tomography (SPECT) with 123I-iodobenzamide (123I-IBZM) was used to study 22 chronic schizophrenic patients. The patients, who were receiving maintenance therapy with typical neuroleptics, had not shown any significant improvement since their admission to the hospital. Basal ganglia/frontal cortex ratios of the uptake of 123I-IBZM did not show significant differences on the basis of neuroleptic dosage in chlorpromazine equivalents. There were, however, significant differences in 123I-IBZM uptake in the basal ganglia among patients characterized by negative, mixed, and positive symptoms of schizophrenia. Although only a small number of patients had shown a positive response to treatment by the time of discharge, D2 receptor blockade was significantly higher in responders than in nonresponders. In addition, there was an inverse correlation between reduced activation as measured by the Brief Psychiatric Rating Scale and the basal ganglia/frontal cortex ratio. These findings suggest a complex pathogenetic link between the blockade of dopamine D2 receptors and psychopathology in chronic schizophrenic patients. SPECT studies with 123I-IBZM appear to have prognostic value in identifying chronic schizophrenic patients who respond poorly to neuroleptic treatment.
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Affiliation(s)
- S Volk
- Department of Clinical Psychiatry II, Johann Wolfgang Goethe Universität, Frankfurt am Main, Germany
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15
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Chessell IP, Francis PT, Pangalos MN, Pearson RC, Bowen DM. Localisation of muscarinic (m1) and other neurotransmitter receptors on corticofugal-projecting pyramidal neurones. Brain Res 1993; 632:86-94. [PMID: 8149248 DOI: 10.1016/0006-8993(93)91142-f] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Experimental lesions and quantitative autoradiography were used to investigate the cellular localisation of receptors. Lesions were produced by intrastriatal injections of either volkensin or ricin, only the former is retrogradely transported. Volkensin treatment caused significant losses in Fr1/Fr2 of neocortex in the number of infragranular pyramidal neurones and binding to deep cortical layers of both [3H]pirenzepine (muscarinic cholinergic m1 receptors) and [3H]kainate (kainate sensitive glutamate receptors). In common with previous findings, which also showed sparing of interneurones, supragranular pyramidal neurones were not reduced in number and the binding to deep cortical layers of [3H]8-hydroxy-2-(n-dipropylamino)tetralin (serotonin 1A receptors) was reduced. Significant increases in [3H]prazosin binding to both total alpha adrenoceptors and the alpha 1b subtype were observed in superficial layers. Adrenoceptors were not decreased in any layer. The binding of [3H] GABA to GABAA receptors was not affected at all. Muscarinic receptors and pyramidal neurones were also reduced in deep cortical layers of Par1/Par2 in common with serotonin 1A (5-HT1A) receptors and total alpha receptors were significantly decreased in the middle layers. Overall m1 and kainate receptors were less affected than 5-HT1A receptors. The results are discussed in terms of the biology of cortical pyramidal neurones, drugs for Alzheimer's disease and novel ligands for improving human brain in vivo scanning techniques.
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MESH Headings
- 8-Hydroxy-2-(di-n-propylamino)tetralin/metabolism
- Animals
- Autoradiography
- Cerebral Cortex/metabolism
- Functional Laterality
- Glycoproteins
- Kainic Acid/metabolism
- Male
- N-Glycosyl Hydrolases
- Neurons/metabolism
- Neurotoxins/pharmacology
- Pirenzepine/metabolism
- Plant Lectins
- Plant Proteins/pharmacology
- Prazosin/metabolism
- Pyramidal Tracts/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, GABA-A/metabolism
- Receptors, Kainic Acid/metabolism
- Receptors, Muscarinic/analysis
- Receptors, Muscarinic/drug effects
- Receptors, Muscarinic/metabolism
- Receptors, Neurotransmitter/analysis
- Receptors, Neurotransmitter/drug effects
- Receptors, Neurotransmitter/metabolism
- Receptors, Serotonin/metabolism
- Ribosome Inactivating Proteins, Type 2
- Ricin/pharmacology
- Tritium
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- I P Chessell
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, UK
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16
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Abstract
This paper (Parts I and II) reviews the measures employed in studying the brain neurophysiological activities of clinical pain. In Part II, these measures include the imaging and measurement of brain blood flow and hemodynamics in various regions of the brain, the scanning of gross and fine brain structures by computerized axial tomography or magnetic resonance imaging, and the imaging and measurement of brain metabolic changes, energy uptake, and receptors bindings through positron emission tomography or single-photon emission computerized tomography. Molecular chemical transformation by the nuclear magnetic resonance analysis of tissue changes and analgesic-receptor interactions is also noted. Most studies of the cerebral measures of traumatic and pathophysiological pain reported in the literature are concerned with headache. The relationships of brain activities among sensory processes of nociception, subjective experience of pain intensity and quality, emotional reaction, and cognitive coping often are complex and not well elucidated in man. Although significant changes in the cerebral physiological parameters are frequently reported in pain patients, the specificity and sensitivity of these measures as objective markers for human pain, reviewed from Part I and Part II together, has not yet been conclusively defined. Also, normative data basis and criteria for classifying abnormality of these brain measures must be established and their validity and reliability be carefully examined so that they can be confidently applied in diagnosis and management of clinical pain. Nevertheless, advancement on measurement of temporal dynamics in 3-D topographic mapping of cortical activities and source localization modeling, together with tomographic imaging of neurochemical metabolisms in the brain will further our scientific understanding of cerebral pain mechanisms. A window on the brain of human pain is being opened.
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Zijlstra S, van der Worp H, Wiegman T, Visser GM, Korf J, Vaalburg W. Synthesis and in vivo distribution in the rat of a dopamine agonist: N-([11C]methyl)norapomorphine. Nucl Med Biol 1993; 20:7-12. [PMID: 8096418 DOI: 10.1016/0969-8051(93)90131-d] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A method for the rapid production and purification of 10,11-dihydroxy-N-([11C]methyl)norapomorphine ([11C]APO), a dopamine agonist (DA), is described. The potency of this ligand for studying the D2-receptors was examined. The label was introduced by N-methylation of norapomorphine hydrobromide with no-carrier-added (n.c.a) [11C]CH3I, produced from cyclotron-produced [11C]carbon dioxide. In 60 min (EOB) a radiochemical yield of 15% (corrected for decay) was achieved, based on [11C]CH3I. The specific activity ranged from 5 to 11 GBq/mumol. The distribution, after intravenous injection, was studied in rats. The radioactivity level in the striatum was higher than in the cerebellum and frontal cortex and was decreased after D2-blockade. The highest uptake ratio (1.47) was found at 30 min after injection. Dopamine depletion with reserpine did increase the striatum/cerebellum ratio at a low dosage of [11C]APO (10 nmol/kg). High uptakes of [11C]apomorphine were found in the lungs, liver and kidneys.
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Affiliation(s)
- S Zijlstra
- PET Center, University Hospital, Groningen, The Netherlands
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18
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Van der Krogt JA, Pauwels EK, Van Doremalen PA, Wijnhoven G, Reiffers S, Van Valkenburg CF, Buruma OJ. 4-[123I]iodospiperone as a ligand for dopamine DA receptors: in vitro and in vivo experiments in a rat model. INTERNATIONAL JOURNAL OF RADIATION APPLICATIONS AND INSTRUMENTATION. PART B, NUCLEAR MEDICINE AND BIOLOGY 1992; 19:759-63. [PMID: 1399697 DOI: 10.1016/0883-2897(92)90137-n] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Radioiodinated spiperone is of interest for dopamine (DA) receptor studies in the living human brain by single photon emission computed tomography (SPECT). Stimulated by data obtained with [11C]-N-methyl-spiperone we synthesized 4-[123I]iodospiperone and investigated the in vitro binding characteristics of this ligand to the striatal membrane of the rat and the in vivo distribution over various rat brain regions. The in vitro binding experiments showed that this radioligand displays about 10 times less affinity for the DA receptor than spiperone and specific binding, as shown with [3H]spiperone, was not observed. Displacement by butaclamol was not observed. The in vivo studies demonstrated that both 4-[123I]iodospiperone and [3H]spiperone concentrate in striatal tissue, respectively, 1.9 and 3.5 times as high as in cerebellar tissue. Haloperidol pretreatment largely prevented this accumulation. In view of the obtained target-to-non-target ratios we believe, however, that this accumulation in brain areas rich in DA-receptors does not offer prospects for clinical receptor imaging with SPECT.
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19
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Ponto LL, Ponto JA. Uses and limitations of positron emission tomography in clinical pharmacokinetics/dynamics (Part II). Clin Pharmacokinet 1992; 22:274-83. [PMID: 1606787 DOI: 10.2165/00003088-199222040-00003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Positron emission tomography (PET) involves imaging the biodistribution and tissue localisation of small amounts of radiolabelled biomolecules or drugs. In Part I of this article, which appeared in the previous issue of the Journal, the applications of pharmacokinetics in PET were discussed in order to derive quantitative measures of physiological function. Part II examines the use of PET imaging as a tool to study the pharmacokinetics and pharmacodynamics of specific drugs.
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Affiliation(s)
- L L Ponto
- PET Imaging Center, Department of Radiology, University of Iowa, Iowa City
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Affiliation(s)
- P J Ell
- Institute of Nuclear Medicine, University College & Middlesex School of Medicine, London, UK
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21
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Bendriem B, Dewey SL, Schlyer DJ, Wolf AP, Volkow ND. Quantitation of the human basal ganglia with positron emission tomography: a phantom study of the effect of contrast and axial positioning. IEEE TRANSACTIONS ON MEDICAL IMAGING 1991; 10:216-222. [PMID: 18222819 DOI: 10.1109/42.79480] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The accurate measurement of the concentration of a radioisotope in small structures with positron emission tomography (PET) requires a correction for quantitation loss due to the partial volume effect and the effect of scattered radiation. To evaluate errors associated with measures in the human basal ganglia (BG), a unilateral model of the BG has been inserted in a 20-cm cylinder. The recovery coefficient (RC=measured activity/true activity) for the BG phantom has been measured on a CTI tomograph with different background concentrations (contrast) and at different axial locations in the gantry. The BG was visualized on four or five slices, depending on its position in the gantry and on the contrast used. The RC was 0.75 with no background (contrast equal to 1.0). Increasing the relative radioactivity concentration in the background increased the RC from 0.75 to 2.00 when the contrast was -0.7 (BG<background). The RC was also affected by the size and the shape of the region of interest (ROI) used (RC from 0.75 to 0.67 with ROI size from 0.12 to 1.41 cm(2)). These results show that accurate RC correction depends not only on the volume of the structure but also on its contrast with its surroundings, as well as on the selection of the ROI.
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Wilson AA, Scheffel UA, Dannals RF, Stathis M, Ravert HT, Wagner HN. In vivo biodistribution of two [18F]-labelled muscarinic cholinergic receptor ligands: 2-[18F]- and 4-[18F]-fluorodexetimide. Life Sci 1991; 48:1385-94. [PMID: 2008155 DOI: 10.1016/0024-3205(91)90435-e] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Two [18F]-labelled analogues of the potent muscarinic cholinergic receptor (m-AChR) antagonist, dexetimide, were evaluated as potential ligands for imaging m-AChR by positron emission tomography (PET). Intravenous administration of both 2-[18F]- or 4-[18F]-fluorodexetimide resulted in high brain uptake of radioactivity in mice. High binding levels were observed in m-AChR rich areas, such as cortex and striatum, with low levels in the receptor-poor cerebellum. Uptake of radioactivity was saturable and could be blocked by pre-administration of dexetimide or atropine. Drugs with different sites of action were ineffective at blocking receptor binding. The results indicate that both radiotracers are promising candidates for use in PET studies.
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Affiliation(s)
- A A Wilson
- Division of Nuclear Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205-2179
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Verbruggen AM. Radiopharmaceuticals: state of the art. EUROPEAN JOURNAL OF NUCLEAR MEDICINE 1990; 17:346-64. [PMID: 2286208 DOI: 10.1007/bf01268027] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the past four years most of the effort in radiopharmaceutical chemistry has been devoted to compounds for positron emission tomography, but widespread use of this technique is still compromised by its high cost. On the other hand, steady progress has also been made in the development of technetium-99m-labelled radiopharmaceuticals. A variety of 99mTc-labelled agents is now available or in clinical evaluation for the study of brain perfusion (99mTc-labelled HMPAO, ECD, MRP20), myocardial perfusion (99mTc-labelled MIBI, teboroxime and phosphines) and renal function (99mTc-MAG3, 99mTc-L,L-EC). Different direct reduction methods and indirect conjugation methods have been developed to label antibodies or their fragments efficiently with 99mTc with preservation of immunoreactivity. However, the strict requirements of the regulatory authorities with respect to purification and quality of these preparations limit their use drastically in clinical practice. Radiopharmaceuticals labelled with beta-emitting radionuclides for radioimmunotherapy and palliative treatment of skeletal metastases are receiving increasing interest. Numerous agents are now available for imaging inflammation, but more clinical experience is required to determine which of them is the most appropriate. The growing importance of radiolabelled receptor-imaging agents is apparent from the commercial availability of the first such compound in Europe.
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Affiliation(s)
- A M Verbruggen
- Laboratory of Radiopharmaceutical Chemistry I.F.W., University Hospital Gasthuisberg, K.U. Leuven, Belgium
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