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Aging redistributes medial prefrontal neuronal excitability and impedes extinction of trace fear conditioning. Neurobiol Aging 2011; 33:1744-57. [PMID: 21531046 DOI: 10.1016/j.neurobiolaging.2011.03.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 03/17/2011] [Accepted: 03/22/2011] [Indexed: 12/21/2022]
Abstract
Cognitive flexibility is critical for survival and reflects the malleability of the central nervous system (CNS) in response to changing environmental demands. Normal aging results in difficulties modifying established behaviors, which may involve medial prefrontal cortex (mPFC) dysfunction. Using extinction of conditioned fear in rats to assay cognitive flexibility, we demonstrate that extinction deficits reminiscent of mPFC dysfunction first appear during middle age, in the absence of hippocampus-dependent context deficits. Emergence of aging-related extinction deficits paralleled a redistribution of neuronal excitability across two critical mPFC regions via two distinct mechanisms. First, excitability decreased in regular spiking neurons of infralimbic-mPFC (IL), a region whose activity is required for extinction. Second, excitability increased in burst spiking neurons of prelimbic-mPFC (PL), a region whose activity hinders extinction. Experiments using synaptic blockers revealed that these aging-related differences were intrinsic. Thus, changes in IL and PL intrinsic excitability may contribute to cognitive flexibility impairments observed during normal aging.
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Balducci C, Forloni G. APP transgenic mice: their use and limitations. Neuromolecular Med 2010; 13:117-37. [PMID: 21152995 DOI: 10.1007/s12017-010-8141-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 11/20/2010] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease is the most widespread form of dementia. Its histopathological hallmarks include vascular and extracellular β-amyloid (Aβ) deposition and intraneuronal neurofibrillary tangles (NFTs). Gradual decline of cognitive functions linked to progressive synaptic loss makes patients unable to store new information in the earlier stages of the pathology, later becoming completely dependent because they are unable to do even elementary daily life actions. Although more than a hundred years have passed since Alois Alzheimer described the first case of AD, and despite many years of intense research, there are still many crucial points to be discovered in the neuropathological pathway. The development of transgenic mouse models engineered with overexpression of the amyloid precursor protein carrying familial AD mutations has been extremely useful. Transgenic mice present the hallmarks of the pathology, and histological and behavioural examination supports the amyloid hypothesis. As in human AD, extracellular Aβ deposits surrounded by activated astrocytes and microglia are typical features, together with synaptic and cognitive defects. Although animal models have been widely used, they are still being continuously developed in order to recapitulate some missing aspects of the disease. For instance, AD therapeutic agents tested in transgenic mice gave encouraging results which, however, were very disappointing in clinical trials. Neuronal cell death and NFTs typical of AD are much harder to replicate in these mice, which thus offer a fundamental but still imperfect tool for understanding and solving dementia pathology.
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Affiliation(s)
- Claudia Balducci
- Department of Neuroscience, Mario Negri Institute for Pharmacological Research, via G. La Masa, 19, 20156, Milan, Italy.
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53
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Leopoldo M, Lacivita E, Berardi F, Perrone R, Hedlund PB. Serotonin 5-HT7 receptor agents: Structure-activity relationships and potential therapeutic applications in central nervous system disorders. Pharmacol Ther 2010; 129:120-48. [PMID: 20923682 DOI: 10.1016/j.pharmthera.2010.08.013] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 08/26/2010] [Indexed: 12/19/2022]
Abstract
Since its discovery in the 1940s in serum, the mammalian intestinal mucosa, and in the central nervous system, serotonin (5-HT) has been shown to be involved in virtually all cognitive and behavioral human functions, and alterations in its neurochemistry have been implicated in the etiology of a plethora of neuropsychiatric disorders. The cloning of 5-HT receptor subtypes has been of importance in enabling them to be classified as specific protein molecules encoded by specific genes. The 5-HT(7) receptor is the most recently classified member of the serotonin receptor family. Since its identification, it has been the subject of intense research efforts driven by its presence in functionally relevant regions of the brain. The availability of some selective antagonists and agonists, in combination with genetically modified mice lacking the 5-HT(7) receptor, has allowed for a better understanding of the pathophysiological role of this receptor. This paper reviews data on localization and pharmacological properties of the 5-HT(7) receptor, and summarizes the results of structure-activity relationship studies aimed at the discovery of selective 5-HT(7) receptor ligands. Additionally, an overview of the potential therapeutic applications of 5-HT(7) receptor agonists and antagonists in central nervous system disorders is presented.
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Affiliation(s)
- Marcello Leopoldo
- Dipartimento Farmaco-Chimico, Università degli Studi di Bari "A. Moro", via Orabona, 4, 70125 Bari, Italy.
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Loss of alpha7 nicotinic receptors enhances beta-amyloid oligomer accumulation, exacerbating early-stage cognitive decline and septohippocampal pathology in a mouse model of Alzheimer's disease. J Neurosci 2010; 30:2442-53. [PMID: 20164328 DOI: 10.1523/jneurosci.5038-09.2010] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Early Alzheimer's disease (AD) is marked by cholinergic hypofunction, neuronal marker loss, and decreased nicotinic acetylcholine receptor (nAChR) density from the cortex and hippocampus. alpha7 nAChRs expressed on cholinergic projection neurons and target regions have been implicated in neuroprotection against beta-amyloid (Abeta) toxicity and maintenance of the septohippocampal phenotype. We tested the role that alpha7 nAChRs perform in the etiology of early AD by genetically deleting the alpha7 nAChR subunit from the Tg2576 mouse model for AD and assessing animals for cognitive function and septohippocampal integrity. Thus, Tg2576 mice transgenic for mutant human amyloid precursor protein (APP) were crossed with alpha7 nAChR knock-out mice (A7KO) to render an animal with elevated Abeta in the absence of alpha7 nAChRs (A7KO-APP). We found that learning and memory deficits seen in 5-month-old APP mice are more severe in the A7KO-APP animals. Analyses of animals in early-stage preplaque cognitive decline revealed signs of neurodegeneration in A7KO-APP hippocampus as well as loss of cholinergic functionality in the basal forebrain and hippocampus. These changes occurred concomitant with the appearance of a dodecameric oligomer of Abeta that was absent from all other genotypic groups, generating the hypothesis that increased soluble oligomeric Abeta may underlie additional impairment of A7KO-APP cognitive function. Thus, alpha7 nAChRs in a mouse model for early-stage AD appear to serve a neuroprotective role through maintenance of the septohippocampal cholinergic phenotype and preservation of hippocampal integrity possibly through influences on Abeta accumulation and oligomerization.
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Kornecook TJ, McKinney AP, Ferguson MT, Dodart JC. Isoform-specific effects of apolipoprotein E on cognitive performance in targeted-replacement mice overexpressing human APP. GENES BRAIN AND BEHAVIOR 2010; 9:182-92. [DOI: 10.1111/j.1601-183x.2009.00545.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Janus C, Welzl H. Mouse models of neurodegenerative diseases: criteria and general methodology. Methods Mol Biol 2010; 602:323-345. [PMID: 20012407 DOI: 10.1007/978-1-60761-058-8_19] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The major symptom of Alzheimer's disease is rapidly progressing dementia, coinciding with the formation of amyloid and tau deposits in the central nervous system, and neuronal death. At present familial cases of dementias provide the most promising foundation for modelling neurodegeneration. We describe the mnemonic and other major behavioral symptoms of tauopathies, briefly outline the genetics underlying familiar cases and discuss the arising implications for modelling the disease in mostly transgenic mouse lines. We then depict to what degree the most recent mouse models replicate pathological and cognitive characteristics observed in patients.There is no universally valid behavioral test battery to evaluate mouse models. The selection of individual tests depends on the behavioral and/or memory system in focus, the type of a model and how well it replicates the pathology of a disease and the amount of control over the genetic background of the mouse model. However it is possible to provide guidelines and criteria for modelling the neurodegeneration, setting up the experiments and choosing relevant tests. One should not adopt a "one (trans)gene, one disease" interpretation, but should try to understand how the mouse genome copes with the protein expression of the transgene in question. Further, it is not possible to recommend some mouse models over others since each model is valuable within its own constraints, and the way experiments are performed often reflects the idiosyncratic reality of specific laboratories. Our purpose is to improve bridging molecular and behavioural approaches in translational research.
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Affiliation(s)
- Christopher Janus
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, USA
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57
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Kojima N, Hanamura K, Yamazaki H, Ikeda T, Itohara S, Shirao T. Genetic disruption of the alternative splicing of drebrin gene impairs context-dependent fear learning in adulthood. Neuroscience 2010; 165:138-50. [DOI: 10.1016/j.neuroscience.2009.10.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 10/02/2009] [Accepted: 10/09/2009] [Indexed: 11/24/2022]
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Rustay NR, Cronin EA, Curzon P, Markosyan S, Bitner RS, Ellis TA, Waring JF, Decker MW, Rueter LE, Browman KE. Mice expressing the Swedish APP mutation on a 129 genetic background demonstrate consistent behavioral deficits and pathological markers of Alzheimer's disease. Brain Res 2010; 1311:136-47. [DOI: 10.1016/j.brainres.2009.11.040] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 11/16/2009] [Accepted: 11/18/2009] [Indexed: 11/28/2022]
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Sarsoza F, Saing T, Kayed R, Dahlin R, Dick M, Broadwater-Hollifield C, Mobley S, Lott I, Doran E, Gillen D, Anderson-Bergman C, Cribbs DH, Glabe C, Head E. A fibril-specific, conformation-dependent antibody recognizes a subset of Abeta plaques in Alzheimer disease, Down syndrome and Tg2576 transgenic mouse brain. Acta Neuropathol 2009; 118:505-17. [PMID: 19360426 PMCID: PMC2737113 DOI: 10.1007/s00401-009-0530-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 03/11/2009] [Accepted: 03/29/2009] [Indexed: 12/20/2022]
Abstract
Beta-amyloid (Abeta) is thought to be a key contributor to the pathogenesis of Alzheimer disease (AD) in the general population and in adults with Down syndrome (DS). Different assembly states of Abeta have been identified that may be neurotoxic. Abeta oligomers can assemble into soluble prefibrillar oligomers, soluble fibrillar oligomers and insoluble fibrils. Using a novel antibody, OC, recognizing fibrils and soluble fibrillar oligomers, we characterized fibrillar Abeta deposits in AD and DS cases. We further compared human specimens to those obtained from the Tg2576 mouse model of AD. Our results show that accumulation of fibrillar immunoreactivity is significantly increased in AD relative to nondemented aged subjects and those with select cognitive impairments (p < 0.0001). Further, there was a significant correlation between the extent of frontal cortex fibrillar deposit accumulation and dementia severity (MMSE r = -0.72). In DS, we observe an early age of onset and age-dependent accumulation of fibrillar OC immunoreactivity with little pathology in similarly aged non-DS individuals. Tg2576 mice show fibrillar accumulation that can be detected as young as 6 months. Interestingly, fibril-specific immunoreactivity was observed in diffuse, thioflavine S-negative Abeta deposits in addition to more mature neuritic plaques. These results suggest that fibrillar deposits are associated with disease in both AD and in adults with DS and their distribution within early Abeta pathology associated with diffuse plaques and correlation with MMSE suggest that these deposits may not be as benign as previously thought.
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Affiliation(s)
- Floyd Sarsoza
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
| | - Tommy Saing
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
| | - Rakez Kayed
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697 USA
| | - Robert Dahlin
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
| | - Malcolm Dick
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
| | | | - Scott Mobley
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
| | - Ira Lott
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Neurology, University of California, Irvine, CA 92697 USA
- Department of Pediatrics, University of California, Irvine, CA 92697 USA
| | - Eric Doran
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Pediatrics, University of California, Irvine, CA 92697 USA
| | - Daniel Gillen
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Statistics, University of California, Irvine, CA 92697 USA
| | - Clifford Anderson-Bergman
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Statistics, University of California, Irvine, CA 92697 USA
| | - David H. Cribbs
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Neurology, University of California, Irvine, CA 92697 USA
| | - Charles Glabe
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697 USA
| | - Elizabeth Head
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697 USA
- Department of Neurology, University of California, Irvine, CA 92697 USA
- Department of Molecular and Biomedical Pharmacology, Sanders-Brown Center on Aging, University of Kentucky, 203 Sanders-Brown Building, 800 South Limestone Street, Lexington, KY 40536 USA
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60
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Kaczorowski CC, Disterhoft JF. Memory deficits are associated with impaired ability to modulate neuronal excitability in middle-aged mice. Learn Mem 2009; 16:362-6. [PMID: 19470651 DOI: 10.1101/lm.1365609] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Normal aging disrupts hippocampal neuroplasticity and learning and memory. Aging deficits were exposed in a subset (30%) of middle-aged mice that performed below criterion on a hippocampal-dependent contextual fear conditioning task. Basal neuronal excitability was comparable in middle-aged and young mice, but learning-related modulation of the post-burst afterhyperpolarization (AHP)--a general mechanism engaged during learning--was impaired in CA1 neurons from middle-aged weak learners. Thus, modulation of neuronal excitability is critical for retention of context fear in middle-aged mice. Disruption of AHP plasticity may contribute to contextual fear deficits in middle-aged mice--a model of age-associated cognitive decline (AACD).
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Affiliation(s)
- Catherine C Kaczorowski
- Northwestern University Interdepartmental Neuroscience Program, Chicago, Illinois 60611, USA.
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61
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Deacon R, Koros E, Bornemann K, Rawlins J. Aged Tg2576 mice are impaired on social memory and open field habituation tests. Behav Brain Res 2009; 197:466-8. [DOI: 10.1016/j.bbr.2008.09.042] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 09/29/2008] [Accepted: 09/30/2008] [Indexed: 10/21/2022]
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Maren S. Pavlovian fear conditioning as a behavioral assay for hippocampus and amygdala function: cautions and caveats. Eur J Neurosci 2009; 28:1661-6. [PMID: 18973583 DOI: 10.1111/j.1460-9568.2008.06485.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pavlovian fear conditioning has become an important model for investigating the neural substrates of learning and memory in rats, mice and humans. The hippocampus and amygdala are widely believed to be essential for fear conditioning to contexts and discrete cues, respectively. Indeed, this parsing of function within the fear circuit has been used to leverage fear conditioning as a behavioral assay of hippocampal and amygdala function, particularly in transgenic mouse models. Recent work, however, blurs the anatomical segregation of cue and context conditioning and challenges the necessity for the hippocampus and amygdala in fear learning. Moreover, nonassociative factors may influence the performance of fear responses under a variety of conditions. Caution must therefore be exercised when using fear conditioning as a behavioral assay for hippocampal- and amygdala-dependent learning.
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Affiliation(s)
- Stephen Maren
- Department of Psychology and Neuroscience Program, University of Michigan, Ann Arbor, MI 48109-1043, USA.
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63
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Dong H, Yuede CM, Coughlan C, Lewis B, Csernansky JG. Effects of memantine on neuronal structure and conditioned fear in the Tg2576 mouse model of Alzheimer's disease. Neuropsychopharmacology 2008; 33:3226-36. [PMID: 18418360 PMCID: PMC2664647 DOI: 10.1038/npp.2008.53] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Memantine, an uncompetitive NMDA receptor antagonist used for the treatment of Alzheimer's disease (AD), has been hypothesized to have neuroprotective properties. However, the similarity of its mechanism of action to other NMDA receptor antagonists has led to concerns that it may also have neurotoxic effects. To assess both the neuroprotective and neurotoxic potential of memantine in a mouse model of AD (Tg2576 mice), we used quantitative light and electron microscopy to investigate the effects of long-term (6 months) administration of memantine (5, 10 and 20 mg/kg) on plaque deposition and neuronal morphology in the hippocampus and overlying cortex. A fear-conditioning paradigm was used to evaluate the behavioral consequences of any observed changes in structure. Administration of the two higher doses of memantine (10 and 20 mg/kg) was associated with a significant decrease in beta-amyloid (Abeta) plaque deposition, increases in synaptic density and the appearance of degenerating axons; the latter two effects were independent of genotype. Administration of the lowest dose of memantine (5 mg/kg) was associated with a significant decrease in Abeta plaque deposition and a significant increase in synaptic density, but not a significant increase in degenerating axons. However, memantine did not significantly improve behavioral deficits associated with genotype in a fear-conditioning paradigm at any dose. These results suggest that chronic memantine administration may have both neuroprotective and neurotoxic effects in a mouse model of AD.
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Affiliation(s)
- Hongxin Dong
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA
| | - Carla M Yuede
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA
| | - Carolyn Coughlan
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA
| | - Brian Lewis
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA
| | - John G Csernansky
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA,Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, MO, USA,Correspondence: Dr JG Csernansky, Department of Psychiatry, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8134, St Louis, MO 63110, USA, Tel: +1 314 747 2160, Fax: + 1 314 747 2182, E-mail:
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64
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Lassalle JM, Halley H, Daumas S, Verret L, Francés B. Effects of the genetic background on cognitive performances of TG2576 mice. Behav Brain Res 2008; 191:104-10. [DOI: 10.1016/j.bbr.2008.03.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Accepted: 03/13/2008] [Indexed: 01/11/2023]
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65
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Age-dependent and -independent behavioral deficits in Tg2576 mice. Behav Brain Res 2008; 189:126-38. [DOI: 10.1016/j.bbr.2007.12.024] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 12/27/2022]
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66
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Duyckaerts C, Potier MC, Delatour B. Alzheimer disease models and human neuropathology: similarities and differences. Acta Neuropathol 2008; 115:5-38. [PMID: 18038275 PMCID: PMC2100431 DOI: 10.1007/s00401-007-0312-8] [Citation(s) in RCA: 276] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2007] [Revised: 10/13/2007] [Accepted: 10/14/2007] [Indexed: 12/02/2022]
Abstract
Animal models aim to replicate the symptoms, the lesions or the cause(s) of Alzheimer disease. Numerous mouse transgenic lines have now succeeded in partially reproducing its lesions: the extracellular deposits of Abeta peptide and the intracellular accumulation of tau protein. Mutated human APP transgenes result in the deposition of Abeta peptide, similar but not identical to the Abeta peptide of human senile plaque. Amyloid angiopathy is common. Besides the deposition of Abeta, axon dystrophy and alteration of dendrites have been observed. All of the mutations cause an increase in Abeta 42 levels, except for the Arctic mutation, which alters the Abeta sequence itself. Overexpressing wild-type APP alone (as in the murine models of human trisomy 21) causes no Abeta deposition in most mouse lines. Doubly (APP x mutated PS1) transgenic mice develop the lesions earlier. Transgenic mice in which BACE1 has been knocked out or overexpressed have been produced, as well as lines with altered expression of neprilysin, the main degrading enzyme of Abeta. The APP transgenic mice have raised new questions concerning the mechanisms of neuronal loss, the accumulation of Abeta in the cell body of the neurons, inflammation and gliosis, and the dendritic alterations. They have allowed some insight to be gained into the kinetics of the changes. The connection between the symptoms, the lesions and the increase in Abeta oligomers has been found to be difficult to unravel. Neurofibrillary tangles are only found in mouse lines that overexpress mutated tau or human tau on a murine tau -/- background. A triply transgenic model (mutated APP, PS1 and tau) recapitulates the alterations seen in AD but its physiological relevance may be discussed. A number of modulators of Abeta or of tau accumulation have been tested. A transgenic model may be analyzed at three levels at least (symptoms, lesions, cause of the disease), and a reading key is proposed to summarize this analysis.
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Affiliation(s)
- Charles Duyckaerts
- Laboratoire de Neuropathologie Raymond Escourolle, Hôpital de La Salpêtrière, 47 Boulevard de l'Hôpital, 75651, Paris Cedex 13, France.
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Chang Q, Gold PE. Age-related changes in memory and in acetylcholine functions in the hippocampus in the Ts65Dn mouse, a model of Down syndrome. Neurobiol Learn Mem 2007; 89:167-77. [PMID: 17644430 PMCID: PMC2246382 DOI: 10.1016/j.nlm.2007.05.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 05/29/2007] [Accepted: 05/30/2007] [Indexed: 10/23/2022]
Abstract
Spatial working memory and the ability of a cholinesterase inhibitor to enhance memory were assessed at 4, 10, and 16 months of ages in control and Ts65Dn mice, a partial trisomy model of Down syndrome, with possibly significant relationships to Alzheimer's disease as well. In addition, ACh release during memory testing was measured in samples collected from the hippocampus using in vivo microdialysis at 4, 10, and 22-25 months of age. When tested on a four-arm spontaneous alternation task, the Ts65Dn mice exhibited impaired memory scores at both 4 and 10 months. At 16 months, control performance had declined toward that of the Ts65Dn mice and the difference in scores across genotypes was not significant. Physostigmine (50 microg/kg) fully reversed memory deficits in the Ts65Dn mice in the 4-month-old group but not in older mice. Ts65Dn and control mice exhibited comparable baseline levels of ACh release at all ages tested; these levels did not decline significantly across age in either genotype. ACh release increased significantly during alternation testing only in the young Ts65Dn and control mice. However, the increase in ACh release during alternation testing was significantly greater in control than Ts65Dn mice at this age. The controls exhibited a significant age-related decline in the testing-related increase in ACh release. With only a small increase during testing in young Ts65Dn mice, the age-related decline in responsiveness of ACh release to testing was not significant in these mice. Overall, these results suggest that diminished responsiveness of ACh release in the hippocampus to behavioral testing may contribute memory impairments in Ts65Dn mice.
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Affiliation(s)
- Qing Chang
- Department of Psychology, Neuroscience Program, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
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68
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Guérin D, Sacquet J, Mandairon N, Jourdan F, Didier A. Early locus coeruleus degeneration and olfactory dysfunctions in Tg2576 mice. Neurobiol Aging 2007; 30:272-83. [PMID: 17618708 DOI: 10.1016/j.neurobiolaging.2007.05.020] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 05/21/2007] [Accepted: 05/24/2007] [Indexed: 02/01/2023]
Abstract
Olfactory deficiency has been reported in the early stages of Alzheimer's disease (AD) in humans but is very poorly understood due to the lack of investigations in animal models of AD. Recent studies point to the noradrenergic system as an important target of the AD pathological process. In addition, noradrenalin has been shown to influence adult neurogenesis which is implicated in cognitive functions. We have therefore investigated the olfactory neurogenesis and cognitive performances in young transgenic Tg2576 mice in relation with the status of the noradrenergic and the cholinergic systems. Tg2576 showed a deficit in neurogenesis in the olfactory bulb evidenced by an increased death of newborn cells and a reduced expression of PSA-NCAM. The locus coeruleus degenerated in Tg2576 between the age of 6.5 and 8 months. These changes were associated with olfactory memory impairments. Our findings indicate that a noradrenergic deficiency could play a role in the early stages of the pathological process in this transgenic model and induce olfactory cognitive impairments through an alteration of olfactory neurogenesis.
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Affiliation(s)
- Delphine Guérin
- Laboratoire de Neuroscience et Systèmes Sensoriels, Université de Lyon, F-69007 Lyon, France
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69
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Dineley KT, Hogan D, Zhang WR, Taglialatela G. Acute inhibition of calcineurin restores associative learning and memory in Tg2576 APP transgenic mice. Neurobiol Learn Mem 2007; 88:217-24. [PMID: 17521929 PMCID: PMC2031869 DOI: 10.1016/j.nlm.2007.03.010] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 03/14/2007] [Accepted: 03/30/2007] [Indexed: 11/27/2022]
Abstract
Misfolded amyloid beta peptide (Abeta) is a pathological hallmark of Alzheimer's disease (AD), a neurodegenerative illness characterized by cognitive deficits and neuronal loss. Transgenic mouse models of Abeta over-production indicate that Abeta-induced cognitive deficits occur in the absence of overt neuronal death, suggesting that while extensive neuronal death may be associated with later stages of the human disease, subtle physiological changes may underlie initial cognitive deficits. Therefore, identifying signaling elements involved in those Abeta-induced cognitive impairments that occur prior to loss of neurons may reveal new potential pharmacological targets. Here, we report that the enzymatic activity of calcineurin, a key protein phosphatase involved in phosphorylation-dependent kinase activity crucial for synaptic plasticity and memory function, is upregulated in the CNS of the Tg2576 animal model for Abeta over-production. Furthermore, acute treatment of Tg2576 mice with the calcineurin inhibitor FK506 (10mg/kg i.p.) improves memory function. These results indicate that calcineurin may mediate some of the cognitive effects of excess Abeta such that inhibition of calcineurin shall be further explored as a potential treatment to reverse cognitive impairments in AD.
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Affiliation(s)
- Kelly T. Dineley
- Dept. of Neurology, the University of Texas Medical Branch at Galveston, TX 77555 -- U.S.A
| | - Dale Hogan
- Dept. of Neurology, the University of Texas Medical Branch at Galveston, TX 77555 -- U.S.A
| | - Wen-Ru Zhang
- Dept. of Neurosciences & Cell Biology, the University of Texas Medical Branch at Galveston, TX 77555 -- U.S.A
| | - Giulio Taglialatela
- Dept. of Neurosciences & Cell Biology, the University of Texas Medical Branch at Galveston, TX 77555 -- U.S.A
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70
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Adriani W, Ognibene E, Heuland E, Ghirardi O, Caprioli A, Laviola G. Motor impulsivity in APP-SWE mice: a model of Alzheimer's disease. Behav Pharmacol 2007; 17:525-33. [PMID: 16940774 DOI: 10.1097/00008877-200609000-00019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Among transgenic mouse models of Alzheimer's disease, APP-SWE mice have been shown to develop beta-amyloid plaques and to exhibit progressive impairment of cognitive function. Human Alzheimer's disease, however, also includes secondary clinical manifestations, spanning from hyperactivity to agitation. The aim of this study was a better characterization of motor impulsivity in APP-SWE mice, observed at 12 months of age, when levels of soluble beta-amyloid are elevated and beta-amyloid neuritic plaques start to appear. Mice were tested for spatial learning abilities in the Morris water maze (seven daily sessions, four trials per day). The distance traveled to reach the hidden platform showed a learning curve in both groups. This profile, however, was somewhat delayed in APP-SWE mice, thus confirming slightly impaired spatial capacities. To evaluate motor impulsivity, animals were trained to nose-poke for a food reward, which was delivered after a waiting interval that increased over days (15-60 s). Further nose-poking during this signaled waiting interval resulted in food-reward loss and electric-shock punishment. APP-SWE mice received an increased quantity of punishment and were able to earn fewer food rewards, suggesting inability to wait already at the lowest delay. After the animals were killed, prefrontal cortex samples were assessed for neurochemical parameters. Serotonin turnover was elevated in the prefrontal cortex of APP-SWE mice compared with controls. The results clearly confirm cognitive deficits, and are consistent with the hypothesis of reduced behavioral-inhibition abilities. Together with recent findings, APP-SWE mice emerge as a suitable animal model, characterized by a number of specific behavioral alterations, resembling primary and secondary symptoms of human Alzheimer's disease.
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Affiliation(s)
- Walter Adriani
- Behavioural Neuroscience Section, Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy
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71
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Eriksen JL, Janus CG. Plaques, tangles, and memory loss in mouse models of neurodegeneration. Behav Genet 2006; 37:79-100. [PMID: 17072762 DOI: 10.1007/s10519-006-9118-z] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 09/21/2006] [Indexed: 10/24/2022]
Abstract
Within the past decade, our understanding of the pathogenic mechanisms in Alzheimer's disease (AD) has dramatically advanced because of the development of transgenic mouse models that recapitulate the key pathological and behavioral phenotypes of the disease. These mouse models have allowed investigators to test detailed questions about how pathology develops and to evaluate potential therapeutic approaches that could slow down the development of this disease. In this review, we discuss the status of transgenic mouse models and review the complex relationship between pathology and behavior in the development of neuropathological syndromes in AD.
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Affiliation(s)
- Jason L Eriksen
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224, USA
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72
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Kostanyan IA, Zhokhov SS, Storozheva ZI, Proshin AT, Surina EA, Babichenko II, Sherstnev VV, Lipkin VM. Neuroprotective effect of the hexapeptide HLDF-6 on rat hippocampal neurons on the in vivo and in vitro models of alzheimer’s disease. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2006. [DOI: 10.1134/s1068162006040066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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73
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Ohno M, Chang L, Tseng W, Oakley H, Citron M, Klein WL, Vassar R, Disterhoft JF. Temporal memory deficits in Alzheimer's mouse models: rescue by genetic deletion of BACE1. Eur J Neurosci 2006; 23:251-60. [PMID: 16420434 DOI: 10.1111/j.1460-9568.2005.04551.x] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Transgenic mouse models of Alzheimer's disease (AD) exhibit amyloid-beta (Abeta) accumulation and related cognitive impairments. Although deficits in hippocampus-dependent place learning have been well characterized in Alzheimer's transgenic mice, little is known about temporal memory function in these AD models. Here, we applied trace fear conditioning to two different Alzheimer's mouse models and investigated the relationship between pathogenic Abeta and temporal memory deficits. This behavioral test requires hippocampus-dependent temporal memory processing as the conditioned and unconditioned stimuli are separated by a trace interval of 30 s. We found that both amyloid precursor protein (APP) transgenic (Tg2576) and APP/presenilin (PS)1 transgenic (Tg6799) mice were impaired in memorizing this association across the time gap. Both transgenic groups performed as well as wild-type control mice in delay fear conditioning when the trace interval was removed, indicating that the trace conditioning deficits are hippocampus-specific. Importantly, Tg6799 mice engineered to lack the major Alzheimer's beta-secretase (beta-site APP-cleaving enzyme 1: BACE1) showed behavioral rescue from temporal memory deficits. Elevated levels of soluble Abeta oligomers found in Tg6799+ mouse brains returned to wild-type control levels without changes in APP/PS1 transgene expression in BACE1-/- * Tg6799+ bigenic mouse brains, suggesting Abeta oligomers as potential mediators of memory loss. Thus, trace fear conditioning is a useful assay to test the mechanisms and therapeutic interventions for Abeta-dependent deficits in temporal associative memory. Our gene-based approach suggests that lowering soluble Abeta oligomers by inhibiting BACE1 may be beneficial for alleviating cognitive disorders in AD.
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Affiliation(s)
- Masuo Ohno
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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74
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Comery TA, Martone RL, Aschmies S, Atchison KP, Diamantidis G, Gong X, Zhou H, Kreft AF, Pangalos MN, Sonnenberg-Reines J, Jacobsen JS, Marquis KL. Acute gamma-secretase inhibition improves contextual fear conditioning in the Tg2576 mouse model of Alzheimer's disease. J Neurosci 2006; 25:8898-902. [PMID: 16192379 PMCID: PMC6725598 DOI: 10.1523/jneurosci.2693-05.2005] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Transgenic mice (Tg2576) overexpressing the Swedish mutation of the human amyloid precursor protein display biochemical, pathological, and behavioral markers consistent with many aspects of Alzheimer's disease, including impaired hippocampal function. Impaired, hippocampal-dependent, contextual fear conditioning (CFC) is observed in mice as young as 20 weeks of age. This impairment can be attenuated after treatment before training with the phosphodiesterase-4 inhibitor rolipram (0.1 mg/kg, i.p.). A rolipram-associated improvement is also observed in the littermate controls, suggesting that the effect of rolipram is independent of beta-amyloid. Acute treatment before training (but not after training or before testing) with the gamma-secretase inhibitor (GSI) N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine-t-butylester (DAPT), at a dose that reduces brain concentrations of beta-amyloid (100 mg/kg), attenuates the impairment in 20- to 65-week-old Tg2576 mice. Importantly, DAPT had no effect on performance of control littermates. These data are supportive of a role of beta-amyloid in the impairment of CFC in Tg2576 mice. Furthermore, they suggest that acute treatment with GSI may provide improved cognitive functioning as well as disease-modifying effects in Alzheimer's disease.
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Affiliation(s)
- Thomas A Comery
- Discovery Neuroscience, Wyeth Research, CN8000, Princeton, New Jersey 08543, USA.
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75
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Quinn JF, Bussiere JR, Hammond RS, Montine TJ, Henson E, Jones RE, Stackman RW. Chronic dietary alpha-lipoic acid reduces deficits in hippocampal memory of aged Tg2576 mice. Neurobiol Aging 2006; 28:213-25. [PMID: 16448723 DOI: 10.1016/j.neurobiolaging.2005.12.014] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 11/19/2005] [Accepted: 12/16/2005] [Indexed: 12/26/2022]
Abstract
Oxidative stress may play a key role in Alzheimer's disease (AD) neuropathology. Here, the effects of the antioxidant, alpha-lipoic acid (ALA) were tested on the Tg2576 mouse, a transgenic model of cerebral amyloidosis associated with AD. Ten-month old Tg2576 and wild type mice were fed an ALA-containing diet (0.1%) or control diet for 6 months and then assessed for the influence of diet on memory and neuropathology. ALA-treated Tg2576 mice exhibited significantly improved learning, and memory retention in the Morris water maze task compared to untreated Tg2576 mice. Twenty-four hours after contextual fear conditioning, untreated Tg2576 mice exhibited significantly impaired context-dependent freezing. ALA-treated Tg2576 mice exhibited significantly more context freezing than the untreated Tg2576 mice. Assessment of brain soluble and insoluble beta-amyloid levels revealed no differences between ALA-treated and untreated Tg2576 mice. Brain levels of nitrotyrosine, a marker of nitrative stress, were elevated in Tg2576 mice, while F2 isoprostanes and neuroprostanes, oxidative stress markers, were not elevated in the Tg2576 mice relative to wild type. These data indicate that chronic dietary ALA can reduce hippocampal-dependent memory deficits of Tg2576 mice without affecting beta-amyloid levels or plaque deposition.
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Affiliation(s)
- Joseph F Quinn
- Portland Veterans Affairs Medical Center, P3 R&D Portland, OR, United States
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76
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Blessing A, Martin M, Wenz M, Zöllig J. Emotionen und Gedächtnis bei Patienten mit Alzheimer-Demenz. ZEITSCHRIFT FUR NEUROPSYCHOLOGIE 2006. [DOI: 10.1024/1016-264x.17.2.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Zusammenfassung: Dieser Übersichtsartikel hat das Ziel, Zusammenhänge von Emotionen und Gedächtnisleistungen bei Alzheimerpatienten aufzuzeigen und dabei auf Ressourcen der Patienten in diesem Bereich einzugehen. Neurophysiologische Veränderungen durch die Alzheimerdemenz werden kurz diskutiert und mit neuroanatomischen Strukturen, die an der Verarbeitung von Emotionen beteiligt sind, in Verbindung gebracht. Auf dieser Grundlage wird ein Überblick über Studien mit Alzheimerpatienten gegeben, die (a) den emotionalen Gedächtniseffekt erforschen, oder (b) Emotionen als Gedächtnisinhalte bei Alzheimerpatienten untersuchen. Abschließend werden offene Forschungsfragen mit Blick auf Konsequenzen dieser Befunde für die nichtmedikamentöse Therapie diskutiert.
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Affiliation(s)
| | - Mike Martin
- Institut für Psychologie, Lehrstuhl Gerontopsychologie, Universität Zürich
| | - Michael Wenz
- Alzheimer Therapiezentrum, Neurologische Klinik Bad Aibling
| | - Jacqueline Zöllig
- Institut für Psychologie, Lehrstuhl Gerontopsychologie, Universität Zürich
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77
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Zhang B, Veasey SC, Wood MA, Leng LZ, Kaminski C, Leight S, Abel T, Lee VMY, Trojanowski JQ. Impaired rapid eye movement sleep in the Tg2576 APP murine model of Alzheimer's disease with injury to pedunculopontine cholinergic neurons. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 167:1361-9. [PMID: 16251420 PMCID: PMC1603771 DOI: 10.1016/s0002-9440(10)61223-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/21/2005] [Indexed: 10/18/2022]
Abstract
Impaired rapid eye movement sleep (REMS) is commonly observed in Alzheimer's disease, suggesting injury to mesopontine cholinergic neurons. We sought to determine whether abnormal beta-amyloid peptides impair REMS and injure mesopontine cholinergic neurons in transgenic (hAPP695.SWE) mice (Tg2576) that model brain amyloid pathologies. Tg2576 mice and wild-type littermates were studied at 2, 6, and 12 months by using sleep recordings, contextual fear conditioning, and immunohistochemistry. At 2 months of age, REMS was indistinguishable by genotype but was reduced in Tg2576 mice at 6 and 12 months. Choline acetyltransferase-positive neurons in the pedunculopontine tegmentum of Tg2576 mice at 2 months evidenced activated caspase-3 immunoreactivity, and at 6 and 12 months the numbers of pedunculopontine tegmentum choline acetyltransferase-positive neurons were reduced in the Tg2576 mice. Other cholinergic groups involved in REMS were unperturbed. At 12 months, Tg2576 mice demonstrated increased 3-nitrotyrosine immunoreactivity in cholinergic projection sites but not in cholinergic soma. We have identified a population of selectively compromised cholinergic neurons in young Tg2576 mice that manifest early onset REMS impairment. The differential vulnerability of these cholinergic neurons to Abeta injury provides an invaluable tool with which to understand mechanisms of sleep/wake perturbations in Alzheimer's disease.
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Affiliation(s)
- Bin Zhang
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Maloney 3, HUP, 3600 Spruce St., Philadelphia, PA 19104-4283, USA
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78
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Ruiz-Opazo N, Kosik KS, Lopez LV, Bagamasbad P, Ponce LRB, Herrera VLM. Attenuated hippocampus-dependent learning and memory decline in transgenic TgAPPswe Fischer-344 rats. Mol Med 2005; 10:36-44. [PMID: 15502881 PMCID: PMC1431353 DOI: 10.2119/2003-00044.herrera] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by increased beta amyloid (Abeta) levels, extracellular Abeta deposits in senile plaques, neurofibrillary tangles, and neuronal loss. However, the physiological role of normal levels of Abeta and its parent protein, the amyloid precursor protein (APP) are unknown. Here we report that low-level transgenic (Tg) expression of the Swedish APP mutant gene (APPswe) in Fischer-344 rats results in attenuated age-dependent cognitive performance decline in 2 hippocampus-dependent learning and memory tasks compared with age-matched nontransgenic Fischer-344 controls. TgAPPswe rats exhibit mild increases in brain APP mRNA (56.8%), Abeta-42 (21%), and Abeta-40 (6.1%) peptide levels at 12 mo of age, with no extracellular Abeta deposits or senile plaques at 6, 12, and 18 mo of age, whereas 3- to 6-fold increases in Abeta levels are detected in plaque-positive human AD patients and transgenic mouse models. The data support the hypothesis that a threshold paradigm underlies Abeta-related pathology, below which APP expression may play a physiological role in specific hippocampus-dependent tasks, most likely related to its neurotrophic role.
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Affiliation(s)
- Nelson Ruiz-Opazo
- Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Kenneth S Kosik
- Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Address correspondence and reprint requests to Victoria LM Herrera, Whitaker Cardiovascular Institute, W609, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118. Phone: 617-638-4020; fax: 617-638-4066; e-mail:
; or to Kenneth S Kosik, Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, 77 Ave Louis Pasteur Avenue, Boston, MA 02115. Phone: 617-525-5230; fax: 617-525-5252; e-mail:
| | - Lyle V Lopez
- Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Pia Bagamasbad
- Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Lorenz RB Ponce
- Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Victoria LM Herrera
- Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Address correspondence and reprint requests to Victoria LM Herrera, Whitaker Cardiovascular Institute, W609, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118. Phone: 617-638-4020; fax: 617-638-4066; e-mail:
; or to Kenneth S Kosik, Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, 77 Ave Louis Pasteur Avenue, Boston, MA 02115. Phone: 617-525-5230; fax: 617-525-5252; e-mail:
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79
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Saura CA, Chen G, Malkani S, Choi SY, Takahashi RH, Zhang D, Gouras GK, Kirkwood A, Morris RGM, Shen J. Conditional inactivation of presenilin 1 prevents amyloid accumulation and temporarily rescues contextual and spatial working memory impairments in amyloid precursor protein transgenic mice. J Neurosci 2005; 25:6755-64. [PMID: 16033885 PMCID: PMC6725351 DOI: 10.1523/jneurosci.1247-05.2005] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Accumulation of beta-amyloid (Abeta) peptides in the cerebral cortex is considered a key event in the pathogenesis of Alzheimer's disease (AD). Presenilin 1 (PS1) plays an essential role in the gamma-secretase cleavage of the amyloid precursor protein (APP) and the generation of Abeta peptides. Reduction of Abeta generation via the inhibition of gamma-secretase activity, therefore, has been proposed as a therapeutic approach for AD. In this study, we examined whether genetic inactivation of PS1 in postnatal forebrain-restricted conditional knock-out (PS1 cKO) mice can prevent the accumulation of Abeta peptides and ameliorate cognitive deficits exhibited by an amyloid mouse model that overexpresses human mutant APP. We found that conditional inactivation of PS1 in APP transgenic mice (PS1 cKO;APP Tg) effectively prevented the accumulation of Abeta peptides and formation of amyloid plaques and inflammatory responses, although it also caused an age-related accumulation of C-terminal fragments of APP. Short-term PS1 inactivation in young PS1 cKO;APP Tg mice rescued deficits in contextual fear conditioning and serial spatial reversal learning in a water maze, which were associated with APP Tg mice. Longer-term PS1 inactivation in older PS1 cKO;APP Tg mice, however, failed to rescue the contextual memory and hippocampal synaptic deficits and had a decreasing ameliorative effect on the spatial memory impairment. These results reveal that in vivo reduction of Abeta via the inactivation of PS1 effectively prevents amyloid-associated neuropathological changes and can, but only temporarily, improve cognitive impairments in APP transgenic mice.
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Affiliation(s)
- Carlos A Saura
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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80
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Kobayashi DT, Chen KS. Behavioral phenotypes of amyloid-based genetically modified mouse models of Alzheimer's disease. GENES BRAIN AND BEHAVIOR 2005; 4:173-96. [PMID: 15810905 DOI: 10.1111/j.1601-183x.2005.00124.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative affliction of the elderly, presenting with progressive memory loss and dementia and terminating with death. There have been significant advances in understanding the biology and subsequent diagnosis of AD; however, the furious pace of research has not yet translated into a disease-modifying treatment. While scientific inquiry in AD is largely centered on identifying biological players and pathological mechanisms, the day-to-day realities of AD patients and their caregivers revolve around their steady and heartbreaking cognitive decline. In the past decade, AD research has been fundamentally transformed by the development of genetically modified animal models of amyloid-driven neurodegeneration. These important in vivo models not only replicate some of the hallmark pathology of the disease, such as plaque-like amyloid accumulations and astrocytic inflammation, but also some of the cognitive impairments relevant to AD. In this article, we will provide a detailed review of the behavioral and cognitive deficits present in several transgenic mouse models of AD and discuss their functional changes in response to experimental treatments.
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Affiliation(s)
- D T Kobayashi
- Pharmacology Department, Elan Pharmaceuticals, South San Francisco, CA 94080, USA
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81
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Lovasic L, Bauschke H, Janus C. Working memory impairment in a transgenic amyloid precursor protein TgCRND8 mouse model of Alzheimer's disease. GENES BRAIN AND BEHAVIOR 2005; 4:197-208. [PMID: 15810906 DOI: 10.1111/j.1601-183x.2004.00104.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The most profound deficits observed in Alzheimer's disease (AD) are in domains of episodic and working memory systems. Transgenic (Tg) mice expressing mutated human amyloid precursor protein (APP) genes offer a model to study the effect of AD pathology on cognition. We reported previously that APP TgCRND8 mice showed deficits in a reference and working memory evaluated in a Morris water-maze test. In this study, we evaluated the working memory of TgCRND8 mice comparing two training paradigms in a six-arm radial water maze. In the first paradigm, the exploration of the maze was constrained, forcing the mice to use a spatial mapping strategy. In the second paradigm, mice were unconstrained in their exploration of the maze. TgCRND8 mice proved to be significantly impaired in spatial working memory in both paradigms as compared with their non-transgenic littermates. The analysis of data revealed that forcing mice to use a spatial strategy during training caused only a moderate improvement in the performance of all mice. However, unconstrained exploration of the maze not only resulted in a fast learning in control mice, but also facilitated the development of a chaining strategy in spatially impaired TgCRND8 mice. In conclusion, TgCRND8 mice showed impairment in spatial working memory but retained a plasticity to choose alternative search strategies.
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Affiliation(s)
- L Lovasic
- Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
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82
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Liu IYC, Lyons WE, Mamounas LA, Thompson RF. Brain-derived neurotrophic factor plays a critical role in contextual fear conditioning. J Neurosci 2005; 24:7958-63. [PMID: 15356210 PMCID: PMC6729916 DOI: 10.1523/jneurosci.1948-04.2004] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this study, brain-derived neurotrophic factor (BDNF) heterozygous knock-outs were tested on fear conditioning, and their wild-type littermates were used as controls. Results showed that BDNF(+/-) mice are impaired in contextual learning, whereas tone learning remains intact. Because BDNF is involved in synaptic transmission and contextual learning is hippocampal dependent, we hypothesized that this deficit is attributable to abnormal BDNF-modulated synaptic plasticity in the hippocampus. A "gain-of-function" experiment was performed next by infusing recombinant BDNF protein into the hippocampal formation to investigate whether this deficit can be rescued. Infusion of BDNF protein into the hippocampus appeared to partially restore contextual fear learning of BDNF(+/-) mice. In conclusion, the present study suggests that BDNF plays a critical role in fear conditioning. Loss of one copy of the BDNF gene leads to impairment of contextual fear learning in BDNF(+/-). This deficit can be partially rescued by infusing BDNF protein into the hippocampus. Other brain regions interacting with the hippocampus in the context conditioned stimulus pathway, for example, the amygdala, may also require normal BDNF expression levels to fully rescue this impairment.
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Affiliation(s)
- Ingrid Y C Liu
- Neuroscience Program, University of Southern California, Los Angeles, California 90089-2520, USA
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83
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Barnes P, Hale G, Good M. Intramaze and extramaze cue processing in adult APPSWE Tg2576 transgenic mice. Behav Neurosci 2005; 118:1184-95. [PMID: 15598128 DOI: 10.1037/0735-7044.118.6.1184] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The present study examined spatial and nonspatial learning in adult Tg2576 mice. Transgenic mice were impaired in acquisition of a T-maze forced-choice alternation task. However, mutant mice were as sensitive as control mice to the introduction of retention intervals and proactive interference, and this suggested that short-term memory processes were intact in Tg2576 mice. Probe trials revealed that the Tg2576 mice did not use an allocentric strategy to navigate to the goal arm. However, mutant mice acquired an intramaze brightness discrimination, a simple room discrimination, and a contextual biconditional left-right discrimination in a T maze. Results suggest that Tg2576 mice are able to process both intramaze and extramaze stimuli but are impaired in forming an allocentric representation of their environment.
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Affiliation(s)
- Philip Barnes
- School of Psychology, Cardiff University, Cardiff, United Kingdom
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84
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Gong B, Vitolo OV, Trinchese F, Liu S, Shelanski M, Arancio O. Persistent improvement in synaptic and cognitive functions in an Alzheimer mouse model after rolipram treatment. J Clin Invest 2005; 114:1624-34. [PMID: 15578094 PMCID: PMC529285 DOI: 10.1172/jci22831] [Citation(s) in RCA: 327] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Accepted: 09/21/2004] [Indexed: 02/03/2023] Open
Abstract
Evidence suggests that Alzheimer disease (AD) begins as a disorder of synaptic function, caused in part by increased levels of amyloid beta-peptide 1-42 (Abeta42). Both synaptic and cognitive deficits are reproduced in mice double transgenic for amyloid precursor protein (AA substitution K670N,M671L) and presenilin-1 (AA substitution M146V). Here we demonstrate that brief treatment with the phosphodiesterase 4 inhibitor rolipram ameliorates deficits in both long-term potentiation (LTP) and contextual learning in the double-transgenic mice. Most importantly, this beneficial effect can be extended beyond the duration of the administration. One course of long-term systemic treatment with rolipram improves LTP and basal synaptic transmission as well as working, reference, and associative memory deficits for at least 2 months after the end of the treatment. This protective effect is possibly due to stabilization of synaptic circuitry via alterations in gene expression by activation of the cAMP-dependent protein kinase (PKA)/cAMP regulatory element-binding protein (CREB) signaling pathway that make the synapses more resistant to the insult inflicted by Abeta. Thus, agents that enhance the cAMP/PKA/CREB pathway have potential for the treatment of AD and other diseases associated with elevated Abeta42 levels.
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Affiliation(s)
- Bing Gong
- The Center for Dementia Research, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA
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85
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Barnes P, Good M. Impaired Pavlovian cued fear conditioning in Tg2576 mice expressing a human mutant amyloid precursor protein gene. Behav Brain Res 2005; 157:107-17. [PMID: 15617777 DOI: 10.1016/j.bbr.2004.06.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Revised: 05/18/2004] [Accepted: 06/17/2004] [Indexed: 11/25/2022]
Abstract
The processing of emotional and/or fear-related events is abnormal in patients with Alzheimer's disease. AD is accompanied by a number of neuropathological features, one of which is the deposition of amyloid plaques. The main aim of the present study was to examine the effects of a human amyloid precursor protein mutation on both the acquisition and expression of fear conditioning in Tg2576 mice. Sixteen-month-old, but not 4-month-old, transgenic mice showed aberrations in post-shock freezing during training. In a retention test carried out 24 h after training, Tg2576 mice showed comparable levels of conditioned fear elicited by contextual cues. However, freezing elicited by a tone conditioned stimulus was impaired in 16-month-old but not 4-month-old Tg2576 mice. The results are discussed with reference to the role of cue competition (overshadowing) in revealing fear conditioning deficits in Tg2576 mice.
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Affiliation(s)
- Philip Barnes
- School of Psychology, Cardiff University, P.O. Box 901, Cardiff CF10 3YG, UK
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86
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Hyde LA, Kazdoba TM, Grilli M, Lozza G, Brusa R, Brussa R, Zhang Q, Wong GT, McCool MF, Zhang L, Parker EM, Higgins GA. Age-progressing cognitive impairments and neuropathology in transgenic CRND8 mice. Behav Brain Res 2005; 160:344-55. [PMID: 15863231 DOI: 10.1016/j.bbr.2004.12.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2004] [Revised: 12/21/2004] [Accepted: 12/21/2004] [Indexed: 12/12/2022]
Abstract
Patients with Alzheimer's disease suffer from progressive cognitive impairments and show distinct post-mortem neuropathology, including beta-amyloid plaques. Transgenic (Tg) CRND8 mice carry a mutated human amyloid precursor protein gene and show age-related increases in beta-amyloid production and plaque deposition. It was previously reported that during the early stages of plaque deposition, Tg CRND8 mice demonstrated Morris maze impairments. However, it is unknown if Tg mice would be impaired at an earlier age prior to plaque deposition or more impaired at a later age with more extensive plaque deposition. In the current study, we describe Tg CRND8 age-progressing beta-amyloid neuropathology and cognitive abilities in greater detail. At all ages, Tg mice showed normal short-term memory in the Y-maze. Pre-plaque Tg and age-matched Non-Tg mice did not differ in learning the spatial Morris water maze. However, both early and late plaque Tg mice showed impairments during acquisition. In addition, although early plaque Tg mice performed well in the probe trial, late plaque Tg mice demonstrated impaired probe trial performance. Therefore compared to their Non-Tg littermates, Tg CRND8 mice demonstrate cognitive impairments that progressed with age and seemed to coincide with the onset of beta-amyloid plaque deposition.
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Affiliation(s)
- Lynn A Hyde
- Schering-Plough Research Institute, NJ 07033, Kenilworth, USA.
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87
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Janus C, Welzl H, Hanna A, Lovasic L, Lane N, St George-Hyslop P, Westaway D. Impaired conditioned taste aversion learning in APP transgenic mice. Neurobiol Aging 2004; 25:1213-9. [PMID: 15312967 DOI: 10.1016/j.neurobiolaging.2003.11.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Revised: 10/30/2003] [Accepted: 11/13/2003] [Indexed: 11/16/2022]
Abstract
Cognition in transgenic mouse models of Alzheimer's disease (AD) has been predominantly characterized in explicit spatial orientation tasks. However, dementia in AD encompasses also implicit memory systems. In the present study a line of transgenic mice (TgCRND8) encoding a double mutated allele of the human amyloid precursor protein (APP) genes was evaluated in an implicit associative learning task of conditioned taste aversion (CTA). CTA is a form of Pavlovian classical conditioning, in which a mouse learns to avoid a novel taste of saccharine (conditioned stimulus) paired with an experimentally induced (systemic injection of lithium chloride) nausea (unconditioned stimulus). In contrast to conditioned non-Tg mice, TgCRND8 APP mice developed weaker aversion against saccharine and quickly increased its consumption in repeated tests. These results indicate that TgCRND8 mice show a significant impairment not only in explicit spatial memory, as has been previously shown [Nature 408 (2000) 979], but also in implicit memory. Control experiments confirmed that TgCRND8 and non-Tg mice had comparable taste sensitivities in response to appetitive as well as aversive tastes. The study suggests that the CTA paradigm can be a sensitive tool to evaluate deficits in implicit associative learning in APP transgenic mouse models of AD.
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Affiliation(s)
- Christopher Janus
- Centre for Research in Neurodegenerative Diseases, University of Toronto, 6 Queen's Park Crescent West, Toronto, Ont., Canada M5S 3H2.
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88
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Middei S, Geracitano R, Caprioli A, Mercuri N, Ammassari-Teule M. Preserved fronto-striatal plasticity and enhanced procedural learning in a transgenic mouse model of Alzheimer's disease overexpressing mutant hAPPswe. Learn Mem 2004; 11:447-52. [PMID: 15286183 PMCID: PMC498330 DOI: 10.1101/lm.80604] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mutations in the amyloid precursor protein (APP) gene inducing abnormal processing and deposition of beta-amyloid protein in the brain have been implicated in the pathogenesis of Alzheimer's disease (AD). Although Tg2576 mice with the Swedish mutation (hAPPswe) exhibit age-related Abeta-plaque formation in brain regions like the hippocampus, the amygdala, and the cortex, these mice show a rather specific deficit in hippocampal-dependent learning and memory tasks. In view of recent findings showing that neural systems subserving different forms of learning are not simply independent but that depressing or enhancing one system affects learning in another system, we decided to investigate fronto-striatal synaptic plasticity and related procedural learning in these mutants. Fronto-striatal long-term depression (LTD) induced by tetanic stimulation of the cortico-striatal input was similar in Tg2576 and wild-type control mice. Behavioral data, however, pointed to an enhancement of procedural learning in the mutants that showed robust motor-based learning in the cross maze and higher active avoidance scores. Thus, in this mouse model of AD, an intact striatal function associated with an impaired hippocampal function seems to provide neural conditions favorable to procedural learning. Our results suggest that focusing on preserved or enhanced forms of learning in AD patients might be of interest to describe the functional reorganization of the brain when one memory system is selectively compromised by neurological disease.
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Affiliation(s)
- Silvia Middei
- CNR Institute of Neuroscience, Laboratory of Psychobiology and Psychopharmacology, IRCCS S. Lucia Foundation, 00179 Rome, Italy
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89
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Shea TB, Ashline D, Ortiz D, Milhalik S, Rogers E. The S-adenosyl homocysteine hydrolase inhibitor 3-deaza-adenosine prevents oxidative damage and cognitive impairment following folate and vitamin E deprivation in a murine model of age-related, oxidative stress-induced neurodegeneration. Neuromolecular Med 2004; 5:171-80. [PMID: 15075443 DOI: 10.1385/nmm:5:2:171] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Deficiencies in folate promote neurodegeneration and potentiate the influence of other risk factors for neurodegeneration. This is accomplished at least in part by increasing levels of the neurotoxin homocysteine (HC). The S-adenosyl homocysteine (SAH) hydrolase inhibitor 3-deaza-adenosine (DZA) prevents HC accumulation following folate deprivation. We tested the ability of dietary supplementation with DZA to counteract the deleterious influence of folate deprivation. Folate deficiency has previously been shown to potentiate the impact of apolipoprotein E (ApoE); ApoE-/- mice deprived of folate demonstrated increased oxidative damage in brain tissue and impaired cognitive performance as compared to normal mice or to ApoE-/- mice receiving folate. Herein, we demonstrate that dietary supplementation with DZA prevented both the increase in oxidative damage and impaired cognition characteristic of ApoE-/- mice following folate deprivation. These findings suggest that manipulation of the methionine cycle by DZA can counteract folate deficiency. Because folate deprivation, increased HC, and apolipoprotein E deficiency are all risk factors for Alzheimer's disease, these findings also underscore that DZA might be useful in a therapeutic approach to delay neurodegeneration in Alzheimer's disease.
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Affiliation(s)
- Thomas B Shea
- Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, MA, USA.
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90
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Götz J, Streffer JR, David D, Schild A, Hoerndli F, Pennanen L, Kurosinski P, Chen F. Transgenic animal models of Alzheimer's disease and related disorders: histopathology, behavior and therapy. Mol Psychiatry 2004; 9:664-83. [PMID: 15052274 DOI: 10.1038/sj.mp.4001508] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Alzheimer's disease (AD) is a devastating neurodegenerative disease that affects more than 15 million people worldwide. Within the next generation, these numbers will more than double. To assist in the elucidation of pathogenic mechanisms of AD and related disorders, such as frontotemporal dementia (FTDP-17), genetically modified mice, flies, fish and worms were developed, which reproduce aspects of the human histopathology, such as beta-amyloid-containing plaques and tau-containing neurofibrillary tangles (NFT). In mice, the tau pathology caused selective behavioral impairment, depending on the distribution of the tau aggregates in the brain. Beta-amyloid induced an increase in the numbers of NFT, whereas the opposite was not observed in mice. In beta-amyloid-producing transgenic mice, memory impairment was associated with increased levels of beta-amyloid. Active and passive beta-amyloid-directed immunization caused the removal of beta-amyloid plaques and restored memory functions. These findings have since been translated to human therapy. This review aims to discuss the suitability and limitations of the various animal models and their contribution to an understanding of the pathophysiology of AD and related disorders.
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Affiliation(s)
- J Götz
- Division of Psychiatry Research, University of Zürich, August Forel Str. 1, CH-8008 Zürich, Switzerland.
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91
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Bhatnagar S, Sun LM, Raber J, Maren S, Julius D, Dallman MF. Changes in anxiety-related behaviors and hypothalamic–pituitary–adrenal activity in mice lacking the 5-HT-3A receptor. Physiol Behav 2004; 81:545-55. [PMID: 15178147 DOI: 10.1016/j.physbeh.2004.01.018] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2003] [Revised: 01/12/2004] [Accepted: 01/21/2004] [Indexed: 11/25/2022]
Abstract
The serotonin-3 (5-HT-3A) receptor has been localized in limbic and brainstem structures that regulate anxiety-related behavior and hypothalamic-pituitary-adrenal (HPA) activity, but its role in regulating anxiety-related behaviors is equivocal, and evidence for its role in regulating HPA activity is limited. Therefore, we used 5-HT-3A receptor knockout (KO) mice to further study these issues. Behavior in the elevated plus maze, open field, light-dark box and after Pavlovian fear conditioning was examined in addition to HPA activity under basal and acute stress conditions. Compared to age-matched adult male wild-type (WT) controls, adult male KO mice exhibited increased distance traveled in the open arms of the elevated plus maze, consistent with decreased measures of anxiety. There were no differences between the two genotypes in exploratory behavior in the open field or light-dark test. KO mice displayed enhanced fear conditioning indexed by fear-induced freezing behavior. KO mice displayed lower adrenocorticotropin (ACTH) responses to restraint or lipopolysaccharide (LPS). In addition, lower vasopressin mRNA in the paraventricular nucleus of the hypothalamus (PVN) and higher corticotropin-releasing hormone (CRH) mRNA in the central amygdala were observed in KO compared to WT mice. Therefore, deletion of the 5-HT-3A receptor revealed an important role for this receptor in regulating HPA responses to acute stress and a potential interaction between the 5-HT-3A receptor and CRH in the amygdala. Together, these data suggest that the 5-HT-3A receptor does not have a unitary role in the regulation of anxiety- and fear-related behaviors but has a potentially substantial role in the regulation of HPA activity.
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Affiliation(s)
- Seema Bhatnagar
- Department of Psychology and the Neuroscience Program, Box 1109, University of Michigan, 525 East University, Ann Arbor, MI 48109-1109, USA.
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92
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Pennanen L, Welzl H, D'Adamo P, Nitsch RM, Götz J. Accelerated extinction of conditioned taste aversion in P301L tau transgenic mice. Neurobiol Dis 2004; 15:500-9. [PMID: 15056457 DOI: 10.1016/j.nbd.2003.11.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2003] [Revised: 09/29/2003] [Accepted: 11/18/2003] [Indexed: 01/01/2023] Open
Abstract
Neurofibrillary tangles, insoluble protein deposits composed of filamentous tau aggregates, are neuropathological hallmarks of Alzheimer's disease and familial frontotemporal dementia (FTDP-17). Transgenic mice expressing the FTDP-17 mutation P301L of tau recapitulate key features of the human pathology, that is, tau proteins aggregate and neurofibrillary tangles begin to appear in the amygdala at 6 months of age. To detect early signs of tau aggregate-associated changes, we investigated behavioral alterations and cognitive deficits in such mice using an amygdala-specific test battery for anxiety-related and cognitive behavior. P301L mice had anxiety levels not different from wild-types, but their exploratory behavior was significantly increased. Acquisition of a fear response to tone and context as well as taste aversion was comparable to wild-types. However, extinction of a conditioned taste aversion was significantly accelerated. We conclude that already aggregation of tau proteins not yet accompanied by massive formation of neurofibrillary tangles causes selective behavioral deficits.
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Affiliation(s)
- Luis Pennanen
- Division of Psychiatry Research, University of Zürich, 8008 Zürich, Switzerland
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93
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Trinchese F, Liu S, Battaglia F, Walter S, Mathews PM, Arancio O. Progressive age-related development of Alzheimer-like pathology in APP/PS1 mice. Ann Neurol 2004; 55:801-14. [PMID: 15174014 DOI: 10.1002/ana.20101] [Citation(s) in RCA: 272] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Increasing evidence points to synaptic plasticity impairment as one of the first events in Alzheimer's disease (AD). However, studies on synaptic dysfunction in different transgenic AD models that overexpress familial AD mutant forms of amyloid precursor protein (APP) and/or presenilin (PS) have provided conflicting results. Both long-term potentiation (LTP) and basal synaptic transmission (BST) have been found to be both unchanged and altered in different models and under differing experimental conditions. Because of their more robust amyloid-beta (Abeta) deposition, double transgenic mice currently are used by several laboratories as an AD model. Here, we report that mice overexpressing APP (K670N:M671L) together with PS1 (M146L) have abnormal LTP as early as 3 months of age. Interestingly, reduced LTP paralleled plaque appearance and increased Abeta levels and abnormal short-term memory (working memory). BST and long-term memory (reference memory) are impaired only later (approximately 6 months) as amyloid burden increases. Abeta pathology across different ages did not correlate with synaptic and cognitive deficits, suggesting that Abeta levels are not a marker of memory decline. In contrast, progression of LTP impairment correlated with the deterioration of working memory, suggesting that percentage of potentiation might be an indicator of the cognitive decline and disease progression in the APP/PS1 mice.
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Affiliation(s)
- Fabrizio Trinchese
- Department of Psychiatry, New York University School of Medicine, New York, NY, USA
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94
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Angelo M, Plattner F, Irvine EE, Giese KP. Improved reversal learning and altered fear conditioning in transgenic mice with regionally restricted p25 expression. Eur J Neurosci 2003; 18:423-31. [PMID: 12887424 DOI: 10.1046/j.1460-9568.2003.02746.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cleavage of the cyclin-dependent kinase 5 activator p35 generates the protein fragment p25, which accumulates in the forebrain of patients with Alzheimer's disease. Although p25 expression has been suggested to affect learning and memory, this hypothesis has not been tested to date. To investigate the role of p25 in hippocampus-dependent learning and memory we have generated transgenic mice expressing p25 preferentially in postnatal forebrain. p25 expression was highest in hippocampus where it averaged approximately 33% of endogenous p35 expression. This low level of p25 expression did not seem to result in hyperphosphorylation of tau, but increased the phosphorylation of neurofilament M and enhanced the expression of tau protein. These molecular changes did not correlate with neurodegeneration or motor abnormalities. In the Morris water maze the p25 mutants were normal in learning an initial platform location, but surprisingly reversal learning was improved when the platform position was changed. The p25 mutants were normal in contextual fear conditioning. However, when trained with a tone presentation the mutants showed reduced contextual conditioning and enhanced tone fear conditioning. We conclude that low p25 expression has pleiotropic effects on learning and memory. As p25 expression can improve learning and memory, p25 formation could be a compensatory mechanism for learning and memory deficits in Alzheimer's disease.
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Affiliation(s)
- Marco Angelo
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
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