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Shehata MK, Ismail AA, Kamel MA. Combined Donepezil with Astaxanthin via Nanostructured Lipid Carriers Effective Delivery to Brain for Alzheimer's Disease in Rat Model. Int J Nanomedicine 2023; 18:4193-4227. [PMID: 37534058 PMCID: PMC10391537 DOI: 10.2147/ijn.s417928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 07/19/2023] [Indexed: 08/04/2023] Open
Abstract
Introduction Donepezil (DPL), a specific acetylcholinesterase inhibitor, is used as a first-line treatment to improve cognitive deficits in Alzheimer's disease (AD) and it might have a disease modifying effect. Astaxanthin (AST) is a natural potent antioxidant with neuroprotective, anti-amyloidogenic, anti-apoptotic, and anti-inflammatory effects. This study aimed to prepare nanostructured lipid carriers (NLCs) co-loaded with donepezil and astaxanthin (DPL/AST-NLCs) and evaluate their in vivo efficacy in an AD-like rat model 30 days after daily intranasal administration. Methods DPL/AST-NLCs were prepared using a hot high-shear homogenization technique, in vitro examined for their physicochemical parameters and in vivo evaluated. AD induction in rats was performed by aluminum chloride. The cortex and hippocampus were isolated from the brain of rats for biochemical testing and histopathological examination. Results DPL/AST-NLCs showed z-average diameter 149.9 ± 3.21 nm, polydispersity index 0.224 ± 0.017, zeta potential -33.7 ± 4.71 mV, entrapment efficiency 81.25 ±1.98% (donepezil) and 93.85 ±1.75% (astaxanthin), in vitro sustained release of both donepezil and astaxanthin for 24 h, spherical morphology by transmission electron microscopy, and they were stable at 4-8 ± 2°C for six months. Differential scanning calorimetry revealed that donepezil and astaxanthin were molecularly dispersed in the NLC matrix in an amorphous state. The DPL/AST-NLC-treated rats showed significantly lower levels of nuclear factor-kappa B, malondialdehyde, β-site amyloid precursor protein cleaving enzyme-1, caspase-3, amyloid beta (Aβ1‑42), and acetylcholinesterase, and significantly higher levels of glutathione and acetylcholine in the cortex and hippocampus than the AD-like untreated rats and that treated with donepezil-NLCs. DPL/AST-NLCs showed significantly higher anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, anti-inflammatory, and anti-apoptotic effects, resulting in significant improvement in the cortical and hippocampal histopathology. Conclusion Nose-to-brain delivery of DPL/AST-NLCs is a promising strategy for the management of AD.
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Affiliation(s)
- Mustafa K Shehata
- Department of Pharmaceutics, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Assem A Ismail
- Department of Pharmaceutics, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Maher A Kamel
- Department of Biochemistry, Medical Research Institute, Alexandria University, Alexandria, Egypt
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Developmental nicotine exposure impairs memory and reduces acetylcholine levels in the hippocampus of mice. Brain Res Bull 2021; 176:1-7. [PMID: 34358612 DOI: 10.1016/j.brainresbull.2021.07.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 06/15/2021] [Accepted: 07/30/2021] [Indexed: 12/22/2022]
Abstract
Nicotine is a strong psychoactive and addictive compound found in tobacco. Use of nicotine in the form of smoking, vaping or other less common methods during pregnancy has been shown to be related to poor health conditions, including cognitive problems, in babies and children. However, mechanisms of such cognitive deficits are not fully understood. In this study we analyzed hippocampus dependent cognitive deficits using a mouse model of developmental nicotine exposure. Pregnant dams were exposed to nicotine and experiments were performed in one month old offspring. Our results show that nicotine exposure did not affect locomotor behavior in mice. Hippocampus dependent working memory and object location memory were diminished in nicotine exposed mice. Furthermore, acetylcholine levels in the hippocampus of nicotine exposed mice were reduced along with reduced activity of acetylcholinesterase enzyme. Analysis of transcripts for proteins that are known to regulate acetylcholine levels revealed a decline in mRNA levels of high affinity choline transporters in the hippocampus of nicotine exposed mice but those of vesicular acetylcholine transporter, choline acetyltransferase, and α7-nicotinic acetylcholine receptors were not altered. These results suggest that developmental nicotine exposure impairs hippocampus dependent memory forms and this effect is likely mediated by altered cholinergic function.
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Central Activation of Alpha7 Nicotinic Signaling Attenuates LPS-Induced Neuroinflammation and Sickness Behavior in Adult but Not in Aged Animals. Molecules 2021; 26:molecules26082107. [PMID: 33916910 PMCID: PMC8067582 DOI: 10.3390/molecules26082107] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/29/2021] [Accepted: 04/01/2021] [Indexed: 12/13/2022] Open
Abstract
We previously reported that lipopolysaccharide (LPS) challenge caused microglial-mediated neuroinflammation and sickness behavior that was amplified in aged mice. As α7 nAChRs are implicated in the "Cholinergic anti-inflammatory pathway", we aimed to determine how α7 nAChR stimulation modulates microglial phenotype in an LPS-induced neuroinflammation model in adult and aged mice. For this, BALB/c mice were injected intraperitoneally with LPS (0.33 mg/kg) and treated with the α7 nAChR agonist PNU282987, using different administration protocols. LPS challenge reduced body weight and induced lethargy and social withdrawal in adult mice. Peripheral (intraperitoneal) co-administration of the α7 nAChR agonist PNU282987 with LPS, attenuated body weight loss and sickness behavior associated with LPS challenge in adult mice, and reduced microglial activation with suppression of IL-1β and TNFα mRNA levels. Furthermore, central (intracerebroventricular) administration of the α7 nAChR agonist, even 2 h after LPS injection, attenuated the decrease in social exploratory behavior and microglial activation induced by peripheral administration of LPS, although this recovery was not achieved if activation of α7 nAChRs was performed peripherally. Finally, we observed that the positive results of central activation of α7 nAChRs were lost in aged mice. In conclusion, we provide evidence that stimulation of α7 nAChR signaling reduces microglial activation in an in vivo LPS-based model, but this cholinergic-dependent regulation seems to be dysfunctional in microglia of aged mice.
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Yang J, Long Y, Xu DM, Zhu BL, Deng XJ, Yan Z, Sun F, Chen GJ. Age- and Nicotine-Associated Gene Expression Changes in the Hippocampus of APP/PS1 Mice. J Mol Neurosci 2019; 69:608-622. [PMID: 31399937 DOI: 10.1007/s12031-019-01389-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 07/18/2019] [Indexed: 12/17/2022]
Abstract
The etiology of Alzheimer's disease (AD) has been intensively studied. However, little is known about the molecular alterations in early-stage and late-stage AD. Hence, we performed RNA sequencing and assessed differentially expressed genes (DEGs) in the hippocampus of 18-month and 7-month-old APP/PS1 mice. Moreover, the DEGs induced by treatment with nicotine, the nicotinic acetylcholine receptor agonist that is known to improve cognition in AD, were also analyzed in old and young APP/PS1 mice. When comparing old APP/PS1 mice with their younger littermates, we found an upregulation in genes associated with calcium overload, immune response, cancer, and synaptic function; the transcripts of 14 calcium ion channel subtypes were significantly increased in aged mice. In contrast, the downregulated genes in aged mice were associated with ribosomal components, mitochondrial respiratory chain complex, and metabolism. Through comparison with DEGs in normal aging from previous reports, we found that changes in calcium channel genes remained one of the prominent features in aged APP/PS1 mice. Nicotine treatment also induced changes in gene expression. Indeed, nicotine augmented glycerolipid metabolism, but inhibited PI3K and MAPK signaling in young mice. In contrast, nicotine affected genes associated with cell senescence and death in old mice. Our study suggests a potential network connection between calcium overload and cellular signaling, in which additional nicotinic activation might not be beneficial in late-stage AD.
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Affiliation(s)
- Jie Yang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Yan Long
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - De-Mei Xu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Bing-Lin Zhu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Xiao-Juan Deng
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Zhen Yan
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, 14214, USA
| | - Fei Sun
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Guo-Jun Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China.
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Abstract
Notwithstanding tremendous research efforts, the cause of Alzheimer's disease (AD) remains elusive and there is no curative treatment. The cholinergic hypothesis presented 35 years ago was the first major evidence-based hypothesis on the etiology of AD. It proposed that the depletion of brain acetylcholine was a primary cause of cognitive decline in advanced age and AD. It relied on a series of observations obtained in aged animals, elderly, and AD patients that pointed to dysfunctions of cholinergic basal forebrain, similarities between cognitive impairments induced by anticholinergic drugs and those found in advanced age and AD, and beneficial effects of drugs stimulating cholinergic activity. This review revisits these major results to show how this hypothesis provided the drive for the development of anticholinesterase inhibitor-based therapies of AD, the almost exclusively approved treatment in use despite transient and modest efficacy. New ideas for improving cholinergic therapies are also compared and discussed in light of the current revival of the cholinergic hypothesis on the basis of two sets of evidence from new animal models and refined imagery techniques in humans. First, human and animal studies agree in detecting signs of cholinergic dysfunctions much earlier than initially believed. Second, alterations of the cholinergic system are deeply intertwined with its reactive responses, providing the brain with efficient compensatory mechanisms to delay the conversion into AD. Active research in this field should provide new insight into development of multitherapies incorporating cholinergic manipulation, as well as early biomarkers of AD enabling earlier diagnostics. This is of prime importance to counteract a disease that is now recognized to start early in adult life.
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Bretin S, Krazem A, Henkous N, Froger-Colleaux C, Mocaer E, Louis C, Perdaems N, Marighetto A, Beracochea D. Synergistic enhancing-memory effect of donepezil and S 47445, an AMPA positive allosteric modulator, in middle-aged and aged mice. Psychopharmacology (Berl) 2018; 235:771-787. [PMID: 29167913 PMCID: PMC5847048 DOI: 10.1007/s00213-017-4792-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 11/14/2017] [Indexed: 11/30/2022]
Abstract
Positive allosteric modulators of AMPA receptors (AMPA-PAMs) are described to facilitate cognitive processes in different memory-based models. Among them, S 47445 is a novel potent and selective AMPA-PAM. In order to assess its efficacy after repeated administration, S 47445 effect was evaluated in two aging-induced memory dysfunction tasks in old mice, one short-term working memory model evaluated in a radial maze task and one assessing contextual memory performance. S 47445 was shown to improve cognition in both models sensitive to aging. In fact, administration of S 47445 at 0.3 mg/kg (s.c.) reversed the age-induced deficits of the working memory model whatever the retention interval. Moreover, in the contextual task, S 47445 also reversed the age-induced deficit at all tested doses (from 0.03 to 0.3 mg/kg, p.o.). Since donepezil, an acetylcholinesterase inhibitor, induces only moderate symptomatic effects on memory in Alzheimer's disease patients, an alternative strategy for treatment of cognitive symptoms could be to act simultaneously on both glutamatergic AMPA receptors and cholinergic pathways by combining pharmacological treatments. The present study further examined such effects by assessing combinations of S 47445 and donepezil given orally during 9 days in aged C57/Bl6J mice using contextual memory task (CSD) and the working memory model of serial alternation task (AT). Interestingly, a significant synergistic memory-enhancing effect was observed with the combination of donepezil at 0.1 mg/kg with S 47445 at 0.1 mg/kg p.o. in the CSD or with S 47445 at 0.1 and 0.3 mg/kg in AT in comparison to compounds given alone and without any pharmacokinetic interaction.
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Affiliation(s)
- S Bretin
- Institut de Recherches Internationales Servier, Pôle d'Innovation Thérapeutique Neuropsychiatrie, Suresnes, France
| | - A Krazem
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), Université de Bordeaux, UMR CNRS 5287, Allée Geoffroy Saint-Hilaire, Bat B2, 33613, Pessac, France
| | - N Henkous
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), Université de Bordeaux, UMR CNRS 5287, Allée Geoffroy Saint-Hilaire, Bat B2, 33613, Pessac, France
| | - C Froger-Colleaux
- Froger-Colleaux C, Porsolt Research Laboratory, Z.A de Glatiné, 53940, Le Genest-Saint-Isle, France
| | - E Mocaer
- Institut de Recherches Internationales Servier, Pôle d'Innovation Thérapeutique Neuropsychiatrie, Suresnes, France
| | - C Louis
- Institut de Recherches Servier, Pôle d'Innovation Thérapeutique Neuropsychiatrie, Croissy-Sur-Seine, France
| | - N Perdaems
- Pôle Expertise en Pharmacocinétique, Orléans, France
| | - A Marighetto
- INSERM, Neurocentre Magendie, Physiopathologie de la plasticité neuronale, U1215, 33077, Bordeaux, France
| | - D Beracochea
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), Université de Bordeaux, UMR CNRS 5287, Allée Geoffroy Saint-Hilaire, Bat B2, 33613, Pessac, France.
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Sors A, Krazem A, Kehr J, Yoshitake T, Dominguez G, Henkous N, Letondor C, Mocaer E, Béracochéa DJ. The Synergistic Enhancing-Memory Effect of Donepezil and S 38093 (a Histamine H 3 Antagonist) Is Mediated by Increased Neural Activity in the Septo-hippocampal Circuitry in Middle-Aged Mice. Front Pharmacol 2016; 7:492. [PMID: 28066242 PMCID: PMC5177663 DOI: 10.3389/fphar.2016.00492] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 12/01/2016] [Indexed: 01/01/2023] Open
Abstract
Donepezil, an acetylcholinesterase inhibitor, induces only moderate symptomatic effects on memory in Alzheimer’s disease patients. An alternative strategy for treatment of cognitive symptoms could be to act simultaneously on both histaminergic and cholinergic pathways, to create a synergistic effect. To that aim, 14 month old C57/Bl6 mice were administered per oesophagy during nine consecutive days with Donepezil (at 0.1 and 0.3 mg/kg) and S 38093 (at 0.1, 0.3, and 1.0 mg/kg), a H3 histaminergic antagonist developed by Servier, alone or in combination and tested for memory in a contextual memory task that modelized the age-induced memory dysfunction. The present study shows that the combination of Donepezil and S 38093 induced a dose-dependent synergistic memory-enhancing effect in middle-aged mice with a statistically higher size of effect never obtained with compounds alone and without any pharmacokinetic interaction between both compounds. We demonstrated that the memory-enhancing effect of the S 38093 and Donepezil combination is mediated by its action on the septo-hippocampal circuitry, since it canceled out the reduction of CREB phosphorylation (pCREB) observed in these brain areas in vehicle-treated middle-aged animals. Overall, the effects of drug combinations on pCREB in the hippocampus indicate that the synergistic promnesiant effects of the combination on memory performance in middle-aged mice stem primarily from an enhancement of neural activity in the septo-hippocampal system.
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Affiliation(s)
- Aurore Sors
- Pôle d'Innovation Thérapeutique Neuropsychiatrie Servier Suresnes, France
| | - Ali Krazem
- CNRS 5287, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux UMR, Pessac, France
| | - Jan Kehr
- Pronexus Analytical AB Bromma, Sweden
| | - Takashi Yoshitake
- Section of Pharmacological Neurochemistry, Department of Physiology and Pharmacology, Karolinska Institute Stockholm, Sweden
| | - Gaelle Dominguez
- CNRS 5287, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux UMR, Pessac, France
| | - Nadia Henkous
- CNRS 5287, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux UMR, Pessac, France
| | - Claire Letondor
- Pôle d'Innovation Thérapeutique Neuropsychiatrie Servier Suresnes, France
| | - Elisabeth Mocaer
- Pôle d'Innovation Thérapeutique Neuropsychiatrie Servier Suresnes, France
| | - Daniel J Béracochéa
- CNRS 5287, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux UMR, Pessac, France
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A phase 2 randomized, controlled trial of the α7 agonist ABT-126 in mild-to-moderate Alzheimer's dementia. ALZHEIMERS & DEMENTIA-TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2015; 1:81-90. [PMID: 29854928 PMCID: PMC5974973 DOI: 10.1016/j.trci.2015.06.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Introduction The safety and efficacy of the novel α7 nicotinic acetylcholine receptor agonist ABT-126 were investigated in subjects with mild-to-moderate Alzheimer's dementia (AD). Methods Subjects not currently receiving acetylcholinesterase inhibitors were randomized to ABT-126 (5 or 25 mg once daily), donepezil 10 mg once daily, or placebo for 12 weeks. The primary efficacy end point was the change from baseline to final evaluation in the 11-item Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog) total score. Results A total of 274 subjects were randomized. Although the study did not meet its primary end point, trends toward improvement were seen with ABT-126 25 mg (least squares mean [standard error] difference from placebo −1.19 [0.90]; one-sided P = .095) and donepezil (−1.43 [0.90]; one-sided P = .057) on the 11-item ADAS-Cog total score change from baseline to the final evaluation. ABT-126 5 mg was numerically similar to placebo. An exposure-response analysis indicated a statistically significant relationship between ABT-126 exposure and the change from baseline in ADAS-Cog, with no evidence of a plateau. No clinically meaningful differences in safety were observed among treatment groups. Discussion Although the ABT-126 25 mg dose did not demonstrate statistically significant improvement, results of the exposure-response analysis suggest that higher doses may produce better efficacy, and the safety profile of ABT-126 in this study supports additional studies with higher doses in subjects with mild-to-moderate AD. Clinical trial register number NCT00948909.
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Philpot RM. Potential Use of Nicotinic Receptor Agonists for the Treatment of Chemotherapy-Induced Cognitive Deficits. Neurochem Res 2015; 40:2018-31. [DOI: 10.1007/s11064-015-1528-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 01/09/2015] [Accepted: 01/28/2015] [Indexed: 10/24/2022]
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Dawson N, Morris BJ, Pratt JA. Functional brain connectivity phenotypes for schizophrenia drug discovery. J Psychopharmacol 2015; 29:169-77. [PMID: 25567554 DOI: 10.1177/0269881114563635] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
While our knowledge of the pathophysiology of schizophrenia has increased dramatically, this has not translated into the development of new and improved drugs to treat this disorder. Human brain imaging and electrophysiological studies have provided dramatic new insight into the mechanisms of brain dysfunction in the disease, with a swathe of recent studies highlighting the differences in functional brain network and neural system connectivity present in the disorder. Only recently has the value of applying these approaches in preclinical rodent models relevant to the disorder started to be recognised. Here we highlight recent findings of altered functional brain connectivity in preclinical rodent models and consider their relevance to those alterations seen in the brains of schizophrenia patients. Furthermore, we highlight the potential translational value of using the paradigm of functional brain connectivity phenotypes in the context of preclinical schizophrenia drug discovery, as a means both to understand the mechanisms of brain dysfunction in the disorder and to reduce the current high attrition rate in schizophrenia drug discovery.
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Affiliation(s)
- Neil Dawson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK
| | - Brian J Morris
- Institute of Neuroscience and Psychology, School of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Psychiatric Research Institute of Neuroscience in Glasgow (PsyRING), University of Glasgow, Glasgow, UK
| | - Judith A Pratt
- Strathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, Glasgow, UK Psychiatric Research Institute of Neuroscience in Glasgow (PsyRING), University of Glasgow, Glasgow, UK
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Bali ZK, Inkeller J, Csurgyók R, Bruszt N, Horváth H, Hernádi I. Differential effects of α7 nicotinic receptor agonist PHA-543613 on spatial memory performance of rats in two distinct pharmacological dementia models. Behav Brain Res 2015; 278:404-10. [DOI: 10.1016/j.bbr.2014.10.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 10/16/2014] [Accepted: 10/20/2014] [Indexed: 12/18/2022]
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Marighetto A, Brayda-Bruno L, Etchamendy N. Studying the impact of aging on memory systems: contribution of two behavioral models in the mouse. Curr Top Behav Neurosci 2015; 10:67-89. [PMID: 21805395 DOI: 10.1007/7854_2011_151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the present chapter, we describe our own attempts to improve our understanding of the pathophysiology of memory in aging. First, we tried to improve animal models of memory degradations occurring in aging, and develop common behavioral tools between mice and humans. Second, we began to use these behavioral tools to identify the molecular/intracellular changes occurring within the integrate network of memory systems in order to bridge the gap between the molecular and system level of analysis. The chapter is divided into three parts (i) modeling aging-related degradation in declarative memory (DM) in mice, (ii) assessing the main components of working memory (WM) with a common radial-maze task in mice and humans and (iii) studying the role of the retinoid cellular signaling path in aging-related changes in memory systems.
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Affiliation(s)
- Aline Marighetto
- Neurocentre Magendie-Inserm U862, 146 Rue Leo Saignat, 33077, Bordeaux-Cedex, France,
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Li S, Nai Q, Lipina TV, Roder JC, Liu F. α7nAchR/NMDAR coupling affects NMDAR function and object recognition. Mol Brain 2013; 6:58. [PMID: 24360204 PMCID: PMC3878138 DOI: 10.1186/1756-6606-6-58] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 12/12/2013] [Indexed: 02/03/2023] Open
Abstract
The α7 nicotinic acetylcholine receptor (nAchR) and NMDA glutamate receptor (NMDAR) are both ligand-gated ion channels permeable to Ca2+ and Na+. Previous studies have demonstrated functional modulation of NMDARs by nAchRs, although the molecular mechanism remains largely unknown. We have previously reported that α7nAchR forms a protein complex with the NMDAR through a protein-protein interaction. We also developed an interfering peptide that is able to disrupt the α7nAchR-NMDAR complex and blocks cue-induced reinstatement of nicotine-seeking in rat models of relapse. In the present study, we investigated whether the α7nAchR-NMDAR interaction is responsible for the functional modulation of NMDAR by α7nAchR using both electrophysiological and behavioral tests. We have found that activation of α7nAchR upregulates NMDAR-mediated whole cell currents and LTP of mEPSC in cultured hippocampal neurons, which can be abolished by the interfering peptide that disrupts the α7nAchR-NMDAR interaction. Moreover, administration of the interfering peptide in mice impairs novel object recognition but not Morris water maze performance. Our results suggest that α7nAchR/NMDAR coupling may selectively affect some aspects of learning and memory.
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Affiliation(s)
| | | | | | | | - Fang Liu
- Department of Neuroscience, Centre for Addiction and Mental Health, Clarke Division, 250 College Street, Toronto, Ontario M5T 1R8, Canada.
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Cutuli D, De Bartolo P, Caporali P, Tartaglione AM, Oddi D, D'Amato FR, Nobili A, D'Amelio M, Petrosini L. Neuroprotective effects of donepezil against cholinergic depletion. ALZHEIMERS RESEARCH & THERAPY 2013; 5:50. [PMID: 24401551 PMCID: PMC3978431 DOI: 10.1186/alzrt215] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 10/16/2013] [Indexed: 11/12/2022]
Abstract
Introduction Intraparenchymal injections of the immunotoxin 192-IgG-saporin into medial septum and nucleus basalis magnocellularis causes a selective depletion of basal forebrain cholinergic neurons. Thus, it represents a valid model to mimic a key component of the cognitive deficits associated with aging and dementia. Here we administered donepezil, a potent acetylcholinesterase inhibitor developed for treating Alzheimer’s disease, 15 days before 192-IgG-saporin injection, and thus we examined donepezil effects on neurodegeneration and cognitive deficits. Methods Caspase-3 activity and cognitive performances of lesioned rats pre-treated with donepezil or saline were analyzed and compared to the outcomes obtained in pre-treated sham-lesioned rats. Results Cholinergic depletion increased hippocampal and neocortical caspase-3 activity and impaired working memory, spatial discrimination, social novelty preference, and ultrasonic vocalizations, without affecting anxiety levels and fear conditioning. In lesioned animals, donepezil pre-treatment reduced hippocampal and neocortical caspase-3 activity and improved working memory and spatial discrimination performances and partially rescued ultrasonic vocalizations, without preventing social novelty alterations. Conclusions Present data indicate that donepezil pre-treatment exerts beneficial effects on behavioral deficits induced by cholinergic depletion, attenuating the concomitant hippocampal and neocortical neurodegeneration.
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Song XY, Hu JF, Chu SF, Zhang Z, Xu S, Yuan YH, Han N, Liu Y, Niu F, He X, Chen NH. Ginsenoside Rg1 attenuates okadaic acid induced spatial memory impairment by the GSK3β/tau signaling pathway and the Aβ formation prevention in rats. Eur J Pharmacol 2013; 710:29-38. [DOI: 10.1016/j.ejphar.2013.03.051] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 03/22/2013] [Accepted: 03/28/2013] [Indexed: 11/28/2022]
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Abstract
Significant insights into the function of genes associated with Alzheimer disease and related dementias have occurred through studying genetically modified animals. Although none of the existing models fully reproduces the complete spectrum of this insidious human disease, critical aspects of Alzheimer pathology and disease processes can be experimentally recapitulated. Genetically modified animal models have helped advance our understanding of the underlying mechanisms of disease and have proven to be invaluable in the preclinical evaluation of potential therapeutic interventions. Continuing refinement and evolution to yield the next generation of animal models will facilitate successes in producing greater translational concordance between preclinical studies and human clinical trials and eventually lead to the introduction of novel therapies into clinical practice.
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Affiliation(s)
- Frank M LaFerla
- Institute for Memory Impairments and Neurological Disorders, Department of Neurobiology and Behavior, University of California, Irvine, 92697-4545, USA.
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Gold AB, Lerman C. Pharmacogenetics of smoking cessation: role of nicotine target and metabolism genes. Hum Genet 2012; 131:10.1007/s00439-012-1143-9. [PMID: 22290489 PMCID: PMC3864572 DOI: 10.1007/s00439-012-1143-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 01/19/2012] [Indexed: 11/24/2022]
Abstract
Many smokers attempt to quit smoking but few are successful in the long term. The heritability of nicotine addiction and smoking relapse have been documented, and research is focused on identifying specific genetic influences on the ability to quit smoking and response to specific medications. Research in genetically modified cell lines and mice has identified nicotine acetylcholine receptor subtypes that mediate the pharmacological and behavioral effects of nicotine sensitivity and withdrawal. Human genetic association studies have identified single nucleotide polymorphisms (SNPs) in genes encoding nicotine acetylcholine receptor subunits and nicotine metabolizing enzymes that influence smoking cessation phenotypes. There is initial promising evidence for a role in smoking cessation for SNPs in the β2 and α5/α3/β4 nAChR subunit genes; however, effects are small and not consistently replicated. There are reproducible and clinically significant associations of genotypic and phenotypic measures of CYP2A6 enzyme activity and nicotine metabolic rate with smoking cessation as well as response to nicotine replacement therapies and bupropion. Prospective clinical trials to identify associations of genetic variants and gene-gene interactions on smoking cessation are needed to generate the evidence base for both medication development and targeted therapy approaches based on genotype.
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Affiliation(s)
- Allison B. Gold
- Center for Interdisciplinary Research on Nicotine Addiction, University of Pennsylvania, 3535 Market Street, Suite 4100, Philadelphia, PA 19104, USA
| | - Caryn Lerman
- Center for Interdisciplinary Research on Nicotine Addiction, University of Pennsylvania, 3535 Market Street, Suite 4100, Philadelphia, PA 19104, USA
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Bilkei-Gorzo A, Drews E, Albayram Ö, Piyanova A, Gaffal E, Tueting T, Michel K, Mauer D, Maier W, Zimmer A. Early onset of aging-like changes is restricted to cognitive abilities and skin structure in Cnr1−/− mice. Neurobiol Aging 2012; 33:200.e11-22. [DOI: 10.1016/j.neurobiolaging.2010.07.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 07/02/2010] [Accepted: 07/09/2010] [Indexed: 12/19/2022]
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Barak S, Weiner I. Putative cognitive enhancers in preclinical models related to schizophrenia: The search for an elusive target. Pharmacol Biochem Behav 2011; 99:164-89. [DOI: 10.1016/j.pbb.2011.03.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/27/2011] [Accepted: 03/12/2011] [Indexed: 12/12/2022]
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Wallace TL, Porter RHP. Targeting the nicotinic alpha7 acetylcholine receptor to enhance cognition in disease. Biochem Pharmacol 2011; 82:891-903. [PMID: 21741954 DOI: 10.1016/j.bcp.2011.06.034] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 06/18/2011] [Accepted: 06/24/2011] [Indexed: 01/05/2023]
Abstract
A promising drug target currently under investigation to improve cognitive deficits in neuropsychiatric and neurological disorders is the neuronal nicotinic alpha7 acetylcholine receptor (α7nAChR). Improving cognitive impairments in diseases such as Alzheimer's (AD) and schizophrenia remains a large unmet medical need, and the α7nAChR has many properties that make it an attractive therapeutic target. The α7nAChR is a ligand gated ion channel that has particularly high permeability to Ca(2+) and is expressed in key brain regions involved in cognitive processes (e.g., hippocampus). The α7nAChRs are localized both pre-synaptically, where they can regulate neurotransmitter release, and post-synaptically where they can activate intracellular signaling cascades and influence downstream processes involved in learning and memory. In particular, activation of the α7nAChR with small molecule agonists enhances long-term potentiation, an in vitro model of synaptic plasticity, and improves performance across multiple cognitive domains in rodents, monkeys, and humans. Positive allosteric modulation of the α7nAChR offers an alternate approach to direct agonism that could prove to be particularly beneficial in certain disease populations where smoking nicotine is prevalent (e.g., schizophrenia) and could interfere with an orthosteric agonist approach. The current review focuses on the neurobiology of the α7nAChR, its role in cognition and the development status of some of the most promising molecules advancing for the treatment of cognitive dysfunction in disease.
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Affiliation(s)
- Tanya L Wallace
- Center for Neuroscience, SRI International, 333 Ravenswood Avenue, M/S 100-69, Menlo Park, CA 94025, USA.
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21
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Bartko SJ, Vendrell I, Saksida LM, Bussey TJ. A computer-automated touchscreen paired-associates learning (PAL) task for mice: impairments following administration of scopolamine or dicyclomine and improvements following donepezil. Psychopharmacology (Berl) 2011; 214:537-48. [PMID: 21086119 DOI: 10.1007/s00213-010-2050-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
Abstract
RATIONALE Performance on the Cambridge Neuropsychological Test Automated Battery touchscreen paired-associates learning (PAL) test is predictive of Alzheimer's disease and impaired in schizophrenia and chronic drug users. An automated computer touchscreen PAL task for rats has been previously established. A pharmacologically validated PAL task for mice would be a highly valuable tool, which could be useful for a number of experimental aims including drug discovery. OBJECTIVES This study sought to investigate the effects of systemic administration of cholinergic agents on task performance in C57Bl/6 mice. METHODS Scopolamine hydrobromide (0.02, 0.2, and 2.0 mg/kg), dicyclomine hydrochloride (M(1) receptor antagonist; 2.0, 4.0, and 8.0 mg/kg), and donepezil hydrochloride (cholinesterase inhibitor; 0.03, 0.1, and 0.3 mg/kg) were administered post-acquisition in C57Bl/6 mice performing the PAL task. RESULTS Scopolamine (0.2 and 2.0 mg/kg) and dicyclomine (at all administered doses) significantly impaired PAL performance. A significant facilitation in PAL was revealed in mice following donepezil administration (0.3 mg/kg). CONCLUSIONS The present study shows that mice can acquire the rodent PAL task and that the cholinergic system is important for PAL task performance. M(1) receptors in particular are likely implicated in normal performance of PAL. The finding that mouse PAL can detect both impairments and improvements indicates that this task could prove to be a highly valuable tool for a number of experimental aims including drug discovery.
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Affiliation(s)
- Susan J Bartko
- Department of Experimental Psychology, University of Cambridge, Downing St., Cambridge, CB2 3EB, UK.
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Floresco SB, Jentsch JD. Pharmacological enhancement of memory and executive functioning in laboratory animals. Neuropsychopharmacology 2011; 36:227-50. [PMID: 20844477 PMCID: PMC3055518 DOI: 10.1038/npp.2010.158] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Investigating how different pharmacological compounds may enhance learning, memory, and higher-order cognitive functions in laboratory animals is the first critical step toward the development of cognitive enhancers that may be used to ameliorate impairments in these functions in patients suffering from neuropsychiatric disorders. Rather than focus on one aspect of cognition, or class of drug, in this review we provide a broad overview of how distinct classes of pharmacological compounds may enhance different types of memory and executive functioning, particularly those mediated by the prefrontal cortex. These include recognition memory, attention, working memory, and different components of behavioral flexibility. A key emphasis is placed on comparing and contrasting the effects of certain drugs on different cognitive and mnemonic functions, highlighting methodological issues associated with this type of research, tasks used to investigate these functions, and avenues for future research. Viewed collectively, studies of the neuropharmacological basis of cognition in rodents and non-human primates have identified targets that will hopefully open new avenues for the treatment of cognitive disabilities in persons affected by mental disorders.
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Affiliation(s)
- Stan B Floresco
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada.
| | - James D Jentsch
- Departments of Psychology and Psychiatry & Bio-behavioral Sciences, University of California, Los Angeles, CA, USA
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Micheau J, Marighetto A. Acetylcholine and memory: a long, complex and chaotic but still living relationship. Behav Brain Res 2010; 221:424-9. [PMID: 21130809 DOI: 10.1016/j.bbr.2010.11.052] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 11/25/2010] [Indexed: 12/21/2022]
Abstract
Even though "procholinergic" drugs are almost the sole kind of treatments currently used as cognitive enhancers in patients with Alzheimer's disease, the role of acetylcholine (ACh) in learning and memory is still poorly understood. In this short review, we focus on the septo-hippocampal cholinergic system and try to demonstrate that understanding ACh-memory relationships requires taking into account two characteristics of memory function. First, this function is polymorphic and relies on multiple neural systems. It appears that hippocampal ACh may not only modulate specific computational function of the hippocampus but also contributes to the functional coordination of multiple memory systems in a task-dependent manner. Second, memorization implies different phases which are differentially regulated by ACh. Namely, several lines of evidence suggest a "biphasic" involvement with hippocampal ACh facilitating memory encoding but hampering memory consolidation and retrieval, and low hippocampal ACh promoting consolidation of declarative memory. By spotting major determinants of memory modulation by hippocampal ACh, we hope that the present non exhaustive review will help to improve our understanding of the complexity of ACh-memory relationships.
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Affiliation(s)
- Jacques Micheau
- Centre for Integrative and Cognitive Neuroscience, University of Bordeaux, CNRS UMR 5228, Avenue des Facultés, 33405 Talence Cedex, France.
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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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Abstract
Alzheimer's disease is a progressive neurodegenerative disease for which no cure exists. There is a substantial need for new therapies that offer improved symptomatic benefit and disease-slowing capabilities. In recent decades there has been substantial progress in understanding the molecular and cellular changes associated with Alzheimer's disease pathology. This has resulted in identification of a large number of new drug targets. These targets include, but are not limited to, therapies that aim to prevent production of or remove the amyloid-beta protein that accumulates in neuritic plaques; to prevent the hyperphosphorylation and aggregation into paired helical filaments of the microtubule-associated protein tau; and to keep neurons alive and functioning normally in the face of these pathologic challenges. We provide a review of these targets for drug development.
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Affiliation(s)
- Joshua D Grill
- Mary S. Easton Center for Alzheimer's Disease Research, Deane F. Johnson Center for Neurotherapeutics, Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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Wang HY, Bakshi K, Shen C, Frankfurt M, Trocmé-Thibierge C, Morain P. S 24795 limits beta-amyloid-alpha7 nicotinic receptor interaction and reduces Alzheimer's disease-like pathologies. Biol Psychiatry 2010; 67:522-30. [PMID: 19932469 DOI: 10.1016/j.biopsych.2009.09.031] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 09/18/2009] [Accepted: 09/30/2009] [Indexed: 11/30/2022]
Abstract
BACKGROUND Beta-amyloid (Abeta) enables Alzheimer's disease (AD) plaque and neurofibrillary pathogenesis. Soluble Abeta promotes intraneuronal Abeta aggregates and tau phosphorylation by interacting with alpha7 nicotinic receptors (alpha7nAChRs). The current study assessed whether the novel alpha7nAChR partial agonist 2-(2-(4-bromophenyl)-2-oxoethyl)-1-methyl pyridinium (S 24795) could reduce AD-like pathologies by interfering with Abeta-alpha7nAChR interaction. METHODS We compared the in vitro effect of S 24795, memantine, galantamine, and Abeta(12-28) on Abeta(42)-alpha7nAChR interaction in rat hippocampal synaptosomes. We further evaluated the effect of S 24795 on Abeta(42)-induced tau phosphorylation with rat hippocampal synaptosomes in vitro. Effects of S 24795 on Abeta(42) immunostaining, Abeta(42)-alpha7nAChR interaction, and/or Abeta(42)-mediated reduction of calcium (Ca(2+)) influx through alpha7nAChR and N-methyl-d-aspartate receptor (NMDAR) were assessed in Abeta(42)-incubated organotypic brain slices and intracerebroventricularly (ICV) Abeta(42)-injected mouse brain. RESULTS Preincubation with S 24795 in vitro reduces Abeta(42)-alpha7nAChR interaction and Abeta(42)-induced tau phosphorylation. In organotypic brain slice cultures and in an ICV Abeta(42) injection in vivo model, S 24795 reduces Abeta(42)-alpha7nAChR association and Abeta(42) immunostaining. S 24795 also normalizes Ca(2+) fluxes through both alpha7nAChR and NMDAR channels in Abeta(42)-infused mouse brains and Abeta(42)-exposed organotypic cortical slices. Unlike S 24795 and Abeta(12-28), galantamine or memantine minimally affect Abeta(42)-alpha7nAChR coupling and Abeta(42)-mediated reduction of alpha7nAChR- and NMDAR-mediated Ca(2+) influx. INTERPRETATION Drugs like S 24795 that disrupt Abeta(42)-alpha7nAChR interaction might alleviate Abeta(42)-mediated synaptic dysfunction and block AD-like pathologies.
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Affiliation(s)
- Hoau-Yan Wang
- Department of Physiology and Pharmacology, Sophie Davis School of Biomedical Education, City University of New York Medical School, New York, New York, USA.
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Dissociating beta-amyloid from alpha 7 nicotinic acetylcholine receptor by a novel therapeutic agent, S 24795, normalizes alpha 7 nicotinic acetylcholine and NMDA receptor function in Alzheimer's disease brain. J Neurosci 2009; 29:10961-73. [PMID: 19726654 DOI: 10.1523/jneurosci.6088-08.2009] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by synaptic dysfunction and cardinal neuropathological features including amyloid plaques and neurofibrillary tangles. Soluble amyloid-beta (Abeta) can suppress synaptic activities by interacting with alpha7 nicotinic acetylcholine receptors (alpha7nAChRs). Here, we show that alpha7nAChR and NMDA glutamatergic receptor (NMDAR) activities are severely compromised in synaptosomes prepared from AD and Abeta(1-42) (Abeta42)-exposed control frontal cortex slices from postmortem tissue. Whereas Abeta(12-28) prevents Abeta42 from binding to alpha7nAChRs, 2-[2-(4-bromophenyl)-2-oxoethyl]-1-methyl pyridinium (S 24795), a novel alpha7nAChR partial agonist, facilitates release of Abeta42 from Abeta42-alpha7nAChR and -Abeta42 complexes. S 24795 interacts with alpha7nAChR and Abeta(15-20) region of the Abeta42 to enable partial recovery of the alpha7nAChR and NMDAR channel function. These findings suggest that the Abeta-alpha7nAChR interaction may be an upstream pathogenic event in AD and demonstrate that some recovery of neuronal channel activities may be achieved in AD brains by removing Abeta from alpha7nAChRs.
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López-Hernández GY, Thinschmidt JS, Morain P, Trocme-Thibierge C, Kem WR, Soti F, Papke RL. Positive modulation of alpha7 nAChR responses in rat hippocampal interneurons to full agonists and the alpha7-selective partial agonists, 4OH-GTS-21 and S 24795. Neuropharmacology 2009; 56:821-30. [PMID: 19705574 DOI: 10.1016/j.neuropharm.2009.01.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
One approach for the identification of therapeutic agents for Alzheimer's disease has focused on the research of alpha7 nAChR-selective agonists such as the partial agonists 3-(4-hydroxy,2-methoxybenzylidene)anabaseine (4OH-GTS-21) and, more recently, 2-[2-(4-bromophenyl)-2-oxoethyl]-1-methyl pyridinium (S 24795). An alternative approach for targeting alpha7 nAChR has been the development of positive modulators for this receptor. In this study we examined the interactions between full or partial agonists and positive modulators of alpha7 nAChRs in situ in brain tissue. Three positive modulators were used, 5-hydroxyindole (5-HI), 1-(5-chloro-2,4-dimethoxy-phenyl)-3-(5-methyl-isoxanol-3-yl)-urea (PNU-120596), and genistein. Whole-cell recordings were performed in stratum radiatum interneurons from rat brain slices. Hippocampal interneurons were stimulated by ACh, choline, S 24795, or 4OH-GTS-21, before and after bath perfusion with the positive modulators. 5-HI was not effective at potentiating 200 microM 4OH-GTS-21-evoked responses, however 5-HI induced a sustained potentiation of responses evoked by 30 microM 4OH-GTS-21. When 1 mM ACh and 200 microM 4OH-GTS-21 were applied alternately alpha7-mediated responses to both agonists were reduced, suggesting that high concentration of 4OH-GTS-21 produces residual inhibition or desensitization and that 5-HI is not effective at overcoming receptor desensitization. Similar results were obtained with alpha7 receptors expressed in Xenopus oocytes. Interestingly, responses evoked by S 24795 were potentiated by 5-HI but not by genistein. Additionally, PNU-120596 was able to potentiate alpha7-mediated responses, regardless of the nature of the agonist. We demonstrated that the potentiation of alpha7 nAChR response would depend on the nature and the effective concentration of the agonist involved and its particular interaction with the positive modulator.
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Affiliation(s)
- Gretchen Y López-Hernández
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610-0267, USA.
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Tarditi A, Caricasole A, Terstappen G. Therapeutic targets for Alzheimer's disease. Expert Opin Ther Targets 2009; 13:551-67. [DOI: 10.1517/14728220902865614] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Levin ED, Petro A, Rezvani AH, Pollard N, Christopher NC, Strauss M, Avery J, Nicholson J, Rose JE. Nicotinic alpha7- or beta2-containing receptor knockout: effects on radial-arm maze learning and long-term nicotine consumption in mice. Behav Brain Res 2008; 196:207-13. [PMID: 18831991 DOI: 10.1016/j.bbr.2008.08.048] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 08/28/2008] [Accepted: 08/31/2008] [Indexed: 11/17/2022]
Abstract
Classically, it has been thought that high-affinity nicotinic receptors-containing beta2 subunits are the most important receptor subtypes for nicotinic involvement in cognitive function and nicotine self-administration, while low affinity alpha7-containing nicotinic receptors have not been thought to be important. In the current study, we found that knockout of either beta2 or alpha7 subunits caused significant deficits in spatial discrimination in mice. The character of the impairment in the two knockouts was different. The beta2 knockout preferentially impaired cognition in males while the alpha7 caused impairment regardless of sex. Both beta2- and alpha7-containing nicotinic receptors also are important for nicotine self-administration, also in different ways. Most animal model studies of nicotine self-administration are relatively short-term whereas the problem of tobacco addiction is considerably longer-term. To better model the impact of nicotinic receptor subtypes on nicotine self-administration over the long-term, we studied the impact of genetic knockout of low affinity alpha7 receptors vs. high-affinity beta2-containing nicotinic receptors. Mice with knockouts of either of these receptors and their wildtype counter parts were given free access to a choice of nicotine-containing and nicotine-free solution in their home cages on a continuous basis over a period of 5 months. During the first few weeks, the beta2-containing nicotinic receptor knockout mice showed a significant decrease in nicotine consumption relative to wildtype mice, whereas the alpha7 knockout mice did not significantly differ from wildtype controls at the beginning of their access to nicotine. Interestingly, in the longer-term after the first few weeks of nicotine access, the beta2 knockout mice returned to wildtype mouse levels of nicotine consumption, whereas the alpha7 knockout mice developed an emergent decrease in nicotine consumption. The alpha7 receptor knockout-induced decrease in nicotine consumption persisted for the 5-month period of the study. Both alpha7- and beta2-containing nicotinic receptors play critical roles in cognitive function and nicotine self-administration. Regarding cognitive function, beta2-containing receptors are important for maintaining normal sex differences in spatial learning and memory, whereas alpha7 receptors are important for cognitive function regardless of sex. Regarding nicotine self-administration high-affinity beta2-containing nicotinic receptors are important for consumption during the initial phase of nicotine access, but it is the alpha7 nicotinic receptors that are important for the longer-term regulation of nicotine consumption.
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Affiliation(s)
- Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA.
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Blokland A, Boess F. Use of behavioural and long-term potentiation models in the development of memory-improving drugs. Expert Opin Drug Discov 2008; 3:1067-80. [DOI: 10.1517/17460441.3.9.1067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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