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Conte M, De Feo MS, Sidrak MMA, Corica F, Gorica J, Granese GM, Filippi L, De Vincentis G, Frantellizzi V. Imaging of Tauopathies with PET Ligands: State of the Art and Future Outlook. Diagnostics (Basel) 2023; 13:diagnostics13101682. [PMID: 37238166 DOI: 10.3390/diagnostics13101682] [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: 04/05/2023] [Revised: 05/05/2023] [Accepted: 05/06/2023] [Indexed: 05/28/2023] Open
Abstract
(1) Background: Tauopathies are a group of diseases characterized by the deposition of abnormal tau protein. They are distinguished into 3R, 4R, and 3R/4R tauopathies and also include Alzheimer's disease (AD) and chronic traumatic encephalopathy (CTE). Positron emission tomography (PET) imaging represents a pivotal instrument to guide clinicians. This systematic review aims to summarize the current and novel PET tracers. (2) Methods: Literature research was conducted on Pubmed, Scopus, Medline, Central, and the Web of Science using the query "pet ligands" and "tauopathies". Articles published from January 2018 to 9 February, 2023, were searched. Only studies on the development of novel PET radiotracers for imaging in tauopathies or comparative studies between existing PET tracers were included. (3) Results: A total of 126 articles were found, as follows: 96 were identified from PubMed, 27 from Scopus, one on Central, two on Medline, and zero on the Web of Science. Twenty-four duplicated works were excluded, and 63 articles did not satisfy the inclusion criteria. The remaining 40 articles were included for quality assessment. (4) Conclusions: PET imaging represents a valid instrument capable of helping clinicians in diagnosis, but it is not always perfect in differential diagnosis, even if further investigations on humans for novel promising ligands are needed.
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Affiliation(s)
- Miriam Conte
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Maria Silvia De Feo
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Marko Magdi Abdou Sidrak
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Ferdinando Corica
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Joana Gorica
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Giorgia Maria Granese
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Luca Filippi
- Department of Nuclear Medicine, Santa Maria Goretti Hospital, 00410 Latina, Italy
| | - Giuseppe De Vincentis
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
| | - Viviana Frantellizzi
- Department of Radiological Sciences, Oncology and Anatomo-Pathology, Sapienza University of Rome, 00161 Rome, Italy
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Chaney AM, Lopez-Picon FR, Serrière S, Wang R, Bochicchio D, Webb SD, Vandesquille M, Harte MK, Georgiadou C, Lawrence C, Busson J, Vercouillie J, Tauber C, Buron F, Routier S, Reekie T, Snellman A, Kassiou M, Rokka J, Davies KE, Rinne JO, Salih DA, Edwards FA, Orton LD, Williams SR, Chalon S, Boutin H. Prodromal neuroinflammatory, cholinergic and metabolite dysfunction detected by PET and MRS in the TgF344-AD transgenic rat model of AD: a collaborative multi-modal study. Am J Cancer Res 2021; 11:6644-6667. [PMID: 34093845 PMCID: PMC8171096 DOI: 10.7150/thno.56059] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/15/2021] [Indexed: 12/25/2022] Open
Abstract
Mouse models of Alzheimer's disease (AD) are valuable but do not fully recapitulate human AD pathology, such as spontaneous Tau fibril accumulation and neuronal loss, necessitating the development of new AD models. The transgenic (TG) TgF344-AD rat has been reported to develop age-dependent AD features including neuronal loss and neurofibrillary tangles, despite only expressing APP and PSEN1 mutations, suggesting an improved modelling of AD hallmarks. Alterations in neuronal networks as well as learning performance and cognition tasks have been reported in this model, but none have combined a longitudinal, multimodal approach across multiple centres, which mimics the approaches commonly taken in clinical studies. We therefore aimed to further characterise the progression of AD-like pathology and cognition in the TgF344-AD rat from young-adults (6 months (m)) to mid- (12 m) and advanced-stage (18 m, 25 m) of the disease. Methods: TgF344-AD rats and wild-type (WT) littermates were imaged at 6 m, 12 m and 18 m with [18F]DPA-714 (TSPO, neuroinflammation), [18F]Florbetaben (Aβ) and [18F]ASEM (α7-nicotinic acetylcholine receptor) and with magnetic resonance spectroscopy (MRS) and with (S)-[18F]THK5117 (Tau) at 15 and 25 m. Behaviour tests were also performed at 6 m, 12 m and 18 m. Immunohistochemistry (CD11b, GFAP, Aβ, NeuN, NeuroChrom) and Tau (S)-[18F]THK5117 autoradiography, immunohistochemistry and Western blot were also performed. Results: [18F]DPA-714 positron emission tomography (PET) showed an increase in neuroinflammation in TG vs wildtype animals from 12 m in the hippocampus (+11%), and at the advanced-stage AD in the hippocampus (+12%), the thalamus (+11%) and frontal cortex (+14%). This finding coincided with strong increases in brain microgliosis (CD11b) and astrogliosis (GFAP) at these time-points as assessed by immunohistochemistry. In vivo [18F]ASEM PET revealed an age-dependent increase uptake in the striatum and pallidum/nucleus basalis of Meynert in WT only, similar to that observed with this tracer in humans, resulting in TG being significantly lower than WT by 18 m. In vivo [18F]Florbetaben PET scanning detected Aβ accumulation at 18 m, and (S)-[18F]THK5117 PET revealed subsequent Tau accumulation at 25m in hippocampal and cortical regions. Aβ plaques were low but detectable by immunohistochemistry from 6 m, increasing further at 12 and 18 m with Tau-positive neurons adjacent to Aβ plaques at 18 m. NeuroChrom (a pan neuronal marker) immunohistochemistry revealed a loss of neuronal staining at the Aβ plaques locations, while NeuN labelling revealed an age-dependent decrease in hippocampal neuron number in both genotypes. Behavioural assessment using the novel object recognition task revealed that both WT & TgF344-AD animals discriminated the novel from familiar object at 3 m and 6 m of age. However, low levels of exploration observed in both genotypes at later time-points resulted in neither genotype successfully completing the task. Deficits in social interaction were only observed at 3 m in the TgF344-AD animals. By in vivo MRS, we showed a decrease in neuronal marker N-acetyl-aspartate in the hippocampus at 18 m (-18% vs age-matched WT, and -31% vs 6 m TG) and increased Taurine in the cortex of TG (+35% vs age-matched WT, and +55% vs 6 m TG). Conclusions: This multi-centre multi-modal study demonstrates, for the first time, alterations in brain metabolites, cholinergic receptors and neuroinflammation in vivo in this model, validated by robust ex vivo approaches. Our data confirm that, unlike mouse models, the TgF344-AD express Tau pathology that can be detected via PET, albeit later than by ex vivo techniques, and is a useful model to assess and longitudinally monitor early neurotransmission dysfunction and neuroinflammation in AD.
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Tiepolt S, Becker GA, Wilke S, Cecchin D, Rullmann M, Meyer PM, Barthel H, Hesse S, Patt M, Luthardt J, Wagenknecht G, Sattler B, Deuther-Conrad W, Ludwig FA, Fischer S, Gertz HJ, Smits R, Hoepping A, Steinbach J, Brust P, Sabri O. (+)-[ 18F]Flubatine as a novel α4β2 nicotinic acetylcholine receptor PET ligand-results of the first-in-human brain imaging application in patients with β-amyloid PET-confirmed Alzheimer's disease and healthy controls. Eur J Nucl Med Mol Imaging 2021; 48:731-746. [PMID: 32935187 PMCID: PMC8036219 DOI: 10.1007/s00259-020-05029-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 09/07/2020] [Indexed: 11/25/2022]
Abstract
PURPOSES We present the first in-human brain PET imaging data of the new α4β2 nicotinic acetylcholine receptor (nAChR)-targeting radioligand (+)-[18F]Flubatine. Aims were to develop a kinetic modeling-based approach to quantify (+)-[18F]Flubatine and compare the data of healthy controls (HCs) and patients with Alzheimer's disease (AD); to investigate the partial volume effect (PVE) on regional (+)-[18F]Flubatine binding; and whether (+)-[18F]Flubatine binding and cognitive test data respective β-amyloid radiotracer accumulation were correlated. METHODS We examined 11 HCs and 9 mild AD patients. All subjects underwent neuropsychological testing and [11C]PiB PET/MRI examination. (+)-[18F]Flubatine PET data were evaluated using full kinetic modeling and regional as well as voxel-based analyses. RESULTS With 270-min p.i., the unchanged parent compound amounted to 97 ± 2%. Adequate fits of the time-activity curves were obtained with the 1 tissue compartment model (1TCM). (+)-[18F]Flubatine distribution volume (binding) was significantly reduced in bilateral mesial temporal cortex in AD patients compared with HCs (right 10.6 ± 1.1 vs 11.6 ± 1.4, p = 0.049; left 11.0 ± 1.1 vs 12.2 ± 1.8, p = 0.046; one-sided t tests each). PVE correction increased not only (+)-[18F]Flubatine binding of approximately 15% but also standard deviation of 0.4-70%. Cognitive test data and (+)-[18F]Flubatine binding were significantly correlated in the left anterior cingulate, right posterior cingulate, and right parietal cortex (r > 0.5, p < 0.05 each). In AD patients, (+)-[18F]Flubatine binding and [11C]PiB standardized uptake value ratios were negatively correlated in several regions; whereas in HCs, a positive correlation between cortical (+)-[18F]Flubatine binding and [11C]PiB accumulation in the white matter was found. No adverse event related to (+)-[18F]Flubatine occurred. CONCLUSION (+)-[18F]Flubatine is a safe and stable PET ligand. Full kinetic modeling can be realized by 1TCM without metabolite correction. (+)-[18F]Flubatine binding affinity was high enough to detect group differences. Of interest, correlation between white matter β-amyloid PET uptake and (+)-[18F]Flubatine binding indicated an association between white matter integrity and availability of α4β2 nAChRs. Overall, (+)-[18F]Flubatine showed favorable characteristics and has therefore the potential to serve as α4β2 nAChR-targeting PET ligand in further clinical trials.
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Affiliation(s)
- Solveig Tiepolt
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Georg-Alexander Becker
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Stephan Wilke
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Diego Cecchin
- Department of Medicine, University-Hospital of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - Michael Rullmann
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Philipp M. Meyer
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Henryk Barthel
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Swen Hesse
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Marianne Patt
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Julia Luthardt
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Gudrun Wagenknecht
- Electronic Systems (ZEA-2), Central Institute for Engineering, Electronics and Analytics, Research Centre Juelich, Wilhelm-Johnen-Straße, 52428 Juelich, Germany
| | - Bernhard Sattler
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstraße 15, 04318 Leipzig, Germany
| | | | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstraße 15, 04318 Leipzig, Germany
| | - Hermann-Josef Gertz
- Department of Psychiatry, University of Leipzig, Semmelweisstraße 10, 04103 Leipzig, Germany
| | - René Smits
- ABX advanced biochemical compounds GmbH, Heinrich-Gläser-Straße 10, 01454 Radeberg, Germany
| | - Alexander Hoepping
- ABX advanced biochemical compounds GmbH, Heinrich-Gläser-Straße 10, 01454 Radeberg, Germany
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzener Landstr. 400, 01328 Dresden, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstraße 15, 04318 Leipzig, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Liebigstraße 18, 04103 Leipzig, Germany
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Papke RL, Lindstrom JM. Nicotinic acetylcholine receptors: Conventional and unconventional ligands and signaling. Neuropharmacology 2020; 168:108021. [PMID: 32146229 PMCID: PMC7610230 DOI: 10.1016/j.neuropharm.2020.108021] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 02/05/2020] [Accepted: 02/25/2020] [Indexed: 12/28/2022]
Abstract
Postsynaptic nAChRs in the peripheral nervous system are critical for neuromuscular and autonomic neurotransmission. Pre- and peri-synaptic nAChRs in the brain modulate neurotransmission and are responsible for the addictive effects of nicotine. Subtypes of nAChRs in lymphocytes and non-synaptic locations may modulate inflammation and other cellular functions. All AChRs that function as ligand-gated ion channels are formed from five homologous subunits organized to form a central cation channel whose opening is regulated by ACh bound at extracellular subunit interfaces. nAChR subtype subunit composition can range from α7 homomers to α4β2α6β2β3 heteromers. Subtypes differ in affinities for ACh and other agonists like nicotine and in efficiencies with which their channels are opened and desensitized. Subtypes also differ in affinities for antagonists and for positive and negative allosteric modulators. Some agonists are "silent" with respect to channel opening, and AChRs may be able to signal metabotropic pathways by releasing G-proteins independent of channel opening. Electrophysiological studies that can resolve single-channel openings and molecular genetic approaches have allowed characterization of the structures of ligand binding sites, the cation channel, and the linkages between them, as well as the organization of AChR subunits and their contributions to function. Crystallography and cryo-electron-microscopy are providing increasing insights into the structures and functions of AChRs. However, much remains to be learned about both AChR structure and function, the in vivo functional roles of some AChR subtypes, and the development of better pharmacological tools directed at AChRs to treat addiction, pain, inflammation, and other medically important issues. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, P.O. Box 100267, Gainesville, FL, 32610-0267, USA.
| | - Jon M Lindstrom
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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King MD, Long T, Pfalmer DL, Andersen TL, McDougal OM. SPIDR: small-molecule peptide-influenced drug repurposing. BMC Bioinformatics 2018; 19:138. [PMID: 29661129 PMCID: PMC5902895 DOI: 10.1186/s12859-018-2153-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 04/09/2018] [Indexed: 11/20/2022] Open
Abstract
Background Conventional de novo drug design is costly and time consuming, making it accessible to only the best resourced research organizations. An emergent approach to new drug development is drug repurposing, in which compounds that have already gone through some level of clinical testing are examined for efficacy against diseases divergent than their original application. Repurposing of existing drugs circumvents the time and considerable cost of early stages of drug development, and can be accelerated by using software to screen existing chemical databases to identify suitable drug candidates. Results Small-molecule Peptide-Influenced Drug Repurposing (SPIDR) was developed to identify small molecule drugs that target a specific receptor by exploring the conformational binding space of peptide ligands. SPIDR was tested using the potent and selective 16-amino acid peptide α-conotoxin MII ligand and the α3β2-nicotinic acetylcholine receptor (nAChR) isoform. SPIDR incorporates a genetic algorithm-based, heuristic search procedure, which was used to explore the ligand binding domain of the α3β2-nAChR isoform using a library consisting of 640,000 α-conotoxin MII peptide analogs. The peptides that exhibited the highest affinity for α3β2-nAChR were used as models for a small-molecule structure similarity search of the PubChem Compound database. SPIDR incorporates the SimSearcher utility, which generates shape distribution signatures of molecules and employs multi-level K-means clustering to insure fast database queries. SPIDR identified non-peptide drugs with estimated binding affinities nearly double that of the native α-conotoxin MII peptide. Conclusions SPIDR has been generalized and integrated into DockoMatic v 2.1. This software contains an intuitive graphical interface for peptide mutant screening workflow and facilitates mapping, clustering, and searching of local molecular databases, making DockoMatic a valuable tool for researchers in drug design and repurposing. Electronic supplementary material The online version of this article (10.1186/s12859-018-2153-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Matthew D King
- Department of Chemistry and Biochemistry, Boise State University, Boise, USA
| | - Thomas Long
- Department of Computer Science, Boise State University, Boise, USA
| | - Daniel L Pfalmer
- Biomolecular Sciences Ph.D. Program, Boise State University, Boise, USA
| | | | - Owen M McDougal
- Department of Chemistry and Biochemistry, Boise State University, Boise, USA.
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Coughlin JM, Du Y, Rosenthal HB, Slania S, Min Koo S, Park A, Solomon G, Vranesic M, Antonsdottir I, Speck CL, Rootes-Murdy K, Lerner A, Rowe SP, Wang Y, Lesniak WG, Minn I, Bakker A, Smith GS, Dannals RF, Kuwabara H, Horti A, Wong DF, Pomper MG. The distribution of the alpha7 nicotinic acetylcholine receptor in healthy aging: An in vivo positron emission tomography study with [ 18F]ASEM. Neuroimage 2018; 165:118-124. [PMID: 28993233 PMCID: PMC5738927 DOI: 10.1016/j.neuroimage.2017.10.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 10/02/2017] [Accepted: 10/05/2017] [Indexed: 11/29/2022] Open
Abstract
Altered function of the alpha7 nicotinic acetylcholine receptor (α7-nAChR) is implicated in several neuropsychiatric diseases. Nevertheless, studies of the human cerebral α7-nAChR even in healthy aging are limited in number and to postmortem tissue. METHODS The distribution of the cerebral α7-nAChR was estimated in nine brain regions in 25 healthy volunteers (ages 21-86 years; median 57 years, interquartile range 52 years) using [18F]ASEM with positron emission tomography (PET) imaging. Regional total distribution volume (VT) measurements were calculated using the Logan method from each subject's 90 min dynamic PET data and their metabolite-corrected plasma input function. Spearman's rank or Pearson's correlation analysis was used depending on the normality of the data. Correlation between age and regional 1) volume relative to intracranial volume (volume ratio) and 2) [18F]ASEM VT was tested. Correlation between regional volume ratio and [18F]ASEM VT was also evaluated. Finally, the relationship between [18F]ASEM VT and neuropsychological measures was investigated in a subpopulation of 15 elderly healthy participants (those 50 years of age and older). Bonferroni correction for multiple comparisons was applied to statistical analyses. RESULTS A negative correlation between tissue volume ratio and age was observed in six of the nine brain regions including striatum and five cortical (temporal, occipital, cingulate, frontal, or parietal) regions. A positive correlation between [18F]ASEM VT and age was observed in all nine brain regions of interest (ROIs). There was no correlation between [18F]ASEM VT and volume ratio in any ROI after controlling for age. Regional [18F]ASEM VT and neuropsychological performance on each of eight representative subtests were not correlated among the well-performing subpopulation of elderly healthy participants. CONCLUSIONS Our results suggest an increase in cerebral α7-nAChR distribution over the course of healthy aging that should be tested in future longitudinal studies. The preservation of the α7-nAChR in the aging human brain supports the development of therapeutic agents that target this receptor for use in the elderly. Further study of the relationship between α7-nAChR availability and cognitive impairment over aging is needed.
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Affiliation(s)
- Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Yong Du
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Hailey B Rosenthal
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Stephanie Slania
- Department of Biomedical Engineering, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Soo Min Koo
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Andrew Park
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Ghedem Solomon
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Melin Vranesic
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Inga Antonsdottir
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Caroline L Speck
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Kelly Rootes-Murdy
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Alexandria Lerner
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Steven P Rowe
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Wojciech G Lesniak
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Il Minn
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Arnold Bakker
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Gwenn S Smith
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Robert F Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Hiroto Kuwabara
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Andrew Horti
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Dean F Wong
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins Medical Institutions, Baltimore, MD, USA; Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Martin G Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
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King MD, Long T, Andersen T, McDougal OM. Genetic Algorithm Managed Peptide Mutant Screening: Optimizing Peptide Ligands for Targeted Receptor Binding. J Chem Inf Model 2016; 56:2378-2387. [PMID: 28024403 DOI: 10.1021/acs.jcim.6b00095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This study demonstrates the utility of genetic algorithms to search exceptionally large and otherwise intractable mutant libraries for sequences with optimal binding affinities for target receptors. The Genetic Algorithm Managed Peptide Mutant Screening (GAMPMS) program was used to search an α-conotoxin (α-CTx) MII mutant library of approximately 41 billion possible peptide sequences for those exhibiting the greatest binding affinity for the α3β2-nicotinic acetylcholine receptor (nAChR) isoform. A series of top resulting peptide ligands with high sequence homology was obtained, with each mutant having an estimated ΔGbind approximately double that of the potent native α-CTx MII ligand. A consensus sequence from the top GAMPMS results was subjected to more rigorous binding free energy calculations by molecular dynamics and compared to α-CTx MII and other related variants for binding with α3β2-nAChR. In this study, the efficiency of GAMPMS to substantially reduce the sample population size through evolutionary selection criteria to produce ligands with higher predicted binding affinity is demonstrated.
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Affiliation(s)
- Matthew D King
- Department of Chemistry and Biochemistry and ‡Department of Computer Science, Boise State University , 1910 University Drive, Boise, Idaho 83725, United States
| | - Thomas Long
- Department of Chemistry and Biochemistry and ‡Department of Computer Science, Boise State University , 1910 University Drive, Boise, Idaho 83725, United States
| | - Timothy Andersen
- Department of Chemistry and Biochemistry and ‡Department of Computer Science, Boise State University , 1910 University Drive, Boise, Idaho 83725, United States
| | - Owen M McDougal
- Department of Chemistry and Biochemistry and ‡Department of Computer Science, Boise State University , 1910 University Drive, Boise, Idaho 83725, United States
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LC-MS Supported Studies on the in Vitro Metabolism of both Enantiomers of Flubatine and the in Vivo Metabolism of (+)-[(18)F]Flubatine-A Positron Emission Tomography Radioligand for Imaging α4β2 Nicotinic Acetylcholine Receptors. Molecules 2016; 21:molecules21091200. [PMID: 27617996 PMCID: PMC6273452 DOI: 10.3390/molecules21091200] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 12/27/2022] Open
Abstract
Both enantiomers of [18F]flubatine are promising radioligands for neuroimaging of α4β2 nicotinic acetylcholine receptors (nAChRs) by positron emission tomography (PET). To support clinical studies in patients with early Alzheimer’s disease, a detailed examination of the metabolism in vitro and in vivo has been performed. (+)- and (−)-flubatine, respectively, were incubated with liver microsomes from mouse and human in the presence of NADPH (β-nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt). Phase I in vitro metabolites were detected and their structures elucidated by LC-MS/MS (liquid chromatography-tandem mass spectrometry). Selected metabolite candidates were synthesized and investigated for structural confirmation. Besides a high level of in vitro stability, the microsomal incubations revealed some species differences as well as enantiomer discrimination with regard to the formation of monohydroxylated products, which was identified as the main metabolic pathway in this assay. Furthermore, after injection of 250 MBq (+)-[18F]flubatine (specific activity > 350 GBq/μmol) into mouse, samples were prepared from brain, liver, plasma, and urine after 30 min and investigated by radio-HPLC (high performance liquid chromatography with radioactivity detection). For structure elucidation of the radiometabolites of (+)-[18F]flubatine formed in vivo, identical chromatographic conditions were applied to LC-MS/MS and radio-HPLC to compare samples obtained in vitro and in vivo. By this correlation approach, we assigned three of four main in vivo radiometabolites to products that are exclusively C- or N-hydroxylated at the azabicyclic ring system of the parent molecule.
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Baier CJ, Pallarés ME, Adrover E, Monteleone MC, Brocco MA, Barrantes FJ, Antonelli MC. Prenatal restraint stress decreases the expression of alpha-7 nicotinic receptor in the brain of adult rat offspring. Stress 2015; 18:435-45. [PMID: 25798813 DOI: 10.3109/10253890.2015.1022148] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Prenatal stress (PS) strongly impacts fetal brain development and function in adulthood. In normal aging and Alzheimer's disease, there is hypothalamic-pituitary-adrenal axis dysfunction and loss of cholinergic neurons and neuronal nicotinic acetylcholine receptors (nAChRs). This study investigated whether prenatal restraint stress affects nAChR expression in the brain of adult offspring. For PS, pregnant dams were placed in a plastic restrainer for 45 min, three times daily during the last week of pregnancy; controls were undisturbed. Male offspring were analyzed at postnatal day (PND) 60 (n = 4 rats per group). Western blot (WB) and fluorescence microscopy showed that PS decreased α7-AChR subunit expression (∼50%) in the frontal cortex in the adult offspring. PS decreased significantly the number of α7-AChR-expressing cells in the medial prefrontal cortex (by ∼25%) and in the sensory-motor cortex (by ∼20%) without affecting the total cell number in those areas. No alterations were found in the hippocampus by quantitative polymerase chain reaction (qPCR), or WB analysis, but a detailed fluorescence microscopy analysis showed that PS affected α7-AChR mainly in the CA3 and dentate gyrus subfields: PS decreased α7-AChR subunit expression by ∼25 and ∼30%, respectively. Importantly, PS decreased the number of α7-AChR-expressing cells and the total cell number (by ∼15 and 20%, respectively) in the dentate gyrus. PS differently affected α4-AChR: PS impaired its mRNA expression in the frontal cortex (by ∼50%), without affecting protein levels. These results demonstrate that disturbances during gestation produce long-term alterations in the expression pattern of α7-AChR in rat brain.
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Affiliation(s)
- Carlos J Baier
- a Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional del Sur (UNS) , Bahía Blanca , Argentina
| | - María E Pallarés
- b Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Ezequiela Adrover
- b Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Melisa C Monteleone
- c Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomus (IIBINTECH), Universidad Nacional de San Martín (UNSAM) - CONICET , San Martín, Buenos Aires , Argentina , and
| | - Marcela A Brocco
- c Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomus (IIBINTECH), Universidad Nacional de San Martín (UNSAM) - CONICET , San Martín, Buenos Aires , Argentina , and
| | - Francisco J Barrantes
- d Laboratorio de Neurobiología Molecular , Facultad de Medicina, Instituto de Investigaciones Biomédicas (BIOMED)-UCA-CONICET, Pontificia Universidad Católica Argentina , Buenos Aires , Argentina
| | - Marta C Antonelli
- b Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires , Argentina
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Smits R, Fischer S, Hiller A, Deuther-Conrad W, Wenzel B, Patt M, Cumming P, Steinbach J, Sabri O, Brust P, Hoepping A. Synthesis and biological evaluation of both enantiomers of [(18)F]flubatine, promising radiotracers with fast kinetics for the imaging of α4β2-nicotinic acetylcholine receptors. Bioorg Med Chem 2013; 22:804-12. [PMID: 24369841 DOI: 10.1016/j.bmc.2013.12.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 11/29/2013] [Accepted: 12/05/2013] [Indexed: 11/30/2022]
Abstract
Both enantiomers of the epibatidine analogue flubatine display high affinity towards the α4β2 nicotinic acetylcholine receptor (nAChR) in vitro, accompanied by negligible interactions with diverse off-target proteins. Extended single dose toxicity studies in rodent indicated a NOEL (No Observed Effect Level) of 6.2μg/kg for (-)-flubatine and 1.55μg/kg for (+)-flubatine. We developed syntheses for both flubatine enantiomers and their corresponding precursors for radiolabeling. The newly synthesized trimethylammonium precursors allowed for highly efficient (18)F-radiolabelling in radiochemical yields >60% and specific activities >750GBq/μmol, thus making the radioligands practical for clinical investigation.
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Affiliation(s)
- René Smits
- ABX Advanced Biochemical Compounds GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Permoserstrasse-15, D-04318 Leipzig, Germany
| | - Achim Hiller
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Permoserstrasse-15, D-04318 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Permoserstrasse-15, D-04318 Leipzig, Germany
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Permoserstrasse-15, D-04318 Leipzig, Germany
| | - Marianne Patt
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Paul Cumming
- ABX Advanced Biochemical Compounds GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Permoserstrasse-15, D-04318 Leipzig, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Permoserstrasse-15, D-04318 Leipzig, Germany
| | - Alexander Hoepping
- ABX Advanced Biochemical Compounds GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany.
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Takarada T, Nakamichi N, Kawagoe H, Ogura M, Fukumori R, Nakazato R, Fujikawa K, Kou M, Yoneda Y. Possible neuroprotective property of nicotinic acetylcholine receptors in association with predominant upregulation of glial cell line-derived neurotrophic factor in astrocytes. J Neurosci Res 2012; 90:2074-85. [DOI: 10.1002/jnr.23101] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/16/2012] [Accepted: 05/24/2012] [Indexed: 11/11/2022]
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12
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Ding M, Ghanekar S, Elmore CS, Zysk JR, Werkheiser JL, Lee CM, Liu J, Chhajlani V, Maier DL. [3H]Chiba-1001(methyl-SSR180711) has low in vitro binding affinity and poor in vivo selectivity to nicotinic alpha-7 receptor in rodent brain. Synapse 2011; 66:315-22. [DOI: 10.1002/syn.21513] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 10/28/2011] [Indexed: 01/02/2023]
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13
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Kroker KS, Rast G, Rosenbrock H. Differential effects of subtype-specific nicotinic acetylcholine receptor agonists on early and late hippocampal LTP. Eur J Pharmacol 2011; 671:26-32. [PMID: 21968142 DOI: 10.1016/j.ejphar.2011.09.167] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 09/13/2011] [Accepted: 09/15/2011] [Indexed: 01/14/2023]
Abstract
Brain nicotinic acetylcholine receptors are involved in several neuropsychiatric disorders, e.g. Alzheimer's and Parkinson's diseases, Tourette's syndrome, schizophrenia, depression, autism, attention deficit hyperactivity disorder, and anxiety. Currently, approaches selectively targeting the activation of specific nicotinic acetylcholine receptors are in clinical development for treatment of memory impairment of Alzheimer's disease patients. These are α4β2 and α7 nicotinic acetylcholine receptor agonists which are believed to enhance cholinergic and glutamatergic neurotransmission, respectively. In order to gain a better insight into the mechanistic role of these two nicotinic acetylcholine receptors in learning and memory, we investigated the effects of the α4β2 nicotinic acetylcholine receptor agonist TC-1827 and the α7 nicotinic acetylcholine receptor partial agonist SSR180711 on hippocampal long-term potentiation (LTP), a widely accepted cellular experimental model of memory formation. Generally, LTP is distinguished in an early and a late form, the former being protein-synthesis independent and the latter being protein-synthesis dependent. TC-1827 was found to increase early LTP in a bell-shaped dose dependent manner, but did not affect late LTP. In contrast, the α7 nicotinic acetylcholine receptor partial agonist SSR180711 showed enhancing effects on both early and late LTP in a bell-shaped manner. Furthermore, SSR180711 not only increased early LTP, but also transformed it into late LTP, which was not observed with the α4β2 nicotinic acetylcholine receptor agonist. Therefore, based on these findings α7 nicotinic acetylcholine receptor (partial) agonists appear to exhibit stronger efficacy on memory improvement than α4β2 nicotinic acetylcholine receptor agonists.
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Affiliation(s)
- Katja S Kroker
- Boehringer Ingelheim Pharma GmbH & Co KG, Department of CNS Diseases Research, Birkendorfer Strasse 65, 88397 Biberach, Germany.
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Dinklo T, Shaban H, Thuring JW, Lavreysen H, Stevens KE, Zheng L, Mackie C, Grantham C, Vandenberk I, Meulders G, Peeters L, Verachtert H, De Prins E, Lesage ASJ. Characterization of 2-[[4-fluoro-3-(trifluoromethyl)phenyl]amino]-4-(4-pyridinyl)-5-thiazolemethanol (JNJ-1930942), a novel positive allosteric modulator of the {alpha}7 nicotinic acetylcholine receptor. J Pharmacol Exp Ther 2010; 336:560-74. [PMID: 21084390 DOI: 10.1124/jpet.110.173245] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The α(7) nicotinic acetylcholine receptor (nAChR) is a potential therapeutic target for the treatment of cognitive deficits associated with schizophrenia, Alzheimer's disease, Parkinson's disease, and attention-deficit/hyperactivity disorder. Activation of α(7) nAChRs improved sensory gating and cognitive function in animal models and in early clinical trials. Here we describe the novel highly selective α(7) nAChR positive allosteric modulator, 2-[[4-fluoro-3-(trifluoromethyl)phenyl]amino]-4-(4-pyridinyl)-5-thiazolemethanol (JNJ-1930942). This compound enhances the choline-evoked rise in intracellular Ca(2+) levels in the GH4C1 cell line expressing the cloned human α(7) nAChR. JNJ-1930942 does not act on α4β2, α3β4 nAChRs or on the related 5-HT3A channel. Electrophysiological assessment in the GH4C1 cell line shows that JNJ-1930942 increases the peak and net charge response to choline, acetylcholine, and N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide (PNU-282987). The potentiation is obtained mainly by affecting the receptor desensitization characteristics, leaving activation and deactivation kinetics as well as recovery from desensitization relatively unchanged. Choline efficacy is increased over its full concentration response range, and choline potency is increased more than 10-fold. The potentiating effect is α(7) channel-dependent, because it is blocked by the α(7) antagonist methyllycaconitine. Moreover, in hippocampal slices, JNJ-1930942 enhances neurotransmission at hippocampal dentate gyrus synapses and facilitates the induction of long-term potentiation of electrically evoked synaptic responses in the dentate gyrus. In vivo, JNJ-1930942 reverses a genetically based auditory gating deficit in DBA/2 mice. JNJ-1930942 will be a useful tool to study the therapeutic potential of α(7) nAChR potentiation in central nervous system disorders in which a deficit in α(7) nAChR neurotransmission is hypothesized to be involved.
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Affiliation(s)
- Theo Dinklo
- Johnson & Johnson Pharmaceutical Research and Development, Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium
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15
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Figueiró M, Ilha J, Pochmann D, Porciúncula LO, Xavier LL, Achaval M, Nunes DS, Elisabetsky E. Acetylcholinesterase inhibition in cognition-relevant brain areas of mice treated with a nootropic Amazonian herbal (Marapuama). PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2010; 17:956-962. [PMID: 20833520 DOI: 10.1016/j.phymed.2010.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The goal of acetylcholinesterase inhibitors (AChEIs) used to treat Alzheimer's patients is an improvement in cholinergic transmission. While currently available AChEIs have limited success, a huge impediment to the development of newer ones is access to the relevant brain areas. Promnesic, anti-amnesic and AChEI properties were identified in a standardized ethanol extract from Ptychopetalum olacoides (POEE), a medicinal plant favored by the elderly in Amazon communities. The purpose of this study was to provide conclusive evidence that orally given POEE induces AChE inhibition in brain areas relevant to cognition. Histochemistry experiments confirmed that the anticholinesterase compound(s) present in POEE are orally bioavailable, inducing meaningful AChE inhibition in the hippocampus CA1 (∼33%) and CA3 (∼20%), and striatum (∼17%). Ellman's colorimetric analysis revealed that G1 and G4 AChE isoforms activities were markedly inhibited (66 and 72%, respectively) in hippocampus and frontal cortex (50 and 63%, respectively), while G4 appeared to be selectively inhibited (72%) in the striatum. Western blotting showed that POEE did not induce significant changes in the AChE immunocontent suggesting that its synthesis is not extensively modified. This study provides definitive proof of meaningful anticholinesterase activity compatible with the observed promnesic and anti-amnesic effects of POEE in mice, reaffirming the potential of this extract for treating neurodegenerative conditions where a hypofunctioning cholinergic neurotransmission is prominent. Adequate assessment of the safety and efficacy of this extract and/or its isolated active compound(s) are warranted.
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Affiliation(s)
- M Figueiró
- Laboratório de Etnofarmacologia, ICBS, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite, 500, Porto Alegre, RS, Brazil
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16
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A transcriptional regulatory element critical for CHRNB4 promoter activity in vivo. Neuroscience 2010; 170:1056-64. [PMID: 20696214 DOI: 10.1016/j.neuroscience.2010.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 08/01/2010] [Accepted: 08/03/2010] [Indexed: 11/23/2022]
Abstract
Genome-wide association studies have underscored the importance of the clustered neuronal nicotinic acetylcholine receptor (nAChR) subunit genes with respect to nicotine dependence as well as lung cancer susceptibility. CHRNB4, which encodes the nAChR β4 subunit, plays a major role in the molecular mechanisms that govern nicotine withdrawal. Thus, elucidating how expression of the β4 gene is regulated is critical for understanding the pathophysiology of nicotine addiction. We previously identified a CA box regulatory element, (5'-CCACCCCT-3') critical for β4 promoter activity in vitro. We further demonstrated that a 2.3-kb fragment of the β4 promoter region containing the 5'-CCACCCCT-3' regulatory element in the β4 gene promoter (CA box) is capable of directing cell-type specific expression of a reporter gene to a myriad of brain regions that endogenously express the β4 gene. To test the hypothesis that the CA box is critical for β4 promoter activity in vivo, transgenic animals expressing a mutant form of the β4 promoter were generated. Reporter gene expression was not detected in any tissue or cell type at embryonic day 18.5 (ED 18.5). Similarly, we observed drastically reduced reporter gene expression at postnatal day 30 (PD30) when compared to wild type (WT) transgenic animals. Finally, we demonstrated that CA box mutation results in decreased interaction of the transcription factor Sp1 with the mutant β4 promoter. Taken together these results demonstrate that the CA box is critical for β4 promoter activity in vivo.
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17
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Improgo MRD, Scofield MD, Tapper AR, Gardner PD. The nicotinic acetylcholine receptor CHRNA5/A3/B4 gene cluster: dual role in nicotine addiction and lung cancer. Prog Neurobiol 2010; 92:212-26. [PMID: 20685379 DOI: 10.1016/j.pneurobio.2010.05.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/15/2010] [Accepted: 05/27/2010] [Indexed: 01/19/2023]
Abstract
More than 1 billion people around the world smoke, with 10 million cigarettes sold every minute. Cigarettes contain thousands of harmful chemicals including the psychoactive compound, nicotine. Nicotine addiction is initiated by the binding of nicotine to nicotinic acetylcholine receptors, ligand-gated cation channels activated by the endogenous neurotransmitter, acetylcholine. These receptors serve as prototypes for all ligand-gated ion channels and have been extensively studied in an attempt to elucidate their role in nicotine addiction. Many of these studies have focused on heteromeric nicotinic acetylcholine receptors containing α4 and β2 subunits and homomeric nicotinic acetylcholine receptors containing the α7 subunit, two of the most abundant subtypes expressed in the brain. Recently however, a series of linkage analyses, candidate-gene analyses and genome-wide association studies have brought attention to three other members of the nicotinic acetylcholine receptor family: the α5, α3 and β4 subunits. The genes encoding these subunits lie in a genomic cluster that contains variants associated with increased risk for several diseases including nicotine dependence and lung cancer. The underlying mechanisms for these associations have not yet been elucidated but decades of research on the nicotinic receptor gene family as well as emerging data provide insight on how these receptors may function in pathological states. Here, we review this body of work, focusing on the clustered nicotinic acetylcholine receptor genes and evaluating their role in nicotine addiction and lung cancer.
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Affiliation(s)
- Ma Reina D Improgo
- Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, 303 Belmont Street, Worcester, MA 01604, United States
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18
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Bruschweiler-Li L, Fuentes Medel YF, Scofield MD, Trang EBT, Binke SA, Gardner PD. Temporally- and spatially-regulated transcriptional activity of the nicotinic acetylcholine receptor beta4 subunit gene promoter. Neuroscience 2010; 166:864-77. [PMID: 20096338 DOI: 10.1016/j.neuroscience.2010.01.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 11/27/2022]
Abstract
Signaling through nicotinic acetylcholine (nACh) receptors underlies a diverse array of behaviors. In order for appropriate signaling to occur via nACh receptors, it is necessary for the genes encoding the receptor subunits to be expressed in a highly regulated temporal and spatial manner. Here we report a transgenic mouse approach to characterize the transcriptional regulation of the gene encoding the nACh receptor beta4 subunit. nACh receptors containing this subunit play critical roles in both the central and peripheral nervous systems. We demonstrate that a 2.3-kilobase pair fragment of the beta4 5'-flanking region is capable of directing reporter gene expression in transgenic animals. Importantly, the transcriptional activity of the promoter region is cell-type-specific and developmentally regulated and overlaps to a great extent with endogenous beta4 mRNA expression. These data indicate that the 2.3-kilobase pair fragment contains transcriptional regulatory elements critical for appropriate beta4 subunit gene expression.
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Affiliation(s)
- L Bruschweiler-Li
- Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, Worcester, MA 01604, USA
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Ikonomovic MD, Wecker L, Abrahamson EE, Wuu J, Counts SE, Ginsberg SD, Mufson EJ, Dekosky ST. Cortical alpha7 nicotinic acetylcholine receptor and beta-amyloid levels in early Alzheimer disease. ACTA ACUST UNITED AC 2009; 66:646-51. [PMID: 19433665 DOI: 10.1001/archneurol.2009.46] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To examine alpha7 nicotinic acetylcholine receptor (nAChR) binding and beta-amyloid (Abeta) peptide load in superior frontal cortex (SFC) across clinical and neuropathological stages of Alzheimer disease (AD). DESIGN Quantitative measures of alpha7 nAChR by [(3)H]methyllycaconitine binding and Abeta concentration by enzyme-linked immunosorbent assay in SFC were compared across subjects with antemortem clinical classification of no cognitive impairment, mild cognitive impairment, or mild to moderate AD, and with postmortem neuropathological diagnoses. SETTING Academic medical center. Subjects Twenty-nine elderly retired clergy. MAIN OUTCOME MEASURES Quantitative measures of alpha7 nAChR binding and Abeta peptide concentration in SFC. RESULTS Higher concentrations of total Abeta peptide in SFC were associated with clinical diagnosis of mild to moderate AD (P = .02), lower Mini-Mental State Examination scores (P = .003), presence of cortical Abeta plaques (P = .02), and likelihood of AD diagnosis by the National Institute on Aging-Reagan criteria (P = .002). Increased alpha7 nAChR binding was associated with National Institute on Aging-Reagan diagnosis (P = .02) and, albeit weakly, the presence of cortical Abeta plaques (P = .08). There was no correlation between the 2 biochemical measures. CONCLUSIONS These observations suggest that during the clinical progression from normal cognition to neurodegenerative disease state, total Abeta peptide concentration increases while alpha7 nAChRs remain relatively stable in SFC. Regardless of subjects' clinical status, however, elevated alpha7 nAChR binding is associated with increased Abeta plaque pathology, supporting the hypothesis that cellular expression of these receptors may be upregulated selectively in Abeta plaque-burdened brain areas.
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Affiliation(s)
- Milos D Ikonomovic
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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20
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Ellis JR, Nathan PJ, Villemagne VL, Mulligan RS, Saunder T, Young K, Smith CL, Welch J, Woodward M, Wesnes KA, Savage G, Rowe CC. Galantamine-induced improvements in cognitive function are not related to alterations in alpha(4)beta (2) nicotinic receptors in early Alzheimer's disease as measured in vivo by 2-[18F]fluoro-A-85380 PET. Psychopharmacology (Berl) 2009; 202:79-91. [PMID: 18949462 DOI: 10.1007/s00213-008-1347-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Accepted: 09/19/2008] [Indexed: 01/25/2023]
Abstract
INTRODUCTION The nicotinic acetylcholine receptor (nAChR) system plays a regulatory role in a number of cognitive processes. Cholinesterase inhibitors (i.e., galantamine) that potentiate cholinergic neurotransmission improve cognitive function in Alzheimer's disease (AD); however, the relationship between these effects and associated changes in nAChRs are yet to be established in vivo. MATERIALS AND METHODS 2-[18F]Fluoro-A-85380 (2-FA) binds to nAChRs and with positron emission tomography (PET) imaging provides a composite measure of receptor density and ligand affinity. This study aimed to: (1) quantify nAChRs in vivo in 15 drug-naïve patients with mild AD before and after chronic treatment with galantamine, using 2-FA and PET, and (2) examine the relationship between treatment-induced changes in nAChRs and improvements in cognitive function. Participants were nonsmokers and underwent extensive cognitive testing and a PET scan after injection of approximately 200 MBq of 2-FA on two occasions (before and after 12 weeks, galantamine treatment). A 3-day washout period preceded the second scan. Brain regional 2-FA binding was assessed through a simplified estimation of distribution volume (DV(S)). RESULTS Performance on global measures of cognition significantly improved following galantamine treatment (p < 0.05). This improvement extended to specific cognitive measures of language and verbal learning. No significant differences in nAChR DV(S) before and after galantamine treatment were found. The treatment-induced improvement in cognition was not correlated with regional or global nAChR DV(S), suggesting that changes in nAChRs may not be responsible for the improvements in cognition following galantamine in patients with mild AD.
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Affiliation(s)
- J R Ellis
- School of Psychology, Psychiatry, and Psychological Medicine, Monash University, Melbourne, Victoria, Australia.
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Abstract
Voltage-clamp techniques are typically used to study the plasma membrane proteins, such as ion channels and transporters that control bioelectrical signals. Many of these proteins have been cloned and can now be studied as potential targets for drug development. The two approaches most commonly used for heterologous expression of cloned ion channels and transporters involve either transfection of the genes into small cells grown in tissue culture or the injection of the genetic material into larger cells. The standard large cells used for the expression of cloned cDNA or synthetic RNA are the egg progenitor cells (oocytes) of the African frog, Xenopus laevis. Until recently, cellular electrophysiology was performed manually by a single operator, one cell at a time. However, methods of high throughput electrophysiology have been developed which are automated and permit data acquisition and analysis from multiple cells in parallel. These methods are breaking a bottleneck in drug discovery, useful in some cases for primary screening as well as for thorough characterization of new drugs. Increasing throughput of high-quality functional data greatly augments the efficiency of academic research and pharmaceutical drug development. Some examples of studies that benefit most from high throughput electrophysiology include pharmaceutical screening of targeted compound libraries, secondary screening of identified compounds for subtype selectivity, screening mutants of ligand-gated channels for changes in receptor function, scanning mutagenesis of protein segments, and mutant-cycle analysis. We describe here the main features and potential applications of OpusXpress, an efficient commercially available system for automated recording from Xenopus oocytes. We show some types of data that have been gathered by this system and review realized and potential applications.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida, USA.
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Sabbagh MN, Walker DG, Reid RT, Stadnick T, Anand K, Lue LF. Absence of effect of chronic nicotine administration on amyloid beta peptide levels in transgenic mice overexpressing mutated human APP (Sw, Ind). Neurosci Lett 2008; 448:217-20. [DOI: 10.1016/j.neulet.2008.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 10/01/2008] [Accepted: 10/01/2008] [Indexed: 11/26/2022]
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Kulak JM, Fan H, Schneider JS. Beta2* and beta4* nicotinic acetylcholine receptor expression changes with progressive parkinsonism in non-human primates. Neurobiol Dis 2007; 27:312-9. [PMID: 17616467 PMCID: PMC9732990 DOI: 10.1016/j.nbd.2007.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 05/21/2007] [Accepted: 06/04/2007] [Indexed: 12/13/2022] Open
Abstract
Autoradiography was used to investigate nicotinic acetylcholine receptor (nAChR) binding in the brains of two groups of macaque monkeys with parkinsonism produced by different types of MPTP exposure: animals with cognitive deficits but no motor symptoms (motor-asymptomatic) and animals with typical motor symptoms of parkinsonism (motor-symptomatic). Motor-asymptomatic animals had no significant changes in [125I]epibatidine binding to beta2*-beta4* nAChRs and [125I]A85380 binding to beta2* nAChRs in cognition-related cortical regions such as Broadman's area 46, orbitofrontal cortex, the anterior cingulate sulcus and the hippocampus, but binding of both radioligands was decreased 70-80% in the caudate and putamen. Motor-symptomatic animals had decreases in beta2* and beta4* nAChR in the principal sulcus (40-60%), anterior cingulate sulcus (30-55%), and orbitofrontal cortex (30-41%), but not in the hippocampus, plus significant decreases in binding (70-80%) in the caudate and putamen. These results suggest that while nAChR expression is similarly decreased in the striatum of motor-asymptomatic and motor-symptomatic MPTP-treated monkeys, there are differences in beta2* and beta4* nAChR expression in cortical regions in these two conditions. Therefore, our data suggest that a therapeutic strategy based on nAChR agonist administration that might improve cognition in early PD patients may, due to a changing nAChR profile, have little or no effect on the same symptoms in more advanced patients.
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Affiliation(s)
- Jennifer M Kulak
- Thomas Jefferson University, Department of Pathology, Anatomy and Cell Biology, 1020 Locust St., 521 JAH Philadelphia, PA 19107, USA.
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Medel YFF, Gardner PD. Transcriptional Repression by a Conserved Intronic Sequence in the Nicotinic Receptor α3 Subunit Gene. J Biol Chem 2007; 282:19062-70. [PMID: 17504758 DOI: 10.1074/jbc.m702354200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The genes encoding the nicotinic acetylcholine receptor alpha3, alpha5, and beta4 subunits are genomically clustered. These genes are co-expressed in a variety of cells in the peripheral and central nervous systems. Their gene products assemble in a number of stoichiometries to generate several nicotinic receptor subtypes that have distinct pharmacological and physiological properties. Signaling through these receptors is critical for a variety of fundamental biological processes. Despite their importance, the transcriptional mechanisms underlying their coordinated expression remain to be completely elucidated. By using a bioinformatics approach, we identified a highly conserved intronic sequence within the fifth intron of the alpha3 subunit gene. Reporter gene analysis demonstrated that this sequence, termed "alpha3 intron 5," inhibits the transcriptional activities of the alpha3 and beta4 subunit gene promoters. This repressive activity is position- and orientation-independent. Importantly, repression occurs in a cell type-specific manner, being present in cells that do not express the receptor genes or expresses them at very low levels. Electrophoretic mobility shift assays demonstrate that nuclear proteins specifically interact with alpha3 intron 5 at two distinct sites. We propose that this intronic repressor element is important for the restricted expression patterns of the nicotinic receptor alpha3 and beta4 subunit genes.
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Affiliation(s)
- Yuly F Fuentes Medel
- Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, Worcester, Massachusetts 01604, USA
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Dunbar G, Boeijinga PH, Demazières A, Cisterni C, Kuchibhatla R, Wesnes K, Luthringer R. Effects of TC-1734 (AZD3480), a selective neuronal nicotinic receptor agonist, on cognitive performance and the EEG of young healthy male volunteers. Psychopharmacology (Berl) 2007; 191:919-29. [PMID: 17225162 DOI: 10.1007/s00213-006-0675-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 12/04/2006] [Indexed: 01/13/2023]
Abstract
OBJECTIVES The aim of this study was to get insight into the central effects of TC-1734 (renamed AZD3480), a selective agonist at the neuronal nicotinic receptor of the alpha4beta2 subtype. MATERIALS AND METHODS Electroencephalography (EEG) techniques and computerized cognitive tests were performed in young, healthy male volunteers during two double-blind and placebo-controlled studies: a rising single dose crossover study (from 2 to 320 mg) and a rising repeated dose study with a parallel group design (50, 100, and 200 mg). RESULTS In contrast to acute administration, administration of AZD3480 over 10 days produced statistically significant enhancement of several cognitive measures (attention and episodic memory) compared to placebo. Regarding EEG data, AZD3480 showed acceleration of the alpha centroid and of the alpha peak in the single-dose study. This EEG profile of the acceleration type was confirmed in the repeated dose study on both day 1 and day 10, with the greatest effect observed with the highest dose. The EEG pattern shown for AZD3480 was consistent with that previously described with other drugs known to improve attention and vigilance (including nicotine). In addition, subjects dosed with AZD3480 showed a statistically significant increase in mismatch negativity (MMN) amplitude at 50 and 200 mg while reducing MMN latency (200 mg only), suggesting an improvement of pre-attentional mechanisms. CONCLUSION These early data in healthy subjects provide encouragement to consider development of AZD3480 as a novel agent for the treatment of cognitive decline in the elderly, including age-associated memory impairment and/or dementia of the Alzheimer's type.
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Affiliation(s)
- G Dunbar
- TARGACEPT Inc., 200 East First Street Suite 300, Winston-Salem, NC 27101-4165, USA
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Popa RV, Pereira EFR, Lopes C, Maelicke A, Albuquerque EX. The N-butylcarbamate derivative of galantamine acts as an allosteric potentiating ligand on alpha7 nicotinic receptors in hippocampal neurons: clinical implications for treatment of Alzheimer's disease. J Mol Neurosci 2007; 30:227-32. [PMID: 17192682 DOI: 10.1385/jmn:30:1:227] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/11/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive impairments that become severe enough to interfere with the daily activities of patients and eventually lead to death (Chung and Cummings, 2000). Arecent study reports that approx 24 million people suffer from dementia worldwide. If the mortality rate does not change and no curative or preventive treatment is developed, this number is expected to double every 20 yr worldwide (Ferri et al., 2005). Although the causes of AD remain obscure, it has been reported that incremental loss of cholinergic neurons and of nicotinic receptor (nAChR) function/expression in specific brain regions correlates well with the severity of the symptoms at early stages of the disease (Hellström-Lindahl et al., 1999; Nordberg, 2001; Perry et al., 2001; Wevers et al., 1999). In patients with more advanced stages of AD, such a correlation between the magnitude of nAChR loss and of cognitive decline does not appear to exist (Sabbagh et al., 2001). The nicotinic cholinergic system plays a central role in modulating different forms of associative learning known to be impaired in AD patients, including the eyeblink classical conditioning (Woodruff-Pak, 2001), and in maintaining neuronal viability. Neuroprotection and cognitive improvement result from increasing the activity of different nAChR subtypes, including those bearing the alpha7 subunit (Carlson et al., 1998; Hejmadi et al., 2003; Kihara et al., 1997; Levin et al., 2006). Thus, increasing nAChR activity in the brain was proposed as a mechanism to slow down the progression of the disease (Maelicke and Albuquerque, 1996).
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Affiliation(s)
- Rodica V Popa
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, MD, USA
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Långström B, Andrén PE, Lindhe O, Svedberg M, Hall H. In Vitro Imaging Techniques in Neurodegenerative Diseases. Mol Imaging Biol 2007; 9:161-75. [PMID: 17318669 DOI: 10.1007/s11307-007-0088-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neurodegeneration induces various changes in the brain, changes that may be investigated using neuroimaging techniques. The in vivo techniques are useful for the visualization of major changes, and the progressing abnormalities may also be followed longitudinally. However, to study and quantify minor abnormalities, neuroimaging of postmortem brain tissue is used. These in vitro methods are complementary to the in vivo techniques and contribute to the knowledge of pathophysiology and etiology of the neurodegenerative diseases. In vitro radioligand autoradiography has given great insight in the involvement of different neuronal receptor systems in these diseases. Data on the dopamine and cholinergic systems in neurodegeneration are discussed in this review. Also, the amyloid plaques are studied using in vitro radioligand autoradiography. Using one of the newer methods, imaging matrix-assisted laser desorption ionization mass spectrometry, the distribution of a large number of peptides and proteins may be detected in vitro on brain cryosections. In this overview, we describe in vitro imaging techniques in the neurodegenerative diseases as a complement to in vivo positron emission tomography and single photon emission computed tomography imaging.
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Affiliation(s)
- Bengt Långström
- Department of Biochemistry and Organic Chemistry, Uppsala University, Uppsala, Sweden.
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Sorger D, Becker GA, Patt M, Schildan A, Grossmann U, Schliebs R, Seese A, Kendziorra K, Kluge M, Brust P, Mukhin AG, Sabri O. Measurement of the alpha4beta2* nicotinic acetylcholine receptor ligand 2-[(18)F]Fluoro-A-85380 and its metabolites in human blood during PET investigation: a methodological study. Nucl Med Biol 2007; 34:331-42. [PMID: 17383583 DOI: 10.1016/j.nucmedbio.2006.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 11/20/2006] [Accepted: 12/17/2006] [Indexed: 10/23/2022]
Abstract
2-[(18)F]fluoro-A-85380 (2-[(18)F]FA) is a new radioligand for noninvasive imaging of alpha4beta2* nicotinic acetylcholine receptors (nAChRs) by positron emission tomography (PET) in human brain. In most cases, quantification of 2-[(18)F]FA receptor binding involves measurement of free nonmetabolized radioligand concentration in blood. This requires an efficient and reliable method to separate radioactive metabolites from the parent compound. In the present study, three analytical methods, thin layer chromatography (TLC), high-performance liquid chromatography (HPLC) and solid phase extraction (SPE) have been tested. Reversed-phase TLC of deproteinized aqueous samples of plasma provides good estimates of 2-[(18)F]FA and its metabolites. However, because of the decreased radioactivity in plasma samples, this method can be used in humans over the first 2 h after radioligand injection only. Reliable quantification of the parent radioligand and its main metabolites was obtained using reversed-phase HPLC, followed by counting of eluted fractions in a well gamma counter. Three main and five minor metabolites of 2-[(18)F]FA were detected in human blood using this method. On average, the unchanged 2-[(18)F]FA fraction in plasma of healthy volunteers measured at 14, 60, 120, 240 and 420 min after radioligand injection was 87.3+/-2.2%, 74.4+/-3%, 68.8+/-5%, 62.3+/-8% and 61.0+/-8%, respectively. In patients with neurodegenerative disorders, the values corresponding to the three last time points were significantly lower. The fraction of nonmetabolized 2-[(18)F]FA in plasma determined using SPE did not differ significantly from that obtained by HPLC (+gamma counting) (n=73, r=.95). Since SPE is less time-consuming than HPLC and provides comparable results, we conclude that SPE appears to be the most suitable method for measurement of 2-[(18)F]FA parent fraction during PET investigations.
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Affiliation(s)
- Dietlind Sorger
- Department of Nuclear Medicine, University of Leipzig, Leipzig, 04103, Germany.
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29
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Sorger D, Becker GA, Hauber K, Schildan A, Patt M, Birkenmeier G, Otto A, Meyer P, Kluge M, Schliebs R, Sabri O. Binding properties of the cerebral alpha4beta2 nicotinic acetylcholine receptor ligand 2-[18F]fluoro-A-85380 to plasma proteins. Nucl Med Biol 2007; 33:899-906. [PMID: 17045170 DOI: 10.1016/j.nucmedbio.2006.07.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 07/26/2006] [Accepted: 07/29/2006] [Indexed: 10/24/2022]
Abstract
INTRODUCTION To determine the availability of nicotinic acetylcholine receptors in different human brain regions using the positron emission tomography (PET) radioligand 2-[18F]fluoro-A-85380 (2-[18F]FA) and invasive approaches for quantification, it is important to correct the arterial input function as well for plasma protein binding (PPB) of the radioligand as for radiolabeled metabolites accumulating in blood. This study deals with some aspects of PPB of 2-[18F]FA. METHODS Patients with different neurological disorders (n=72), such as Parkinson's disease, Alzheimer's disease and multiple sclerosis, and a group of healthy volunteers (n=15) subjected for PET imaging were analyzed for their PPB level of 2-[18F]FA using ultrafiltration. Protein gel electrophoresis of plasma samples was performed to identify the binding protein of 2-[18F]FA. The dependency of PPB on time and on free ligand concentration was analyzed to obtain the binding parameters Bmax and Kd. RESULTS Albumin was identified to be the binding protein of 2-[18F]FA. PPB of 2-[18F]FA was low at 17+/-4% and did not show significant differences between the groups of patients. Corresponding to this, a narrow range of plasma albumin of 0.62+/-0.05 mM was observed. Bmax was determined as twice the albumin concentration, which indicates two binding sites for 2-[18F]FA on the protein. No time dependence of the PPB could be observed. By relating PPB to Bmax, an average Kd value of 6.0+/-1.5 mM was obtained. CONCLUSION This study shows the dependency of PPB of 2-[18F]FA on human albumin plasma concentration. An equation utilizing Bmax and Kd to easily estimate PPB is presented.
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Affiliation(s)
- Dietlind Sorger
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany.
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Biton B, Bergis OE, Galli F, Nedelec A, Lochead AW, Jegham S, Godet D, Lanneau C, Santamaria R, Chesney F, Léonardon J, Granger P, Debono MW, Bohme GA, Sgard F, Besnard F, Graham D, Coste A, Oblin A, Curet O, Vigé X, Voltz C, Rouquier L, Souilhac J, Santucci V, Gueudet C, Françon D, Steinberg R, Griebel G, Oury-Donat F, George P, Avenet P, Scatton B. SSR180711, a novel selective alpha7 nicotinic receptor partial agonist: (1) binding and functional profile. Neuropsychopharmacology 2007; 32:1-16. [PMID: 17019409 DOI: 10.1038/sj.npp.1301189] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this paper, we report on the pharmacological and functional profile of SSR180711 (1,4-Diazabicyclo[3.2.2]nonane-4-carboxylic acid, 4-bromophenyl ester), a new selective alpha7 acetylcholine nicotinic receptor (n-AChRs) partial agonist. SSR180711 displays high affinity for rat and human alpha7 n-AChRs (K(i) of 22+/-4 and 14+/-1 nM, respectively). Ex vivo (3)[H]alpha-bungarotoxin binding experiments demonstrate that SSR180711 rapidly penetrates into the brain (ID(50)=8 mg/kg p.o.). In functional studies performed with human alpha7 n-AChRs expressed in Xenopus oocytes or GH4C1 cells, the compound shows partial agonist effects (intrinsic activity=51 and 36%, EC(50)=4.4 and 0.9 microM, respectively). In rat cultured hippocampal neurons, SSR180711 induced large GABA-mediated inhibitory postsynaptic currents and small alpha-bungarotoxin sensitive currents through the activation of presynaptic and somato-dendritic alpha7 n-AChRs, respectively. In mouse hippocampal slices, the compound increased the amplitude of both glutamatergic (EPSCs) and GABAergic (IPSCs) postsynaptic currents evoked in CA1 pyramidal cells. In rat and mouse hippocampal slices, a concentration of 0.3 muM of SSR180711 increased long-term potentiation (LTP) in the CA1 field. Null mutation of the alpha7 n-AChR gene totally abolished SSR180711-induced modulation of EPSCs, IPSCs and LTP in mice. Intravenous administration of SSR180711 strongly increased the firing rate of single ventral pallidum neurons, extracellularly recorded in anesthetized rats. In microdialysis experiments, administration of the compound (3-10 mg/kg i.p.) dose-dependently increased extracellular acetylcholine (ACh) levels in the hippocampus and prefrontal cortex of freely moving rats. Together, these results demonstrate that SSR180711 is a selective and partial agonist at human, rat and mouse alpha7 n-AChRs, increasing glutamatergic neurotransmission, ACh release and LTP in the hippocampus.
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Affiliation(s)
- Bruno Biton
- Central Nervous System Research Department, Sanofi-Aventis, Bagneux, France.
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Dunbar G, Demazières A, Monreal A, Cisterni C, Metzger D, Kuchibhatla R, Luthringer R. Pharmacokinetics and safety profile of ispronicline (TC-1734), a new brain nicotinic receptor partial agonist, in young healthy male volunteers. J Clin Pharmacol 2006; 46:715-26. [PMID: 16809797 DOI: 10.1177/0091270006288730] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent research suggests that drugs activating nicotine acetylcholine receptors might be promising therapy in cognitive decline seen in the elderly, including Alzheimer's disease. Ispronicline (TC-1734), a brain-selective alpha4beta2 nicotine acetylcholine receptor partial agonist, has shown memory-enhancing properties in rodents and a good tolerability profile. The safety and the full pharmacokinetic profile of TC-1734 and its N-desalkylated metabolite, TC-1784, were investigated in 2 phase I studies, and results are reported in this article. Study A used a double-blind, placebo-controlled, crossover design with a rising single-dose scheme (2-320 mg). Study B used a double-blind, placebo-controlled, parallel-group design with a rising multiple-dose scheme (doses: 50, 100, and 200 mg, once daily, x 10 days). Cmax of TC-1734 was reached around 1 to 2 hours postdose, and mean terminal half-life (t1/2) ranged from 3 to 5.3 hours (single doses) and from 2.7 to 8.8 hours (repeated doses). No accumulation of TC-1734 was observed after 10 days. Renal clearance appeared to be a minor method of elimination of TC-1734 and TC-1784. A high interindividual variability was noted for all parameters. Across the dose ranges explored, TC-1734 was safe and well tolerated. No changes of clinical significance were seen on laboratory and cardiovascular parameters. Adverse events were generally of mild to moderate intensity, with dizziness and headache being reported most frequently.
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Affiliation(s)
- G Dunbar
- TARGACEPT, Winston-Salem, North Carolina, USA
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32
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Mitkovski S, Villemagne VL, Novakovic KE, O'Keefe G, Tochon-Danguy H, Mulligan RS, Dickinson KL, Saunder T, Gregoire MC, Bottlaender M, Dolle F, Rowe CC. Simplified quantification of nicotinic receptors with 2[18F]F-A-85380 PET. Nucl Med Biol 2006; 32:585-91. [PMID: 16026705 DOI: 10.1016/j.nucmedbio.2005.04.013] [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] [Received: 04/04/2005] [Revised: 04/26/2005] [Accepted: 04/26/2005] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Neuronal nicotinic acetylcholine receptors (nAChRs), widely distributed in the human brain, are implicated in various neurophysiological processes as well as being particularly affected in neurodegenerative conditions such as Alzheimer's disease. We sought to evaluate a minimally invasive method for quantification of nAChR distribution in the normal human brain, suitable for routine clinical application, using 2[(18)F]F-A-85380 and positron emission tomography (PET). METHODS Ten normal volunteers (four females and six males, aged 63.40+/-9.22 years) underwent a dynamic 120-min PET scan after injection of 226 MBq 2[(18)F]F-A-85380 along with arterial blood sampling. Regional binding was assessed through standardized uptake value (SUV) and distribution volumes (DV) obtained using both compartmental (DV(2CM)) and graphical analysis (DV(Logan)). A simplified approach to the estimation of DV (DV(simplified)), defined as the region-to-plasma ratio at apparent steady state (90-120 min post injection), was compared with the other quantification approaches. RESULTS DV(Logan) values were higher than DV(2CM). A strong correlation was observed between DV(simplified), DV(Logan) (r=.94) and DV(2CM) (r=.90) in cortical regions, with lower correlations in thalamus (r=.71 and .82, respectively). Standardized uptake value showed low correlation against DV(Logan) and DV(2CM). CONCLUSION DV(simplified) determined by the ratio of tissue to metabolite-corrected plasma using a single 90- to 120-min PET acquisition appears acceptable for quantification of cortical nAChR binding with 2[(18)F]F-A-85380 and suitable for clinical application.
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Affiliation(s)
- Sascha Mitkovski
- Department of Nuclear Medicine and Centre for PET, Austin Hospital, Victoria 3084, Melbourne, Australia
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Chu LW, Ma ESK, Lam KKY, Chan MF, Lee DHS. Increased alpha 7 nicotinic acetylcholine receptor protein levels in Alzheimer's disease patients. Dement Geriatr Cogn Disord 2005; 19:106-12. [PMID: 15591800 DOI: 10.1159/000082661] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/23/2004] [Indexed: 01/16/2023] Open
Abstract
We compared the intact alpha7 nicotinic acetylcholine receptor (alpha7nAChR) protein levels in the peripheral blood leukocytes in 15 Alzheimer's disease (AD) patients and 13 normal elderly control subjects. Demographic data and Mini-Mental State Examination (MMSE) scores were obtained. Western blot analysis for alpha7nAChR protein levels in peripheral blood leukocytes was performed. There were no significant differences in sex and age between the AD and control groups. The mean MMSE score of the AD subjects was significantly lower than that of the normal control subjects (15.4 +/- 5.5 vs. 28.5 +/- 1.9 respectively; p < 0.001). The median value of normalized alpha7nAChR protein levels (optical density, arbitrary unit) of the AD group was significantly higher than that of the normal control group (0.6923 vs. 0.4803 respectively; p = 0.045, Mann-Whitney U test). The normalized alpha7nAChR protein levels showed a significant inverse correlation with the MMSE scores (Spearman rho = -0.45; p = 0.016; n = 28). Receiver Operating Characteristic curve analyses showed that the area under curve was 0.72 (95% CI 0.52- 0.87). If the cut-off of the alpha7nAChR protein level was >0.312, the sensitivity, specificity, positive predictive value and negative predictive value would be 80, 39, 60 and 63%, respectively. These findings showed that the alpha7nAChR protein levels would be a potentially useful diagnostic marker for AD.
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Affiliation(s)
- L W Chu
- Division of Geriatric Medicine, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong, China.
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Oikawa H, Nakamichi N, Kambe Y, Ogura M, Yoneda Y. An increase in intracellular free calcium ions by nicotinic acetylcholine receptors in a single cultured rat cortical astrocyte. J Neurosci Res 2005; 79:535-44. [PMID: 15635597 DOI: 10.1002/jnr.20398] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are composed of an assembly between at least seven alpha (alpha2-alpha7, alpha9) and three beta (beta2-beta4) subunits in mammals. The addition of 50 mM KCl or 1 mM nicotine immediately increased the number of cells with high fluorescence intensity in rat cortical astrocytes on fluo-3 fluorescence measurement. Nicotine was effective at increasing the fluorescence intensity in astrocytes cultured for 2 days after replating, but not in those used 1 or 5 days after replating, without markedly affecting the cellular viability irrespective of the exposure period. Nicotine markedly increased the fluorescence intensity in a concentration-dependent manner at a concentration range of 10-100 microM in cultured astrocytes when analyzed on a responsive single cell. In these responsive single cells, the increase by nicotine was significantly prevented by the heteromeric alpha4/beta2 subtype antagonist dihydro-beta-erythroidine and the homomeric alpha7 subtype antagonist methyllycaconitine, as well as by nifedipine and EGTA but not thapsigargin. Methyllycaconitine failed to inhibit further the increase by nicotine in the presence of nifedipine, however, whereas the expression of mRNA was seen for all mammalian neuronal nAChR subunits in cultured rat cortical astrocytes as well as neurons. These results suggest that nicotine may increase intracellular free Ca2+ through the influx of extracellular Ca2+ across L-type voltage-gated Ca2+ channels rather than Ca2+ release from intracellular stores, in a manner related to the alpha4/beta2 and/or alpha7 nAChR channels functionally expressed in cultured rat cortical astrocytes.
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Affiliation(s)
- Hirotaka Oikawa
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa, Japan
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Herber DL, Severance EG, Cuevas J, Morgan D, Gordon MN. Biochemical and histochemical evidence of nonspecific binding of alpha7nAChR antibodies to mouse brain tissue. J Histochem Cytochem 2004; 52:1367-76. [PMID: 15385583 DOI: 10.1177/002215540405201013] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Alpha 7 nicotinic acetylcholine receptors are involved in learning and memory, and are implicated in the pathology of Alzheimer's disease and schizophrenia. Detection of alpha7 subunits can be accomplished via immunodetection or alpha-bungarotoxin-binding techniques. Standard protocols for immunohistochemistry and Western blotting were followed using several commercially available antibodies. Various mice were evaluated, including non-transgenics, APP, PS1, APP+PS1, and alpha7 knockouts. Initial results with amyloid-depositing mice revealed alpha7 immunolabeled astrocytes, in addition to expected neuronal staining. Subsequent studies with intrahippocampal injections of lipopolysaccharide (LPS) into alpha7 knockout mice showed that both neuronal and astrocytic labeling by alpha7 antibodies was nonspecific. On Western blots of mouse brain proteins, none of the bands detected with antibodies directed against alpha7 subunits diminished in the alpha7 knockout mice. Although LPS-related changes in the expression of some bands were found, these also were unaffected by the alpha7 genotype of the mice. In general, the Western staining patterns for these antibodies revealed few overlapping bands. These immunodetection data are in contrast to genotyping results and mRNA analyses that confirmed the disruption of the alpha7 allele and lack of alpha7 message in the knockouts. These findings suggest caution in interpreting results when using several commercially available alpha7 nicotinic receptor antibodies.
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Affiliation(s)
- Donna L Herber
- Department of pharmacology and Therapeutics, University of South Florida, 12901 Bruce B. Downs Blvd., MDC Box 9, Tampa, FL 33612-4799, USA
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Abstract
Neurodegenerative diseases are increasingly common in elderly patients, who present a particular anaesthetic challenge. The majority of people over the age of 70 years have some degree of cerebral atrophy. The pathogenesis of neurodegenerative diseases is due to alterations in the transport, degradation and aggregation of proteins. Alterations in physiology that occur with advancing age affect both the pharmacokinetics and pharmacodynamics of drugs used in the elderly. Changes in pharmacokinetics result in either increased or reduced drug concentrations depending on the variable contributions of absorption, metabolism and elimination. The distribution of a drug depends on its protein binding, cardiac output and blood volume, which are all altered in the elderly. Metabolism and excretion of drugs are also affected due to changes in hepatic and renal mass and blood flow in the elderly. A number of drugs are used in neurodegenerative disorders including antidepressants, benzodiazepines, antipsychotics, acetylcholinesterase inhibitors and levodopa. Polypharmacy is a common problem, which can lead to adverse drug interactions and an exacerbation of dementia. Levodopa, bromocriptine and tricyclic antidepressants are known to cause orthostatic hypotension in patients with neurodegenerative disease. Elderly patients are liable to excessive sedation from benzodiazepines in both the pre- and postoperative period; therefore these drugs should be prescribed in low doses. For induction of general anaesthesia propofol is a suitable agent in patients with neurodegenerative disease due to its rapid metabolism, but may not be suitable in patients with Parkinson's disease as it can induce spontaneous involuntary movements. Volatile inhalational agents should be administered carefully in the elderly, as they are more sensitive to the depressant cerebral and cardiovascular effects. Levodopa should be avoided in conjunction with halothane, which sensitises the heart to catecholamines. Co-administration of monoamine oxidase inhibitors and opioids should be avoided as it can cause agitation, muscular rigidity, sweating and hyperpyrexia. If an anticholinergic agent is required, then glycopyrronium bromide is the drug of choice in this group of patients, as it does not cross the blood brain barrier. Patients should continue to take their usual medications in hospital and do not let the change in routine alter the times at which treatments are administered. This is particularly relevant to the timing of levodopa in Parkinson's disease, as missed treatment can be detrimental. Regional anaesthesia may, however, have significant advantages in patients with Parkinson's disease, who can continue to take oral levodopa preoperatively, during surgery, if required, and early in the postoperative period. Anti-emetic drugs such as phenothiazines, butyrophenones and metoclopramide should be used carefully in the postoperative period in these patients as their antidopaminergic effects may induce or exacerbate parkinsonian effects.
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Affiliation(s)
- Deborah A Burton
- Department of Anaesthesia, St George's Hospital Medical School, London, England.
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37
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Verbois SL, Hopkins DM, Scheff SW, Pauly JR. Chronic intermittent nicotine administration attenuates traumatic brain injury-induced cognitive dysfunction. Neuroscience 2003; 119:1199-208. [PMID: 12831873 DOI: 10.1016/s0306-4522(03)00206-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Traumatic brain injury (TBI) initiates immediate and secondary neuropathological cascades that can result in persistent neurological dysfunction. Previous studies from our laboratory have shown that experimental rat brain injury causes a rapid and persistent decrease in CNS alpha7* nicotinic cholinergic receptor (nAChr) expression. The purpose of this study was to investigate whether intermittent nicotine injections could improve cognitive performance in the Morris water maze (MWM) following experimental brain injury. Adult male rats were anesthetized and subjected to a 1.5 mm controlled cortical impact (CCI) injury of the somatosensory cortex. Animals received twice daily i.p. nicotine injections for 11 days prior to CCI, 11 days following CCI or during both pre- and post-surgical intervals. MWM training was initiated 12 days post-injury. In the training phase of cognitive testing, twice-daily nicotine treatment following injury attenuated trauma-induced deficits in the distance traveled to reach the escape platform. This group of animals also had improvements in several measures of the probe test, including time spent, distance traveled and total entries into the target quadrant. TBI caused significant deficits in alpha7* nAChr expression in several regions of the hippocampus and cerebral cortex, which were largely unaffected by intermittent nicotine treatment. However, nicotine treatment up-regulated [(3)H]-epibatidine binding to non-alpha7* nAChrs, attenuating TBI-induced deficits in receptor expression in several brain regions evaluated. These results suggest that nicotine is efficacious at attenuating CCI-induced cognitive deficits in a manner independent of changes in alpha7* nAChr expression, perhaps via up-regulation of non-alpha7* nAChrs.
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Affiliation(s)
- S L Verbois
- Division of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0082, USA
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38
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Bontempi B, Whelan KT, Risbrough VB, Lloyd GK, Menzaghi F. Cognitive enhancing properties and tolerability of cholinergic agents in mice: a comparative study of nicotine, donepezil, and SIB-1553A, a subtype-selective ligand for nicotinic acetylcholine receptors. Neuropsychopharmacology 2003; 28:1235-46. [PMID: 12700710 DOI: 10.1038/sj.npp.1300150] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Several studies have demonstrated the importance of nicotinic mechanisms in the pathophysiology of neurodegenerative and cognitive disorders, warranting the search and development of novel nicotinic ligands as potential therapeutic agents. The present study was designed to assess whether the subtype-selective nicotinic acetylcholine receptor (nAChR) ligand SIB-1553A [(+/-)-4-([2-(1-methyl-2-pyrrolidinyl)ethyl]thio)phenol hydrochloride], with predominant agonist activity at beta4 subunit-containing human nAChRs, and no activity at muscle nAChR subtypes, could enhance cognitive performance in rodents with a more desirable safety/tolerability profile as compared to the nonselective prototypic nAChR ligand nicotine. SIB-1553A was equi-efficacious to nicotine in improving working memory performance in scopolamine-treated mice as measured by increased alternation in a T-maze, and was more efficacious than nicotine in improving the baseline cognitive performance of aged mice. This effect on working memory was confirmed in a delayed nonmatching to place task using the eight-arm radial maze. SIB-1553A produced dose-dependent side effects (ie motor deficits and seizures), although these effects were observed at doses 12 to 640-fold above those required to increase cognitive performance. Overall, SIB-1553A was significantly less potent than nicotine in eliciting these undesirable effects. Thus, the subtype-selective profile of SIB-1553A appears to translate into a more efficacious and better tolerated nAChR ligand as compared to nicotine. In the present studies, cognitive enhancement induced by SIB-1553A was similar in magnitude to that produced by the clinically efficacious acetylcholinesterase inhibitor donepezil. Taken together, the present data confirm the importance of nAChR subtypes in modulating cognitive processes, and suggest that activation of nAChR subtypes by selective nAChR ligands may be a viable approach to enhance cognitive performance.
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39
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Abstract
Nicotinic receptors (NRs) belong to the group of polymeric receptors of the cell membrane and are key elements of cholinergic transmission. Numerous subtypes of NRs exist with the alpha 4 beta 2 and alpha 7 types being encountered most frequently. Deficiencies in NRs seem to play a role in Alzheimer's disease, which is characterised by accumulation of senile plaques, mainly composed of beta-amyloid peptide (beta A). Although the aetiology of this disease is unknown, different pathogenesis hypotheses implicating alpha 7 NRs have been proposed, with the receptors exerting a direct or indirect action on the mechanism of beta A toxicity. Allosteric modulators of NRs, such as the cholinesterase inhibitor galantamine, that facilitate the action of acetylcholine on these receptors may provide therapeutic benefits in the areas of cognition, attention and antineurodegenerative activity.
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Affiliation(s)
- Michel Bourin
- Research Group Neurobiology of Anxiety and Depression, Faculty of Medicine, Nantes, France.
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40
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Wang N, Orr-Urtreger A, Korczyn AD. The role of neuronal nicotinic acetylcholine receptor subunits in autonomic ganglia: lessons from knockout mice. Prog Neurobiol 2002; 68:341-60. [PMID: 12531234 DOI: 10.1016/s0301-0082(02)00106-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChR), composed of 12 subunits (alpha2-alpha10, beta2-beta4), are expressed in autonomic ganglia, playing a central role in autonomic transmission. The repertoire of nicotinic subunits in autonomic ganglia includes alpha3, alpha5, alpha7, beta2 and beta4 subunits. In the last 10 years, heterologous expression studies have revealed much about the nature of neuronal nAChRs. However, there is only limited understanding of subunit actions in autonomic system. Functional deletions of subunit by gene knockout in animals could overcome these limitations. We review recent studies on nAChRs on autonomic ganglia for physiological and pharmacological properties and potential locations of the subunits.
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Affiliation(s)
- Ningshan Wang
- Department of Physiology and Pharmacology, Sackler Medical School, Tel Aviv University, Ramat Aviv, Israel
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41
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Verbois SL, Scheff SW, Pauly JR. Time-dependent changes in rat brain cholinergic receptor expression after experimental brain injury. J Neurotrauma 2002; 19:1569-85. [PMID: 12542858 DOI: 10.1089/089771502762300238] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Alterations in neurotransmitter receptor expression in the central nervous system may contribute to physiological and behavioral deficits that follow traumatic brain injury (TBI). Previous studies from our laboratory have demonstrated significant and widespread deficits in alpha7* nicotinic cholinergic receptor (alpha7* nAChr) expression 2 days following cortical contusion brain injury. The purpose of this study was to evaluate changes in alpha7* nAChr expression over a wider range of post-TBI recovery intervals. Animals were anesthetized and subjected to a moderate cortical contusion brain injury (2 mm cortical compression). Animals were euthanatized at various post-TBI time intervals, ranging from 1 h to 21 days, and quantitative autoradiography was used to evaluate cholinergic receptor subtype expression in the cerebral cortex and hippocampus. As previously reported, the alpha7* nAChr was the most sensitive target of TBI-induced plasticity. Significant decreases in alpha-[(125)I]-bungarotoxin (BTX) binding occurred as early as 1 h post-TBI, and persisted in some brain regions for up to 21 days. A kinetic analysis of changes in BTX binding, performed 2 days following brain injury, indicated that the binding deficits are not due to significant changes in receptor affinity. TBI-induced changes in alpha3*/alpha4* nACh receptors, muscarinic cholinergic receptors, and NMDA-type glutamate receptor expression were lower in magnitude, restricted to fewer brain regions and more transient in nature. Persistent deficits in alpha7* nAChr expression following TBI may contribute to impaired functional outcome following brain injury.
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MESH Headings
- Animals
- Autoradiography
- Brain/cytology
- Brain/metabolism
- Bridged Bicyclo Compounds, Heterocyclic/metabolism
- Bridged Bicyclo Compounds, Heterocyclic/pharmacology
- Bungarotoxins/metabolism
- Bungarotoxins/pharmacology
- Disease Models, Animal
- Dizocilpine Maleate/metabolism
- Dizocilpine Maleate/pharmacology
- Excitatory Amino Acid Antagonists/metabolism
- Excitatory Amino Acid Antagonists/pharmacology
- Image Processing, Computer-Assisted
- Kinetics
- Male
- Muscarinic Antagonists/metabolism
- Muscarinic Antagonists/pharmacology
- Nicotinic Agonists/metabolism
- Nicotinic Agonists/pharmacology
- Protein Binding
- Pyridines/metabolism
- Pyridines/pharmacology
- Quinuclidinyl Benzilate/metabolism
- Quinuclidinyl Benzilate/pharmacology
- Radioligand Assay/methods
- Rats
- Rats, Sprague-Dawley
- Receptors, Cholinergic/metabolism
- Receptors, Muscarinic/metabolism
- Receptors, N-Methyl-D-Aspartate
- Receptors, Nicotinic/classification
- Receptors, Nicotinic/metabolism
- Time
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Affiliation(s)
- S Leigh Verbois
- Division of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0082, USA
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Vesey R, Birrell JM, Bolton C, Chipperfield RS, Blackwell AD, Dening TR, Sahakian BJ. Cholinergic nicotinic systems in Alzheimer's disease: prospects for pharmacological intervention. CNS Drugs 2002; 16:485-500. [PMID: 12056923 DOI: 10.2165/00023210-200216070-00005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Within the last few years, research into the cause and progression of Alzheimer's disease has made significant advances. Although there is still no preventative treatment or cure for this neurodegenerative illness, the development of drugs that may alleviate some of the cognitive symptoms associated with it is advancing. Cholinesterase inhibitors are at present the most effective form of treatment and have shown significant overall response rates in clinical trials. However, although some patients show substantial improvement when treated with this class of drugs, there is considerable variability in the amount of benefit gained in different individuals in terms of their cognitive and behavioural functioning. Furthermore, unfortunately some patients gain little or no benefit from these drugs. It would therefore be of great advantage to explore alternative therapeutic possibilities. This article reviews the potential involvement of the nicotinic cholinergic system in Alzheimer's disease and discusses the possibility of nicotinic pharmacotherapy. Substantial evidence indicates the involvement of the nicotinic cholinergic system in the pathology of Alzheimer's disease. Drugs targeting these sites may not only have a positive effect on cognitive function, but also have additional therapeutic benefits in terms of restoring the hypoactivity in the excitatory amino acid pyramidal system and even slowing the emergence of Alzheimer's disease pathology. The conclusion of this review is that nicotinic treatments are an important potential source of new therapeutic interventions in Alzheimer's disease.
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Affiliation(s)
- Robyn Vesey
- Department of Psychiatry, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge, UK
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Sala F, Mulet J, Choi S, Jung SY, Nah SY, Rhim H, Valor LM, Criado M, Sala S. Effects of ginsenoside Rg2 on human neuronal nicotinic acetylcholine receptors. J Pharmacol Exp Ther 2002; 301:1052-9. [PMID: 12023537 DOI: 10.1124/jpet.301.3.1052] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Ginseng saponins, major active components of ginseng root used by folk medicine in the treatment of various diseases, produce multiple pharmacological responses having many effects on the central and peripheral nervous system. Specifically, ginsenoside Rg(2) has been shown to block the nicotinic acetylcholine receptors in bovine chromaffin cells. We have studied the effect of Rg(2) on different types of human neuronal nicotinic acetylcholine receptors (nAChRs), both homomeric and heteromeric, expressed in Xenopus oocytes. Rg(2) did not affect the acetylcholine (ACh)-induced currents in alpha(7) human receptors, however Rg(2) affected the peak currents, and mainly the desensitization of heteromeric receptors alpha(3)beta(4), alpha(3)beta(2), alpha(4)beta(4), and alpha(4)beta(2). Both effects, a diminution of peak current and an increase of desensitization, are dose-dependent and are very similar for all the receptors. The mechanism of action has been studied in more detail in alpha(3)beta(4) and alpha(4)beta(2) receptors where we found a negligible shift in the ACh dose-response curves and a persistence of the Rg(2) effects at high ACh concentrations, indicative of a noncompetitive antagonism. A lack of voltage dependence on the reduction of the peak currents induced by ACh also suggests that Rg(2) does not act as an open channel blocker of human nAChR. The results indicate that Rg(2) acts specifically on heteromeric human nAChRs modulating their desensitization and suggest a possible mechanism by which this saponin contributes to the multiple therapeutic effects of ginseng.
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Affiliation(s)
- Francisco Sala
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Cientificas, Campus de San Juan, Apdo. Correos 18, 03550 Alicante, Spain
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