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Wong NR, Rubin LH, Harrington CK, Jenkins KR, Shinehouse LK, Yoon M, Kilgore JJ, Soule AR, Lesniak WG, Rowe SP, Horti AG, Kamath V, Dannals RF, Du Y, Pomper MG, Coughlin JM. Hippocampal Availability of the α7 Nicotinic Acetylcholine Receptor in Recent-Onset Psychosis. JAMA Netw Open 2024; 7:e2427163. [PMID: 39133487 PMCID: PMC11320165 DOI: 10.1001/jamanetworkopen.2024.27163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 06/13/2024] [Indexed: 08/13/2024] Open
Abstract
Importance Studies using human postmortem tissue and imaging with positron emission tomography (PET) support a low hippocampal availability of the α7 nicotinic acetylcholine receptor (α7-nAChR) in psychotic conditions, particularly in schizophrenia or schizoaffective disorder (nonaffective psychosis). If validated further, the finding may have implications for clinical diagnosis and treatment. Objective To test for lower availability of the α7-nAChR in the hippocampus of individuals with recent-onset psychosis compared with healthy control individuals and its association with lower cognitive performance or higher psychotic symptom burden within recent-onset psychosis. Design, Setting, and Participants In this cross-sectional study, healthy individuals without history of psychosis and patients within 10 years of a first onset of psychotic disorder were recruited from the greater Baltimore, Maryland, and Washington, DC, area. Fluorine 18-labeled ASEM ([18F] ASEM) PET data were acquired from participants enrolled between March 1, 2014, and July 31, 2023, from an academic research institution. Data acquired between March 1, 2014, and January 31, 2018 (n = 26), were published as a pilot study and were combined with new data acquired between January 1, 2019, and July 31, 2023 (n = 33). Main Outcome and Measures Regional [18F]ASEM total distribution volume (VT) that measures α7-nAChR availability, global cognition composite score, and total scores on the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms. Results A total of 59 participants (30 women [51%]; mean [SD] age, 25.5 [5.2] years), including 35 with recent-onset psychosis and 24 healthy controls, completed the study. In age-adjusted analyses, lower hippocampal [18F]ASEM VT was found in individuals with recent-onset psychosis (mean [SE], 17.87 [0.60]) compared with healthy controls (mean [SE], 19.82 [0.73]) (P = .04). In addition, [18F]ASEM VT was lower in individuals with nonaffective psychosis (mean [SE], 16.30 [0.83]) compared with healthy controls (P = .006) or those with affective psychosis (mean [SE], 19.34 [0.80]) (P = .03). Across recent-onset psychosis and after controlling for age, lower hippocampal [18F]ASEM VT was associated with more positive (r = -0.44; P = .009) but not negative symptoms, and higher hippocampal VT was associated with better global cognition composite score (r = 0.38; P = .03). Conclusions and Relevance In this cross-sectional study of individuals with recent-onset psychosis compared with healthy controls, a lower hippocampal α7-nAChR availability was found in recent-onset psychosis, and its availability was lower in those with nonaffective vs affective psychosis. Further study of the association between low availability of the α7-nAChR and recent-onset psychosis is warranted toward informing diagnostic or therapeutic strategies related to these findings.
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Affiliation(s)
- Nicole R. Wong
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Leah H. Rubin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Epidemiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Courtney K. Harrington
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Katelyn R. Jenkins
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Laura K. Shinehouse
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mark Yoon
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jessica J. Kilgore
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ana R. Soule
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Wojciech G. Lesniak
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Steven P. Rowe
- Department of Radiology, University of North Carolina, Chapel Hill
| | - Andrew G. Horti
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Vidyulata Kamath
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Robert F. Dannals
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Yong Du
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Martin G. Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jennifer M. Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Cools R, Kerkhofs K, Leitao RCF, Bormans G. Preclinical Evaluation of Novel PET Probes for Dementia. Semin Nucl Med 2023; 53:599-629. [PMID: 37149435 DOI: 10.1053/j.semnuclmed.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 05/08/2023]
Abstract
The development of novel PET imaging agents that selectively bind specific dementia-related targets can contribute significantly to accurate, differential and early diagnosis of dementia causing diseases and support the development of therapeutic agents. Consequently, in recent years there has been a growing body of literature describing the development and evaluation of potential new promising PET tracers for dementia. This review article provides a comprehensive overview of novel dementia PET probes under development, classified by their target, and pinpoints their preclinical evaluation pathway, typically involving in silico, in vitro and ex/in vivo evaluation. Specific target-associated challenges and pitfalls, requiring extensive and well-designed preclinical experimental evaluation assays to enable successful clinical translation and avoid shortcomings observed for previously developed 'well-established' dementia PET tracers are highlighted in this review.
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Affiliation(s)
- Romy Cools
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Kobe Kerkhofs
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium; NURA, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Renan C F Leitao
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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3
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Fontana IC, Kumar A, Nordberg A. The role of astrocytic α7 nicotinic acetylcholine receptors in Alzheimer disease. Nat Rev Neurol 2023; 19:278-288. [PMID: 36977843 DOI: 10.1038/s41582-023-00792-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 03/30/2023]
Abstract
The ongoing search for therapeutic interventions in Alzheimer disease (AD) has highlighted the complexity of this condition and the need for additional biomarkers, beyond amyloid-β (Aβ) and tau, to improve clinical assessment. Astrocytes are brain cells that control metabolic and redox homeostasis, among other functions, and are emerging as an important focus of AD research owing to their swift response to brain pathology in the initial stages of the disease. Reactive astrogliosis - the morphological, molecular and functional transformation of astrocytes during disease - has been implicated in AD progression, and the definition of new astrocytic biomarkers could help to deepen our understanding of reactive astrogliosis along the AD continuum. As we highlight in this Review, one promising biomarker candidate is the astrocytic α7 nicotinic acetylcholine receptor (α7nAChR), upregulation of which correlates with Aβ pathology in the brain of individuals with AD. We revisit the past two decades of research into astrocytic α7nAChRs to shed light on their roles in the context of AD pathology and biomarkers. We discuss the involvement of astrocytic α7nAChRs in the instigation and potentiation of early Aβ pathology and explore their potential as a target for future reactive astrocyte-based therapeutics and imaging biomarkers in AD.
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Affiliation(s)
- Igor C Fontana
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Amit Kumar
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
- Theme Inflammation and Aging, Karolinska University Hospital, Stockholm, Sweden.
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4
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Dean B, Haroutunian V, Scarr E. Lower levels of cortical [ 3H]pirenzepine binding to postmortem tissue defines a sub-group of older people with schizophrenia with less severe cognitive deficits. Schizophr Res 2023; 255:274-282. [PMID: 37079947 DOI: 10.1016/j.schres.2023.03.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 02/15/2023] [Accepted: 03/18/2023] [Indexed: 04/22/2023]
Abstract
Multiple lines of evidence argue for lower levels of cortical muscarinic M1 receptors (CHRM1) in people with schizophrenia which is possibly due to a sub-group within the disorder who have a marked loss of CHRM1 (muscarinic receptor deficit sub-group (MRDS)). In this study we sought to determine if the lower levels of CHRM1 was apparent in older people with schizophrenia and whether the loss of CHRM1 was associated with symptom severity by measuring levels of cortical [3H]pirenzepine binding to CHRM1 from 56 people with schizophrenia and 43 controls. Compared to controls (173 ± 6.3 fmol / mg protein), there were lower levels of cortical [3H]pirenzepine binding in the people with schizophrenia (mean ± SEM: 153 ± 6.0 fmol / mg protein; p = 0.02; Cohen's d = - 0.46). [3H]pirenzepine binding in the people with schizophrenia, but not controls, was not normally distributed and best fitted a two-population solution. The nadir of binding separating the two groups of people with schizophrenia was 121 fmol / mg protein and levels of [3H]pirenzepine binding below this value had a 90.7 % specificity for the disorder. Compared to controls, the score from the Clinical Dementia Rating Scale (CDR) did not differ significantly in MRDS but were significantly higher in the sub-group with normal radioligand binding. Positive and Negative Syndrome Scale scores did not differ between the two sub-groups with schizophrenia. Our current study replicates and earlier finding showing a MRDS within schizophrenia and, for the first time, suggest this sub-group have less severe cognitive deficits others with schizophrenia.
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Affiliation(s)
- Brian Dean
- The Synaptic Biology and Cognition Laboratory, The Florey Institute for Neuroscience and Mental Health, Parkville, Victoria, Australia; Florey Department of Neuroscience and Mental Health, the University of Melbourne, Parkville, Victoria, Australia.
| | - Vahram Haroutunian
- Departments of Psychiatry and Neuroscience, The Icahn School of Medicine at Mount Sinai, New York, NY, USA; The Mental Illness Research, Education and Clinical Centers, JJ Peters VA Medical Center, Bronx, NY, USA
| | - Elizabeth Scarr
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia
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5
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Wang DM, Xia LY, Zhou HX, Tian Y, Dai QL, Xiu MH, Chen DC, Wang L, Zhang XY. Smoking affects the association between cognitive impairment and P50 inhibition defects in patients with chronic schizophrenia: A case-control study. Asian J Psychiatr 2023; 79:103391. [PMID: 36516649 DOI: 10.1016/j.ajp.2022.103391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 09/23/2022] [Accepted: 10/09/2022] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Smoking affects sensory gating, as assessed by the event related potential P50, which is evoked by auditory stimuli and is considered to be involved in the pathophysiology of schizophrenia (SCZ). However, few studies have compared sensory gating and cognitive performance between smoking and non-smoking SCZ patients in the Chinese Han population. METHODS We recruited two groups of Chinese subjects: 128 male chronic SCZ patients and 76 male healthy controls, measuring cognition with the MATRICS Consensus Cognitive Battery (MCCB) and sensory gating with the P50 EEG components. Based on their smoking status, they were further divided into 4 subgroups: smoking SCZ patients, non-smoking SCZ patients, smoking healthy controls, and non-smoking healthy controls. We assessed psychopathological symptoms of the patients using the Positive and Negative Syndrome Scale (PANSS). RESULTS Compared with healthy controls, SCZ patients had lower MCCB total score and scores of all 10 tests (all p < 0.05), while SCZ patients had higher S2 amplitudes and P50 ratios (both p < 0.05). When comparing smoking versus non-smoking SCZ patients, non-smokers had significantly better spatial span (p < 0.05). Furthermore, the S1 amplitude was negatively correlated with the Brief Visuospatial Memory Test (BVMT-R) in smoking patients (p < 0.05), while the S1 latency was negatively correlated with spatial span in non-smoking patients (p < 0.01). CONCLUSIONS Our finding shows a difference in the relationship between sensory gated P50 and cognition in smoking and non-smoking SCZ patients, suggesting that nicotine may improve cognitive and P50 deficits in SCZ patients.
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Affiliation(s)
- Dong-Mei Wang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Lu-Yao Xia
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Hui-Xia Zhou
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Yang Tian
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Qi-Long Dai
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Mei-Hong Xiu
- Beijing HuiLongGuan Hospital, Peking University, Beijing, China
| | - Da-Chun Chen
- Beijing HuiLongGuan Hospital, Peking University, Beijing, China
| | - Li Wang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Xiang-Yang Zhang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China.
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6
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Gupta L, Hoffman KW. Exploring the intersection of the microbiome and the developing brain: Impacts on schizophrenia risk. Schizophr Res 2022; 247:92-100. [PMID: 34483026 DOI: 10.1016/j.schres.2021.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 08/04/2021] [Accepted: 08/08/2021] [Indexed: 12/21/2022]
Abstract
Recent findings show that the perinatal maternal and infant microbiomes have profound potential to impact long term health outcomes. Of particular interest are the ways in which the microbiome influences the developing brain during one of its most critical windows. Schizophrenia and psychosis risk are strongly connected to disruptions in perinatal neurodevelopment. In this review we present an overview of critical aspects in development of both the microbiome and brain, discuss their overlap, and consider what role the microbiome plays in schizophrenia risk during the perinatal window. Considering this, we discuss ways in which expecting and new mothers may reduce offspring schizophrenia risk.
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Affiliation(s)
- Lipi Gupta
- The University of Pennsylvania, Department of Psychiatry, Philadelphia, PA, United States
| | - Kevin W Hoffman
- The University of Pennsylvania, Department of Psychiatry, Philadelphia, PA, United States.
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7
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Di Lascio S, Fornasari D, Benfante R. The Human-Restricted Isoform of the α7 nAChR, CHRFAM7A: A Double-Edged Sword in Neurological and Inflammatory Disorders. Int J Mol Sci 2022; 23:ijms23073463. [PMID: 35408823 PMCID: PMC8998457 DOI: 10.3390/ijms23073463] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/13/2022] [Accepted: 03/21/2022] [Indexed: 12/13/2022] Open
Abstract
CHRFAM7A is a relatively recent and exclusively human gene arising from the partial duplication of exons 5 to 10 of the α7 neuronal nicotinic acetylcholine receptor subunit (α7 nAChR) encoding gene, CHRNA7. CHRNA7 is related to several disorders that involve cognitive deficits, including neuropsychiatric, neurodegenerative, and inflammatory disorders. In extra-neuronal tissues, α7nAChR plays an important role in proliferation, differentiation, migration, adhesion, cell contact, apoptosis, angiogenesis, and tumor progression, as well as in the modulation of the inflammatory response through the “cholinergic anti-inflammatory pathway”. CHRFAM7A translates the dupα7 protein in a multitude of cell lines and heterologous systems, while maintaining processing and trafficking that are very similar to the full-length form. It does not form functional ion channel receptors alone. In the presence of CHRNA7 gene products, dupα7 can assemble and form heteromeric receptors that, in order to be functional, should include at least two α7 subunits to form the agonist binding site. When incorporated into the receptor, in vitro and in vivo data showed that dupα7 negatively modulated α7 activity, probably due to a reduction in the number of ACh binding sites. Very recent data in the literature report that the presence of the duplicated gene may be responsible for the translational gap in several human diseases. Here, we will review the studies that have been conducted on CHRFAM7A in different pathologies, with the intent of providing evidence regarding when and how the expression of this duplicated gene may be beneficial or detrimental in the pathogenesis, and eventually in the therapeutic response, to CHRNA7-related neurological and non-neurological diseases.
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Affiliation(s)
- Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, 20129 Milan, Italy; (S.D.L.); (D.F.)
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, 20129 Milan, Italy; (S.D.L.); (D.F.)
- CNR Institute of Neuroscience, 20845 Vedano al Lambro, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, 20129 Milan, Italy; (S.D.L.); (D.F.)
- CNR Institute of Neuroscience, 20845 Vedano al Lambro, Italy
- NeuroMi, Milan Center for Neuroscience, University of Milano Bicocca, 20126 Milan, Italy
- Correspondence:
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8
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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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9
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Zhou Y, Kuang G, Li J, Halldin C, Nordberg A, Långström B, Tu Y, Ågren H. In silico studies of ASEM analogues targeting α7-nAChR and experimental verification. RSC Adv 2021; 11:3942-3951. [PMID: 35747361 PMCID: PMC9134020 DOI: 10.1039/d0ra10435c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/11/2021] [Indexed: 01/05/2023] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7-nAChR) is implicated in a variety of neurodegenerative and neuropsychiatric disorders, such as Alzheimer's disease (AD) and schizophrenia. The progress of these disorders can be studied using positron emission tomography (PET) with radiotracers for α7-nAChR. [18F]ASEM and [18F] para-ASEM (also referred to as [18F]DBT-10) are novel and potent α7-nAChR PET radiotracers which have successfully been used in human subjects and nonhuman primates, though further improvement of them is still a pressing task in the community of neurodegeneration research. In this work, we demonstrate the use of modern in silico techniques to predict the binding modes, binding strengths, and residence times for molecular PET tracers binding to proteins, using ASEM and DBT-10 as a showcase of the predictive and interpretational power of such techniques, in particular free energy perturbation theory. The corresponding compounds were synthesized and further tested by in vitro binding experiment for validation. Encouragingly, our in silico modeling can correctly predict the binding affinities of the ASEM analogues. The structure-activity relationships for the ortho- and para-substitutions are well explained at the atomistic level and provide structure-based guiding for the future development of PET tracers for α7-nAChR. A discussion is presented on the complementary use of in silico rational methods based on atomic and electronic principles for in vitro characterization of PET tracers.
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Affiliation(s)
- Yang Zhou
- School of Pharmacy, Jinan University Guangzhou 510632 China
- Department of Physics and Astronomy, Uppsala University Box 516 SE-751 20 Uppsala Sweden
| | - Guanglin Kuang
- Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center S-106 91 Stockholm Sweden
| | - Junhao Li
- Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center S-106 91 Stockholm Sweden
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research 171 76 Stockholm Sweden
| | - Agneta Nordberg
- Nordberg Translational Molecular Imaging Lab, Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet 141 84 Stockholm Sweden
- Theme Aging Karolinska University Hospital S-141 86 Stockholm Sweden
| | - Bengt Långström
- Department of Chemistry, Uppsala University SE- 751 23 Uppsala Sweden
| | - Yaoquan Tu
- Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center S-106 91 Stockholm Sweden
| | - Hans Ågren
- Department of Physics and Astronomy, Uppsala University Box 516 SE-751 20 Uppsala Sweden
- College of Chemistry and Chemical Engineering, Henan University Kaifeng Henan 475004 P.R. China
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10
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Georgiou R, Lamnisos D, Giannakou K. Anticholinergic Burden and Cognitive Performance in Patients With Schizophrenia: A Systematic Literature Review. Front Psychiatry 2021; 12:779607. [PMID: 35027893 PMCID: PMC8748260 DOI: 10.3389/fpsyt.2021.779607] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 10/21/2021] [Indexed: 01/06/2023] Open
Abstract
Objective: Cognitive impairment in schizophrenia forms the key cause of the disease's disability, leading to serious functional, and socioeconomic implications. Dopaminergic-cholinergic balance is considered essential to cognitive performance in schizophrenia and patients are often treated with many drugs with anticholinergic properties. This study aims to examine the cognitive impact of anticholinergic burden in patients with schizophrenia. Methods: A systematic literature review was performed on English-language studies published on PubMed, Embase, and Web of Science, from inception to June 2021, to identify research studies that examined the effect of anticholinergic load on cognition in clinically stable patients with schizophrenia. No restrictions on study design, age of participants, or geographical distribution were applied. Two researchers performed independently the screening and shortlisting of the eligible articles. A narrative synthesis of the main characteristics and findings of studies included was reported. Results: In total, 17 articles of varying methodological design met the inclusion criteria. Three of them found statistically significant improvement in cognition after anticholinergic tapering without adverse effects. Thirteen studies found a statistically significant association between high anticholinergic burden and cognitive impairment (neurocognitive composite scores and individual cognitive domains such as learning and memory, executive function, processing speed), apart from a study, related to the specific characteristics of clozapine. Conclusions: Medication with increased anticholinergic load has been found in most of the studies to negatively affect neurocognitive performance of patients with schizophrenia. However, the clinical and methodological heterogeneity of studies included limit our interpretation and conclusions.
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Affiliation(s)
- Rafaella Georgiou
- Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus
| | - Demetris Lamnisos
- Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus
| | - Konstantinos Giannakou
- Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus
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11
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Dean B, Pavey G, Scarr E. Higher levels of α7 nicotinic receptors, but not choline acetyltransferase, in the dorsolateral prefrontal cortex from a sub-group of patients with schizophrenia. Schizophr Res 2020; 222:283-290. [PMID: 32507381 DOI: 10.1016/j.schres.2020.05.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/16/2020] [Accepted: 05/15/2020] [Indexed: 12/12/2022]
Abstract
It has been suggested the study of sub-groups within the syndrome of schizophrenia will assist in elucidating the complex pathophysiology of the syndrome. Hence, we have studied a number of cholinergic markers in the cortex from a sub-group of subjects with schizophrenia that have a marked decrease in levels of muscarinic M1 receptors (MRDS). The displacement of [3H]NMS by cortical extracts was used to measure tissue anticholinergic load, [125I]α bungarotoxin binding was used to measure levels of the α7 nicotinic receptor (CHRNA7) and western blotting was used to measure levels of choline acetyltransferase (ChAT) 68 and 82 as well as synaptosome nerve-associated protein 25 (SNAP25). In comparing schizophrenia, MRDS and non-MRDS to controls, there were no differences in levels of ChAT 68 or 82, SNAP 25 or cholinergic load in BA 9. However, levels of CHRNA7 were higher in BA 9, but not BA 6 or 44, from subjects with MRDS. These data argue that there is no change in cholinergic innovation (measured using ChAT), presynaptic neurons (measured using SNAP25) or cholinergic load in schizophrenia, MRDS or non-MRDS. However, increased levels of CHRNA7 may be contributing to a breakdown in cholinergic homeostasis in BA 9, but not BA 6 or 44, in subjects with MRDS.
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Affiliation(s)
- Brian Dean
- The Molecular Psychiatry Laboratory, The Florey Institute for Neuroscience and Mental Health, Victoria, Australia; The Centre for Mental Health, Swinburne University of Technology, Hawthorn, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia.
| | - Geoffrey Pavey
- The Molecular Psychiatry Laboratory, The Florey Institute for Neuroscience and Mental Health, Victoria, Australia
| | - Elizabeth Scarr
- The Molecular Psychiatry Laboratory, The Florey Institute for Neuroscience and Mental Health, Victoria, Australia; Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
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Santos JR, Tomaz PRX, Scholz JR, Gaya PV, Abe TO, Krieger JE, Pereira AC, Santos PCJDL. Profile of the Nicotinic Cholinergic Receptor Alpha 7 Subunit Gene Expression is Associated with Response to Varenicline Treatment. Genes (Basel) 2020; 11:E746. [PMID: 32640505 PMCID: PMC7397196 DOI: 10.3390/genes11070746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/15/2020] [Accepted: 06/25/2020] [Indexed: 12/11/2022] Open
Abstract
INTRODUCTION Smoking is considered the leading cause of preventable morbidity and mortality worldwide. Studies have sought to identify predictors of response to smoking cessation treatments. The aim of this study was to analyze a possible association of target gene expression for smoking cessation with varenicline. METHODS We included 74 smokers starting treatment with varenicline. Gene expression analysis was performed through the custom RT² Profiler qPCR array assay, including 17 genes. Times for sample collection were before the start of therapy (T0) and two weeks (T2) and four weeks (T4) after the start of treatment. RESULTS For gene expression analysis, we selected 14 patients who had success and 13 patients resistant to varenicline treatment. Success was considered to be when a patient achieved tobacco abstinence until the fourth week of treatment and resistant was when a patient had not stopped smoking as of the fourth week of treatment. We observed a significant difference for CHRNA7 gene expression: in the resistant group, samples from T2 and T4 had lower expression compared with T0 (fold change: 0.38, P = 0.007; fold change: 0.67, P = 0.004; respectively). CONCLUSION This exploratory clinical study, searching for a possible predictor of effectiveness for varenicline, reaffirmed the association of the α7 nAChR subunit for nicotine dependence and smoking therapy effectiveness with varenicline.
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Affiliation(s)
- Juliana Rocha Santos
- Laboratory of Genetics and Molecular Cardiology, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.R.X.T.); (J.E.K.); (A.C.P.)
| | - Paulo Roberto Xavier Tomaz
- Laboratory of Genetics and Molecular Cardiology, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.R.X.T.); (J.E.K.); (A.C.P.)
| | - Jaqueline Ribeiro Scholz
- Smoking Cessation Program Department, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.V.G.); (T.O.A.)
| | - Patrícia Viviane Gaya
- Smoking Cessation Program Department, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.V.G.); (T.O.A.)
| | - Tânia Ogawa Abe
- Smoking Cessation Program Department, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.V.G.); (T.O.A.)
| | - José Eduardo Krieger
- Laboratory of Genetics and Molecular Cardiology, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.R.X.T.); (J.E.K.); (A.C.P.)
| | - Alexandre Costa Pereira
- Laboratory of Genetics and Molecular Cardiology, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-904, Brazil; (J.R.S.); (P.R.X.T.); (J.E.K.); (A.C.P.)
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Donat CK, Hansen HH, Hansen HD, Mease RC, Horti AG, Pomper MG, L’Estrade ET, Herth MM, Peters D, Knudsen GM, Mikkelsen JD. In Vitro and In Vivo Characterization of Dibenzothiophene Derivatives [ 125I]Iodo-ASEM and [ 18F]ASEM as Radiotracers of Homo- and Heteromeric α7 Nicotinic Acetylcholine Receptors. Molecules 2020; 25:molecules25061425. [PMID: 32245032 PMCID: PMC7144377 DOI: 10.3390/molecules25061425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 12/18/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is involved in several cognitive and physiologic processes; its expression levels and patterns change in neurologic and psychiatric diseases, such as schizophrenia and Alzheimer’s disease, which makes it a relevant drug target. Development of selective radioligands is important for defining binding properties and occupancy of novel molecules targeting the receptor. We tested the in vitro binding properties of [125I]Iodo-ASEM [(3-(1,4-diazabycyclo[3.2.2]nonan-4-yl)-6-(125I-iododibenzo[b,d]thiopentene 5,5-dioxide)] in the mouse, rat and pig brain using autoradiography. The in vivo binding properties of [18F]ASEM were investigated using positron emission tomography (PET) in the pig brain. [125I]Iodo-ASEM showed specific and displaceable high affinity (~1 nM) binding in mouse, rat, and pig brain. Binding pattern overlapped with [125I]α-bungarotoxin, specific binding was absent in α7 nAChR gene-deficient mice and binding was blocked by a range of α7 nAChR orthosteric modulators in an affinity-dependent order in the pig brain. Interestingly, relative to the wild-type, binding in β2 nAChR gene-deficient mice was lower for [125I]Iodo-ASEM (58% ± 2.7%) than [125I]α-bungarotoxin (23% ± 0.2%), potentially indicating different binding properties to heteromeric α7β2 nAChR. [18F]ASEM PET in the pig showed high brain uptake and reversible tracer kinetics with a similar spatial distribution as previously reported for α7 nAChR. Blocking with SSR-180,711 resulted in a significant decrease in [18F]ASEM binding. Our findings indicate that [125I]Iodo-ASEM allows sensitive and selective imaging of α7 nAChR in vitro, with better signal-to-noise ratio than previous tracers. Preliminary data of [18F]ASEM in the pig brain demonstrated principal suitable kinetic properties for in vivo quantification of α7 nAChR, comparable to previously published data.
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Affiliation(s)
- Cornelius K. Donat
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Department of Brain Sciences, Imperial College London, London W12 0 LS, UK
- Correspondence: (C.K.D.); (J.D.M.); Tel.: +45-40205378 (J.D.M)
| | - Henrik H. Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Hanne D. Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Ronnie C. Mease
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Andrew G. Horti
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Elina T. L’Estrade
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark;
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Matthias M. Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark;
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | | | - Gitte M. Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Jens D. Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Correspondence: (C.K.D.); (J.D.M.); Tel.: +45-40205378 (J.D.M)
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McCluskey SP, Plisson C, Rabiner EA, Howes O. Advances in CNS PET: the state-of-the-art for new imaging targets for pathophysiology and drug development. Eur J Nucl Med Mol Imaging 2020; 47:451-489. [PMID: 31541283 PMCID: PMC6974496 DOI: 10.1007/s00259-019-04488-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/15/2019] [Indexed: 02/07/2023]
Abstract
PURPOSE A limit on developing new treatments for a number of central nervous system (CNS) disorders has been the inadequate understanding of the in vivo pathophysiology underlying neurological and psychiatric disorders and the lack of in vivo tools to determine brain penetrance, target engagement, and relevant molecular activity of novel drugs. Molecular neuroimaging provides the tools to address this. This article aims to provide a state-of-the-art review of new PET tracers for CNS targets, focusing on developments in the last 5 years for targets recently available for in-human imaging. METHODS We provide an overview of the criteria used to evaluate PET tracers. We then used the National Institute of Mental Health Research Priorities list to identify the key CNS targets. We conducted a PubMed search (search period 1st of January 2013 to 31st of December 2018), which yielded 40 new PET tracers across 16 CNS targets which met our selectivity criteria. For each tracer, we summarised the evidence of its properties and potential for use in studies of CNS pathophysiology and drug evaluation, including its target selectivity and affinity, inter and intra-subject variability, and pharmacokinetic parameters. We also consider its potential limitations and missing characterisation data, but not specific applications in drug development. Where multiple tracers were present for a target, we provide a comparison of their properties. RESULTS AND CONCLUSIONS Our review shows that multiple new tracers have been developed for proteinopathy targets, particularly tau, as well as the purinoceptor P2X7, phosphodiesterase enzyme PDE10A, and synaptic vesicle glycoprotein 2A (SV2A), amongst others. Some of the most promising of these include 18F-MK-6240 for tau imaging, 11C-UCB-J for imaging SV2A, 11C-CURB and 11C-MK-3168 for characterisation of fatty acid amide hydrolase, 18F-FIMX for metabotropic glutamate receptor 1, and 18F-MNI-444 for imaging adenosine 2A. Our review also identifies recurrent issues within the field. Many of the tracers discussed lack in vivo blocking data, reducing confidence in selectivity. Additionally, late-stage identification of substantial off-target sites for multiple tracers highlights incomplete pre-clinical characterisation prior to translation, as well as human disease state studies carried out without confirmation of test-retest reproducibility.
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Affiliation(s)
- Stuart P McCluskey
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK.
| | - Christophe Plisson
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Eugenii A Rabiner
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Oliver Howes
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK
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Coughlin JM, Horti AG, Pomper MG. Opportunities in precision psychiatry using PET neuroimaging in psychosis. Neurobiol Dis 2019; 131:104428. [PMID: 30904669 PMCID: PMC6744961 DOI: 10.1016/j.nbd.2019.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/15/2019] [Accepted: 03/19/2019] [Indexed: 12/21/2022] Open
Abstract
With the movement toward precision medicine in healthcare, recent studies of individuals with psychosis have begun to explore positron emission tomography (PET) as a tool to test for biochemical signatures that may distinguish subtypes of psychosis that guide subtype-specific therapeutic interventions. This review presents selected PET findings that exemplify early promise in using molecular imaging to predict treatment response, provide rationale for new therapeutic targets, and monitor target engagement in biomarker-defined subtypes of psychosis. PET data, among other data types, may prove useful in the scientific pursuit of identifying precision strategies to improve clinical outcomes for individuals with psychosis.
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Affiliation(s)
- Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Andrew G Horti
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Martin G Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Ouach A, Vercouillie J, Bertrand E, Rodrigues N, Pin F, Serriere S, Boiaryna L, Chartier A, Percina N, Tangpong P, Gulhan Z, Mothes C, Deloye JB, Guilloteau D, Page G, Suzenet F, Buron F, Chalon S, Routier S. Bis(het)aryl-1,2,3-triazole quinuclidines as α7 nicotinic acetylcholine receptor ligands: Synthesis, structure affinity relationships, agonism activity, [18F]-radiolabeling and PET study in rats. Eur J Med Chem 2019; 179:449-469. [DOI: 10.1016/j.ejmech.2019.06.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/16/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022]
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Vingerhoets C, Bakker G, Schrantee A, van der Pluijm M, Bloemen OJN, Reneman L, Caan M, Booij J, van Amelsvoort TAMJ. Influence of muscarinic M 1 receptor antagonism on brain choline levels and functional connectivity in medication-free subjects with psychosis: A placebo controlled, cross-over study. Psychiatry Res Neuroimaging 2019; 290:5-13. [PMID: 31252222 DOI: 10.1016/j.pscychresns.2019.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 06/21/2019] [Accepted: 06/22/2019] [Indexed: 01/18/2023]
Abstract
An increasing number of studies implicate the muscarinic cholinergic system in cognitive dysfunction associated with psychosis. This study examined the effect of muscarinic M1 receptor modulation on anterior cingulate cortex (ACC) and striatal choline concentrations and the relation with cognitive performance, as well as functional connectivity of cognitive networks. Thirty medication-free subjects with a psychosis spectrum disorder and 30 gender, age and IQ-matched healthy control subjects underwent 1H-proton magnetic resonance spectroscopy (1H-MRS) twice, once after placebo and once after a single dose of biperiden (M1 receptor antagonist, 4 mg). A subset of 19 psychotic subjects and 28 controls underwent resting-state functional magnetic resonance imaging (rs-fMRI) as well. No significant differences were found in ACC and striatal choline levels, nor in functional connectivity, between the two groups after placebo. Moreover, M1 antagonism did not significantly affect choline levels or functional connectivity. No correlations were found between choline levels and cognition as well as psychotic symptoms. Our findings do not support an association between the cholinergic system and cognition and psychotic symptoms. However, the lack of group differences in choline concentrations and functional connectivity, both after biperiden and placebo, may indicate that there were no severe cholinergic abnormalities present in our sample.
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Affiliation(s)
- Claudia Vingerhoets
- Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, the Netherlands; Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands.
| | - Geor Bakker
- Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, the Netherlands; Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands; Development and Experimental Medicine, Sosei-Heptaris, Cambridge, United Kingdom
| | - Anouk Schrantee
- Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands; Spinoza Centre for Neuroimaging, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, the Netherlands
| | - Marieke van der Pluijm
- Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands
| | - Oswald J N Bloemen
- Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, the Netherlands; GGZ Centraal, Center for Mental Health Care Innova, Amersfoort, the Netherlands
| | - Liesbeth Reneman
- Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands
| | - Matthan Caan
- Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands; Department of Biomedical Engineering, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam University medical center, location Academic Medical Center, Amsterdam, the Netherlands
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Dyrvig M, Mikkelsen JD, Lichota J. DNA methylation regulates CHRNA7 transcription and can be modulated by valproate. Neurosci Lett 2019; 704:145-152. [PMID: 30974230 DOI: 10.1016/j.neulet.2019.04.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 04/03/2019] [Accepted: 04/07/2019] [Indexed: 01/29/2023]
Abstract
The CHRNA7 gene encoding the α7 nicotinic acetylcholine receptor (nAChR) has repeatedly been linked with schizophrenia and the P50 sensory gating deficit. The α7 nAChR is considered a promising drug target for treatment of cognitive dysfunction in schizophrenia and improves memory and executive functions in patients and healthy individuals. However, clinical trials with pro-cognitive drugs are challenged by large inter-individual response variations and these have been linked to genotypic variations reducing CHRNA7 expression and α7 nAChR function. Genetic variants as well as environmental conditions may cause epigenetic dysregulation and it has previously been found that DNA methylation of a region surrounding the transcription start site of CHRNA7 is important for tissue specific regulation and gene silencing. In the present study we identify two additional regions involved in epigenetic regulation of the CHRNA7 promoter. In human temporal cortex we find large variations in expression of CHRNA7 and establish evidence for a significant correlation with DNA methylation levels of one region. We then establish evidence that genotypic variations can influence methylation levels of the CHRNA7 promoter. Epigenetic dysregulation can be reversed by pharmacological intervention and in HeLa cells. Valproate, a commonly used mood stabiliser, caused demethylation and increased CHRNA7 expression in HeLA cells. Similar demethylation effect and increased CHRNA7 expression was obtained in SH-SY5Y cells stimulated concomitantly with valproate and nicotine. In summary, both genetic and epigenetic information could be useful to predict treatment outcomes in patients and epigenetic modulation may serve as a mechanism for potentiating the effects of α7 nAChR agonists.
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Affiliation(s)
- Mads Dyrvig
- Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Denmark
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Jacek Lichota
- Laboratory of Metabolism Modifying Medicine, Department of Health Science and Technology, Aalborg University, Denmark.
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Palomero-Gallagher N, Zilles K. Cyto- and receptor architectonic mapping of the human brain. HANDBOOK OF CLINICAL NEUROLOGY 2018; 150:355-387. [PMID: 29496153 DOI: 10.1016/b978-0-444-63639-3.00024-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mapping of the human brain is more than the generation of an atlas-based parcellation of brain regions using histologic or histochemical criteria. It is the attempt to provide a topographically informed model of the structural and functional organization of the brain. To achieve this goal a multimodal atlas of the detailed microscopic and neurochemical structure of the brain must be registered to a stereotaxic reference space or brain, which also serves as reference for topographic assignment of functional data, e.g., functional magnet resonance imaging, electroencephalography, or magnetoencephalography, as well as metabolic imaging, e.g., positron emission tomography. Although classic maps remain pioneering steps, they do not match recent concepts of the functional organization in many regions, and suffer from methodic drawbacks. This chapter provides a summary of the recent status of human brain mapping, which is based on multimodal approaches integrating results of quantitative cyto- and receptor architectonic studies with focus on the cerebral cortex in a widely used reference brain. Descriptions of the methods for observer-independent and statistically testable cytoarchitectonic parcellations, quantitative multireceptor mapping, and registration to the reference brain, including the concept of probability maps and a toolbox for using the maps in functional neuroimaging studies, are provided.
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Affiliation(s)
- Nicola Palomero-Gallagher
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany; Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty, RWTH, Aachen, Germany
| | - Karl Zilles
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany; Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty, RWTH, Aachen, Germany; JARA-BRAIN, Jülich-Aachen Research Alliance, Jülich, Germany.
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α7 Nicotinic receptor-modulating agents reverse the hyperdopaminergic tone in the MAM model of schizophrenia. Neuropsychopharmacology 2018; 43:1712-1720. [PMID: 29695783 PMCID: PMC6006162 DOI: 10.1038/s41386-018-0066-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 04/02/2018] [Indexed: 01/05/2023]
Abstract
Recent evidence has emerged supporting a role for the cholinergic system in schizophrenia, including the potential of α7 modulators as a treatment strategy. However, preclinical studies to date have relied on studies in normal systems rather than on a validated developmental model of schizophrenia. Furthermore, there have been only few studies on whether orthosteric and allosteric modulators have differential impacts in such models. Thus, we investigated the effects of α7 agonists and positive allosteric modulators (PAMs) on dopamine (DA) neuron activity in the ventral tegmental area (VTA) in the methylazoxymethanol acetate (MAM) developmental disruption model of schizophrenia. Four different drugs were evaluated: PNU282987 (full agonist), SSR180711 (partial agonist) NS1738 (PAM type I) and PNU120596 (PAM type II). PNU120596 increased the number of spontaneously active VTA DA neurons in normal rats. In contrast, PNU282987 and SSR180711 reduced the hyperdopaminergic tone in MAM rats. This appeared to be due to effects on DA afferent regulation, in that PNU282987 or SSR180711 infusion into the ventral hippocampus of MAM rats replicated the decrease in the number of spontaneously active VTA DA neurons. In contrast, infusion of the same drugs into the basolateral amygdala increased the number of spontaneously active VTA DA neurons in normal rats without impacting MAM rats. These data suggest that α7 receptors may represent a promising target in the development of new pharmacological therapies for schizophrenia.
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Wong DF, Kuwabara H, Horti AG, Roberts JM, Nandi A, Cascella N, Brasic J, Weerts EM, Kitzmiller K, Phan JA, Gapasin L, Sawa A, Valentine H, Wand G, Mishra C, George N, McDonald M, Lesniak W, Holt DP, Azad BB, Dannals RF, Kem W, Freedman R, Gjedde A. Brain PET Imaging of α7-nAChR with [18F]ASEM: Reproducibility, Occupancy, Receptor Density, and Changes in Schizophrenia. Int J Neuropsychopharmacol 2018; 21. [PMID: 29522184 PMCID: PMC6030963 DOI: 10.1093/ijnp/pyy021] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The α7 nicotinic acetylcholine receptor increasingly has been implicated in normal brain physiology, as well as in neuropsychiatric disorders. The highly cortical distribution of α7 nicotinic acetylcholine receptor suggests a role in cognition. METHODS We expanded the first-in-human PET imaging of α7 nicotinic acetylcholine receptor with [18F]ASEM from 5 to 21 healthy nonsmoking volunteers and added a feasibility study in 6 male patients with schizophrenia. Study aims included: (1) confirmation of test-retest reproducibility of [18F]ASEM binding, (2) demonstration of specificity by competition with DMXB-A, an α7 nicotinic acetylcholine receptor partial agonist, (3) estimation of [18F]ASEM binding potentials and α7 nicotinic acetylcholine receptor density in vivo in humans, and (4) demonstrating the feasibility of studying α7 nicotinic acetylcholine receptor as a target for schizophrenia. RESULTS Test-retest PET confirmed reproducibility (>90%) (variability ≤7%) of [18F]ASEM volume of distribution (VT) estimates in healthy volunteers. Repeated sessions of PET in 5 healthy subjects included baseline and effect of inhibition after oral administration of 150 mg DMXB-A. From reduction of binding potentials, we estimated the dose-dependent occupancy of α7 nicotinic acetylcholine receptor by DMXB-A at 17% to 49% for plasma concentrations at 60 to 200 nM DMXB-A. In agreement with evidence postmortem, α7 nicotinic acetylcholine receptor density averaged 0.67 to 0.82 nM and inhibitor affinity constant averaged 170 to 385 nM. Median VT in a feasibility study of 6 patients with schizophrenia was lower than in healthy volunteers in cingulate cortex, frontal cortex, and hippocampus (P = 0.02, corrected for multiple comparions, Mann-Whitney test). CONCLUSIONS The current results confirm the reproducibility of [18F]ASEM VT estimates and the specificity of the tracer for α7 nicotinic acetylcholine receptor. Preliminary findings from our feasibility study of [18F]ASEM binding in patients with schizophrenia are suggestive and provide guidance for future studies with more subjects.
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Affiliation(s)
- Dean F Wong
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland,Department of Psychiatry and Behavioral Sciences, Baltimore, Maryland,Solomon Snyder Department of Neuroscience, Baltimore, Maryland,Department of Neurology, Baltimore, Maryland,Johns Hopkins University School of Medicine, Baltimore, Maryland,Correspondence: Dean F. Wong, MD, PhD, Radiology, Nuclear Medicine, Johns Hopkins Medical Institutions, JHOC Room 3244, Baltimore, MD ()
| | - Hiroto Kuwabara
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Andrew G Horti
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Joshua M Roberts
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Ayon Nandi
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Nicola Cascella
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland,Sheppard-Pratt Hospital, Baltimore, Maryland
| | - James Brasic
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Elise M Weerts
- Department of Psychiatry and Behavioral Sciences, Baltimore, Maryland
| | - Kelly Kitzmiller
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Jenny A Phan
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland,Department of Biomedicine, Aarhus University, Aarhus, Denmark,Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Lorena Gapasin
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Akira Sawa
- Department of Psychiatry and Behavioral Sciences, Baltimore, Maryland
| | - Heather Valentine
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Gary Wand
- Department of Psychiatry and Behavioral Sciences, Baltimore, Maryland,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chakradhar Mishra
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Noble George
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Michael McDonald
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Wojtek Lesniak
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Daniel P Holt
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Babak B Azad
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - Robert F Dannals
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland
| | - William Kem
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland,Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida
| | - Robert Freedman
- Department of Psychiatry, University of Colorado, Aurora, Colorado
| | - Albert Gjedde
- Russell H. Morgan Department of Radiology and Radiological Sciences, Baltimore, Maryland,Department of Nuclear Medicine, University of Southern Denmark, Odense, Denmark
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22
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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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23
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Wylie KP, Smucny J, Legget KT, Tregellas JR. Targeting Functional Biomarkers in Schizophrenia with Neuroimaging. Curr Pharm Des 2017; 22:2117-23. [PMID: 26818860 DOI: 10.2174/1381612822666160127113912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/26/2016] [Indexed: 01/09/2023]
Abstract
Many of the most debilitating symptoms for psychiatric disorders such as schizophrenia remain poorly treated. As such, the development of novel treatments is urgently needed. Unfortunately, the costs associated with high failure rates for investigational compounds as they enter clinical trials has led to pharmaceutical companies downsizing or eliminating research programs needed to develop these drugs. One way of increasing the probability of success for investigational compounds is to incorporate alternative methods of identifying biological targets in order to more effectively screen new drugs. A promising method of accomplishing this goal for psychiatric drugs is to use functional magnetic resonance imaging (fMRI). fMRI investigates neural circuits, shedding light on the biology that generates symptoms such as hallucinations. Once identified, relevant neural circuits can be targeted with pharmacologic interventions and the response to these drugs measured with fMRI. This review describes the early use of fMRI in this context, and discusses the alpha7 nicotinic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (DMXB-A), as an example of the potential value of fMRI for psychiatric drug development.
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Affiliation(s)
- Korey P Wylie
- Department of Psychiatry, Anschutz Medical Campus, Bldg. 500, Mail Stop F546, 13001 East 17th Place, Aurora, CO, 80045, USA.
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24
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A Novel Multisensory Integration Task Reveals Robust Deficits in Rodent Models of Schizophrenia: Converging Evidence for Remediation via Nicotinic Receptor Stimulation of Inhibitory Transmission in the Prefrontal Cortex. J Neurosci 2017; 36:12570-12585. [PMID: 27974613 DOI: 10.1523/jneurosci.1628-16.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/20/2016] [Accepted: 10/19/2016] [Indexed: 12/24/2022] Open
Abstract
Atypical multisensory integration is an understudied cognitive symptom in schizophrenia. Procedures to evaluate multisensory integration in rodent models are lacking. We developed a novel multisensory object oddity (MSO) task to assess multisensory integration in ketamine-treated rats, a well established model of schizophrenia. Ketamine-treated rats displayed a selective MSO task impairment with tactile-visual and olfactory-visual sensory combinations, whereas basic unisensory perception was unaffected. Orbitofrontal cortex (OFC) administration of nicotine or ABT-418, an α4β2 nicotinic acetylcholine receptor (nAChR) agonist, normalized MSO task performance in ketamine-treated rats and this effect was blocked by GABAA receptor antagonism. GABAergic currents were also decreased in OFC of ketamine-treated rats and were normalized by activation of α4β2 nAChRs. Furthermore, parvalbumin (PV) immunoreactivity was decreased in the OFC of ketamine-treated rats. Accordingly, silencing of PV interneurons in OFC of PV-Cre mice using DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) selectively impaired MSO task performance and this was reversed by ABT-418. Likewise, clozapine-N-oxide-induced inhibition of PV interneurons in brain slices was reversed by activation of α4β2 nAChRs. These findings strongly imply a role for prefrontal GABAergic transmission in the integration of multisensory object features, a cognitive process with relevance to schizophrenia. Accordingly, nAChR agonism, which improves various facets of cognition in schizophrenia, reversed the severe MSO task impairment in this study and appears to do so via a GABAergic mechanism. Interactions between GABAergic and nAChR receptor systems warrant further investigation for potential therapeutic applications. The novel behavioral procedure introduced in the current study is acutely sensitive to schizophrenia-relevant cognitive impairment and should prove highly valuable for such research. SIGNIFICANCE STATEMENT Adaptive behaviors are driven by integration of information from different sensory modalities. Multisensory integration is disrupted in patients with schizophrenia, but little is known about the neural basis of this cognitive symptom. Development and validation of multisensory integration tasks for animal models is essential given the strong link between functional outcome and cognitive impairment in schizophrenia. We present a novel multisensory object oddity procedure that detects selective multisensory integration deficits in a rat model of schizophrenia using various combinations of sensory modalities. Moreover, converging data are consistent with a nicotinic-GABAergic mechanism of multisensory integration in the prefrontal cortex, results with strong clinical relevance to the study of cognitive impairment and treatment in schizophrenia.
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25
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Smucny J, Tregellas JR. Targeting neuronal dysfunction in schizophrenia with nicotine: Evidence from neurophysiology to neuroimaging. J Psychopharmacol 2017; 31:801-811. [PMID: 28441884 PMCID: PMC5963521 DOI: 10.1177/0269881117705071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Patients with schizophrenia self-administer nicotine at rates higher than is self-administered for any other psychiatric illness. Although the reasons are unclear, one hypothesis suggests that nicotine is a form of 'self-medication' in order to restore normal levels of nicotinic signaling and target abnormalities in neuronal function associated with cognitive processes. This brief review discusses evidence from neurophysiological and neuroimaging studies in schizophrenia patients that nicotinic agonists may effectively target dysfunctional neuronal circuits in the illness. Evidence suggests that nicotine significantly modulates a number of these circuits, although relatively few studies have used modern neuroimaging techniques (e.g. functional magnetic resonance imaging (fMRI)) to examine the effects of nicotinic drugs on disease-related neurobiology. The neuronal effects of nicotine and other nicotinic agonists in schizophrenia remain a priority for psychiatry research.
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Affiliation(s)
- Jason Smucny
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jason R Tregellas
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA,Research Service, Denver VA Medical Center, Denver, CO, USA
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26
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Potential of α7 nicotinic acetylcholine receptor PET imaging in atherosclerosis. Methods 2017; 130:90-104. [PMID: 28602809 DOI: 10.1016/j.ymeth.2017.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/02/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023] Open
Abstract
Atherosclerotic events are usually acute and often strike otherwise asymptomatic patients. Although multiple clinical risk factors have been associated with atherosclerosis, as of yet no further individual prediction can be made as to who will suffer from its consequences based on biomarker analysis or traditional imaging methods like CT, MRI or angiography. Previously, non-invasive imaging with 18F-fluorodeoxyglucose (18F-FDG) PET was shown to potentially fill this niche as it offers high sensitive detection of metabolic processes associated with inflammatory changes in atherosclerotic plaques. However, 18F-FDG PET imaging of arterial vessels suffers from non-specificity and has still to be proven to reliably identify vulnerable plaques, carrying a high risk of rupture. Therefore, it may be regarded only as a secondary marker for monitoring treatment effects and it does not offer alternative treatment options or direct insight in treatment mechanisms. In this review, an overview is given of the current status and the potential of PET imaging of inflammation and angiogenesis in atherosclerosis in general and special emphasis is given to imaging of α7 nicotinic acetylcholine receptors (α7 nAChRs). Due to the gaps that still exist in our understanding of atherogenesis and the limitations of the available PET tracers, the search continues for a more specific radioligand, able to differentiate between stable atherosclerosis and plaques prone to rupture. The potential role of the α7 nAChR as imaging marker for plaque vulnerability is explored. Today, strong evidence exists that nAChRs are involved in the atherosclerotic disease process. They are suggested to mediate the deleterious effects of the major tobacco component, nicotine, a nAChR agonist. Mainly based on in vitro data, α7 nAChR stimulation might increase plaque burden via increased neovascularization. However, in animal studies, α7 nAChR manipulation appears to reduce plaque size due to its inhibitory effects on inflammatory cells. Thus, reliable identification of α7 nAChRs by in vivo imaging is crucial to investigate the exact role of α7 nAChR in atherosclerosis before any therapeutic approach in the human setting can be justified. In this review, we discuss the first experience with α7 nAChR PET tracers and developmental considerations regarding the "optimal" PET tracer to image vascular nAChRs.
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27
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Corsi-Zuelli FMDG, Brognara F, Quirino GFDS, Hiroki CH, Fais RS, Del-Ben CM, Ulloa L, Salgado HC, Kanashiro A, Loureiro CM. Neuroimmune Interactions in Schizophrenia: Focus on Vagus Nerve Stimulation and Activation of the Alpha-7 Nicotinic Acetylcholine Receptor. Front Immunol 2017; 8:618. [PMID: 28620379 PMCID: PMC5449450 DOI: 10.3389/fimmu.2017.00618] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/10/2017] [Indexed: 12/28/2022] Open
Abstract
Schizophrenia is one of the most debilitating mental disorders and is aggravated by the lack of efficacious treatment. Although its etiology is unclear, epidemiological studies indicate that infection and inflammation during development induces behavioral, morphological, neurochemical, and cognitive impairments, increasing the risk of developing schizophrenia. The inflammatory hypothesis of schizophrenia is also supported by clinical studies demonstrating systemic inflammation and microglia activation in schizophrenic patients. Although elucidating the mechanism that induces this inflammatory profile remains a challenge, mounting evidence suggests that neuroimmune interactions may provide therapeutic advantages to control inflammation and hence schizophrenia. Recent studies have indicated that vagus nerve stimulation controls both peripheral and central inflammation via alpha-7 nicotinic acetylcholine receptor (α7nAChR). Other findings have indicated that vagal stimulation and α7nAChR-agonists can provide therapeutic advantages for neuropsychiatric disorders, such as depression and epilepsy. This review analyzes the latest results regarding: (I) the immune-to-brain pathogenesis of schizophrenia; (II) the regulation of inflammation by the autonomic nervous system in psychiatric disorders; and (III) the role of the vagus nerve and α7nAChR in schizophrenia.
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Affiliation(s)
| | - Fernanda Brognara
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | | | - Carlos Hiroji Hiroki
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Rafael Sobrano Fais
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Cristina Marta Del-Ben
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Luis Ulloa
- Department of Surgery, Center of Immunology and Inflammation, Rutgers University-New Jersey Medical School, Newark, NJ, United States
| | - Helio Cesar Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Alexandre Kanashiro
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Camila Marcelino Loureiro
- Department of Internal Medicine, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
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28
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Lewis AS, van Schalkwyk GI, Bloch MH. Alpha-7 nicotinic agonists for cognitive deficits in neuropsychiatric disorders: A translational meta-analysis of rodent and human studies. Prog Neuropsychopharmacol Biol Psychiatry 2017; 75:45-53. [PMID: 28065843 PMCID: PMC5446073 DOI: 10.1016/j.pnpbp.2017.01.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 12/24/2016] [Accepted: 01/03/2017] [Indexed: 12/28/2022]
Abstract
Cognitive dysfunction in schizophrenia (SCZ) and Alzheimer's disease (AD) is a major driver of functional disability but is largely unresponsive to current therapeutics. Animal models of cognitive dysfunction relevant to both disorders suggest the α7 nicotinic acetylcholine receptor (nAChR) may be a promising drug development target, with multiple clinical trials subsequently testing this hypothesis in individuals with SCZ and AD. However, the translational value of rodent cognitive tasks for predicting the overall efficacy of this therapeutic target in clinical trials is unknown. To compare effect sizes between rodent and human studies, we searched PubMed and the Cochrane Library for all randomized, placebo-controlled trials of compounds with pharmacological activity at the α7 nAChR for treatment of cognitive dysfunction in SCZ and AD and identified 18 studies comprising 2670 subjects treated with eight different compounds acting as full or partial agonists. Cognitive outcomes were standardized, and random-effects meta-analyses revealed no statistically significant effects of α7 nAChR agonists on overall cognition or any of eight cognitive subdomains when all doses were included (Range of all cognitive outcomes: Cohen's d=-0.077 to 0.12, negative favoring drug). In contrast, analysis of 29 rodent studies testing the same α7 agonists revealed large effect sizes in multiple commonly used preclinical behavioral tests of cognition (Range: d=-1.18 to - 0.73). Our results suggest that targeting the α7 nAChR with agonists is not a robust treatment for cognitive dysfunction in SCZ or AD and necessitate a better understanding of the translational gap for therapeutics targeting the α7 nAChR.
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Affiliation(s)
- Alan S. Lewis
- Department of Psychiatry, Yale University, 34 Park Street, 3rd Floor, Research, New Haven, CT 06508, United States,Corresponding author at: 34 Park Street, 3rd Floor, Research, New Haven, CT 06508, United States. (A.S. Lewis)
| | | | - Michael H. Bloch
- Yale Child Study Center, 230 S. Frontage Road, New Haven, CT 06520, United States
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29
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Increased risk of developing schizophrenia in animals exposed to cigarette smoke during the gestational period. Prog Neuropsychopharmacol Biol Psychiatry 2017; 75:199-206. [PMID: 28229913 DOI: 10.1016/j.pnpbp.2017.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/12/2016] [Accepted: 02/12/2017] [Indexed: 11/22/2022]
Abstract
Cigarette smoking during the prenatal period has been investigated as a causative factor of obstetric abnormalities, which lead to cognitive and behavioural changes associated with schizophrenia. The aim of this study was to investigate behaviour and AChE activity in brain structures in adult rats exposed to cigarette smoke during the prenatal period. Pregnant rats were divided into non-PCSE (non-prenatal cigarette smoke exposure) and PCSE (prenatal cigarette smoke exposure) groups. On post-natal day 60, the rats received saline or ketamine for 7days and were subjected to behavioural tasks. In the locomotor activity task, the non-PCSE+ketamine and PCSE+ketamine groups exhibited increased locomotor activity compared with the saline group. In the social interaction task, the non-PCSE+ketamine and PCSE+ketamine groups exhibited an increased latency compared with the control groups. However, the PCSE+ketamine group exhibited a decreased latency compared with the non-PCSE+ketamine group, which indicates that the cigarette exposure appeared to decrease, the social deficits generated by ketamine. In the inhibitory avoidance task, the non-PCSE+ketamine, PCSE, and PCSE+ketamine groups exhibited impairments in working memory, short-term memory, and long-term memory. In the pre-pulse inhibition (PPI) test, cigarette smoke associated with ketamine resulted in impaired PPI in 3 pre-pulse (PP) intensity groups compared with the control groups. In the biochemical analysis, the AChE activity in brain structures increased in the ketamine groups; however, the PCSE+ketamine group exhibited an exacerbated effect in all brain structures. The present study indicates that exposure to cigarette smoke during the prenatal period may affect behaviour and cerebral cholinergic structures during adulthood.
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30
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Kuang G, Zhou Y, Zou R, Halldin C, Nordberg A, Långström B, Ågren H, Tu Y. Characterization of the binding mode of the PET tracer [18F]ASEM to a chimera structure of the α7 nicotinic acetylcholine receptor. RSC Adv 2017. [DOI: 10.1039/c7ra00496f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The binding free energy profile of the radio-ligand [18F]ASEM with the α7 nicotinic acetylcholine receptor was revealed by metadynamic simulations.
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Affiliation(s)
- Guanglin Kuang
- Division of Theoretical Chemistry and Biology
- School of Biotechnology
- Royal Institute of Technology (KTH)
- AlbaNova University Center
- Stockholm
| | - Yang Zhou
- Division of Theoretical Chemistry and Biology
- School of Biotechnology
- Royal Institute of Technology (KTH)
- AlbaNova University Center
- Stockholm
| | - Rongfeng Zou
- Division of Theoretical Chemistry and Biology
- School of Biotechnology
- Royal Institute of Technology (KTH)
- AlbaNova University Center
- Stockholm
| | - Christer Halldin
- Karolinska Institutet
- Department of Clinical Neuroscience
- Centre for Psychiatric Research
- Stockholm
- Sweden
| | - Agneta Nordberg
- Department of Neurobiology, Care Sciences and Society
- Center of Alzheimer Research, Translational Alzheimer Neurobiology
- Karolinska University Hospital
- Stockholm
- Sweden
| | - Bengt Långström
- Department of Chemistry
- Uppsala University
- 751 23 Uppsala
- Sweden
| | - Hans Ågren
- Division of Theoretical Chemistry and Biology
- School of Biotechnology
- Royal Institute of Technology (KTH)
- AlbaNova University Center
- Stockholm
| | - Yaoquan Tu
- Division of Theoretical Chemistry and Biology
- School of Biotechnology
- Royal Institute of Technology (KTH)
- AlbaNova University Center
- Stockholm
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31
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Kalkman HO, Feuerbach D. Modulatory effects of α7 nAChRs on the immune system and its relevance for CNS disorders. Cell Mol Life Sci 2016; 73:2511-30. [PMID: 26979166 PMCID: PMC4894934 DOI: 10.1007/s00018-016-2175-4] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/25/2016] [Accepted: 03/01/2016] [Indexed: 02/08/2023]
Abstract
The clinical development of selective alpha-7 nicotinic acetylcholine receptor (α7 nAChR) agonists has hitherto been focused on disorders characterized by cognitive deficits (e.g., Alzheimer's disease, schizophrenia). However, α7 nAChRs are also widely expressed by cells of the immune system and by cells with a secondary role in pathogen defense. Activation of α7 nAChRs leads to an anti-inflammatory effect. Since sterile inflammation is a frequently observed phenomenon in both psychiatric disorders (e.g., schizophrenia, melancholic and bipolar depression) and neurological disorders (e.g., Alzheimer's disease, Parkinson's disease, and multiple sclerosis), α7 nAChR agonists might show beneficial effects in these central nervous system disorders. In the current review, we summarize information on receptor expression, the intracellular signaling pathways they modulate and reasons for receptor dysfunction. Information from tobacco smoking, vagus nerve stimulation, and cholinesterase inhibition is used to evaluate the therapeutic potential of selective α7 nAChR agonists in these inflammation-related disorders.
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Affiliation(s)
- Hans O Kalkman
- Neuroscience Research, NIBR, Fabrikstrasse 22-3.001.02, 4002, Basel, Switzerland.
- , Gänsbühlgartenweg 7, 4132, Muttenz, Switzerland.
| | - Dominik Feuerbach
- Neuroscience Research, NIBR, Fabrikstrasse 22-3.001.02, 4002, Basel, Switzerland
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Chalon S, Vercouillie J, Guilloteau D, Suzenet F, Routier S. PET tracers for imaging brain α7 nicotinic receptors: an update. Chem Commun (Camb) 2016; 51:14826-31. [PMID: 26359819 DOI: 10.1039/c5cc04536c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Positron emission tomography (PET) molecular imaging of brain targets is a powerful tool to diagnose, follow up, and develop treatments and personalized medicine for a number of acute and chronic brain disorders. The availability of β+ emitter tracers labelled with [(11)C] or [(18)F] having optimal characteristics of affinity and selectivity for alpha-7 nicotinic receptors (α7R) has received considerable attention, due to the major implication of these receptors in brain functions. The aim of this review is to identify the interest and need for the in vivo exploration of α7R by PET molecular imaging, which tools are currently available for this and how to progress.
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Affiliation(s)
- S Chalon
- UMR Inserm U930, Université François-Rabelais de Tours, F-37000 Tours, France.
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Landek-Salgado MA, Faust TE, Sawa A. Molecular substrates of schizophrenia: homeostatic signaling to connectivity. Mol Psychiatry 2016; 21:10-28. [PMID: 26390828 PMCID: PMC4684728 DOI: 10.1038/mp.2015.141] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 06/24/2015] [Accepted: 06/25/2015] [Indexed: 02/06/2023]
Abstract
Schizophrenia (SZ) is a devastating psychiatric condition affecting numerous brain systems. Recent studies have identified genetic factors that confer an increased risk of SZ and participate in the disease etiopathogenesis. In parallel to such bottom-up approaches, other studies have extensively reported biological changes in patients by brain imaging, neurochemical and pharmacological approaches. This review highlights the molecular substrates identified through studies with SZ patients, namely those using top-down approaches, while also referring to the fruitful outcomes of recent genetic studies. We have subclassified the molecular substrates by system, focusing on elements of neurotransmission, targets in white matter-associated connectivity, immune/inflammatory and oxidative stress-related substrates, and molecules in endocrine and metabolic cascades. We further touch on cross-talk among these systems and comment on the utility of animal models in charting the developmental progression and interaction of these substrates. Based on this comprehensive information, we propose a framework for SZ research based on the hypothesis of an imbalance in homeostatic signaling from immune/inflammatory, oxidative stress, endocrine and metabolic cascades that, at least in part, underlies deficits in neural connectivity relevant to SZ. Thus, this review aims to provide information that is translationally useful and complementary to pathogenic hypotheses that have emerged from genetic studies. Based on such advances in SZ research, it is highly expected that we will discover biomarkers that may help in the early intervention, diagnosis or treatment of SZ.
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Affiliation(s)
- M A Landek-Salgado
- Department of Psychiatry, John Hopkins University School of Medicine, Baltimore, MD, USA
| | - T E Faust
- Department of Psychiatry, John Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Neuroscience, John Hopkins University School of Medicine, Baltimore, MD, USA
| | - A Sawa
- Department of Psychiatry, John Hopkins University School of Medicine, Baltimore, MD, USA
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Anti-inflammatory role of microglial alpha7 nAChRs and its role in neuroprotection. Biochem Pharmacol 2015; 97:463-472. [DOI: 10.1016/j.bcp.2015.07.032] [Citation(s) in RCA: 213] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/27/2015] [Indexed: 12/15/2022]
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Bertrand D, Lee CHL, Flood D, Marger F, Donnelly-Roberts D. Therapeutic Potential of α7 Nicotinic Acetylcholine Receptors. Pharmacol Rev 2015; 67:1025-73. [DOI: 10.1124/pr.113.008581] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Sinkus ML, Graw S, Freedman R, Ross RG, Lester HA, Leonard S. The human CHRNA7 and CHRFAM7A genes: A review of the genetics, regulation, and function. Neuropharmacology 2015; 96:274-88. [PMID: 25701707 PMCID: PMC4486515 DOI: 10.1016/j.neuropharm.2015.02.006] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 02/04/2015] [Accepted: 02/06/2015] [Indexed: 01/16/2023]
Abstract
The human α7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) is ubiquitously expressed in both the central nervous system and in the periphery. CHRNA7 is genetically linked to multiple disorders with cognitive deficits, including schizophrenia, bipolar disorder, ADHD, epilepsy, Alzheimer's disease, and Rett syndrome. The regulation of CHRNA7 is complex; more than a dozen mechanisms are known, one of which is a partial duplication of the parent gene. Exons 5-10 of CHRNA7 on chromosome 15 were duplicated and inserted 1.6 Mb upstream of CHRNA7, interrupting an earlier partial duplication of two other genes. The chimeric CHRFAM7A gene product, dupα7, assembles with α7 subunits, resulting in a dominant negative regulation of function. The duplication is human specific, occurring neither in primates nor in rodents. The duplicated α7 sequence in exons 5-10 of CHRFAM7A is almost identical to CHRNA7, and thus is not completely queried in high throughput genetic studies (GWAS). Further, pre-clinical animal models of the α7nAChR utilized in drug development research do not have CHRFAM7A (dupα7) and cannot fully model human drug responses. The wide expression of CHRNA7, its multiple functions and modes of regulation present challenges for study of this gene in disease. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Melissa L Sinkus
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Sharon Graw
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA; Veterans Affairs Medical Research Center, Denver, CO 80262, USA.
| | - Randal G Ross
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Henry A Lester
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA; Veterans Affairs Medical Research Center, Denver, CO 80262, USA.
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Horti AG. Development of [(18)F]ASEM, a specific radiotracer for quantification of the α7-nAChR with positron-emission tomography. Biochem Pharmacol 2015; 97:566-575. [PMID: 26232729 DOI: 10.1016/j.bcp.2015.07.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/24/2015] [Indexed: 12/20/2022]
Abstract
The alpha-7 subtype of the nicotinic acetylcholine receptor (α7-nAChR) is fundamental to physiology; it mediates various brain functions and represents an important target for drug discovery. Exploration of the brain nicotinic acetylcholine receptors (nAChRs) using positron-emission tomography (PET) will make it possible to better understand the important role of this receptor and to study its involvement in schizophrenia, bipolar disorder, Alzheimer's and Parkinson's diseases, drug dependence, inflammation and many other disorders and simplify the development of nicotinic drugs for treatment of these disorders. Until recently, PET imaging of α7-nAChRs has been impeded by the absence of good radiotracers. This review describes various endeavors to develop α7-nAChR PET tracers by several research groups including the author's group. Most initial PET tracers for imaging α7-nAChRs did not exhibit suitable imaging properties due to their low specific binding. Newly discovered [(18)F]ASEM is the first highly specific α7-nAChR radioligand and in 2014 it was translated to human PET imaging.
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Affiliation(s)
- Andrew G Horti
- Department of Radiology, The Johns Hopkins School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287-0816, USA.
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Smith DM, Fisher D, Blier P, Ilivitsky V, Knott V. The separate and combined effects of monoamine oxidase A inhibition and nicotine on the mismatch negativity event related potential. Pharmacol Biochem Behav 2015; 137:44-52. [PMID: 26226350 DOI: 10.1016/j.pbb.2015.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/29/2015] [Accepted: 07/13/2015] [Indexed: 12/20/2022]
Abstract
The mismatch negativity (MMN) auditory event-related potential (ERP) has been extensively studied as a potential biomarker for abnormal auditory processing in schizophrenia (SZ), a population which exhibits abnormally high smoking rates. The relationship between nicotinic activation and cognition in SZ may be related to underlying nicotinic and NMDA receptor dysfunction within the disease. However, transient cognitive improvements via smoking in patients may also result from monoamine oxidase (MAO) inhibition, achieved through tobacco smoke. In 24 healthy non-smoking males, we investigated the separate and combined effects of nicotine and MAO-A inhibition via moclobemide (75mg) on the optimal-5 variation of the MMN paradigm. No significant drug effects were observed in our total sample, however, stratification of individuals into low (N=12) and high (N=12) baseline MMN amplitude groups revealed increases in duration MMN amplitude relative to placebo by nicotine, as well as moclobemide, but not after the combination of the two. Because previous research has shown there was no effect of monoamine modulation on MMN, this study shows an unexpected effect of moclobemide on duration MMN.
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Affiliation(s)
- Dylan M Smith
- University of Ottawa Institute of Mental Health Research, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.
| | - Derek Fisher
- Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada
| | - Pierre Blier
- University of Ottawa Institute of Mental Health Research, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; Royal Ottawa Mental Health Centre, Ottawa, Ontario, Canada
| | | | - Verner Knott
- University of Ottawa Institute of Mental Health Research, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; Royal Ottawa Mental Health Centre, Ottawa, Ontario, Canada
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Wong DF, Kuwabara H, Pomper M, Holt DP, Brasic JR, George N, Frolov B, Willis W, Gao Y, Valentine H, Nandi A, Gapasin L, Dannals RF, Horti AG. Human brain imaging of α7 nAChR with [(18)F]ASEM: a new PET radiotracer for neuropsychiatry and determination of drug occupancy. Mol Imaging Biol 2015; 16:730-8. [PMID: 25145965 DOI: 10.1007/s11307-014-0779-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE Using the α7-nAChR radiotracer, [(18)F]ASEM, we present the first successful human positron emission tomography (PET) studies. Rodent occupancy with three clinically employed α7-nAChR drugs confirms the specificity of the radiotracer. PROCEDURES Five healthy male subjects were imaged for 90 min following IV [(18)F]ASEM. Two subjects were scanned for the second time (test/retest; TRV). Mouse biodistribution of [(18)F]ASEM was carried out in CD1 mice injected with using human equivalent doses of DMXB-A, EVP-6124, and varenicline to block specific binding. RESULTS [(18)F]ASEM readily entered the brain and peaked at 15 min post-injection with reversible kinetics and a peak %SUV of about 400 %. The regional human brain distribution of [(18)F]ASEM matched previous in vitro data and baboon PET results. The precuneus, parietal, occipital, cingulate cortexes, putamen, and thalamus showed high values of distribution volume (>20 ml/ml) and binding potentials >1 with TRV averaged 10.8 ± 5.1 %. In mouse distribution studies, there was significant dose-dependent blockade in the mouse brain with DMXB-A as well as the other two α7-nAChR drugs. CONCLUSIONS The characteristics of [(18)F]ASEM are consistent with the ability to quantify α7-nAChR in the human brain. [(18)F]ASEM is suitable for imaging neuropsychiatric disorders and target engagement (receptor occupancy) of potential α7-nAChR drugs.
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Affiliation(s)
- Dean F Wong
- Department of Radiology, School of Medicine, The Johns Hopkins University, Baltimore, MD, USA,
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Beinat C, Reekie T, Banister SD, O'Brien-Brown J, Xie T, Olson TT, Xiao Y, Harvey A, O'Connor S, Coles C, Grishin A, Kolesik P, Tsanaktsidis J, Kassiou M. Structure-activity relationship studies of SEN12333 analogues: determination of the optimal requirements for binding affinities at α7 nAChRs through incorporation of known structural motifs. Eur J Med Chem 2015; 95:277-301. [PMID: 25827398 DOI: 10.1016/j.ejmech.2015.03.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 03/11/2015] [Accepted: 03/12/2015] [Indexed: 12/27/2022]
Abstract
Alpha7 nicotinic acetylcholine receptors (nAChRs) have implications in the regulation of cognitive processes such as memory and attention and have been identified as a promising therapeutic target for the treatment of the cognitive deficits associated with schizophrenia and Alzheimer's disease (AD). Structure affinity relationship studies of the previously described α7 agonist SEN12333 (8), have resulted in the identification of compound 45, a potent and selective agonist of the α7 nAChR with enhanced affinity and improved physicochemical properties over the parent compound (SEN12333, 8).
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Affiliation(s)
- Corinne Beinat
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia; Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tristan Reekie
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | - Samuel D Banister
- Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Teresa Xie
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC 20057, USA
| | - Thao T Olson
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC 20057, USA
| | - Yingxian Xiao
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC 20057, USA
| | | | | | | | | | | | - John Tsanaktsidis
- CSIRO Materials Science & Engineering, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168, Australia
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia; Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
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Wischhof L, Irrsack E, Osorio C, Koch M. Prenatal LPS-exposure--a neurodevelopmental rat model of schizophrenia--differentially affects cognitive functions, myelination and parvalbumin expression in male and female offspring. Prog Neuropsychopharmacol Biol Psychiatry 2015; 57:17-30. [PMID: 25455585 DOI: 10.1016/j.pnpbp.2014.10.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/08/2014] [Accepted: 10/10/2014] [Indexed: 01/15/2023]
Abstract
Maternal infection during pregnancy increases the risk for the offspring to develop schizophrenia. Gender differences can be seen in various features of the illness and sex steroid hormones (e.g. estrogen) have strongly been implicated in the disease pathology. In the present study, we evaluated sex differences in the effects of prenatal exposure to a bacterial endotoxin (lipopolysaccharide, LPS) in rats. Pregnant dams received LPS-injections (100 μg/kg) at gestational day 15 and 16. The offspring was then tested for prepulse inhibition (PPI), locomotor activity, anxiety-like behavior and object recognition memory at various developmental time points. At postnatal day (PD) 33 and 60, prenatally LPS-exposed rats showed locomotor hyperactivity which was similar in male and female offspring. Moreover, prenatal LPS-treatment caused PPI deficits in pubertal (PD45) and adult (PD90) males while PPI impairments were found only at PD45 in prenatally LPS-treated females. Following prenatal LPS-administration, recognition memory for objects was impaired in both sexes with males being more severely affected. Additionally, we assessed prenatal infection-induced alterations of parvalbumin (Parv) expression and myelin fiber density. Male offspring born to LPS-challenged mothers showed decreased myelination in cortical and limbic brain regions as well as reduced numbers of Parv-expressing cells in the medial prefrontal cortex (mPFC), hippocampus and entorhinal cortex. In contrast, LPS-exposed female rats showed only a modest decrease in myelination and Parv immunoreactivity. Collectively, our data indicate that some of the prenatal immune activation effects are sex dependent and further strengthen the importance of taking into account gender differences in animal models of schizophrenia.
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Affiliation(s)
- Lena Wischhof
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany.
| | - Ellen Irrsack
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
| | - Carmen Osorio
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
| | - Michael Koch
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
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42
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Hashimoto K. Targeting of α7 Nicotinic Acetylcholine Receptors in the Treatment of Schizophrenia and the Use of Auditory Sensory Gating as a Translational Biomarker. Curr Pharm Des 2015; 21:3797-806. [PMID: 26044974 PMCID: PMC5024727 DOI: 10.2174/1381612821666150605111345] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/04/2015] [Indexed: 11/22/2022]
Abstract
Accumulating evidence suggests that the α7 subtype of nicotinic acetylcholine receptors (nAChRs) plays a key role in inflammatory processes, thought to be involved in the pathophysiology of neuropsychiatric diseases, such as schizophrenia and Alzheimer's disease. Preclinical and clinical studies showed that the diminished suppression of P50 auditory evoked potentials in patients with schizophrenia may be associated with a decreased density of α7 nAChRs in the brain. This points to a role for auditory sensory gating (P50) as a translational biomarker. A number of agonists and positive allosteric modulators (PAMs) for α7 nAChR promoted beneficial effects in animal models with sensory gating and cognitive deficits. Additionally, several clinical studies showed that α7 nAChR agonists could improve suppression in auditory P50 evoked potentials, as well as cognitive deficits, and negative symptoms in patients with schizophrenia. Taken together, α7 nAChR presents as an extremely attractive therapeutic target for schizophrenia. In this article, the author discusses recent findings on α7 nAChR agonists such as DMXB-A, RG3487, TC-5619, tropisetron, EVP-6124 (encenicline), ABT-126, AQW051 and α7 nAChR PAMs such as JNJ-39393406, PNU- 120596 and AVL-3288 (also known as UCI-4083), and their potential as therapeutic drugs for neuropsychiatric diseases, such as schizophrenia.
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Affiliation(s)
- Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic, Mental Health, 1-8-1 Inohana, Chiba 260-8670, Japan.
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43
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Wang Y, Xiao C, Indersmitten T, Freedman R, Leonard S, Lester HA. The duplicated α7 subunits assemble and form functional nicotinic receptors with the full-length α7. J Biol Chem 2014; 289:26451-26463. [PMID: 25056953 DOI: 10.1074/jbc.m114.582858] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor gene (CHRNA7) is linked to schizophrenia. A partial duplication of CHRNA7 (CHRFAM7A) is found in humans on 15q13-14. Exon 6 of CHRFAM7A harbors a 2-bp deletion polymorphism, CHRFAM7AΔ2bp, which is also associated with schizophrenia. To understand the effects of the duplicated subunits on α7 receptors, we fused α7, dupα7, and dupΔα7 subunits with various fluorescent proteins. The duplicated subunits co-localized with full-length α7 subunits in mouse neuroblastoma cells (Neuro2a) as well as rat hippocampal neurons. We investigated the interaction between the duplicated subunits and full-length α7 by measuring Förster resonance energy transfer using donor recovery after photobleaching and fluorescence lifetime imaging microscopy. The results revealed that the duplicated proteins co-assemble with α7. In electrophysiological studies, Leu at the 9'-position in the M2 membrane-spanning segment was replaced with Cys in dupα7 or dupΔα7, and constructs were co-transfected with full-length α7 in Neuro2a cells. Exposure to ethylammonium methanethiosulfonate inhibited acetylcholine-induced currents, showing that the assembled functional nicotinic acetylcholine receptors (nAChRs) included the duplicated subunit. Incorporation of dupα7 and dupΔα7 subunits modestly changes the sensitivity of receptors to choline and varenicline. Thus, the duplicated proteins are assembled and transported to the cell membrane together with full-length α7 subunits and alter the function of the nAChRs. The characterization of dupα7 and dupΔα7 as well as their influence on α7 nAChRs may help explain the pathophysiology of schizophrenia and may suggest therapeutic strategies.
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Affiliation(s)
- Ying Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Cheng Xiao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Tim Indersmitten
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Robert Freedman
- Department of Psychiatry, University of Colorado at Denver, Denver, Colorado 80045
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado at Denver, Denver, Colorado 80045
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and.
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Higley MJ, Picciotto MR. Neuromodulation by acetylcholine: examples from schizophrenia and depression. Curr Opin Neurobiol 2014; 29:88-95. [PMID: 24983212 DOI: 10.1016/j.conb.2014.06.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/02/2014] [Accepted: 06/05/2014] [Indexed: 02/06/2023]
Abstract
The contribution of acetylcholine to psychiatric illnesses remains an area of active research. For example, increased understanding of mechanisms underlying cholinergic modulation of cortical function has provided insight into attentional dysfunction in schizophrenia. Acetylcholine normally enhances cortical sensitivity to external stimuli and decreases corticocortical communication, increasing focused attention; however, increases in ACh signaling can lead to symptoms related to anxiety and depression. For example, while stress-induced ACh release can result in adaptive responses to environmental stimuli, chronic elevations in cholinergic signaling may produce maladaptive behaviors. Here, we review several innovations in human imaging, molecular genetics and physiological control of circuits that have begun to identify mechanisms linking altered cholinergic neuromodulation to schizophrenia and depression.
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Affiliation(s)
- Michael J Higley
- Dept. of Neurobiology, Yale University School of Medicine, New Haven, CT 06511, United States; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06511, United States.
| | - Marina R Picciotto
- Dept. of Neurobiology, Yale University School of Medicine, New Haven, CT 06511, United States; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06511, United States; Dept. of Psychiatry, Yale University School of Medicine, New Haven, CT 06511, United States.
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45
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Nicotinic acetylcholine receptors in attention circuitry: the role of layer VI neurons of prefrontal cortex. Cell Mol Life Sci 2014; 71:1225-44. [PMID: 24122021 PMCID: PMC3949016 DOI: 10.1007/s00018-013-1481-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/03/2013] [Accepted: 09/16/2013] [Indexed: 12/15/2022]
Abstract
Cholinergic modulation of prefrontal cortex is essential for attention. In essence, it focuses the mind on relevant, transient stimuli in support of goal-directed behavior. The excitation of prefrontal layer VI neurons through nicotinic acetylcholine receptors optimizes local and top-down control of attention. Layer VI of prefrontal cortex is the origin of a dense feedback projection to the thalamus and is one of only a handful of brain regions that express the α5 nicotinic receptor subunit, encoded by the gene chrna5. This accessory nicotinic receptor subunit alters the properties of high-affinity nicotinic receptors in layer VI pyramidal neurons in both development and adulthood. Studies investigating the consequences of genetic deletion of α5, as well as other disruptions to nicotinic receptors, find attention deficits together with altered cholinergic excitation of layer VI neurons and aberrant neuronal morphology. Nicotinic receptors in prefrontal layer VI neurons play an essential role in focusing attention under challenging circumstances. In this regard, they do not act in isolation, but rather in concert with cholinergic receptors in other parts of prefrontal circuitry. This review urges an intensification of focus on the cellular mechanisms and plasticity of prefrontal attention circuitry. Disruptions in attention are one of the greatest contributing factors to disease burden in psychiatric and neurological disorders, and enhancing attention may require different approaches in the normal and disordered prefrontal cortex.
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46
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McFadden KL, Cornier MA, Tregellas JR. The role of alpha-7 nicotinic receptors in food intake behaviors. Front Psychol 2014; 5:553. [PMID: 24936193 PMCID: PMC4047526 DOI: 10.3389/fpsyg.2014.00553] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 05/19/2014] [Indexed: 12/31/2022] Open
Abstract
Nicotine alters appetite and energy expenditure, leading to changes in body weight. While the exact mechanisms underlying these effects are not fully established, both central and peripheral involvement of the alpha-7 nicotinic acetylcholine receptor (α7nAChR) has been suggested. Centrally, the α7nAChR modulates activity of hypothalamic neurons involved in food intake regulation, including proopiomelanocortin and neuropeptide Y. α7nAChRs also modulate glutamatergic and dopaminergic systems controlling reward processes that affect food intake. Additionally, α7nAChRs are important peripheral mediators of chronic inflammation, a key contributor to health problems in obesity. This review focuses on nicotinic cholinergic effects on eating behaviors, specifically those involving the α7nAChR, with the hypothesis that α7nAChR agonism leads to appetite suppression. Recent studies are highlighted that identify links between α7nAChR expression and obesity, insulin resistance, and diabetes and describe early findings showing an α7nAChR agonist to be associated with reduced weight gain in a mouse model of diabetes. Given these effects, the α7nAChR may be a useful therapeutic target for strategies to treat and manage obesity.
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Affiliation(s)
- Kristina L McFadden
- Department of Psychiatry, School of Medicine, University of Colorado - Anschutz Medical Campus Aurora, CO, USA
| | - Marc-Andre Cornier
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, School of Medicine, University of Colorado - Anschutz Medical Campus Aurora, CO, USA
| | - Jason R Tregellas
- Department of Psychiatry, School of Medicine, University of Colorado - Anschutz Medical Campus Aurora, CO, USA ; Research Service, Veterans Affairs Medical Center Denver, CO, USA
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47
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Brunzell DH, McIntosh JM, Papke RL. Diverse strategies targeting α7 homomeric and α6β2* heteromeric nicotinic acetylcholine receptors for smoking cessation. Ann N Y Acad Sci 2014; 1327:27-45. [PMID: 24730978 DOI: 10.1111/nyas.12421] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Preclinical studies suggest that a diversity of nicotinic acetylcholine receptors (nAChRs) with different sensitivities to nicotine may contribute to tobacco addiction. Using rodent intravenous nicotine self-administration as a preclinical model with good predictive validity for therapeutic efficacy for tobacco cessation, investigators have identified heteromeric α6β2* and homomeric α7 nAChRs as promising novel therapeutic targets to promote smoking abstinence (*denotes possible assembly with other subunits). The data suggest that diverse strategies that target these subclasses of nAChRs, namely inhibition of α6β2* nAChRs and stimulation of α7 nAChRs, will support tobacco cessation. α6β2* nAChRs, members of the high-affinity family of β2* nAChRs, function similarly to α4β2* nAChRs, the primary target of the FDA-approved drug varenicline, but have a much more selective neuroanatomical pattern of expression in catecholaminergic nuclei. Although activation of β2* nAChRs facilitates nicotine self-administration, stimulation of α7 nAChRs appears to negatively modulate both nicotine reinforcement and β2* nAChR function in the mesolimbic dopamine system. Although challenges and caveats must be considered in the development of therapeutics that target these nAChR subpopulations, an accumulation of data suggests that α7 nAChR agonists, partial agonists, or positive allosteric modulators and α6β2* nAChR antagonists, partial agonists, or negative allosteric modulators may prove to be effective therapeutics for tobacco cessation.
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Affiliation(s)
- Darlene H Brunzell
- Department of Pharmacology and Toxicology, Interdisciplinary Neuroscience Program and Institute for Drug and Alcohol Studies, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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48
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Effect of alpha7 nicotinic acetylcholine receptor agonists on attentional set-shifting impairment in rats. Psychopharmacology (Berl) 2014; 231:673-83. [PMID: 24057763 DOI: 10.1007/s00213-013-3275-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 09/03/2013] [Indexed: 11/27/2022]
Abstract
RATIONALE Attentional set shifting, a measure of executive function, is impaired in schizophrenia patients. Current standard of care has little therapeutic benefit for treating cognitive dysfunction in schizophrenia; therefore, novel drugs and animal models for testing novel therapies are needed. The NMDA receptor antagonist, MK-801, produces deficits in a rat maze-based set-shifting paradigm, an effect which parallels deficits observed on tests of executive function in schizophrenia patients. Alpha7 nicotinic acetylcholine receptor (nAChR) agonists, currently under clinical development by several companies, show promise in treating cognitive symptoms in schizophrenia patients and can improve cognition in various animal models. OBJECTIVES The objectives of the present study were to determine whether the MK-801 deficit in set shifting could be reproduced in a drug discovery setting and to determine whether cognitive improvement could be detected for the first time in this task with alpha7 nAChR agonists. RESULTS The data presented here replicate findings that a systemic injection of the NMDA receptor antagonist MK-801 can induce a deficit in set shifting in rats. Furthermore, the deficit could be reversed by the atypical antipsychotic clozapine as well as by several alpha7 nAch receptor agonists (SSR-180711, PNU-282987, GTS-21) with varying in vitro properties. CONCLUSIONS Results indicate that the MK-801 set-shift assay is a useful preclinical tool for measuring prefrontal cortical function in rodents and can be used to identify novel mechanisms for the potential treatment of cognitive deficits in schizophrenia.
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49
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Lewis AS, Picciotto MR. High-affinity nicotinic acetylcholine receptor expression and trafficking abnormalities in psychiatric illness. Psychopharmacology (Berl) 2013; 229:477-85. [PMID: 23624811 PMCID: PMC3766461 DOI: 10.1007/s00213-013-3126-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 04/15/2013] [Indexed: 12/22/2022]
Abstract
RATIONALE Nicotinic acetylcholine receptors (nAChRs) are a critical component of the cholinergic system of neurotransmission in the brain that modulates important physiological processes such as reward, cognition, and mood. Abnormalities in this system are accordingly implicated in multiple psychiatric illnesses, including addiction, schizophrenia, and mood disorders. There is significantly increased tobacco use, and therefore nicotine intake, in patient populations, and pharmacological agents that act on various nicotinic receptor subtypes ameliorate clinical features of these disorders. Better understanding of the molecular mechanisms underlying cholinergic dysfunction in psychiatric disease will permit more targeted design of novel therapeutic agents. RESULTS The objective of this review is to describe the multiple cellular pathways through which chronic nicotine exposure regulates nAChR expression, and to juxtapose these mechanisms with evidence for altered expression of high-affinity nAChRs in human psychiatric illness. Here, we summarize multiple studies from pre-clinical animal models to human in vivo imaging and post-mortem experiments demonstrating changes in nAChR regulation and expression in psychiatric illness. CONCLUSIONS We conclude that a mechanistic explanation of nAChR abnormalities in psychiatric illness will arise from a fuller understanding of normal nAChR trafficking, along with the detailed study of human tissue, perhaps using novel biotechnological advances, such as induced pluripotent stem cells.
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Affiliation(s)
| | - Marina R. Picciotto
- Correspondence Dr. Marina R. Picciotto, Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3rd Floor Research, New Haven, CT, 06508, USA, , Phone: (203) 737-2041
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50
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Bortz DM, Mikkelsen JD, Bruno JP. Localized infusions of the partial alpha 7 nicotinic receptor agonist SSR180711 evoke rapid and transient increases in prefrontal glutamate release. Neuroscience 2013; 255:55-67. [PMID: 24095692 DOI: 10.1016/j.neuroscience.2013.09.047] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 09/11/2013] [Accepted: 09/20/2013] [Indexed: 10/26/2022]
Abstract
The ability of local infusions of the alpha 7 nicotinic acetycholine receptor (α7 nAChR) partial agonist SSR180711 to evoke glutamate release in prefrontal cortex was determined in awake rats using a microelectrode array. Infusions of SSR180711 produced dose-dependent increases in glutamate levels. The lower dose (1.0μg in 0.4μL) evoked a rapid rise (∼1.0s) in glutamate (1.41±0.30μM above baseline). The higher dose (5.0μg) produced a similarly rapid, yet larger increase (3.51±0.36μM above baseline). After each dose, the glutamate signal was cleared to basal levels within 7-18s. SSR180711-evoked glutamate was mediated by the α7 nAChR as co-infusion of the selective α7 nAChR antagonist α-bungarotoxin (10.0μM)+SSR1808711 (5.0μg) reduced the effect of 5.0μg alone by 87% (2.62 vs. 0.35μM). Finally, the clearance of the SSR180711 (5.0μg)-evoked glutamate was bidirectionally affected by drugs that inhibited (threo-beta-benzyl-oxy-aspartate (TβOA), 100.0μM) or facilitated (ceftriaxalone, 200mg/kg, i.p.) excitatory amino acid transporters. TβOA slowed both the clearance (s) and rate of clearance (μM/s) by 10-fold, particularly at the mid-late stages of the return to baseline. Ceftriaxone reduced the magnitude of the SSR180711-evoked increase by 65%. These results demonstrate that pharmacological stimulation of α7 nAChRs within the prefrontal cortex is sufficient to evoke rapid yet transient increases in glutamate levels. Such increases may underlie the cognition-enhancing effects of the drug in animals; further justifying studies on the use of α7 nAChR-positive modulators in treating cognition-impairing disorders in humans.
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Affiliation(s)
- D M Bortz
- Department of Psychology, The Ohio State University, Columbus, OH, United States
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