1
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Zhang NK, Zhang SK, Zhang LI, Tao HW, Zhang GW. Sensory processing deficits and related cortical pathological changes in Alzheimer's disease. Front Aging Neurosci 2023; 15:1213379. [PMID: 37649717 PMCID: PMC10464619 DOI: 10.3389/fnagi.2023.1213379] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 07/24/2023] [Indexed: 09/01/2023] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder primarily affecting cognitive functions. However, sensory deficits in AD start to draw attention due to their high prevalence and early onsets which suggest that they could potentially serve as diagnostic biomarkers and even contribute to the disease progression. This literature review examines the sensory deficits and cortical pathological changes observed in visual, auditory, olfactory, and somatosensory systems in AD patients, as well as in various AD animal models. Sensory deficits may emerge at the early stages of AD, or even precede the cognitive decline, which is accompanied by cortical pathological changes including amyloid-beta deposition, tauopathy, gliosis, and alterations in neuronal excitability, synaptic inputs, and functional plasticity. Notably, these changes are more pronounced in sensory association areas and superficial cortical layers, which may explain the relative preservation of basic sensory functions but early display of deficits of higher sensory functions. We propose that sensory impairment and the progression of AD may establish a cyclical relationship that mutually perpetuates each condition. This review highlights the significance of sensory deficits with or without cortical pathological changes in AD and emphasizes the need for further research to develop reliable early detection and intervention through sensory systems.
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Affiliation(s)
- Nicole K. Zhang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Selena K. Zhang
- Biomedical Engineering Program, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - Li I. Zhang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Department of Physiology & Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Huizhong W. Tao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Department of Physiology & Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Guang-Wei Zhang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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2
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Terry AV, Jones K, Bertrand D. Nicotinic acetylcholine receptors in neurological and psychiatric diseases. Pharmacol Res 2023; 191:106764. [PMID: 37044234 DOI: 10.1016/j.phrs.2023.106764] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/30/2023] [Accepted: 04/07/2023] [Indexed: 04/14/2023]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that are widely distributed both pre- and post-synaptically in the mammalian brain. By modulating cation flux across cell membranes, neuronal nAChRs regulate neuronal excitability and the release of a variety of neurotransmitters to influence multiple physiologic and behavioral processes including synaptic plasticity, motor function, attention, learning and memory. Abnormalities of neuronal nAChRs have been implicated in the pathophysiology of neurologic disorders including Alzheimer's disease, Parkinson's disease, epilepsy, and Tourette´s syndrome, as well as psychiatric disorders including schizophrenia, depression, and anxiety. The potential role of nAChRs in a particular illness may be indicated by alterations in the expression of nAChRs in relevant brain regions, genetic variability in the genes encoding for nAChR subunit proteins, and/or clinical or preclinical observations where specific ligands showed a therapeutic effect. Over the past 25 years, extensive preclinical and some early clinical evidence suggested that ligands at nAChRs might have therapeutic potential for neurologic and psychiatric disorders. However, to date the only approved indications for nAChR ligands are smoking cessation and the treatment of dry eye disease. It has been argued that progress in nAChR drug discovery has been limited by translational gaps between the preclinical models and the human disease as well as unresolved questions regarding the pharmacological goal (i.e., agonism, antagonism or receptor desensitization) depending on the disease.
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Affiliation(s)
- Alvin V Terry
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, Georgia, 30912.
| | - Keri Jones
- Educational Innovation Institute, Medical College of Georgia at Augusta University, Augusta, Georgia, 30912
| | - Daniel Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
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3
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Parasoglou P, Osorio RS, Khegai O, Kovbasyuk Z, Miller M, Ho A, Dehkharghani S, Wisniewski T, Convit A, Mosconi L, Brown R. Phosphorus metabolism in the brain of cognitively normal midlife individuals at risk for Alzheimer's disease. NEUROIMAGE. REPORTS 2022; 2:100121. [PMID: 36532654 PMCID: PMC9757821 DOI: 10.1016/j.ynirp.2022.100121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Background Neurometabolic abnormalities and amyloid-beta plaque deposition are important early pathophysiologic changes in Alzheimer's disease (AD). This study investigated the relationship between high-energy phosphorus-containing metabolites, glucose uptake, and amyloid plaque using phosphorus magnetic resonance spectroscopy (31P-MRS) and positron emission tomography (PET). Methods We measured 31P-MRS, fluorodeoxyglucose (FDG)-PET, and Pittsburgh Compound B (PiB)-PET in a cohort of 20 cognitively normal middle-aged adults at risk for AD. We assessed 31P-MRS reliability by scanning a separate cohort of 13 healthy volunteers twice each. We calculated the coefficient-of-variation (CV) of metabolite ratios phosphocreatine-to-adenosine triphosphate (PCr/α-ATP), inorganic phosphate (Pi)-to-α-ATP, and phosphomonoesters-to-phosphodiesters (PME/PDE), and pH in pre-defined brain regions. We performed linear regression analysis to determine the relationship between 31P measurements and tracer uptake, and Dunn's multiple comparison tests to investigate regional differences in phosphorus metabolism. Finally, we performed linear regression analysis on 31P-MRS measurements in both cohorts to investigate the relationship of phosphorus metabolism with age. Results Most regional 31P metabolite ratio and pH inter- and intra-day CVs were well below 10%. There was an inverse relationship between FDG-SUV levels and metabolite ratios PCr/α-ATP, Pi/α-ATP, and PME/PDE in several brain regions in the AD risk group. There were also several regional differences among 31P metabolites and pH in the AD risk group including elevated PCr/α-ATP, depressed PME/PDE, and elevated pH in the temporal cortices. Increased PCr/α-ATP throughout the brain was associated with aging. Conclusions Phosphorus spectroscopy in the brain can be performed with high repeatability. Phosphorus metabolism varies with region and age, and is related to glucose uptake in adults at risk for AD. Phosphorus spectroscopy may be a valuable approach to study early changes in brain energetics in high-risk populations.
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Affiliation(s)
- Prodromos Parasoglou
- Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Ricardo S. Osorio
- Department of Psychiatry, New York University School of Medicine, New York, NY, USA
| | - Oleksandr Khegai
- Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Zanetta Kovbasyuk
- Department of Psychiatry, New York University School of Medicine, New York, NY, USA
| | - Margo Miller
- Department of Psychiatry, New York University School of Medicine, New York, NY, USA
| | - Amanda Ho
- Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Seena Dehkharghani
- Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
- Department of Neurology, Center for Cognitive Neurology, New York University Grossman School of Medicine, New York, NY, USA
| | - Thomas Wisniewski
- Department of Psychiatry, New York University School of Medicine, New York, NY, USA
- Department of Neurology, Center for Cognitive Neurology, New York University Grossman School of Medicine, New York, NY, USA
- Department of Pathology, New York University Grossman School of Medicine, New York, NY, USA
| | - Antonio Convit
- Department of Psychiatry, New York University School of Medicine, New York, NY, USA
- Nathan S Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Lisa Mosconi
- Department of Neurology, Weill Cornell Medical College, New York, NY, USA
- Department of Radiology, Weill Cornell Medical College, New York, NY, USA
| | - Ryan Brown
- Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
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4
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Sharp L, Brannigan G. Spontaneous lipid binding to the nicotinic acetylcholine receptor in a native membrane. J Chem Phys 2021; 154:185102. [PMID: 34241006 DOI: 10.1063/5.0046333] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The nicotinic acetylcholine receptor (nAChR) and other pentameric ligand-gated ion channels are native to neuronal membranes with an unusual lipid composition. While it is well-established that these receptors can be significantly modulated by lipids, the underlying mechanisms have been primarily studied in model membranes with few lipid species. Here, we use coarse-grained molecular dynamics simulation to probe specific binding of lipids in a complex quasi-neuronal membrane. We ran a total of 50 μs of simulations of a single nAChR in a membrane composed of 36 species of lipids. Competition between multiple lipid species produces a complex distribution. We find that overall, cholesterol selects for concave inter-subunit sites and polyunsaturated fatty acids select for convex M4 sites, while monounsaturated and saturated lipids are unenriched in the nAChR boundary. We propose the "density-threshold affinity" as a metric calculated from continuous density distributions, which reduces to a standard affinity in two-state binding. We find that the density-threshold affinity for M4 weakens with chain rigidity, which suggests that flexible chains may help relax packing defects caused by the conical protein shape. For any site, PE headgroups have the strongest affinity of all phospholipid headgroups, but anionic lipids still yield moderately high affinities for the M4 sites as expected. We observe cooperative effects between anionic headgroups and saturated chains at the M4 site in the inner leaflet. We also analyze affinities for individual anionic headgroups. When combined, these insights may reconcile several apparently contradictory experiments on the role of anionic phospholipids in modulating nAChR.
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Affiliation(s)
- Liam Sharp
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey 08102, USA
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey 08102, USA
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5
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Nikiforuk A, Litwa E, Krawczyk M, Popik P, Arias H. Desformylflustrabromine, a positive allosteric modulator of α4β2-containing nicotinic acetylcholine receptors, enhances cognition in rats. Pharmacol Rep 2020; 72:589-599. [PMID: 32207091 PMCID: PMC7329799 DOI: 10.1007/s43440-020-00092-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/04/2020] [Accepted: 02/05/2020] [Indexed: 11/30/2022]
Abstract
Rationale The α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) may represent useful targets for cognitive improvement. It has been recently proposed that a strategy based on positive allosteric modulation of α4β2-nAChRs reveals several advantages over the direct agonist approach. Nevertheless, the procognitive effects of α4β2-nAChR positive allosteric modulators (PAMs) have not been extensively characterized. Objectives The aim of the present study was to evaluate the procognitive efficacy of desformylflustrabromine (dFBr), a selective α4β2-nAChR PAM. Methods Cognitive effects were investigated in the novel object recognition task (NORT) and the attentional set-shifting task (ASST) in rats. Results The results demonstrate that dFBr attenuated the delay-induced impairment in NORT performance and facilitated cognitive flexibility in the ASST. The beneficial effects of dFBr were inhibited by dihydro-β-erythroidine, a relatively selective α4β2-nAChR antagonist, indicating the involvement of α4β2-nAChRs in cognitive processes. The tested α4β2-PAM was also effective against ketamine- and scopolamine-induced deficits of object recognition memory. Moreover, procognitive effects were also observed after combined treatment with inactive doses of dFBr and TC-2403, a selective α4β2-nAChR agonist. Conclusions These findings indicate that dFBr presents procognitive activity, supporting the strategy based on α4β2-nAChR potentiation as a plausible therapy for cognitive impairment. Electronic supplementary material The online version of this article (10.1007/s43440-020-00092-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Agnieszka Nikiforuk
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland.
| | - Ewa Litwa
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - Martyna Krawczyk
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - Piotr Popik
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - Hugo Arias
- Department of Pharmacology and Physiology, Oklahoma State University College of Osteopathic Medicine, Tahlequah, OK, USA
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6
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Sharp L, Salari R, Brannigan G. Boundary lipids of the nicotinic acetylcholine receptor: Spontaneous partitioning via coarse-grained molecular dynamics simulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:887-896. [PMID: 30664881 DOI: 10.1016/j.bbamem.2019.01.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 01/10/2019] [Accepted: 01/11/2019] [Indexed: 12/20/2022]
Abstract
Reconstituted nicotinic acetylcholine receptors (nAChRs) exhibit significant gain-of-function upon addition of cholesterol to reconstitution mixtures, and cholesterol affects the organization of nAChRs within domain-forming membranes, but whether nAChR partitions to cholesterol-rich liquid-ordered ("raft" or lo) domains or cholesterol-poor liquid-disordered (ldo) domains is unknown. We use coarse-grained molecular dynamics simulations to observe spontaneous interactions of cholesterol, saturated lipids, and polyunsaturated (PUFA) lipids with nAChRs. In binary Dipalmitoylphosphatidylcholine:Cholesterol (DPPC:CHOL) mixtures, both CHOL and DPPC acyl chains were observed spontaneously entering deep "non-annular" cavities in the nAChR TMD, particularly at the subunit interface and the β subunit center, facilitated by the low amino acid density in the cryo-EM structure of nAChR in a native membrane. Cholesterol was highly enriched in the annulus around the TMD, but this effect extended over (at most) 5-10 Å. In domain-forming ternary mixtures containing PUFAs, the presence of a single receptor did not significantly affect the likelihood of domain formation. nAChR partitioned to any cholesterol-poor ldo domain that was present, regardless of whether the ldo or lo domain lipids had PC or PE headgroups. Enrichment of PUFAs among boundary lipids was positively correlated with their propensity for demixing from cholesterol-rich phases. Long n-3 chains (tested here with Docosahexaenoic Acid, DHA) were highly enriched in annular and non-annular embedded sites, partially displacing cholesterol and completely displacing DPPC, and occupying sites even deeper within the bundle. Shorter n-6 chains were far less effective at displacing cholesterol from non-annular sites.
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Affiliation(s)
- Liam Sharp
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ, United States of America
| | - Reza Salari
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ, United States of America
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ, United States of America; Department of Physics, Rutgers University-Camden, Camden, NJ, United States of America.
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7
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Nakaizumi K, Ouchi Y, Terada T, Yoshikawa E, Kakimoto A, Isobe T, Bunai T, Yokokura M, Suzuki K, Magata Y. In vivo Depiction of α7 Nicotinic Receptor Loss for Cognitive Decline in Alzheimer’s Disease. J Alzheimers Dis 2018; 61:1355-1365. [DOI: 10.3233/jad-170591] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kyoko Nakaizumi
- Department of Psychiatry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yasuomi Ouchi
- Department of Biofunctional Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tatsuhiro Terada
- Department of Biofunctional Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Etsuji Yoshikawa
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu, Japan
| | - Akihiro Kakimoto
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu, Japan
| | - Takashi Isobe
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu, Japan
| | - Tomoyasu Bunai
- Department of Biofunctional Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masamichi Yokokura
- Department of Psychiatry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Katsuaki Suzuki
- Department of Biofunctional Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
- Kohseikai Ogasa Hospital, Kakegawa, Japan
| | - Yasuhiro Magata
- Department of Molecular Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
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8
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Jackson A, Silk S, Buhidma Y, Shoaib M. Varenicline, the clinically effective smoking cessation agent, restores probabilistic response reversal performance during withdrawal from nicotine. Addict Biol 2017; 22:1316-1328. [PMID: 27440124 DOI: 10.1111/adb.12423] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 06/02/2016] [Accepted: 06/06/2016] [Indexed: 01/07/2023]
Abstract
There is recognition that cognitive problems can contribute to renewed drug taking in former addicts. Our previous work has indicated that current smokers show reduced performance on a probabilistic reversal learning (PRL) task, relative to former smokers. To further explore PRL performance and its relevance to smoking, in addition to the role of nicotine, we developed a model of nicotine withdrawal-induced deficits in rodents. A second goal was to test varenicline, an α4β2 partial agonist, for its ability to restore any cognitive impairment. Acute effects of nicotine and varenicline on PRL performance in non-dependent animals were minimal and confined to speed of responding. When rats were made dependent on nicotine via osmotic minipumps implanted for 7 days (3.16 mg/kg/day), repeated tests at specified withdrawal time points revealed PRL disruption peaking at 12 and 24 hours following surgical removal of minipumps. Withdrawal was characterized by significant deficits in the number of reversals (P < 0.05), speed of responding (P < 0.01) and increases in omissions (P < 0.05). Nicotine (0.2 mg/kg SC) or varenicline (0.3 and 1.0 mg/kg SC) administered 10-minute prior to PRL test sessions during withdrawal, relieved the performance deficits. At 24-hour withdrawal, nicotine and varenicline (1 mg/kg) prevented decrements in reversals, in addition to ameliorating slower speed of responding. The high dose of varenicline only reduced omissions. These results confirm the role of nicotine in withdrawal-induced disruption of PRL performance and suggest that the model may be useful for investigating efficacy of potential new treatments for smoking cessation.
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Affiliation(s)
- Anne Jackson
- School of Pharmacy and Biomolecular Sciences; University of Brighton; Brighton East Sussex UK
| | - Sarah Silk
- Institute of Neuroscience, The Medical School; University of Newcastle; Newcastle upon Tyne UK
| | - Yazead Buhidma
- Institute of Neuroscience, The Medical School; University of Newcastle; Newcastle upon Tyne UK
| | - Mohammed Shoaib
- Institute of Neuroscience, The Medical School; University of Newcastle; Newcastle upon Tyne UK
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9
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Accumulation of human full-length tau induces degradation of nicotinic acetylcholine receptor α4 via activating calpain-2. Sci Rep 2016; 6:27283. [PMID: 27277673 PMCID: PMC4899694 DOI: 10.1038/srep27283] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 05/13/2016] [Indexed: 01/07/2023] Open
Abstract
Cholinergic impairments and tau accumulation are hallmark pathologies in sporadic Alzheimer’s disease (AD), however, the intrinsic link between tau accumulation and cholinergic deficits is missing. Here, we found that overexpression of human wild-type full-length tau (termed hTau) induced a significant reduction of α4 subunit of nicotinic acetylcholine receptors (nAChRs) with an increased cleavage of the receptor producing a ~55kDa fragment in primary hippocampal neurons and in the rat brains, meanwhile, the α4 nAChR currents decreased. Further studies demonstrated that calpains, including calpain-1 and calpain-2, were remarkably activated with no change of caspase-3, while simultaneous suppression of calpain-2 by selective calpain-2 inhibitor but not calpain-1 attenuated the hTau-induced degradation of α4 nAChR. Finally, we demonstrated that hTau accumulation increased the basal intracellular calcium level in primary hippocampal neurons. We conclude that the hTau accumulation inhibits nAChRs α4 by activating calpain-2. To our best knowledge, this is the first evidence showing that the intracellular accumulation of tau causes cholinergic impairments.
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10
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Woodruff-Pak DS, Gould TJ. Neuronal Nicotinic Acetylcholine Receptors: Involvement in Alzheimer’s Disease and Schizophrenia. ACTA ACUST UNITED AC 2016; 1:5-20. [PMID: 17715584 DOI: 10.1177/1534582302001001002] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play a role in a variety of diseases of the central nervous system including Alzheimer's disease (AD) and schizophrenia. There is great interest in evaluating disease-related nAChR changes, and pharmacological treatment of nAChR deficits is a promising therapy. In AD, 7 nAChRs remain relatively stable, contrasting to 4 2 nAChRs that are lost in substantial numbers. -amyloid, a major neuropathology in AD, blocks 4 2 and 7 nAChRs. Agonists selective to 7 nAChRs are neuroprotective against amyloid. Paradoxically, 7 nAChRs may function as receptors for -amyloid. These results indicate 7 nAChR antagonists may be appropriate therapy in AD. In schizophrenia, 7 nAChRs are significantly reduced in hippocampus and neocortex. The exceptionally high rate of smoking in schizophrenics is likely a form of self-medication. Therapy with 7 nAChR agonists relieves some schizophrenic symptoms. Despite disparities in etiology and symptomatology, AD and schizophrenia share a target for therapeutic intervention— 7 nAChRs.
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11
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Dineley KT, Pandya AA, Yakel JL. Nicotinic ACh receptors as therapeutic targets in CNS disorders. Trends Pharmacol Sci 2015; 36:96-108. [PMID: 25639674 PMCID: PMC4324614 DOI: 10.1016/j.tips.2014.12.002] [Citation(s) in RCA: 340] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 01/30/2023]
Abstract
The neurotransmitter acetylcholine (ACh) can regulate neuronal excitability by acting on the cys-loop cation-conducting ligand-gated nicotinic ACh receptor (nAChR) channels. These receptors are widely distributed throughout the central nervous system (CNS), being expressed on neurons and non-neuronal cells, where they participate in a variety of physiological responses such as anxiety, the central processing of pain, food intake, nicotine seeking behavior, and cognitive functions. In the mammalian brain, nine different subunits have been found thus far, which assemble into pentameric complexes with much subunit diversity; however, the α7 and α4β2 subtypes predominate in the CNS. Neuronal nAChR dysfunction is involved in the pathophysiology of many neurological disorders. Here we will briefly discuss the functional makeup and expression of the nAChRs in mammalian brain, and their role as targets in neurodegenerative diseases (in particular Alzheimer's disease, AD), neurodevelopmental disorders (in particular autism and schizophrenia), and neuropathic pain.
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Affiliation(s)
- Kelly T Dineley
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston (UTMB), Galveston, TX, USA
| | - Anshul A Pandya
- Chukchi Campus, Department of Bioscience, College of Rural and Community Development, University of Alaska Fairbanks, P.O. Box 297, Kotzebue, AK 99752-0297, USA
| | - Jerrel L Yakel
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health (NIEHS/NIH), Department of Health and Human Services (DHHS), F2-08, P.O. Box 12233, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA.
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12
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Hirao K, Pontone GM, Smith GS. Molecular imaging of neuropsychiatric symptoms in Alzheimer's and Parkinson's disease. Neurosci Biobehav Rev 2015; 49:157-70. [PMID: 25446948 PMCID: PMC4806385 DOI: 10.1016/j.neubiorev.2014.11.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Revised: 10/27/2014] [Accepted: 11/12/2014] [Indexed: 01/14/2023]
Abstract
Neuropsychiatric symptoms (NPS) are very common in neurodegenerative diseases and are a major contributor to disability and caregiver burden. There is accumulating evidence that NPS may be a prodrome and/or a "risk factor" of neurodegenerative diseases. The medications used to treat these symptoms in younger patients are not very effective in patients with neurodegenerative disease and may have serious side effects. An understanding of the neurobiology of NPS is critical for the development of more effective intervention strategies. Targeting these symptoms may also have implications for prevention of cognitive or motor decline. Molecular brain imaging represents a bridge between basic and clinical observations and provides many opportunities for translation from animal models and human post-mortem studies to in vivo human studies. Molecular brain imaging studies in Alzheimer's disease (AD) and Parkinson's disease (PD) are reviewed with a primary focus on positron emission tomography studies of NPS. Future directions for the field of molecular imaging in AD and PD to understand the neurobiology of NPS will be discussed.
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Affiliation(s)
- Kentaro Hirao
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, USA; Department of Geriatric Medicine, Tokyo Medical University, Tokyo, Japan
| | - Gregory M Pontone
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, USA
| | - Gwenn S Smith
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, USA.
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13
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Kamynina AV, Ponomareva EV, Koroev DO, Volkova TD, Kolykhalov IV, Selezneva ND, Gavrilova SI, Vol'pina OM. [The reduced level of antibodies to acetylcholine receptor alpha 7 fragment in the blood serum of patients with Alzheimer's disease]. Zh Nevrol Psikhiatr Im S S Korsakova 2015; 115:128-132. [PMID: 26978506 DOI: 10.17116/jnevro2015115112128-132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Determination of antibodies to neuronal membrane proteins in the blood serum of patients is of interest for diagnosis and optimization of treatment of Alzheimer's disease (AD). Authors studied the level of antibodies to acetylcholine receptor alpha 7 protein fragment (AChR), prion protein (РrР) and glycation end-products (RAGE) as well as to intracellular proteins nucleophosmin (Nuc) and survivin (Sur) in the serum of AD patients. MATERIAL AND METHODS Serum samples of 26 patients with probable AD and 13 healthy people were studied. Exposed sections of each protein were used for the choice of peptides for antibody visualization. ELIZA was a main method in this study. RESULTS AND CONCLUSION Antibodies to several proteins were identified but significant differences were found only for AChR-(173-193). The results demonstrated the involvement of AChR and AChR-antibodies in the development of AD. Determination of antibodies to AChR-(173-193) may be a marker of AD and a method for specifying the diagnosis of AD.
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Affiliation(s)
- A V Kamynina
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow
| | | | - D O Koroev
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow
| | - T D Volkova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow
| | | | | | | | - O M Vol'pina
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow
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14
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Avila-Muñoz E, Arias C. When astrocytes become harmful: functional and inflammatory responses that contribute to Alzheimer's disease. Ageing Res Rev 2014; 18:29-40. [PMID: 25078115 DOI: 10.1016/j.arr.2014.07.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/03/2014] [Accepted: 07/21/2014] [Indexed: 12/24/2022]
Abstract
A growing body of research suggests that astrocytes play roles as contributors to the pathophysiology of Alzheimer's disease (AD). Several lines of evidence propose that activated astrocytes produce and release proinflammatory molecules that may be critical for the generation of amyloid-β peptide (Aβ). However, accumulating evidence indicates that Aβ may activate astrocytes, which leads to an increase in cytokines that has been suggested to be a causative factor in the cognitive dysfunction of AD; thus, a vicious circle may be created. Intrinsic inflammatory mechanisms may provide a regulatory system that is capable of influencing the neuronal microenvironment that affects neuronal survival. In this article, we address the evidence surrounding the interactions of dysfunctional astrocytes with neighboring neurons that may initiate a cascade of events that culminates with neuronal injury and the expression of the hallmark lesions of AD. Comprehensive knowledge of the molecular mechanisms underlying the participation of astrocytes in neurodegeneration could aid the development of therapies to restore proper astrocyte function that can be used in AD patients to prevent or alleviate the progression of the disease in a more efficient and comprehensive manner.
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15
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Sasaki S, Horie Y. The Effects of an Uninterrupted Switch from Donepezil to Galantamine without Dose Titration on Behavioral and Psychological Symptoms of Dementia in Alzheimer's Disease. Dement Geriatr Cogn Dis Extra 2014; 4:131-9. [PMID: 24987402 PMCID: PMC4067716 DOI: 10.1159/000362871] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Aims To elucidate the efficacy of galantamine on cognition and behavioral and psychological symptoms of dementia (BPSD) in outpatients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) who have switched from donepezil to galantamine. Materials and Methods We performed an uninterrupted switch from donepezil to galantamine without a washout period or dose titration in 44 ambulatory outpatients with amnestic MCI (n = 12) or mild-to-moderate AD (n = 32). Three months after the switch, the efficacy of galantamine was evaluated with the Mini-Mental State Examination (MMSE), and the Neuropsychiatric Inventory (NPI) and NPI Brief Questionnaire Form (NPI-Q), respectively, using the Wilcoxon signed-rank test. Results NPI scores improved significantly on BPSD, especially on delusions, agitation and aberrant motor activity in AD patients (p = 0.027); improvement was remarkable in patients with moderate AD (MMSE score 10-19; p = 0.007), while insignificant in those with MCI (MMSE score ≥24; p = 0.648). The NPI-Q score also improved significantly regarding both the severity of the disease (p = 0.009) and caregiver distress (p = 0.012) in AD patients. MMSE scores hardly improved in either MCI (p = 0.394) or AD patients (p = 0.265). Conclusions An uninterrupted switch from donepezil to galantamine could be a useful alternative treatment option for AD patients whose BPSD are unresponsive to donepezil, or whose caregivers are not satisfied with donepezil treatment. © 2014 S. Karger AG, Basel
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Affiliation(s)
- Shoichi Sasaki
- Department of Neurology, Tokyo Women's Medical University, Tokyo, Japan
| | - Yoshiharu Horie
- Division of Biostatistics, Kitasato University Graduate School, Sagamihara, Japan
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16
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Falsafi SK, Roßner S, Ghafari M, Groessl M, Morawski M, Gerner C, Lubec G. Changes of several brain receptor complexes in the cerebral cortex of patients with Alzheimer disease: probable new potential pharmaceutical targets. Amino Acids 2013; 46:223-33. [PMID: 24292102 DOI: 10.1007/s00726-013-1623-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 11/04/2013] [Indexed: 12/31/2022]
Abstract
Although Alzheimer disease (AD) has been linked to defects in major brain receptors, studies thus far have been limited to the determination of receptor subunits or specific ligand binding studies. However, the availability of current technology enables the determination and quantification of brain receptor complexes. Thus, we examined levels of native receptor complexes in the brains of patients with AD. Cortical tissue was obtained from control subjects (n = 12 females and 12 males) and patients with AD (n = 12 females and 12 males) within a 3-h postmortem time period. The tissues were kept frozen until further biochemical analyses. Membrane proteins were extracted and subsequently enriched by ultracentrifugation using a sucrose gradient. Membrane proteins were then electrophoresed onto native gels and immunoblotted using antibodies against individual brain receptors. We found that the levels were comparable for complexes containing GluR2, GluR3 and GluR4 as well as 5-HT1A. Moreover, the levels of complexes containing muscarinic AChR M1, NR1 and GluR1 were significantly increased in male patients with AD. Nicotinic AChRs 4 and 7 as well as dopaminergic receptors D1 and D2 were also increased in males and females with AD. These findings reveal a pattern of altered receptor complex levels that may contribute to the deterioration of the concerted activity of these receptors and thus result in cognitive deficits observed in patients with AD. It should be emphasised that receptor complexes function as working units rather than individual subunits. Thus, the receptor deficits identified may be relevant for the design of experimental therapies. Therefore, specific pharmacological modulation of these receptors is within the pharmaceutical repertoire.
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Affiliation(s)
- Soheil Keihan Falsafi
- Department of Pediatrics, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
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17
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Reinvang I, Espeseth T, Westlye LT. APOE-related biomarker profiles in non-pathological aging and early phases of Alzheimer's disease. Neurosci Biobehav Rev 2013; 37:1322-35. [DOI: 10.1016/j.neubiorev.2013.05.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/10/2013] [Accepted: 05/10/2013] [Indexed: 02/01/2023]
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18
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Nery AA, Magdesian MH, Trujillo CA, Sathler LB, Juliano MA, Juliano L, Ulrich H, Ferreira ST. Rescue of amyloid-Beta-induced inhibition of nicotinic acetylcholine receptors by a peptide homologous to the nicotine binding domain of the alpha 7 subtype. PLoS One 2013; 8:e67194. [PMID: 23894286 PMCID: PMC3718777 DOI: 10.1371/journal.pone.0067194] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/15/2013] [Indexed: 11/19/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by brain accumulation of the neurotoxic amyloid-β peptide (Aβ) and by loss of cholinergic neurons and nicotinic acetylcholine receptors (nAChRs). Recent evidence indicates that memory loss and cognitive decline in AD correlate better with the amount of soluble Aβ than with the extent of amyloid plaque deposits in affected brains. Inhibition of nAChRs by soluble Aβ40 is suggested to contribute to early cholinergic dysfunction in AD. Using phage display screening, we have previously identified a heptapeptide, termed IQ, homologous to most nAChR subtypes, binding with nanomolar affinity to soluble Aβ40 and blocking Aβ-induced inhibition of carbamylcholine-induced currents in PC12 cells expressing α7 nAChRs. Using alanine scanning mutagenesis and whole-cell current recording, we have now defined the amino acids in IQ essential for reversal of Aβ40 inhibition of carbamylcholine-induced responses in PC12 cells, mediated by α7 subtypes and other endogenously expressed nAChRs. We further investigated the effects of soluble Aβ, IQ and analogues of IQ on α3β4 nAChRs recombinantly expressed in HEK293 cells. Results show that nanomolar concentrations of soluble Aβ40 potently inhibit the function of α3β4 nAChRs, and that subsequent addition of IQ or its analogues does not reverse this effect. However, co-application of IQ makes the inhibition of α3β4 nAChRs by Aβ40 reversible. These findings indicate that Aβ40 inhibits different subtypes of nAChRs by interacting with specific receptor domains homologous to the IQ peptide, suggesting that IQ may be a lead for novel drugs to block the inhibition of cholinergic function in AD.
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Affiliation(s)
- Arthur A. Nery
- Department of Biochemistry, Chemistry Institute, São Paulo University, São Paulo, SP, Brazil
| | - Margaret H. Magdesian
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Cleber A. Trujillo
- Department of Biochemistry, Chemistry Institute, São Paulo University, São Paulo, SP, Brazil
| | - Luciana B. Sathler
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Maria A. Juliano
- Department of Biophysics, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Luiz Juliano
- Department of Biophysics, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Henning Ulrich
- Department of Biochemistry, Chemistry Institute, São Paulo University, São Paulo, SP, Brazil
- * E-mail: (HU); (STF)
| | - Sergio T. Ferreira
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- * E-mail: (HU); (STF)
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Nie H, Wang Z, Zhao W, Lu J, Zhang C, Lok K, Wang Y, Shen H, Xu Z, Yin M. New nicotinic analogue ZY-1 enhances cognitive functions in a transgenic mice model of Alzheimer's disease. Neurosci Lett 2013; 537:29-34. [PMID: 23340201 DOI: 10.1016/j.neulet.2013.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/18/2012] [Accepted: 01/03/2013] [Indexed: 10/27/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder marked by progressive loss of memory and cognitive function. One of the new approaches for treating AD is direct stimulation of nicotinic acetylcholine receptors (nAChRs) in the brain. α4β2-nAChR agonists have shown promising potential in preclinical cognition models of AD. The present report describes the pharmacological properties of ZY-1, a new nicotinic analogue that activates α4β2-nAChR. We describe in detail the binding profile and pharmacological effects of ZY-1 on transgenic AD mice. ZY-1 has high affinity to α4β2-nAChR. In a Morris water maze test, ZY-1 significantly decreases the escape latency and increases both the times in the platform quadrant and the times of platform crossing of transgenic mice. ZY-1 enhances cognitive functions in transgenic mice models of AD. As a novel nicotinic analogue, ZY-1 deserves further study as a potential candidate against AD.
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Affiliation(s)
- Huizhen Nie
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
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20
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Bennett C, Arroyo S, Berns D, Hestrin S. Mechanisms generating dual-component nicotinic EPSCs in cortical interneurons. J Neurosci 2012; 32:17287-96. [PMID: 23197720 PMCID: PMC3525105 DOI: 10.1523/jneurosci.3565-12.2012] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/11/2012] [Accepted: 09/18/2012] [Indexed: 01/26/2023] Open
Abstract
Activation of cortical nicotinic receptors by cholinergic axons from the basal forebrain (BF) significantly impacts cortical function, and the loss of nicotinic receptors is a hallmark of aging and neurodegenerative disease. We have previously shown that stimulation of BF axons generates a fast α7 and a slow non-α7 receptor-dependent response in cortical interneurons. However, the synaptic mechanisms that underlie this dual-component nicotinic response remain unclear. Here, we report that fast α7 receptor-mediated EPSCs in the mouse cortex are highly variable and insensitive to perturbations of acetylcholinesterase (AChE), while slow non-α7 receptor-mediated EPSCs are reliable and highly sensitive to AChE activity. Based on these data, we propose that the fast and slow nicotinic responses reflect differences in synaptic structure between cholinergic varicosities activating α7 and non-α7 classes of nicotinic receptors.
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Affiliation(s)
- Corbett Bennett
- Department of Comparative Medicine, Stanford University School of Medicine, and
| | - Sergio Arroyo
- Department of Comparative Medicine, Stanford University School of Medicine, and
| | - Dominic Berns
- Department of Biology, Stanford University, Stanford, California 94305
| | - Shaul Hestrin
- Department of Comparative Medicine, Stanford University School of Medicine, and
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21
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Modeling the binding mechanism of Alzheimer's Aβ1-42 to nicotinic acetylcholine receptors based on similarity with snake α-neurotoxins. Neurotoxicology 2012; 34:236-42. [PMID: 23022323 DOI: 10.1016/j.neuro.2012.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/14/2012] [Accepted: 09/14/2012] [Indexed: 11/21/2022]
Abstract
For over a decade, it has been known that amyloid β (Aβ) peptides of Alzheimer's disease bind to the nicotinic α7 acetylcholine receptor (AChR) with picomolar affinity, and that snake α-neurotoxins competitively inhibit this binding. Here we propose a model of the binding mechanism of Aβ peptides to α7-AChR at atomic level. The binding mechanism is based on sequence and structure similarities of Aβ residues with functional residues of snake α-neurotoxins (ATX) in complex with AChR. The binding mechanism involves residue (Aβ)K28 (similar to (ATX)R32) which forms cation/π interactions in the acetylcholine binding site, and residues (Aβ)G29-(Aβ)I32 [GAII] (similar to (ATX)G33-(ATX)I36 [GTII]) which form an intermolecular β-sheet with residues (α7)F189-(α7)E191 of AChR. Through these interactions, we propose that the AChR serves as a chaperone for Aβ conformational changes from α- to β-hairpin. The interactions which block channel opening provide fundamental insight into Aβ neurotoxicity and cognition impairment, that could contribute to pathogenic processes in Alzheimer's disease, thus paving the way for structure based therapies.
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22
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Lemoine D, Jiang R, Taly A, Chataigneau T, Specht A, Grutter T. Ligand-gated ion channels: new insights into neurological disorders and ligand recognition. Chem Rev 2012; 112:6285-318. [PMID: 22988962 DOI: 10.1021/cr3000829] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Damien Lemoine
- Laboratoire de Biophysicochimie des Récepteurs Canaux, UMR 7199 CNRS, Conception et Application de Molécules Bioactives, Faculté de Pharmacie, Université de Strasbourg , 67400 Illkirch, France
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23
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Chronic treatment with rivastigmine in patients with Alzheimer’s disease: A study on primary motor cortex excitability tested by 5Hz-repetitive transcranial magnetic stimulation. Clin Neurophysiol 2012; 123:902-9. [DOI: 10.1016/j.clinph.2011.09.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 09/01/2011] [Accepted: 09/05/2011] [Indexed: 12/27/2022]
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24
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Neuronal receptors as targets for the action of amyloid-beta protein (Aβ) in the brain. Expert Rev Mol Med 2012; 14:e2. [PMID: 22261393 DOI: 10.1017/s1462399411002134] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Accumulation of neurotoxic soluble amyloid-beta protein (Aβ) oligomers in the brains of patients with Alzheimer disease (AD) and their role in AD pathogenesis have emerged as topics of considerable interest in recent years. Soluble Aβ oligomers impair synaptic and neuronal function, leading to neurodegeneration that is clinically manifested by memory and cognitive dysfunction. The precise mechanisms whereby Aβ oligomers cause neurotoxicity remain unknown. Emerging insights into the mechanistic link between neuronal receptors and soluble Aβ oligomers highlight the potential role of these receptors in Aβ-mediated neurotoxicity in AD. The current review focuses on studies describing interactions between soluble Aβ oligomers and neuronal receptors, and their role in AD pathogenesis. Furthermore, these studies provide insight into potential therapies for AD using compounds directed at putative target receptors for the action of Aβ in the central nervous system. We focus on interactions of Aβ with subtypes of acetylcholine and glutamatergic receptors. Additionally, neuronal receptors such as insulin, amylin and receptor for advanced glycation end products could be potential targets for soluble Aβ-oligomer-mediated neurotoxicity. Aβ interactions with other receptors such as the p75 neurotrophin receptors, which are highly expressed on cholinergic basal forebrain neurons lost in AD, are also highlighted.
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25
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Mehta M, Adem A, Kahlon MS, Sabbagh MN. The nicotinic acetylcholine receptor: smoking and Alzheimer's disease revisited. Front Biosci (Elite Ed) 2012; 4:169-80. [PMID: 22201862 PMCID: PMC5502782 DOI: 10.2741/367] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Epidemiological studies regarding Alzheimer's disease (AD) in smokers currently suggest inconsistent results. The clinicopathological findings also vary as to how AD pathology is affected by smoking behavior. Even though clinicopathological, functional, and epidemiological studies in humans do not present a consistent picture, much of the in vitro data implies that nicotine has neuroprotective effects when used in neurodegenerative disorder models. Current studies of the effects of nicotine and nicotinic agonists on cognitive function in both the non-demented and those with AD are not convincing. More data is needed to determine whether repetitive activation of nAChR with intermittent or acute exposure to nicotine, acute activation of nAChR, or long-lasting inactivation of nAChR secondary to chronic nicotine exposure will have a therapeutic effect and/or explain the beneficial effects of those types of drugs. Other studies show multifaceted connections between nicotine, nicotinic agonists, smoking, and nAChRs implicated in AD etiology. Although many controversies still exist, ongoing studies are revealing how nicotinic receptor changes and functions may be significant to the neurochemical, pathological, and clinical changes that appear in AD.
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Affiliation(s)
- Mona Mehta
- Banner Sun Health Research Institute, Sun City, AZ
| | - Abdu Adem
- Department of Pharmacology, Faculty of Medicine and Health Sciences, Al Ain, United Arab Emirates 3. Arizona Neurological Institute, Sun City, AZ
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26
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Ho YS, Lee CH, Wu CH. The Alpha 9-Nicotinic Acetylcholine Receptor Serves as a Molecular Target for Breast Cancer Therapy. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.jecm.2011.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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27
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Paris D, Beaulieu-Abdelahad D, Bachmeier C, Reed J, Ait-Ghezala G, Bishop A, Chao J, Mathura V, Crawford F, Mullan M. Anatabine lowers Alzheimer's Aβ production in vitro and in vivo. Eur J Pharmacol 2011; 670:384-91. [PMID: 21958873 DOI: 10.1016/j.ejphar.2011.09.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/29/2011] [Accepted: 09/07/2011] [Indexed: 11/30/2022]
Abstract
Brain Aβ accumulation represents a key pathological hallmark in Alzheimer's disease. In this study, we investigated the impact of anatabine, a minor alkaloid present in plants of the Solanacea family on Aβ production in vitro using a cell line overexpressing the human amyloid precursor protein (APP) and in vivo using a transgenic mouse model of Alzheimer's disease. In vitro, anatabine lowers Aβ₁₋₄₀ and Aβ₁₋₄₂ levels in a dose dependent manner and reduces sAPPβ production without impacting sAPPα levels suggesting that anatabine lowers Aβ production by mainly impacting the β-cleavage of APP. Additionally, we show that anatabine lowers NFκB activation at doses that inhibit Aβ production in vitro. Since NFκB is known to regulate BACE-1 expression (the rate limiting enzyme responsible for Aβ production), we determined the impact of anatabine on BACE-1 transcription. We show that anatabine inhibits BACE-1 transcription and reduces BACE-1 protein levels in human neuronal like SHSY-5Y cells suggesting that the Aβ lowering properties of anatabine are mediated via a regulation of BACE-1 expression. In vivo, we show that an acute treatment with anatabine for four days significantly lowers brain soluble Aβ₁₋₄₀ and Aβ₁₋₄₂ levels in a transgenic mouse model of Alzheimer's disease. Altogether our data suggest that anatabine may represent an interesting compound for regulating brain Aβ accumulation.
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Affiliation(s)
- Daniel Paris
- Roskamp Institute, 2040 Whitfield Avenue, Sarasota, FL 34243, USA.
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28
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The cholinergic system in aging and neuronal degeneration. Behav Brain Res 2011; 221:555-63. [DOI: 10.1016/j.bbr.2010.11.058] [Citation(s) in RCA: 692] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 11/26/2010] [Indexed: 11/19/2022]
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29
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Baddick CG, Marks MJ. An autoradiographic survey of mouse brain nicotinic acetylcholine receptors defined by null mutants. Biochem Pharmacol 2011; 82:828-41. [PMID: 21575611 DOI: 10.1016/j.bcp.2011.04.019] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 04/29/2011] [Accepted: 04/29/2011] [Indexed: 02/04/2023]
Abstract
Nine nicotinic receptor subunits are expressed in the central nervous system indicating that a variety of nicotinic acetylcholine receptors (nAChR) may be assembled. A useful method with which to identify putative nAChR is radioligand binding. In the current study the binding of [(125)I]α-bungarotoxin, [(125)I]α-conotoxinMII, 5[(125)I]-3-((2S)-azetidinylmethoxy)pyridine (A-85380), and [(125)I]epibatidine has been measured autoradiographically to provide data on many nAChR binding sites. Each binding site was evaluated semi-quantitatively for samples prepared from wild-type and α2, α4, α6, α7, β2, β4, α5 and β3 null mutant mice. Deletion of the α7 subunit completely and selectively eliminated [(125)I]α-bungarotoxin binding. The binding of [(125)I]α-conotoxinMII was eliminated in most brain regions by deletion of either the α6 or β2 subunit and is reduced by deletion of either the α4 or β3 subunit. The binding of 5[(125)I]A-85380 was completely eliminated by deletion of the β2 subunit and significantly reduced by deletion of the α4 subunit. Most, but not all, α4-independent sites require expression of the α6 subunit. The effect of gene deletion on total [(125)I]epibatidine binding was very similar to that on [(125)I]A-85380 binding. [(125)I]Epibatidine also labels β4* nAChR, which was readily apparent for incubations conducted in the presence of 100nM cytisine. The effects of α3 gene deletion could not be evaluated, but persistence of residual sites implies the expression of α3* nAChR. Taken together these results confirm and extend previously published evaluations of the effect of nAChR gene deletion and help to define the nAChR subtypes measurable by ligand binding.
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From smoking to cancers: novel targets to neuronal nicotinic acetylcholine receptors. JOURNAL OF ONCOLOGY 2011; 2011:693424. [PMID: 21772846 PMCID: PMC3136181 DOI: 10.1155/2011/693424] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/18/2011] [Accepted: 03/17/2011] [Indexed: 12/11/2022]
Abstract
Cigarette smoking bears a strong etiological association with many neovascularization-related diseases, including cancer, cardiovascular disease, and age-related macular degeneration. Cigarette smoke is a complex mixture of many compounds, including nicotine, which is the major active and addictive component of tobacco. Nicotine and its specific metabolized carcinogens directly bind to nicotinic acetylcholine receptors (nAChRs) on cell membranes and trigger the nAChR signal cascade. The nAChRs were originally thought to be ligand-gated ion channels that modulate physiological processes ranging from neurotransmission to cancer signaling. For several decades, the nAChRs served as a prototypic molecule for neurotransmitter receptors; however, they are now important therapeutic targets for various diseases, including Alzheimer's and Parkinson's diseases, schizophrenia, and even cancer. This paper describes recent advances in our understanding of the assembly, activity, and biological functions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands.
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Wu J, Ishikawa M, Zhang J, Hashimoto K. Brain imaging of nicotinic receptors in Alzheimer's disease. Int J Alzheimers Dis 2010; 2010:548913. [PMID: 21253523 PMCID: PMC3022172 DOI: 10.4061/2010/548913] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 12/08/2010] [Indexed: 11/30/2022] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels which are widely distributed in the human brain. Several lines of evidence suggest that two major subtypes (α4β2 and α7) of nAChRs play an important role in the pathophysiology of Alzheimer's disease (AD). Postmortem studies demonstrated alterations in the density of these subtypes of nAChRs in the brain of patients with AD. Currently, nAChRs are one of the most attractive therapeutic targets for AD. Therefore, several researchers have made an effort to develop novel radioligands that can be used to study quantitatively the distribution of these two subtypes in the human brain with positron emission tomography (PET) and single-photon emission computed tomography (SPECT). In this paper, we discuss the current topics on in vivo imaging of two subtypes of nAChRs in the brain of patients with AD.
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Affiliation(s)
- Jin Wu
- Division of Clinical Neuroscience, Center for Forensic Mental Health, Chiba University, 1-8-1 Inohana Chiba 260-8670, Japan
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Kendziorra K, Wolf H, Meyer PM, Barthel H, Hesse S, Becker GA, Luthardt J, Schildan A, Patt M, Sorger D, Seese A, Gertz HJ, Sabri O. Decreased cerebral α4β2* nicotinic acetylcholine receptor availability in patients with mild cognitive impairment and Alzheimer's disease assessed with positron emission tomography. Eur J Nucl Med Mol Imaging 2010; 38:515-25. [PMID: 21069319 DOI: 10.1007/s00259-010-1644-5] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 10/04/2010] [Indexed: 01/14/2023]
Abstract
PURPOSE Postmortem studies indicate a loss of nicotinic acetylcholine receptor (nAChRs) in Alzheimer's disease (AD). In order to establish whether these changes in the cholinergic system occur at an early stage of AD, we carried out positron emission tomography (PET) with a specific radioligand for the α4β2* nicotinic acetylcholine receptor (α4β2* nAChR) in patients with mild to moderate AD and in patients with amnestic mild cognitive impairment (MCI), who have a high risk to progress to AD. METHODS Nine patients with moderate AD, eight patients with MCI and seven age-matched healthy controls underwent 2-[(18)F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[(18)F]FA-85380) PET. After coregistration with individual magnetic resonance imaging the binding potential (BP(ND)) of 2-[(18)F]FA-85380 was calculated using either the corpus callosum or the cerebellum as reference regions. PET data were analysed by region of interest analysis and by voxel-based analysis. RESULTS Both patients with AD and MCI showed a significant reduction in 2-[(18)F]FA-85380 BP(ND) in typical AD-affected brain regions. Thereby, the corpus callosum was identified as the most suitable reference region. The 2-[(18)F]FA-85380 BP(ND) correlated with the severity of cognitive impairment. Only MCI patients that converted to AD in the later course (n = 5) had a reduction in 2-[(18)F]FA-85380 BP(ND). CONCLUSION 2-[(18)F]FA-85380 PET appears to be a sensitive and feasible tool for the detection of a reduction in α4β2* nAChRs which seems to be an early event in AD. In addition, 2-[(18)F]FA-85380 PET might give prognostic information about a conversion from MCI to AD.
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Affiliation(s)
- Kai Kendziorra
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany.
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Reinvang I, Deary IJ, Fjell AM, Steen VM, Espeseth T, Parasuraman R. Neurogenetic effects on cognition in aging brains: a window of opportunity for intervention? Front Aging Neurosci 2010; 2:143. [PMID: 21103005 PMCID: PMC2987509 DOI: 10.3389/fnagi.2010.00143] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 09/17/2010] [Indexed: 12/15/2022] Open
Abstract
Knowledge of genetic influences on cognitive aging can constrain and guide interventions aimed at limiting age-related cognitive decline in older adults. Progress in understanding the neural basis of cognitive aging also requires a better understanding of the neurogenetics of cognition. This selective review article describes studies aimed at deriving specific neurogenetic information from three parallel and interrelated phenotype-based approaches: psychometric constructs, cognitive neuroscience-based processing measures, and brain imaging morphometric data. Developments in newer genetic analysis tools, including genome wide association, are also described. In particular, we focus on models for establishing genotype-phenotype associations within an explanatory framework linking molecular, brain, and cognitive levels of analysis. Such multiple-phenotype approaches indicate that individual variation in genes central to maintaining synaptic integrity, neurotransmitter function, and synaptic plasticity are important in affecting age-related changes in brain structure and cognition. Investigating phenotypes at multiple levels is recommended as a means to advance understanding of the neural impact of genetic variants relevant to cognitive aging. Further knowledge regarding the mechanisms of interaction between genetic and preventative procedures will in turn help in understanding the ameliorative effect of various experiential and lifestyle factors on age-related cognitive decline.
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Affiliation(s)
- Ivar Reinvang
- Department of Psychology, University of OsloOslo, Norway
| | - Ian J. Deary
- Department of Psychology, University of EdinburghEdinburgh, UK
| | | | - Vidar M. Steen
- Department of Clinical Medicine, University of BergenBergen, Norway
- Center for Medical Genetics and Molecular Medicine, Haukeland University HospitalBergen, Norway
| | | | - Raja Parasuraman
- Department of Psychology, George Mason UniversityFairfax, VA, USA
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Toyohara J, Hashimoto K. α7 Nicotinic Receptor Agonists: Potential Therapeutic Drugs for Treatment of Cognitive Impairments in Schizophrenia and Alzheimer's Disease. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2010; 4:37-56. [PMID: 21249164 PMCID: PMC3023065 DOI: 10.2174/1874104501004010037] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 01/19/2023]
Abstract
Accumulating evidence suggests that α7 nicotinic receptors (α7 nAChRs), a subtype of nAChRs, play a role in the pathophysiology of neuropsychiatric diseases, including schizophrenia and Alzheimer's disease (AD). A number of psychopharmacological and genetic studies shown that α7 nAChRs play an important role in the deficits of P50 auditory evoked potential in patients with schizophrenia, and that (α nAChR agonists would be potential therapeutic drugs for cognitive impairments associated with P50 deficits in schizophrenia. Furthermore, some studies have demonstrated that α7 nAChRs might play a key role in the amyloid-β (Aβ)-mediated pathology of AD, and that α7 nAChR agonists would be potential therapeutic drugs for Aβ deposition in the brains of patients with AD. Interestingly, the altered expression of α7 nAChRs in the postmortem brain tissues from patients with schizophrenia and AD has been reported. Based on all these findings, selective α7 nAChR agonists can be considered potential therapeutic drugs for cognitive impairments in both schizophrenia and AD. In this article, we review the recent research into the role of α7 nAChRs in the pathophysiology of these diseases and into the potential use of novel α7 nAChR agonists as therapeutic drugs.
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Affiliation(s)
- Jun Toyohara
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
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Epistasis between APOE and nicotinic receptor gene CHRNA4 in age related cognitive function and decline. J Int Neuropsychol Soc 2010; 16:424-32. [PMID: 20331911 DOI: 10.1017/s1355617710000263] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Healthy participants (n = 237) aged 45-79 were tested neuropsychologically with tests of memory, speed, and cognitive control and followed up for 3-5 years (mean, 3.4 years). The sample was genotyped for apolipoprotein E (APOE) and CHolinergic Receptor for Nicotine Alpha 4 (CHRNA4), and genetic effects on cognitive function at initial testing and on cognitive decline was studied. We predicted relatively stronger effects of APOE on memory, and of CHRNA4 on speeded tasks. The predictions were partially confirmed, but we found interactive effects of APOE and CHRNA4 in several cognitive domains. Being an APOE epsilon4/CHRNA4 TT carrier was associated with slower and less efficient performance, and with steeper decline in speed tasks and in delayed recall. Age dependent genetic effects were found for both APOE and CHRNA4, where old participants (60-79 years) showed a negative influence of TT carrier status on initial memory performance, but a tendency for steeper memory decline in epsilon4 carriers. Inconsistent and small effects of APOE reported in previous studies of healthy groups may be caused by failure to consider epistasis of APOE with nicotinic receptor and other genes.
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Subtype-selective nicotinic agonists enhance olfactory working memory in normal rats: a novel use of the odour span task. Neurosci Lett 2010; 471:114-8. [PMID: 20083163 DOI: 10.1016/j.neulet.2010.01.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/02/2010] [Accepted: 01/06/2010] [Indexed: 11/22/2022]
Abstract
Nicotinic agonists have been shown to enhance performance in cognitive tasks based on attention and memory. The aim of this study was to use a test of olfactory working memory; the odour span task (OST) in rodents, to investigate the effects of subtype-specific nicotinic agonists on working memory in normal rats. Rats were trained in a non-matching to sample (NMTS) rule and then the full OST, which involved identifying a novel odour from an increasing number of presented odours. Male hooded Lister rats were treated with nicotine, selective nicotinic agonists or vehicle (saline). In order to validate the task, muscarinic and nicotinic receptor antagonists were also examined. Nicotine at both 0.05 and 0.1mg/kg significantly increased mean span length in the OST. The selective alpha 4 beta 2 nicotinic receptor agonist metanicotine (0.1mg/kg s.c.) and the selective alpha 7 nicotinic receptor agonist (R)-N-(1-azabicyclo[2.2.2]oct-3-yl)(5-(2-pyridyl)thiophene-2-carboxamide) (compound A, 10mg/kg i.p.) also improved performance. In contrast, mecamylamine and scopolamine significantly decreased mean span length. These findings suggest a role for the activation of both alpha 4 beta 2 and alpha 7 subtypes of neuronal nicotinic receptor in mediating enhancements of olfactory working memory capacity in normal, non-compromised rats. These nicotinic receptor subtypes may therefore prove to be useful targets for the development of novel treatments for neuropsychiatric disorders that involve cognitive dysfunction.
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Ikonomovic MD, Wecker L, Abrahamson EE, Wuu J, Counts SE, Ginsberg SD, Mufson EJ, Dekosky ST. Cortical alpha7 nicotinic acetylcholine receptor and beta-amyloid levels in early Alzheimer disease. ACTA ACUST UNITED AC 2009; 66:646-51. [PMID: 19433665 DOI: 10.1001/archneurol.2009.46] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To examine alpha7 nicotinic acetylcholine receptor (nAChR) binding and beta-amyloid (Abeta) peptide load in superior frontal cortex (SFC) across clinical and neuropathological stages of Alzheimer disease (AD). DESIGN Quantitative measures of alpha7 nAChR by [(3)H]methyllycaconitine binding and Abeta concentration by enzyme-linked immunosorbent assay in SFC were compared across subjects with antemortem clinical classification of no cognitive impairment, mild cognitive impairment, or mild to moderate AD, and with postmortem neuropathological diagnoses. SETTING Academic medical center. Subjects Twenty-nine elderly retired clergy. MAIN OUTCOME MEASURES Quantitative measures of alpha7 nAChR binding and Abeta peptide concentration in SFC. RESULTS Higher concentrations of total Abeta peptide in SFC were associated with clinical diagnosis of mild to moderate AD (P = .02), lower Mini-Mental State Examination scores (P = .003), presence of cortical Abeta plaques (P = .02), and likelihood of AD diagnosis by the National Institute on Aging-Reagan criteria (P = .002). Increased alpha7 nAChR binding was associated with National Institute on Aging-Reagan diagnosis (P = .02) and, albeit weakly, the presence of cortical Abeta plaques (P = .08). There was no correlation between the 2 biochemical measures. CONCLUSIONS These observations suggest that during the clinical progression from normal cognition to neurodegenerative disease state, total Abeta peptide concentration increases while alpha7 nAChRs remain relatively stable in SFC. Regardless of subjects' clinical status, however, elevated alpha7 nAChR binding is associated with increased Abeta plaque pathology, supporting the hypothesis that cellular expression of these receptors may be upregulated selectively in Abeta plaque-burdened brain areas.
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Affiliation(s)
- Milos D Ikonomovic
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Dome P, Lazary J, Kalapos MP, Rihmer Z. Smoking, nicotine and neuropsychiatric disorders. Neurosci Biobehav Rev 2009; 34:295-342. [PMID: 19665479 DOI: 10.1016/j.neubiorev.2009.07.013] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/23/2009] [Accepted: 07/30/2009] [Indexed: 12/20/2022]
Abstract
Tobacco smoking is an extremely addictive and harmful form of nicotine (NIC) consumption, but unfortunately also the most prevalent. Although disproportionately high frequencies of smoking and its health consequences among psychiatric patients are widely known, the neurobiological background of this epidemiological association is still obscure. The diverse neuroactive effects of NIC and some other major tobacco smoke constituents in the central nervous system may underlie this association. This present paper summarizes the pharmacology of NIC and its receptors (nAChR) based on a systematic review of the literature. The role of the brain's reward system(s) in NIC addiction and the results of functional and structural neuroimaging studies on smoking-related states and behaviors (i.e. dependence, craving, withdrawal) are also discussed. In addition, the epidemiological, neurobiological, and genetic aspects of smoking in several specific neuropsychiatric disorders are reviewed and the clinical relevance of smoking in these disease states addressed.
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Affiliation(s)
- Peter Dome
- Department of Clinical and Theoretical Mental Health, Kutvolgyi Clinical Center, Semmelweis University, Faculty of Medicine, Kutvolgyi ut 4, 1125 Budapest, Hungary.
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Gotti C, Clementi F, Fornari A, Gaimarri A, Guiducci S, Manfredi I, Moretti M, Pedrazzi P, Pucci L, Zoli M. Structural and functional diversity of native brain neuronal nicotinic receptors. Biochem Pharmacol 2009; 78:703-11. [PMID: 19481063 DOI: 10.1016/j.bcp.2009.05.024] [Citation(s) in RCA: 364] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 05/16/2009] [Accepted: 05/19/2009] [Indexed: 11/30/2022]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels present in the central and peripheral nervous systems, that are permeable to mono- and divalent cations. They share a common basic structure but their pharmacological and functional properties arise from the wide range of different subunit combinations making up distinctive subtypes. nAChRs are involved in many physiological functions in the central and peripheral nervous systems, and are the targets of the widely used drug of abuse nicotine. In addition to tobacco dependence, changes in their number and/or function are associated with neuropsychiatric disorders, ranging from epilepsy to dementia. Although some of the neural circuits involved in the acute and chronic effects of nicotine have been identified, much less is known about which native nAChR subtypes are involved in specific physiological functions and pathophysiological conditions. We briefly review some recent findings concerning the structure and function of native nAChRs, focusing on the subtypes identified in the mesostriatal and habenulo-interpeduncular pathways, two systems involved in nicotine reinforcement and withdrawal. We also discuss recent findings concerning the effect of chronic nicotine on the expression of native subtypes.
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Affiliation(s)
- Cecilia Gotti
- Department of Medical Pharmacology, CNR, Institute of Neuroscience, Cellular and Molecular Pharmacology, University of Milan, Milan, Italy.
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Buckingham SD, Jones AK, Brown LA, Sattelle DB. Nicotinic acetylcholine receptor signalling: roles in Alzheimer's disease and amyloid neuroprotection. Pharmacol Rev 2009; 61:39-61. [PMID: 19293145 DOI: 10.1124/pr.108.000562] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Alzheimer's disease (AD), the major contributor to dementia in the elderly, involves accumulation in the brain of extracellular plaques containing the beta-amyloid protein (Abeta) and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. AD is also characterized by a loss of neurons, particularly those expressing nicotinic acetylcholine receptors (nAChRs), thereby leading to a reduction in nAChR numbers. The Abeta(1-42) protein, which is toxic to neurons, is critical to the onset and progression of AD. The discovery of new drug therapies for AD is likely to be accelerated by an improved understanding of the mechanisms whereby Abeta causes neuronal death. We examine the evidence for a role in Abeta(1-42) toxicity of nAChRs; paradoxically, nAChRs can also protect neurons when activated by nicotinic ligands. Abeta peptides and nicotine differentially activate several intracellular signaling pathways, including the phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene homolog pathway, the extracellular signal-regulated kinase/mitogen-activated protein kinase, and JAK-2/STAT-3 pathways. These pathways control cell death or survival and the secretion of Abeta peptides. We propose that understanding the differential activation of these pathways by nicotine and/or Abeta(1-42) may offer the prospect of new routes to therapy for AD.
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Affiliation(s)
- Steven D Buckingham
- Medical Research Council Functional Genomics Unit, Department of Physiology Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK, OX1 3QX
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Albuquerque EX, Pereira EFR, Alkondon M, Rogers SW. Mammalian nicotinic acetylcholine receptors: from structure to function. Physiol Rev 2009; 89:73-120. [PMID: 19126755 PMCID: PMC2713585 DOI: 10.1152/physrev.00015.2008] [Citation(s) in RCA: 1241] [Impact Index Per Article: 82.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The classical studies of nicotine by Langley at the turn of the 20th century introduced the concept of a "receptive substance," from which the idea of a "receptor" came to light. Subsequent studies aided by the Torpedo electric organ, a rich source of muscle-type nicotinic receptors (nAChRs), and the discovery of alpha-bungarotoxin, a snake toxin that binds pseudo-irreversibly to the muscle nAChR, resulted in the muscle nAChR being the best characterized ligand-gated ion channel hitherto. With the advancement of functional and genetic studies in the late 1980s, the existence of nAChRs in the mammalian brain was confirmed and the realization that the numerous nAChR subtypes contribute to the psychoactive properties of nicotine and other drugs of abuse and to the neuropathology of various diseases, including Alzheimer's, Parkinson's, and schizophrenia, has since emerged. This review provides a comprehensive overview of these findings and the more recent revelations of the impact that the rich diversity in function and expression of this receptor family has on neuronal and nonneuronal cells throughout the body. Despite these numerous developments, our understanding of the contributions of specific neuronal nAChR subtypes to the many facets of physiology throughout the body remains in its infancy.
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Affiliation(s)
- Edson X Albuquerque
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, MD, USA
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Terrière E, Dempsey MF, Herrmann LL, Tierney KM, Lonie JA, O'Carroll RE, Pimlott S, Wyper DJ, Herholz K, Ebmeier KP. 5-(123)I-A-85380 binding to the α4β2-nicotinic receptor in mild cognitive impairment. Neurobiol Aging 2008; 31:1885-93. [PMID: 19036475 DOI: 10.1016/j.neurobiolaging.2008.10.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 09/08/2008] [Accepted: 10/06/2008] [Indexed: 10/21/2022]
Abstract
Treatments currently licensed for Alzheimer's dementia target cholinergic brain systems. In vivo nicotinic receptor binding may provide an early marker of illness and treatment suitability. In this pilot, we examined nine patients with amnestic mild cognitive impairment (MCI) and 10 age and education matched healthy volunteers with high resolution SPECT and the nicotinic receptor ligand 5-(123)I-A-85380. Uptake data were analysed using voxel-based techniques for group comparisons and regression analyses with cognitive impairment as covariates. MCI patients had discrete reductions in uptake in medial temporal cortex. Correlations with cognitive impairment were found in left temporo-parietal areas (Addenbrooke's Cognitive Examination) and bilateral temporo-limbic areas (Rey Auditory Verbal Learning Test), and right parahippocampal gyrus (Rey Complex Figure Test) within the patient group. In vivo nicotinic receptor binding appears to be sensitive to brain changes in MCI. Larger scale explorations of patients undergoing treatment will be necessary to evaluate its use in predicting or monitoring treatment response.
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Reid RT, Sabbagh MN. Effects of cholinesterase inhibitors on rat nicotinic receptor levels in vivo and in vitro. J Neural Transm (Vienna) 2008; 115:1437-44. [PMID: 18726544 DOI: 10.1007/s00702-008-0107-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Accepted: 08/06/2008] [Indexed: 11/25/2022]
Abstract
Cholinesterase inhibitors (ChEIs) are the mainstay of treatment for AD but differ by secondary mechanisms of action. We determine the effects of sub-chronic dosing of ChEIs on alpha7 and non-alpha7 nAChRs and determine if differences can be observed between them. Sprague-Dawley rats were administered donepezil, galantamine; rivastigmine at two doses each, in saline SQ twice daily or with nicotine (0.4 mg/kg) as a positive control. After 14 days the animals were sacrificed, and the levels of nAChRs were measured using [3H]-EPI to measure non-alpha7 nAChRs and [3H]-MLA to measure alpha7 nAChRs. In the cortex, all compounds tested at the higher doses significantly increased the levels of both [3H]-EPI and [3H]-MLA. In the hippocampus all compounds significantly increased [3H]-EPI but had no effect on [3H]-MLA binding. No effects were observed in the striatum with treatment. There were no differences observed among the ChEIs. In cell cultures, none of the ChEIs increased non-alpha7 or alpha7 receptor binding. Treatment with ChEIs result in similar increases in receptor levels which suggest that the increases in nAChRs may be due simply to the increases in synaptic levels of acetylcholine.
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Affiliation(s)
- Richard T Reid
- Erik and Ese Banck Clinical Research Center, 8716 Production Avenue, San Diego, CA 92121, USA.
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Calabrese EJ. Alzheimer's disease drugs: an application of the hormetic dose-response model. Crit Rev Toxicol 2008; 38:419-51. [PMID: 18568864 DOI: 10.1080/10408440802003991] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
This article provides an evaluation of the dose-response features of drugs that are intended to improve memory, some of which have been used in the treatment of Alzheimer's disease (AD). A common feature of these drugs is that they act via an inverted U-shaped dose response, consistent with the hormetic dose response model. This article assesses historical foundations that lead to the development of AD drugs, their dose-response features and how the quantitative features of such dose responses affected drug discovery and development, and the successes and possible failures of such agents in preclinical and clinical settings. This story begins about 150 years ago with the discovery of an active agent in the Calabar bean plant called physostigmine, its unfolding medical applications, and its implications for dose-response relationships, memory enhancement, and improved drug discovery activities. The article also demonstrates the occurrence of U-shaped dose responses for memory with numerous endogenous agonists including neurosteroids, various peptides (e.g., vasopressin, CCK-8, neuropeptide Y), and other agents (e.g., epinephrine, antagonists for platelet activity factor and nicotinic receptors), supporting the generalizability of the hormetic biphasic dose response. Finally, the significance of the U-shaped dose response is critical for successful clinical application, since it defines the therapeutic window.
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Affiliation(s)
- Edward J Calabrese
- Environmental Health Sciences Division, School of Public Health, University of Massachusetts, Amherst, Massachusetts 01003, USA.
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Sabri O, Kendziorra K, Wolf H, Gertz HJ, Brust P. Acetylcholine receptors in dementia and mild cognitive impairment. Eur J Nucl Med Mol Imaging 2008; 35 Suppl 1:S30-45. [PMID: 18228017 DOI: 10.1007/s00259-007-0701-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To clarify whether changes in the cholinergic transmission occur early in the course of Alzheimer's disease (AD), we carried out positron emission tomography (PET) with the radioligand 2-[(18)F]F-A-85380, which is supposed to be specific for alpha4beta2 nicotinic acetylcholine receptors (nAChRs). METHOD We included patients with moderate to severe AD and patients with amnestic mild cognitive impairment (MCI), presumed to present preclinical AD. RESULTS Both patients with AD and MCI showed significant reductions in alpha4beta2 nAChRs in brain regions typically affected by AD pathology. These findings indicate that a reduction in alpha4beta2 nAChRs occurs during early symptomatic stages of AD. The alpha4beta2 nAChR availability in these regions correlated with the severity of cognitive impairment, indicating a stage sensitivity of the alpha4beta2 nAChR status. CONCLUSION Together, our results provide evidence for the potential of 2-[(18)]F-A-85380 nAChR PET in the diagnosis of patients at risk for AD. Because of the extraordinary long acquisition time with 2-[(18)F]F-A-85380, we developed the new alpha4beta2 nAChR-specific radioligands (+)- and (-)-[(18)F]norchloro-fluoro-homoepibatidine (NCFHEB) and evaluated them preclinically. (-)-[(18)F]NCFHEB shows twofold higher brain uptake and significantly shorter acquisition times. Therefore, (-)-[(18)F]NCFHEB should be a suitable radioligand for larger clinical investigations.
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Affiliation(s)
- Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Stephanstrasse 11, Leipzig, Germany.
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Cholinergic and glutamatergic alterations beginning at the early stages of Alzheimer disease: participation of the phospholipase A2 enzyme. Psychopharmacology (Berl) 2008; 198:1-27. [PMID: 18392810 DOI: 10.1007/s00213-008-1092-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 01/28/2008] [Indexed: 12/14/2022]
Abstract
RATIONALE Alzheimer disease (AD), a progressive neurodegenerative disorder, is the leading cause of dementia in the elderly. A combination of cholinergic and glutamatergic dysfunction appears to underlie the symptomatology of AD, and thus, treatment strategies should address impairments in both systems. Evidence suggests the involvement of phospholipase A(2) (PLA(2)) enzyme in memory impairment and neurodegeneration in AD via actions on both cholinergic and glutamatergic systems. OBJECTIVES To review cholinergic and glutamatergic alterations underlying cognitive impairment and neuropathology in AD and attempt to link PLA(2) with such alterations. METHODS Medline databases were searched (no date restrictions) for published articles with links among the terms Alzheimer disease (mild, moderate, severe), mild cognitive impairment, choline acetyltransferase, acetylcholinesterase, NGF, NGF receptor, muscarinic receptor, nicotinic receptor, NMDA, AMPA, metabotropic glutamate receptor, atrophy, glucose metabolism, phospholipid metabolism, sphingolipid, membrane fluidity, phospholipase A(2), arachidonic acid, attention, memory, long-term potentiation, beta-amyloid, tau, inflammation, and reactive species. Reference lists of the identified articles were checked to identify additional studies of interest. RESULTS Overall, results suggest the hypothesis that persistent inhibition of cPLA(2) and iPLA(2) isoforms at early stages of AD may play a central role in memory deficits and beta-amyloid production through down-regulation of cholinergic and glutamate receptors. As the disease progresses, beta-amyloid induced up-regulation of cPLA(2) and sPLA(2) isoforms may play critical roles in inflammation and oxidative stress, thus participating in the neurodegenerative process. CONCLUSION Activation and inhibition of specific PLA(2) isoforms at different stages of AD could be of therapeutic importance and delay cognitive dysfunction and neurodegeneration.
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Liu RY, Gu R, Qi XL, Zhang T, Zhao Y, He Y, Pei JJ, Guan ZZ. Decreased nicotinic receptors and cognitive deficit in rats intracerebroventricularly injected with beta-amyloid peptide(1-42) and fed a high-cholesterol diet. J Neurosci Res 2008; 86:183-93. [PMID: 17705292 DOI: 10.1002/jnr.21463] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To investigate whether the changes in nicotinic receptors (nAChRs) and in learning and memory associated with Alzheimer's disease (AD) are influenced by both beta-amyloid peptide (Abeta) and cholesterol in vivo, we examined the effects of intracerebroventricular injection of Abeta(1-42) and/or a high-cholesterol diet on brain levels of nAChRs and learning and memory in rats. The levels of nAChR subunit proteins and the corresponding mRNA were measured by Western blotting and RT-PCR, respectively; and learning and memory were evaluated with the Morris Water Maze examination. Injection of Abeta(1-42) resulted in deposition of this peptide, activation of astrocytes, decreased levels of the alpha7 and alpha4 protein subunits of the nAChR, and elevated expression of alpha7 mRNA, as well as impaired learning and spatial memory. A high-cholesterol diet activated astrocytes and, more importantly, potentiated the toxic effects of Abeta on nAChR subunit levels and on learning and memory. These findings may be highly relevant to the mechanisms underlying the cognitive deficits associated with AD.
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Affiliation(s)
- Ru-Yu Liu
- Department of Pathology, Guiyang Medical University, Guizhou, People's Republic of China
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48
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Kloc R, Luchowska E, Wielosz M, Owe-Larsson B, Urbanska EM. Memantine increases brain production of kynurenic acid via protein kinase A-dependent mechanism. Neurosci Lett 2008; 435:169-73. [DOI: 10.1016/j.neulet.2008.02.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 02/11/2008] [Accepted: 02/12/2008] [Indexed: 11/30/2022]
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49
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Wüllner U, Gündisch D, Herzog H, Minnerop M, Joe A, Warnecke M, Jessen F, Schütz C, Reinhardt M, Eschner W, Klockgether T, Schmaljohann J. Smoking upregulates α4β2* nicotinic acetylcholine receptors in the human brain. Neurosci Lett 2008; 430:34-7. [DOI: 10.1016/j.neulet.2007.10.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 08/03/2007] [Accepted: 10/11/2007] [Indexed: 11/26/2022]
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50
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Conejero-Goldberg C, Davies P, Ulloa L. Alpha7 nicotinic acetylcholine receptor: a link between inflammation and neurodegeneration. Neurosci Biobehav Rev 2007; 32:693-706. [PMID: 18180036 DOI: 10.1016/j.neubiorev.2007.10.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Revised: 10/23/2007] [Accepted: 10/26/2007] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD) is the leading cause of dementia affecting over 25 million people worldwide. Classical studies focused on the description and characterization of the pathological hallmarks found in AD patients including the neurofibrillary tangles and the amyloid plaques. Current strategies focus on the etiology of these hallmarks and the different mechanisms contributing to neurodegeneration. Among them, recent studies reveal the close interplay between the immunological and the neurodegenerative processes. This article examines the implications of the alpha7 nicotinic acetylcholine receptor (alpha7nAChR) as a critical link between inflammation and neurodegeneration in AD. Alpha7nAChRs are not only expressed in neurons but also in Glia cells where they can modulate the immunological responses contributing to AD. Successful therapeutic strategies against AD should consider the connections between inflammation and neurodegeneration. Among them, alpha7nAChR may represent a pharmacological target to control these two mechanisms during the pathogenesis of neurodegenerative and behavioral disorders.
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Affiliation(s)
- Concepcion Conejero-Goldberg
- The Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, NY 11030, USA.
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