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Toyn JH, Ahlijanian MK. Interpreting Alzheimer's disease clinical trials in light of the effects on amyloid-β. ALZHEIMERS RESEARCH & THERAPY 2014; 6:14. [PMID: 25031632 PMCID: PMC4014014 DOI: 10.1186/alzrt244] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The failure of several potential Alzheimer’s disease therapeutics in mid- to late-stage clinical development has provoked significant discussion regarding the validity of the amyloid hypothesis. In this review, we propose a minimum criterion of 25% for amyloid-β (Aβ) lowering to achieve clinically meaningful slowing of disease progression. This criterion is based on genetic, risk factor, clinical and preclinical studies. We then compare this minimum criterion with the degree of Aβ lowering produced by the potential therapies that have failed in clinical trials. If the proposed minimum Aβ lowering criterion is used, then the amyloid hypothesis has yet to be adequately tested in the clinic. Therefore, we believe that the amyloid hypothesis remains valid and remains to be confirmed or refuted in future clinical trials.
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Affiliation(s)
- Jeremy H Toyn
- Bristol-Myers Squibb Research and Development, Neuroscience Biology, 5 Research Parkway, Wallingford, Connecticut 06492, USA
| | - Michael K Ahlijanian
- Bristol-Myers Squibb Research and Development, Neuroscience Biology, 5 Research Parkway, Wallingford, Connecticut 06492, USA
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52
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Bhattacharya S, Haertel C, Maelicke A, Montag D. Galantamine slows down plaque formation and behavioral decline in the 5XFAD mouse model of Alzheimer's disease. PLoS One 2014; 9:e89454. [PMID: 24586789 PMCID: PMC3931790 DOI: 10.1371/journal.pone.0089454] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/21/2014] [Indexed: 11/19/2022] Open
Abstract
The plant alkaloid galantamine is an established symptomatic drug treatment for Alzheimer's disease (AD), providing temporary cognitive and global relief in human patients. In this study, the 5X Familial Alzheimer's Disease (5XFAD) mouse model was used to investigate the effect of chronic galantamine treatment on behavior and amyloid β (Aβ) plaque deposition in the mouse brain. Quantification of plaques in untreated 5XFAD mice showed a gender specific phenotype; the plaque density increased steadily reaching saturation in males after 10 months of age, whereas in females the density further increased until after 14 months of age. Moreover, females consistently displayed a higher plaque density in comparison to males of the same age. Chronic oral treatment with galantamine resulted in improved performance in behavioral tests, such as open field and light-dark avoidance, already at mildly affected stages compared to untreated controls. Treated animals of both sexes showed significantly lower plaque density in the brain, i.e., the entorhinal cortex and hippocampus, gliosis being always positively correlated to plaque load. A high dose treatment with a daily uptake of 26 mg/kg body weight was tolerated well and produced significantly larger positive effects than a lower dose treatment (14 mg/kg body weight) in terms of plaque density and behavior. These results strongly support that galantamine, in addition to improving cognitive and behavioral symptoms in AD, may have disease-modifying and neuroprotective properties, as is indicated by delayed Aβ plaque formation and reduced gliosis.
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Affiliation(s)
- Soumee Bhattacharya
- Neurogenetics Special Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Christin Haertel
- Neurogenetics Special Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | | | - Dirk Montag
- Neurogenetics Special Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany
- * E-mail:
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53
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Sierksma A, van den Hove D, Pfau F, Philippens M, Bruno O, Fedele E, Ricciarelli R, Steinbusch H, Vanmierlo T, Prickaerts J. Improvement of spatial memory function in APPswe/PS1dE9 mice after chronic inhibition of phosphodiesterase type 4D. Neuropharmacology 2014; 77:120-30. [DOI: 10.1016/j.neuropharm.2013.09.015] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/21/2013] [Accepted: 09/09/2013] [Indexed: 11/30/2022]
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54
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Léger GC, Massoud F. Novel disease-modifying therapeutics for the treatment of Alzheimer’s disease. Expert Rev Clin Pharmacol 2014; 6:423-42. [DOI: 10.1586/17512433.2013.811237] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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55
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Hage S, Marinangeli C, Stanga S, Octave JN, Quetin-Leclercq J, Kienlen-Campard P. Gamma-Secretase Inhibitor Activity of aPterocarpus erinaceusExtract. NEURODEGENER DIS 2014; 14:39-51. [DOI: 10.1159/000355557] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 09/10/2013] [Indexed: 11/19/2022] Open
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56
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Chen CY, Liao YF, Chang MY, Hu MK. Difluorophenylglycinols as new modulators of proteolytic processing of amyloid precursor proteins. Arch Pharm (Weinheim) 2013; 347:161-73. [PMID: 24339192 DOI: 10.1002/ardp.201300283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 09/07/2013] [Accepted: 09/17/2013] [Indexed: 11/06/2022]
Abstract
Synthesis and evaluation of difluorophenylglycinols as new modulators of proteolytic processing of the amyloid-β precursor proteins for Alzheimer's therapies were described. A range of N-substituted (R)- and (S)-difluorophenylglycinols, structured on the amino alcohol framework, were explored by incorporating the arylsulfonyl moieties and various N-substituents. Evans' chiral auxiliary strategy was employed for the asymmetric synthesis of these enantiomeric difluorophenylglycinols. Compounds with effects on the γ-secretase inhibition and ERK-mediated signaling pathways were evaluated on cell-based assays. Among them, N-cyclopropylmethyl derivatives R-12c and R-13c showed modest γ-secretase inhibition as well as ERK-dependent activation.
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Affiliation(s)
- Chia-Yu Chen
- School of Pharmacy, National Defense Medical Center, Taipei, Taiwan
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57
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Henderson SJ, Andersson C, Narwal R, Janson J, Goldschmidt TJ, Appelkvist P, Bogstedt A, Steffen AC, Haupts U, Tebbe J, Freskgård PO, Jermutus L, Burrell M, Fowler SB, Webster CI. Sustained peripheral depletion of amyloid-β with a novel form of neprilysin does not affect central levels of amyloid-β. ACTA ACUST UNITED AC 2013; 137:553-64. [PMID: 24259408 PMCID: PMC3914468 DOI: 10.1093/brain/awt308] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lowering levels of peripheral amyloid-β has been proposed as a strategy to reduce plaques in patients with Alzheimer’s disease. Henderson et al. test a modified version of the amyloid-degrading enzyme neprilysin in rats, monkeys and Tg2576 mice. Levels of amyloid-β were reduced in the bloodstream, but not in the CNS. Alzheimer’s disease is characterized by the accumulation of amyloid deposits in the brain and the progressive loss of cognitive functions. Although the precise role of amyloid-β in disease progression remains somewhat controversial, many efforts to halt or reverse disease progression have focussed on reducing its synthesis or enhancing its removal. It is believed that brain and peripheral soluble amyloid-β are in equilibrium and it has previously been hypothesized that a reduction in peripheral amyloid-β can lower brain amyloid-β, thereby reducing formation of plaques predominantly composed of insoluble amyloid-β; the so-called peripheral sink hypothesis. Here we describe the use of an amyloid-β degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to albumin to extend plasma half-life and has been engineered to confer increased amyloid-β degradation activity. We used this molecule to investigate the effect of degradation of peripheral amyloid-β on amyloid-β levels in the brain and cerebrospinal fluid after repeated intravenous dosing for up to 4 months in Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved highly effective at degradation of amyloid-β in the periphery but did not alter brain or cerebrospinal fluid amyloid-β levels, suggesting that the peripheral sink hypothesis is not valid and is the first time that this has been demonstrated in non-human primates.
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Affiliation(s)
- Simon J Henderson
- 1 MedImmune, Milstein Building, Granta Park, Cambridge, CB21 6GH, UK
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58
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Hanson JE, La H, Plise E, Chen YH, Ding X, Hanania T, Sabath EV, Alexandrov V, Brunner D, Leahy E, Steiner P, Liu L, Scearce-Levie K, Zhou Q. SAHA enhances synaptic function and plasticity in vitro but has limited brain availability in vivo and does not impact cognition. PLoS One 2013; 8:e69964. [PMID: 23922875 PMCID: PMC3724849 DOI: 10.1371/journal.pone.0069964] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/13/2013] [Indexed: 12/16/2022] Open
Abstract
Suberoylanilide hydroxamic acid (SAHA) is an inhibitor of histone deacetylases (HDACs) used for the treatment of cutaneous T cell lymphoma (CTCL) and under consideration for other indications. In vivo studies suggest reducing HDAC function can enhance synaptic function and memory, raising the possibility that SAHA treatment could have neurological benefits. We first examined the impacts of SAHA on synaptic function in vitro using rat organotypic hippocampal brain slices. Following several days of SAHA treatment, basal excitatory but not inhibitory synaptic function was enhanced. Presynaptic release probability and intrinsic neuronal excitability were unaffected suggesting SAHA treatment selectively enhanced postsynaptic excitatory function. In addition, long-term potentiation (LTP) of excitatory synapses was augmented, while long-term depression (LTD) was impaired in SAHA treated slices. Despite the in vitro synaptic enhancements, in vivo SAHA treatment did not rescue memory deficits in the Tg2576 mouse model of Alzheimer's disease (AD). Along with the lack of behavioral impact, pharmacokinetic analysis indicated poor brain availability of SAHA. Broader assessment of in vivo SAHA treatment using high-content phenotypic characterization of C57Bl6 mice failed to demonstrate significant behavioral effects of up to 150 mg/kg SAHA following either acute or chronic injections. Potentially explaining the low brain exposure and lack of behavioral impacts, SAHA was found to be a substrate of the blood brain barrier (BBB) efflux transporters Pgp and Bcrp1. Thus while our in vitro data show that HDAC inhibition can enhance excitatory synaptic strength and potentiation, our in vivo data suggests limited brain availability may contribute to the lack of behavioral impact of SAHA following peripheral delivery. These results do not predict CNS effects of SAHA during clinical use and also emphasize the importance of analyzing brain drug levels when interpreting preclinical behavioral pharmacology.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 2
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Behavior, Animal/drug effects
- Brain/drug effects
- Brain/enzymology
- Brain/metabolism
- CA1 Region, Hippocampal/drug effects
- CA1 Region, Hippocampal/physiology
- Cognition/drug effects
- Conditioning, Psychological/drug effects
- Excitatory Postsynaptic Potentials/drug effects
- Fear/drug effects
- Histone Deacetylases/metabolism
- Humans
- Hydroxamic Acids/administration & dosage
- Hydroxamic Acids/pharmacokinetics
- Hydroxamic Acids/pharmacology
- Inhibitory Concentration 50
- Isoenzymes/metabolism
- Long-Term Potentiation/drug effects
- Membranes/drug effects
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Neuronal Plasticity/drug effects
- Phenotype
- Rats
- Rats, Sprague-Dawley
- Synapses/drug effects
- Synapses/physiology
- Vorinostat
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Affiliation(s)
- Jesse E Hanson
- Department of Neuroscience, Genentech, Inc South San Francisco, California, United States of America.
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59
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Chen Z, Zhong C. Decoding Alzheimer's disease from perturbed cerebral glucose metabolism: implications for diagnostic and therapeutic strategies. Prog Neurobiol 2013; 108:21-43. [PMID: 23850509 DOI: 10.1016/j.pneurobio.2013.06.004] [Citation(s) in RCA: 446] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 06/03/2013] [Accepted: 06/18/2013] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is an age-related devastating neurodegenerative disorder, which severely impacts on the global economic development and healthcare system. Though AD has been studied for more than 100 years since 1906, the exact cause(s) and pathogenic mechanism(s) remain to be clarified. Also, the efficient disease-modifying treatment and ideal diagnostic method for AD are unavailable. Perturbed cerebral glucose metabolism, an invariant pathophysiological feature of AD, may be a critical contributor to the pathogenesis of this disease. In this review, we firstly discussed the features of cerebral glucose metabolism in physiological and pathological conditions. Then, we further reviewed the contribution of glucose transportation abnormality and intracellular glucose catabolism dysfunction in AD pathophysiology, and proposed a hypothesis that multiple pathogenic cascades induced by impaired cerebral glucose metabolism could result in neuronal degeneration and consequently cognitive deficits in AD patients. Among these pathogenic processes, altered functional status of thiamine metabolism and brain insulin resistance are highly emphasized and characterized as major pathogenic mechanisms. Finally, considering the fact that AD patients exhibit cerebral glucose hypometabolism possibly due to impairments of insulin signaling and altered thiamine metabolism, we also discuss some potential possibilities to uncover diagnostic biomarkers for AD from abnormal glucose metabolism and to develop drugs targeting at repairing insulin signaling impairment and correcting thiamine metabolism abnormality. We conclude that glucose metabolism abnormality plays a critical role in AD pathophysiological alterations through the induction of multiple pathogenic factors such as oxidative stress, mitochondrial dysfunction, and so forth. To clarify the causes, pathogeneses and consequences of cerebral hypometabolism in AD will help break the bottleneck of current AD study in finding ideal diagnostic biomarker and disease-modifying therapy.
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Affiliation(s)
- Zhichun Chen
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
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60
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Reversible pathologic and cognitive phenotypes in an inducible model of Alzheimer-amyloidosis. J Neurosci 2013; 33:3765-79. [PMID: 23447589 DOI: 10.1523/jneurosci.4251-12.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transgenic mice that express mutant amyloid precursor protein (APPsi) using tet-Off vector systems provide an alternative model for assessing short- and long-term effects of Aβ-targeting therapies on phenotypes related to the deposition of Alzheimer-type amyloid. Here we use such a model, termed APPsi:tTA, to determine what phenotypes persist in mice with high amyloid burden after new production of APP/Aβ has been suppressed. We find that 12- to 13-month-old APPsi:tTA mice are impaired in cognitive tasks that assess short- and long-term memories. Acutely suppressing new APPsi/Aβ production produced highly significant improvements in performing short-term spatial memory tasks, which upon continued suppression translated to superior performance in more demanding tasks that assess long-term spatial memory and working memory. Deficits in episodic-like memory and cognitive flexibility, however, were more persistent. Arresting mutant APPsi production caused a rapid decline in the brain levels of soluble APP ectodomains, full-length APP, and APP C-terminal fragments. As expected, amyloid deposits persisted after new APP/Aβ production was inhibited, whereas, unexpectedly, we detected persistent pools of solubilizable, relatively mobile, Aβ42. Additionally, we observed persistent levels of Aβ-immunoreactive entities that were of a size consistent with SDS-resistant oligomeric assemblies. Thus, in this model with significant amyloid pathology, a rapid amelioration of cognitive deficits was observed despite persistent levels of oligomeric Aβ assemblies and low, but detectable solubilizable Aβ42 peptides. These findings implicate complex relationships between accumulating Aβ and activities of APP, soluble APP ectodomains, and/or APP C-terminal fragments in mediating cognitive deficits in this model of amyloidosis.
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61
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Wright AL, Zinn R, Hohensinn B, Konen LM, Beynon SB, Tan RP, Clark IA, Abdipranoto A, Vissel B. Neuroinflammation and neuronal loss precede Aβ plaque deposition in the hAPP-J20 mouse model of Alzheimer's disease. PLoS One 2013; 8:e59586. [PMID: 23560052 PMCID: PMC3613362 DOI: 10.1371/journal.pone.0059586] [Citation(s) in RCA: 224] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 02/15/2013] [Indexed: 12/20/2022] Open
Abstract
Recent human trials of treatments for Alzheimer's disease (AD) have been largely unsuccessful, raising the idea that treatment may need to be started earlier in the disease, well before cognitive symptoms appear. An early marker of AD pathology is therefore needed and it is debated as to whether amyloid-βAβ? plaque load may serve this purpose. We investigated this in the hAPP-J20 AD mouse model by studying disease pathology at 6, 12, 24 and 36 weeks. Using robust stereological methods, we found there is no neuron loss in the hippocampal CA3 region at any age. However loss of neurons from the hippocampal CA1 region begins as early as 12 weeks of age. The extent of neuron loss increases with age, correlating with the number of activated microglia. Gliosis was also present, but plateaued during aging. Increased hyperactivity and spatial memory deficits occurred at 16 and 24 weeks. Meanwhile, the appearance of plaques and oligomeric Aβ were essentially the last pathological changes, with significant changes only observed at 36 weeks of age. This is surprising given that the hAPP-J20 AD mouse model is engineered to over-expresses Aβ. Our data raises the possibility that plaque load may not be the best marker for early AD and suggests that activated microglia could be a valuable marker to track disease progression.
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MESH Headings
- Age Factors
- Alzheimer Disease/diagnosis
- Alzheimer Disease/genetics
- Alzheimer Disease/metabolism
- Alzheimer Disease/pathology
- Amyloid beta-Protein Precursor/genetics
- Amyloid beta-Protein Precursor/metabolism
- Animals
- Biomarkers/metabolism
- CA1 Region, Hippocampal/metabolism
- CA1 Region, Hippocampal/pathology
- CA3 Region, Hippocampal/cytology
- CA3 Region, Hippocampal/metabolism
- Cell Count
- Disease Models, Animal
- Early Diagnosis
- Gene Expression
- Gliosis/diagnosis
- Gliosis/genetics
- Gliosis/metabolism
- Gliosis/pathology
- Humans
- Inflammation
- Male
- Memory Disorders/diagnosis
- Memory Disorders/genetics
- Memory Disorders/metabolism
- Memory Disorders/pathology
- Mice
- Mice, Transgenic
- Microglia/metabolism
- Microglia/pathology
- Neurons/metabolism
- Neurons/pathology
- Plaque, Amyloid/diagnosis
- Plaque, Amyloid/genetics
- Plaque, Amyloid/metabolism
- Plaque, Amyloid/pathology
- Stereotaxic Techniques
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Affiliation(s)
- Amanda L. Wright
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Raphael Zinn
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Barbara Hohensinn
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Lyndsey M. Konen
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
| | - Sarah B. Beynon
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
| | - Richard P. Tan
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
| | - Ian A. Clark
- Research School of Biology, Australian National University, Canberra, Australia
| | - Andrea Abdipranoto
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
| | - Bryce Vissel
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
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62
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Hammerschmidt T, Kummer MP, Terwel D, Martinez A, Gorji A, Pape HC, Rommelfanger KS, Schroeder JP, Stoll M, Schultze J, Weinshenker D, Heneka MT. Selective loss of noradrenaline exacerbates early cognitive dysfunction and synaptic deficits in APP/PS1 mice. Biol Psychiatry 2013; 73:454-63. [PMID: 22883210 PMCID: PMC4712953 DOI: 10.1016/j.biopsych.2012.06.013] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 05/24/2012] [Accepted: 06/06/2012] [Indexed: 12/20/2022]
Abstract
BACKGROUND Degeneration of the locus coeruleus (LC), the major noradrenergic nucleus in the brain, occurs early and is ubiquitous in Alzheimer's disease (AD). Experimental lesions to the LC exacerbate AD-like neuropathology and cognitive deficits in several transgenic mouse models of AD. Because the LC contains multiple neuromodulators known to affect amyloid β toxicity and cognitive function, the specific role of noradrenaline (NA) in AD is not well understood. METHODS To determine the consequences of selective NA deficiency in an AD mouse model, we crossed dopamine β-hydroxylase (DBH) knockout mice with amyloid precursor protein (APP)/presenilin-1 (PS1) mice overexpressing mutant APP and PS1. Dopamine β-hydroxylase (-/-) mice are unable to synthesize NA but otherwise have normal LC neurons and co-transmitters. Spatial memory, hippocampal long-term potentiation, and synaptic protein levels were assessed. RESULTS The modest impairments in spatial memory and hippocampal long-term potentiation displayed by young APP/PS1 or DBH (-/-) single mutant mice were augmented in DBH (-/-)/APP/PS1 double mutant mice. Deficits were associated with reduced levels of total calcium/calmodulin-dependent protein kinase II and N-methyl-D-aspartate receptor 2A and increased N-methyl-D-aspartate receptor 2B levels and were independent of amyloid β accumulation. Spatial memory performance was partly improved by treatment with the NA precursor drug L-threo-dihydroxyphenylserine. CONCLUSIONS These results indicate that early LC degeneration and subsequent NA deficiency in AD may contribute to cognitive deficits via altered levels of calcium/calmodulin-dependent protein kinase II and N-methyl-D-aspartate receptors and suggest that NA supplementation could be beneficial in early AD.
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Affiliation(s)
- Thea Hammerschmidt
- Department of Neurology, Clinical Neurosciences, University of Bonn, and Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Sigmund-Freud-Strasse 25, 53127 Bonn, Germany,Institute of Physiology I, Westfälische Wilhelms-University Münster, 48149 Münster, Germany
| | - Markus P. Kummer
- Department of Neurology, Clinical Neurosciences, University of Bonn, and Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Dick Terwel
- Department of Neurology, Clinical Neurosciences, University of Bonn, and Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Ana Martinez
- Genes and Behavior Dept., Max Planck Institute of Biophysical Chemistry, 37077 Göttingen, Germany
| | - Ali Gorji
- Institute of Physiology I, Westfälische Wilhelms-University Münster, 48149 Münster, Germany
| | - Hans-Christian Pape
- Institute of Physiology I, Westfälische Wilhelms-University Münster, 48149 Münster, Germany
| | | | | | - Monika Stoll
- Leibniz-Institut für Arterioskleroseforschung, Genetische Epidemiologie vaskulärer Erkrankungen, 48149 Münster, Germany
| | - Joachim Schultze
- LIMES Institute, Genomics and Immunoregulation, University of Bonn, 53115 Bonn, Germany
| | | | - Michael T. Heneka
- Department of Neurology, Clinical Neurosciences, University of Bonn, and Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Sigmund-Freud-Strasse 25, 53127 Bonn, Germany,corresponding author: Michael T. Heneka, University of Bonn, Dept. of Neurology, Clinical Neuroscience, Sigmund-Freud-Strasse 25, 53127 Bonn, +49 228 287 13091, +49 228 287 13166,
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63
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Giuliani A, Beggiato S, Baldassarro VA, Mangano C, Giardino L, Imbimbo BP, Antonelli T, Calzà L, Ferraro L. CHF5074 restores visual memory ability and pre-synaptic cortical acetylcholine release in pre-plaque Tg2576 mice. J Neurochem 2013; 124:613-20. [PMID: 23278303 DOI: 10.1111/jnc.12136] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 12/23/2012] [Accepted: 12/24/2012] [Indexed: 12/11/2022]
Abstract
CHF5074, a new microglial modulator, attenuates memory deficit in Alzheimer's disease transgenic mice. In this study, the effect of an acute or subacute CHF5074 treatment on in vivo novel object recognition test and on [³H]Acetylcholine (ACh) and GABA release in pre-plaque (7-month-old) Tg2576 mice have been compared with those induced by the γ-secretase inhibitor LY450139 (semagacestat). Vehicle-treated Tg2576 mice displayed an impairment of recognition memory compared with wild-type animals. This impairment was recovered in transgenic animals acutely treated with CHF5074 (30 mg/kg), while LY450139 (1, 3, 10 mg/kg) was ineffective. In frontal cortex synaptosomes from vehicle-treated Tg2576 mice, K⁺-evoked [³H]ACh release was lower than that measured in wild-type mice. This reduction was absent in transgenic animals subacutely treated with CHF5074 (30 mg/kg daily for 8 days), while it was slightly, not significantly, amplified by LY450139 (3 mg/kg daily for 8 days). There were no differences between the groups on spontaneous [³H]ACh release as well as spontaneous and K⁺-evoked GABA release. These results suggest that CHF5074 has beneficial effects on visual memory and cortical cholinergic dysfunctions in pre-plaque Tg2576 mice. Together with previous findings, these data suggest that CHF5074 could be a possible candidate for early Alzheimer's disease therapeutic regimens.
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Affiliation(s)
- Alessandro Giuliani
- Department of Veterinary Medicine and Health Science, University of Bologna, Bologna, Italy
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64
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The β-secretase-derived C-terminal fragment of βAPP, C99, but not Aβ, is a key contributor to early intraneuronal lesions in triple-transgenic mouse hippocampus. J Neurosci 2013; 32:16243-1655a. [PMID: 23152608 DOI: 10.1523/jneurosci.2775-12.2012] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Triple-transgenic mice (3xTgAD) overexpressing Swedish-mutated β-amyloid precursor protein (βAPP(swe)), P310L-Tau (Tau(P301L)), and physiological levels of M146V-presenilin-1 (PS1(M146V)) display extracellular amyloid-β peptides (Aβ) deposits and Tau tangles. More disputed is the observation that these mice accumulate intraneuronal Aβ that has been linked to synaptic dysfunction and cognitive deficits. Here, we provide immunohistological, genetic, and pharmacological evidences for early, age-dependent, and hippocampus-specific accumulation of the β-secretase-derived βAPP fragment C99 that is observed from 3 months of age and enhanced by pharmacological blockade of γ-secretase. Notably, intracellular Aβ is only detectable several months later and appears, as is the case of C99, in enlarged cathepsin B-positive structures, while extracellular Aβ deposits are detected ~12 months of age and beyond. Early C99 production occurs mainly in the CA1/subicular interchange area of the hippocampus corresponding to the first region exhibiting plaques and tangles in old mice. Furthermore, the comparison of 3xTgAD mice with double-transgenic mice bearing the βAPP(swe) and Tau(P301L) mutations but expressing endogenous PS1 (2xTgAD) demonstrate that C99 accumulation is not accounted for by a loss of function triggered by PS1 mutation that would have prevented C99 secondary cleavage by γ-secretase. Together, our work identifies C99 as the earliest βAPP catabolite and main contributor to the intracellular βAPP-related immunoreactivity in 3xTgAD mice, suggesting its implication as an initiator of the neurodegenerative process and cognitive alterations taking place in this mouse model.
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Mitani Y, Yarimizu J, Akashiba H, Shitaka Y, Ni K, Matsuoka N. Amelioration of cognitive deficits in plaque-bearing Alzheimer's disease model mice through selective reduction of nascent soluble Aβ42 without affecting other Aβ pools. J Neurochem 2013; 125:465-72. [DOI: 10.1111/jnc.12125] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/10/2012] [Accepted: 12/11/2012] [Indexed: 01/17/2023]
Affiliation(s)
- Yasuyuki Mitani
- Pharmacology Research Labs; Astellas Pharma Inc; Tsukuba Ibaraki Japan
| | - Junko Yarimizu
- Pharmacology Research Labs; Astellas Pharma Inc; Tsukuba Ibaraki Japan
| | - Hiroki Akashiba
- Pharmacology Research Labs; Astellas Pharma Inc; Tsukuba Ibaraki Japan
| | | | - Keni Ni
- Pharmacology Research Labs; Astellas Pharma Inc; Tsukuba Ibaraki Japan
| | - Nobuya Matsuoka
- Pharmacology Research Labs; Astellas Pharma Inc; Tsukuba Ibaraki Japan
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66
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Svedružić ŽM, Popović K, Šendula-Jengić V. Modulators of γ-secretase activity can facilitate the toxic side-effects and pathogenesis of Alzheimer's disease. PLoS One 2013; 8:e50759. [PMID: 23308095 PMCID: PMC3538728 DOI: 10.1371/journal.pone.0050759] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 10/25/2012] [Indexed: 11/18/2022] Open
Abstract
Background Selective modulation of different Aβ products of an intramembrane protease γ-secretase, could be the most promising strategy for development of effective therapies for Alzheimer's disease. We describe how different drug-candidates can modulate γ-secretase activity in cells, by studying how DAPT affects changes in γ-secretase activity caused by gradual increase in Aβ metabolism. Results Aβ 1–40 secretion in the presence of DAPT shows biphasic activation-inhibition dose-response curves. The biphasic mechanism is a result of modulation of γ-secretase activity by multiple substrate and inhibitor molecules that can bind to the enzyme simultaneously. The activation is due to an increase in γ-secretase's kinetic affinity for its substrate, which can make the enzyme increasingly more saturated with otherwise sub-saturating substrate. The noncompetitive inhibition that prevails at the saturating substrate can decrease the maximal activity. The synergistic activation-inhibition effects can drastically reduce γ-secretase's capacity to process its physiological substrates. This reduction makes the biphasic inhibitors exceptionally prone to the toxic side-effects and potentially pathogenic. Without the modulation, γ-secretase activity on it physiological substrate in cells is only 14% of its maximal activity, and far below the saturation. Significance Presented mechanism can explain why moderate inhibition of γ-secretase cannot lead to effective therapies, the pharmacodynamics of Aβ-rebound phenomenon, and recent failures of the major drug-candidates such as semagacestat. Novel improved drug-candidates can be prepared from competitive inhibitors that can bind to different sites on γ-secretase simultaneously. Our quantitative analysis of the catalytic capacity can facilitate the future studies of the therapeutic potential of γ-secretase and the pathogenic changes in Aβ metabolism.
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Affiliation(s)
- Željko M Svedružić
- Medical Biochemistry, PB Rab, Faculty of Medicine, University of Rijeka, Rab, Croatia.
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67
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Drug pipeline in neurodegeneration based on transgenic mice models of Alzheimer's disease. Ageing Res Rev 2013; 12:116-40. [PMID: 22982398 DOI: 10.1016/j.arr.2012.09.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/31/2012] [Accepted: 09/04/2012] [Indexed: 11/21/2022]
Abstract
Alzheimer's disease (AD) is one of the most important neurodegenerative disorders, bringing about huge medical and social burden in the elderly worldwide. Many aspects of its pathogenesis have remained unclear and no effective treatment exists for it. Within the past 20 years, various mice models harboring AD-related human mutations have been produced. These models imitate diverse AD-related pathologies and have been used for basic and therapeutic investigations in AD. In this regard, there are a wide variety of preclinical trials of potential therapeutic modalities using AD mice models which are of paramount importance for future clinical trials and applications. This review summarizes more than 140 substances and treatment modalities being used in transgenic AD mice models from 2001 to 2011. We also discuss advantages and disadvantages of each model to be used in therapeutic development for AD.
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Albright CF, Dockens RC, Meredith JE, Olson RE, Slemmon R, Lentz KA, Wang JS, Denton RR, Pilcher G, Rhyne PW, Raybon JJ, Barten DM, Burton C, Toyn JH, Sankaranarayanan S, Polson C, Guss V, White R, Simutis F, Sanderson T, Gillman KW, Starrett JE, Bronson J, Sverdlov O, Huang SP, Castaneda L, Feldman H, Coric V, Zaczek R, Macor JE, Houston J, Berman RM, Tong G. Pharmacodynamics of selective inhibition of γ-secretase by avagacestat. J Pharmacol Exp Ther 2012; 344:686-95. [PMID: 23275065 DOI: 10.1124/jpet.112.199356] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A hallmark of Alzheimer's disease (AD) pathology is the accumulation of brain amyloid β-peptide (Aβ), generated by γ-secretase-mediated cleavage of the amyloid precursor protein (APP). Therefore, γ-secretase inhibitors (GSIs) may lower brain Aβ and offer a potential new approach to treat AD. As γ-secretase also cleaves Notch proteins, GSIs can have undesirable effects due to interference with Notch signaling. Avagacestat (BMS-708163) is a GSI developed for selective inhibition of APP over Notch cleavage. Avagacestat inhibition of APP and Notch cleavage was evaluated in cell culture by measuring levels of Aβ and human Notch proteins. In rats, dogs, and humans, selectivity was evaluated by measuring plasma blood concentrations in relation to effects on cerebrospinal fluid (CSF) Aβ levels and Notch-related toxicities. Measurements of Notch-related toxicity included goblet cell metaplasia in the gut, marginal-zone depletion in the spleen, reductions in B cells, and changes in expression of the Notch-regulated hairy and enhancer of split homolog-1 from blood cells. In rats and dogs, acute administration of avagacestat robustly reduced CSF Aβ40 and Aβ42 levels similarly. Chronic administration in rats and dogs, and 28-day, single- and multiple-ascending-dose administration in healthy human subjects caused similar exposure-dependent reductions in CSF Aβ40. Consistent with the 137-fold selectivity measured in cell culture, we identified doses of avagacestat that reduce CSF Aβ levels without causing Notch-related toxicities. Our results demonstrate the selectivity of avagacestat for APP over Notch cleavage, supporting further evaluation of avagacestat for AD therapy.
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Affiliation(s)
- Charles F Albright
- Research and Development, Bristol-Myers Squibb, Wallingford, Connecticut 06492, USA.
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69
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Nagakura A, Shitaka Y, Yarimizu J, Matsuoka N. Characterization of cognitive deficits in a transgenic mouse model of Alzheimer's disease and effects of donepezil and memantine. Eur J Pharmacol 2012; 703:53-61. [PMID: 23276665 DOI: 10.1016/j.ejphar.2012.12.023] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 12/07/2012] [Accepted: 12/18/2012] [Indexed: 11/18/2022]
Abstract
Alzheimer's disease is characterized by a progressive decline in cognitive function and involves β-amyloid (Aβ) in its pathogenesis. To characterize cognitive deficits associated with Aβ accumulation, we analyzed PS1/APP mice overexpressing mutant presenilin-1 (PS1, M146L; line 6.2) and amyloid precursor protein (APP, K670N/M671L; line Tg2576), a mouse model of Alzheimer's disease with accelerated Aβ production. Age-dependent changes in working and spatial memory behaviors were investigated using Y-maze and Morris water maze tasks, respectively, in female PS1/APP mice at ages of 2, 4, 6, and 12 months. Significant deficits in working and spatial memory were observed from 4 and 6 months of age, respectively. Acute single-dose administrations of memantine, a low-to-moderate-affinity N-methyl-d-aspartate (NMDA) antagonist, showed improvements in working memory deficits at 4 months of age, whereas donepezil, an acetylcholinesterase (AChE) inhibitor, did not. However, both drugs improved spatial memory dysfunction at 6 months of age at therapeutically relevant doses. No age-related dramatic changes were observed in expression levels of several proteins relating to memory dysfunction and also the mechanisms of donepezil and memantine in the cerebral cortex of PS1/APP mice until 6 months of age. Taken together, these results suggest dysfunctions in cholinergic and/or glutamatergic transmissions may be involved in the cognitive deficits associated with Aβ toxicity. Since donepezil and memantine have been widely used for treating patients of Alzheimer's disease, these results also suggest that cognitive deficits in PS1/APP mice assessed in the Y-maze and Morris water maze tasks are a useful animal model for evaluating novel Alzheimer's disease therapeutics.
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Affiliation(s)
- Akira Nagakura
- Pharmacology Research Laboratories, Drug Discovery Research, Astellas Pharma Inc., Tsukuba, Ibaraki 305-8585, Japan.
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70
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Rogers K, Felsenstein KM, Hrdlicka L, Tu Z, Albayya F, Lee W, Hopp S, Miller MJ, Spaulding D, Yang Z, Hodgdon H, Nolan S, Wen M, Costa D, Blain JF, Freeman E, De Strooper B, Vulsteke V, Scrocchi L, Zetterberg H, Portelius E, Hutter-Paier B, Havas D, Ahlijanian M, Flood D, Leventhal L, Shapiro G, Patzke H, Chesworth R, Koenig G. Modulation of γ-secretase by EVP-0015962 reduces amyloid deposition and behavioral deficits in Tg2576 mice. Mol Neurodegener 2012; 7:61. [PMID: 23249765 PMCID: PMC3573960 DOI: 10.1186/1750-1326-7-61] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022] Open
Abstract
Background A hallmark of Alzheimer’s disease is the presence of senile plaques in human brain primarily containing the amyloid peptides Aβ42 and Aβ40. Many drug discovery efforts have focused on decreasing the production of Aβ42 through γ-secretase inhibition. However, identification of γ-secretase inhibitors has also uncovered mechanism-based side effects. One approach to circumvent these side effects has been modulation of γ-secretase to shift Aβ production to favor shorter, less amyloidogenic peptides than Aβ42, without affecting the overall cleavage efficiency of the enzyme. This approach, frequently called γ-secretase modulation, appears more promising and has lead to the development of new therapeutic candidates for disease modification in Alzheimer’s disease. Results Here we describe EVP-0015962, a novel small molecule γ-secretase modulator. EVP-0015962 decreased Aβ42 in H4 cells (IC50 = 67 nM) and increased the shorter Aβ38 by 1.7 fold at the IC50 for lowering of Aβ42. AβTotal, as well as other carboxyl-terminal fragments of amyloid precursor protein, were not changed. EVP-0015962 did not cause the accumulation of other γ-secretase substrates, such as the Notch and ephrin A4 receptors, whereas a γ-secretase inhibitor reduced processing of both. A single oral dose of EVP-0015962 (30 mg/kg) decreased Aβ42 and did not alter AβTotal peptide levels in a dose-dependent manner in Tg2576 mouse brain at an age when overt Aβ deposition was not present. In Tg2576 mice, chronic treatment with EVP-0015962 (20 or 60 mg/kg/day in a food formulation) reduced Aβ aggregates, amyloid plaques, inflammatory markers, and cognitive deficits. Conclusions EVP-0015962 is orally bioavailable, detected in brain, and a potent, selective γ-secretase modulator in vitro and in vivo. Chronic treatment with EVP-0015962 was well tolerated in mice and lowered the production of Aβ42, attenuated memory deficits, and reduced Aβ plaque formation and inflammation in Tg2576 transgenic animals. In summary, these data suggest that γ-secretase modulation with EVP-0015962 represents a viable therapeutic alternative for disease modification in Alzheimer’s disease.
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Affiliation(s)
- Kathryn Rogers
- EnVivo Pharmaceuticals, Inc, 500 Arsenal Street, Watertown, MA 02472, USA
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71
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Palmeri A, Privitera L, Giunta S, Loreto C, Puzzo D. Inhibition of phosphodiesterase-5 rescues age-related impairment of synaptic plasticity and memory. Behav Brain Res 2012; 240:11-20. [PMID: 23174209 DOI: 10.1016/j.bbr.2012.10.060] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/26/2012] [Accepted: 10/30/2012] [Indexed: 12/14/2022]
Abstract
Aging is characterized by a progressive cognitive decline that leads to memory impairment. Because the cyclic nucleotide cascade is essential for the integrity of synaptic function and memory, and it is down-regulated during aging and in neurodegenerative disorders, we investigated whether an increase in cGMP levels might rescue age-related synaptic and memory deficits in mice. We demonstrated that acute perfusion with the phosphodiesterase-5 inhibitor sildenafil (50 nM) ameliorated long-term potentiation in hippocampal slices from 26-30-month-old mice. Moreover, chronic intraperitoneal injection of sildenafil (3mg/kg for 3 weeks) improved age-related spatial learning and reference memory as tested by the Morris Water Maze, and recognition memory as tested by the Object Recognition Test. Finally, sildenafil restored central cAMP responsive element-binding protein (CREB) phosphorylation, which is crucial for synaptic plasticity and memory. Our data suggest that inhibition of phosphodiesterase-5 may be beneficial to treat age-related cognitive dysfunction in a physiological mouse model of aging.
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Affiliation(s)
- Agostino Palmeri
- Department of Bio-Medical Sciences - Section of Physiology, University of Catania, Catania, 95125, Italy
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72
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The glial modulatory drug AV411 attenuates mechanical allodynia in rat models of neuropathic pain. ACTA ACUST UNITED AC 2012; 2:279-91. [PMID: 18176632 DOI: 10.1017/s1740925x0700035x] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Controlling neuropathic pain is an unmet medical need and we set out to identify new therapeutic candidates. AV411 (ibudilast) is a relatively nonselective phosphodiesterase inhibitor that also suppresses glial-cell activation and can partition into the CNS. Recent data strongly implicate activated glial cells in the spinal cord in the development and maintenance of neuropathic pain. We hypothesized that AV411 might be effective in the treatment of neuropathic pain and, hence, tested whether it attenuates the mechanical allodynia induced in rats by chronic constriction injury (CCI) of the sciatic nerve, spinal nerve ligation (SNL) and the chemotherapeutic paclitaxel (Taxol). Twice-daily systemic administration of AV411 for multiple days resulted in a sustained attenuation of CCI-induced allodynia. Reversal of allodynia was of similar magnitude to that observed with gabapentin and enhanced efficacy was observed in combination. We further show that multi-day AV411 reduces SNL-induced allodynia, and reverses and prevents paclitaxel-induced allodynia. Also, AV411 cotreatment attenuates tolerance to morphine in nerve-injured rats. Safety pharmacology, pharmacokinetic and initial mechanistic analyses were also performed. Overall, the results indicate that AV411 is effective in diverse models of neuropathic pain and support further exploration of its potential as a therapeutic agent for the treatment of neuropathic pain.
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73
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Effects of Single Doses of Avagacestat (BMS-708163) on Cerebrospinal Fluid Aβ Levels in Healthy Young Men. Clin Drug Investig 2012; 32:761-9. [DOI: 10.1007/s40261-012-0006-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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74
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Schenk D, Basi GS, Pangalos MN. Treatment strategies targeting amyloid β-protein. Cold Spring Harb Perspect Med 2012; 2:a006387. [PMID: 22951439 DOI: 10.1101/cshperspect.a006387] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
With the advent of the key discovery in the mid-1980s that the amyloid β-protein (Aβ) is the core constituent of the amyloid plaque pathology found in Alzheimer disease (AD), an intensive effort has been underway to attempt to mitigate its role in the hope of treating the disease. This effort fully matured when it was clarified that the Aβ is a normal product of cleavage of the amyloid precursor protein, and well-defined proteases for this process were identified. Further therapeutic options have been developed around the concept of anti-Aβ aggregation inhibitors and the surprising finding that immunization with Aβ itself leads to reduction of pathology in animal models of the disease. Here we review the progress in this field toward the goal of targeting Aβ for treatment and prevention of AD and identify some of the major challenges for the future of this area of medicine.
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Affiliation(s)
- Dale Schenk
- Netotope Biosciences Inc., San Francisco, CA 94080, USA
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75
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Comparative monitoring of oral theophylline treatment in blood serum, saliva, and nasal mucus. Ther Drug Monit 2012; 34:217-21. [PMID: 22377744 DOI: 10.1097/ftd.0b013e3182492a20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Theophylline, used in the treatment for various pulmonary pathologies, is usually given orally with drug levels measured primarily in blood serum and occasionally in saliva. Although theophylline treatment is now not commonly used it has been effective to correct smell loss (hyposmia). This is important because 21 million people in the United States exhibit hyposmia and oral theophylline has corrected hyposmia in about 50% of these patients. This result suggests that oral theophylline may result in the drug not only appearing in the serum but also in nasal mucus, thereby playing a role in correcting hyposmia. No prior report of theophylline in nasal mucus has been made and no comparison of levels in nasal mucus, blood serum, or saliva has been previously reported. PURPOSE The aim was to determine, after oral theophylline treatment, if it is present in nasal mucus and, if present, to compare the levels with those in serum and saliva. METHODS Oral theophylline was given to 23 hyposmic patients at daily doses of 200, 300, 400, 600, and 800 mg for periods of 2-10 months. During each period, blood serum, saliva, and nasal mucus were collected and theophylline measured in each fluid. RESULTS Theophylline was found in nasal mucus and in saliva and blood serum at each drug dose in each patient to whom it was given. The mean level of theophylline in nasal mucus was 74% that of serum; mean level in saliva was 67% of serum; mean level in nasal mucus was 111% that in saliva. CONCLUSIONS Theophylline is present in nasal mucus after oral administration. Levels in nasal mucus reflect blood and saliva levels in a consistent manner and offer a simple convenient noninvasive method to monitor theophylline doses of the oral drug.
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76
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Sierksma ASR, Rutten K, Sydlik S, Rostamian S, Steinbusch HWM, van den Hove DLA, Prickaerts J. Chronic phosphodiesterase type 2 inhibition improves memory in the APPswe/PS1dE9 mouse model of Alzheimer's disease. Neuropharmacology 2012; 64:124-36. [PMID: 22771768 DOI: 10.1016/j.neuropharm.2012.06.048] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/22/2012] [Accepted: 06/24/2012] [Indexed: 01/08/2023]
Abstract
Alzheimer's disease (AD) is characterized by progressive cognitive deficits and synaptic dysfunction. Over the last decade phosphodiesterase inhibitors (PDEIs) have received increasing attention as putative cognition enhancers and have been suggested as a novel treatment strategy for AD. Given their ability to prevent hydrolysis of cAMP and/or cGMP, they can stimulate the cAMP/protein kinase A (PKA)/cAMP element-binding protein (CREB) and cGMP/PKG/CREB pathway to enhance synaptic transmission by increasing CREB phosphorylation (pCREB) and brain-derived neurotrophic factor (BDNF) transcription. Based on previous research, we hypothesized that chronic PDE2I treatment would improve AD-related cognitive deficits, by decreasing amyloid-β (Aβ) plaque load, enhancing pCREB and BDNF levels and increasing synaptic density in the hippocampus of 8-month-old APPswe/PS1dE9 mice. Results indicated that chronic PDE2I treatment could indeed improve memory performance in APPswe/PS1dE9 mice, without affecting anxiety, depressive-like behavior or hypothalamus-pituitary-adrenal axis regulation. However, no treatment effects were observed on Aβ plaque load, pCREB or BDNF concentrations, or presynaptic density in the hippocampus, suggesting that other signaling pathways and/or effector molecules might be responsible for its cognition-enhancing effects. Presynaptic density in the stratum lucidum of the CA3 subregion was significantly higher in APPswe/PS1dE9 mice compared to WT controls, possibly reflecting a compensatory mechanism. In conclusion, PDEs in general, and PDE2 specifically, could be considered as promising therapeutic targets for cognition enhancement in AD, although the underlying mechanism of action remains to be elucidated. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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Affiliation(s)
- Annerieke S R Sierksma
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Science, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Maastricht, The Netherlands
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77
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c-Fos expression reveals aberrant neural network activity during cued fear conditioning in APPswe transgenic mice. Neurobiol Learn Mem 2012; 98:1-11. [DOI: 10.1016/j.nlm.2012.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 02/24/2012] [Accepted: 03/07/2012] [Indexed: 01/28/2023]
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78
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Consequences of inhibiting amyloid precursor protein processing enzymes on synaptic function and plasticity. Neural Plast 2012; 2012:272374. [PMID: 22792491 PMCID: PMC3390164 DOI: 10.1155/2012/272374] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/22/2012] [Indexed: 12/21/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease, one of whose major pathological hallmarks is the accumulation of amyloid plaques comprised of aggregated β-amyloid (Aβ) peptides. It is now recognized that soluble Aβ oligomers may lead to synaptic dysfunctions early in AD pathology preceding plaque deposition. Aβ is produced by a sequential cleavage of amyloid precursor protein (APP) by the activity of β- and γ-secretases, which have been identified as major candidate therapeutic targets of AD. This paper focuses on how Aβ alters synaptic function and the functional consequences of inhibiting the activity of the two secretases responsible for Aβ generation. Abnormalities in synaptic function resulting from the absence or inhibition of the Aβ-producing enzymes suggest that Aβ itself may have normal physiological functions which are disrupted by abnormal accumulation of Aβ during AD pathology. This interpretation suggests that AD therapeutics targeting the β- and γ-secretases should be developed to restore normal levels of Aβ or combined with measures to circumvent the associated synaptic dysfunction(s) in order to have minimal impact on normal synaptic function.
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79
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Critical role of soluble amyloid-β for early hippocampal hyperactivity in a mouse model of Alzheimer's disease. Proc Natl Acad Sci U S A 2012; 109:8740-5. [PMID: 22592800 DOI: 10.1073/pnas.1206171109] [Citation(s) in RCA: 490] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by a progressive dysfunction of central neurons. Recent experimental evidence indicates that in the cortex, in addition to the silencing of a fraction of neurons, other neurons are hyperactive in amyloid-β (Aβ) plaque-enriched regions. However, it has remained unknown what comes first, neuronal silencing or hyperactivity, and what mechanisms might underlie the primary neuronal dysfunction. Here we examine the activity patterns of hippocampal CA1 neurons in a mouse model of AD in vivo using two-photon Ca(2+) imaging. We found that neuronal activity in the plaque-bearing CA1 region of older mice is profoundly altered. There was a marked increase in the fractions of both silent and hyperactive neurons, as previously also found in the cortex. Remarkably, in the hippocampus of young mice, we observed a selective increase in hyperactive neurons already before the formation of plaques, suggesting that soluble species of Aβ may underlie this impairment. Indeed, we found that acute treatment with the γ-secretase inhibitor LY-411575 reduces soluble Aβ levels and rescues the neuronal dysfunction. Furthermore, we demonstrate that direct application of soluble Aβ can induce neuronal hyperactivity in wild-type mice. Thus, our study identifies hippocampal hyperactivity as a very early functional impairment in AD transgenic mice and provides direct evidence that soluble Aβ is crucial for hippocampal hyperactivity.
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80
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Lalonde R, Fukuchi K, Strazielle C. APP transgenic mice for modelling behavioural and psychological symptoms of dementia (BPSD). Neurosci Biobehav Rev 2012; 36:1357-75. [PMID: 22373961 PMCID: PMC3340431 DOI: 10.1016/j.neubiorev.2012.02.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 02/10/2012] [Accepted: 02/13/2012] [Indexed: 12/17/2022]
Abstract
The discovery of gene mutations responsible for autosomal dominant Alzheimer's disease has enabled researchers to reproduce in transgenic mice several hallmarks of this disorder, notably Aβ accumulation, though in most cases without neurofibrillary tangles. Mice expressing mutated and wild-type APP as well as C-terminal fragments of APP exhibit variations in exploratory activity reminiscent of behavioural and psychological symptoms of Alzheimer dementia (BPSD). In particular, open-field, spontaneous alternation, and elevated plus-maze tasks as well as aggression are modified in several APP transgenic mice relative to non-transgenic controls. However, depending on the precise murine models, changes in open-field and elevated plus-maze exploration occur in either direction, either increased or decreased relative to controls. It remains to be determined which neurotransmitter changes are responsible for this variability, in particular with respect to GABA, 5HT, and dopamine.
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Affiliation(s)
- R Lalonde
- Département de Psychologie, Faculté des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France.
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81
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Neutralization of soluble, synaptotoxic amyloid β species by antibodies is epitope specific. J Neurosci 2012; 32:2696-702. [PMID: 22357853 DOI: 10.1523/jneurosci.1676-11.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Several anti-amyloid β (Aβ) antibodies are under evaluation for the treatment of Alzheimer's disease (AD). Clinical studies using the N-terminal-directed anti-Aβ antibody bapineuzumab have demonstrated reduced brain PET-Pittsburg-B signals, suggesting the reduction of Aβ plaques, and reduced levels of total and phosphorylated tau protein in the CSF of treated AD patients. Preclinical studies using 3D6 (the murine form of bapineuzumab) have demonstrated resolution of Aβ plaque and vascular burdens, neuritic dystrophy, and preservation of synaptic density in the transgenic APP mouse models. In contrast, few studies have evaluated the direct interaction of this antibody with synaptotoxic soluble Aβ species. In the current report, we demonstrated that 3D6 binds to soluble, synaptotoxic assemblies of Aβ(1-42) and prevents multiple downstream functional consequences in rat hippocampal neurons including changes in glutamate AMPA receptor trafficking, AD-type tau phosphorylation, and loss of dendritic spines. In vivo, we further demonstrated that 3D6 prevents synaptic loss and acutely reverses the behavioral deficit in the contextual fear conditioning task in transgenic mouse models of AD, two endpoints thought to be linked to synaptotoxic soluble Aβ moieties. Importantly C-terminal anti-Aβ antibodies were ineffective on these endpoints. These results, taken with prior studies, suggest that N-terminal anti-Aβ antibodies effectively interact with both soluble and insoluble forms of Aβ and therefore appear particularly well suited for testing the Aβ hypothesis of AD.
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82
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Svedružić ZM, Popović K, Smoljan I, Sendula-Jengić V. Modulation of γ-secretase activity by multiple enzyme-substrate interactions: implications in pathogenesis of Alzheimer's disease. PLoS One 2012; 7:e32293. [PMID: 22479317 PMCID: PMC3316526 DOI: 10.1371/journal.pone.0032293] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 01/24/2012] [Indexed: 11/19/2022] Open
Abstract
Background We describe molecular processes that can facilitate pathogenesis of Alzheimer's disease (AD) by analyzing the catalytic cycle of a membrane-imbedded protease γ-secretase, from the initial interaction with its C99 substrate to the final release of toxic Aβ peptides. Results The C-terminal AICD fragment is cleaved first in a pre-steady-state burst. The lowest Aβ42/Aβ40 ratio is observed in pre-steady-state when Aβ40 is the dominant product. Aβ42 is produced after Aβ40, and therefore Aβ42 is not a precursor for Aβ40. The longer more hydrophobic Aβ products gradually accumulate with multiple catalytic turnovers as a result of interrupted catalytic cycles. Saturation of γ-secretase with its C99 substrate leads to 30% decrease in Aβ40 with concomitant increase in the longer Aβ products and Aβ42/Aβ40 ratio. To different degree the same changes in Aβ products can be observed with two mutations that lead to an early onset of AD, ΔE9 and G384A. Four different lines of evidence show that γ-secretase can bind and cleave multiple substrate molecules in one catalytic turnover. Consequently depending on its concentration, NotchΔE substrate can activate or inhibit γ-secretase activity on C99 substrate. Multiple C99 molecules bound to γ-secretase can affect processive cleavages of the nascent Aβ catalytic intermediates and facilitate their premature release as the toxic membrane-imbedded Aβ-bundles. Conclusions Gradual saturation of γ-secretase with its substrate can be the pathogenic process in different alleged causes of AD. Thus, competitive inhibitors of γ-secretase offer the best chance for a successful therapy, while the noncompetitive inhibitors could even facilitate development of the disease by inducing enzyme saturation at otherwise sub-saturating substrate. Membrane-imbedded Aβ-bundles generated by γ-secretase could be neurotoxic and thus crucial for our understanding of the amyloid hypothesis and AD pathogenesis.
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Affiliation(s)
- Zeljko M Svedružić
- Medical Biochemistry, Faculty of Medicine, University of Rijeka, Rab, Croatia.
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83
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Differential effects between γ-secretase inhibitors and modulators on cognitive function in amyloid precursor protein-transgenic and nontransgenic mice. J Neurosci 2012; 32:2037-50. [PMID: 22323718 DOI: 10.1523/jneurosci.4264-11.2012] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
γ-Secretase inhibitors (GSIs) reduce amyloid-β (Aβ) peptides but inevitably increase the β-C-terminal fragment (β-CTF) of amyloid precursor protein (APP), potentially having undesirable effects on synapses. In contrast, γ-secretase modulators (GSMs) reduce Aβ42 without increasing β-CTF. Although the Aβ-lowering effects of these compounds have been extensively studied, little effort has been made to investigate their effects on cognition. Here, we compared the effects of two GSIs--(2S)-2-hydroxy-3-methyl-N-[(2S)-1-{[(1S)-3-methyl-2-oxo-2,3,4,5-tetrahydro-1H-3-benzazepin-1-yl]amino}-1-oxopropan-2-yl]butanamide (LY450139, semagacestat) and (2R)-2-[[(4-chlorophenyl)sulfonyl][[2-fluoro-4-(1,2,4-oxazol-3-yl)phenyl]methyl]amino-5,5,5-trifluoropentanamide (BMS-708163)--and a second-generation GSM [{(2S,4R)-1-[(4R)-1,1,1-trifluoro-7-methyloctan-4-yl]-2-[4-(trifluoromethyl)phenyl]piperidin-4-yl}acetic acid (GSM-2)] on spatial working memory in APP-transgenic (Tg2576) and nontransgenic mice using the Y-maze task. While acute dosing with either GSI ameliorated memory deficits in 5.5-month-old Tg2576 mice, these effects disappeared after 8 d subchronic dosing. Subchronic dosing with either GSI rather impaired normal cognition in 3-month-old Tg2576 mice, with no inhibition on the processing of other γ-secretase substrates, such as Notch, N-cadherin, or EphA4, in the brain. LY450139 also impaired normal cognition in wild-type mice; however, the potency was 10-fold lower than that in Tg2576 mice, indicating an APP-dependent mechanism likely with β-CTF accumulation. Immunofluorescence studies revealed that the β-CTF accumulation was localized in the presynaptic terminals of the hippocampal stratum lucidum and dentate hilus, implying an effect on presynaptic function in the mossy fibers. In contrast, both acute and subchronic dosing with GSM-2 significantly ameliorated memory deficits in Tg2576 mice and did not affect normal cognition in wild-type mice. We demonstrated a clear difference between GSI and GSM in effects on functional consequences, providing new insights into strategies for developing these drugs against Alzheimer's disease.
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84
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Bruno O, Fedele E, Prickaerts J, Parker LA, Canepa E, Brullo C, Cavallero A, Gardella E, Balbi A, Domenicotti C, Bollen E, Gijselaers HJM, Vanmierlo T, Erb K, Limebeer CL, Argellati F, Marinari UM, Pronzato MA, Ricciarelli R. GEBR-7b, a novel PDE4D selective inhibitor that improves memory in rodents at non-emetic doses. Br J Pharmacol 2012; 164:2054-63. [PMID: 21649644 DOI: 10.1111/j.1476-5381.2011.01524.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Strategies designed to enhance cerebral cAMP have been proposed as symptomatic treatments to counteract cognitive deficits. However, pharmacological therapies aimed at reducing PDE4, the main class of cAMP catabolizing enzymes in the brain, produce severe emetic side effects. We have recently synthesized a 3-cyclopentyloxy-4-methoxybenzaldehyde derivative, structurally related to rolipram, and endowed with selective PDE4D inhibitory activity. The aim of the present study was to investigate the effect of the new drug, namely GEBR-7b, on memory performance, nausea, hippocampal cAMP and amyloid-β (Aβ) levels. EXPERIMENTAL APPROACH To measure memory performance, we performed object recognition tests on rats and mice treated with GEBR-7b or rolipram. The emetic potential of the drug, again compared with rolipram, was evaluated in rats using the taste reactivity test and in mice using the xylazine/ketamine anaesthesia test. Extracellular hippocampal cAMP was evaluated by intracerebral microdialysis in freely moving rats. Levels of soluble Aβ peptides were measured in hippocampal tissues and cultured N2a cells by elisa. KEY RESULTS GEBR-7b increased hippocampal cAMP, did not influence Aβ levels and improved spatial, as well as object memory performance in the object recognition tests. The effect of GEBR-7b on memory was 3 to 10 times more potent than that of rolipram, and its effective doses had no effect on surrogate measures of emesis in rodents. CONCLUSION AND IMPLICATIONS Our results demonstrate that GEBR-7b enhances memory functions at doses that do not cause emesis-like behaviour in rodents, thus offering a promising pharmacological perspective for the treatment of memory impairment.
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Affiliation(s)
- O Bruno
- Departments of Pharmaceutical Sciences/Experimental Medicine, Section of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
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Multicenter, Randomized, Double-Blind, Placebo-Controlled, Single-Ascending Dose Study of the Oral γ-Secretase Inhibitor BMS-708163 (Avagacestat): Tolerability Profile, Pharmacokinetic Parameters, and Pharmacodynamic Markers. Clin Ther 2012; 34:654-67. [DOI: 10.1016/j.clinthera.2012.01.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/11/2012] [Accepted: 01/26/2012] [Indexed: 01/26/2023]
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86
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Bales KR. The value and limitations of transgenic mouse models used in drug discovery for Alzheimer's disease: an update. Expert Opin Drug Discov 2012; 7:281-97. [DOI: 10.1517/17460441.2012.666234] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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87
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Cramer PE, Cirrito JR, Wesson DW, Lee CYD, Karlo JC, Zinn AE, Casali BT, Restivo JL, Goebel WD, James MJ, Brunden KR, Wilson DA, Landreth GE. ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models. Science 2012; 335:1503-6. [PMID: 22323736 DOI: 10.1126/science.1217697] [Citation(s) in RCA: 813] [Impact Index Per Article: 67.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease (AD) is associated with impaired clearance of β-amyloid (Aβ) from the brain, a process normally facilitated by apolipoprotein E (apoE). ApoE expression is transcriptionally induced through the action of the nuclear receptors peroxisome proliferator-activated receptor gamma and liver X receptors in coordination with retinoid X receptors (RXRs). Oral administration of the RXR agonist bexarotene to a mouse model of AD resulted in enhanced clearance of soluble Aβ within hours in an apoE-dependent manner. Aβ plaque area was reduced more than 50% within just 72 hours. Furthermore, bexarotene stimulated the rapid reversal of cognitive, social, and olfactory deficits and improved neural circuit function. Thus, RXR activation stimulates physiological Aβ clearance mechanisms, resulting in the rapid reversal of a broad range of Aβ-induced deficits.
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Affiliation(s)
- Paige E Cramer
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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88
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Kumar S, Okello EJ, Harris JR. Experimental inhibition of fibrillogenesis and neurotoxicity by amyloid-beta (Aβ) and other disease-related peptides/proteins by plant extracts and herbal compounds. Subcell Biochem 2012; 65:295-326. [PMID: 23225009 DOI: 10.1007/978-94-007-5416-4_13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Amyloid-β (Aβ) fibrillogenesis and associated cyto/neurotoxicity are major pathological events and hallmarks in diseases such as Alzheimer's disease (AD). The understanding of Aβ molecular pathogenesis is currently a pharmacological target for rational drug design and discovery based on reduction of Aβ generation, inhibition of Aβ fibrillogenesis and aggregation, enhancement of Aβ clearance and amelioration of associated cytotoxicity. Molecular mechanisms for other amyloidoses, such as transthyretin amyloidosis, AL-amyloidosis, as well as α-synuclein and prion protein are also pharmacological targets for current drug therapy, design and discovery. We report on natural herbal compounds and extracts that are capable binding to and inhibiting different targets associated with AD and other amyloid-associated diseases, providing a basis for future therapeutic strategies. Many herbal compounds, including curcumin, galantamine, quercetin and other polyphenols, are under active investigation and hold considerable potential for future prophylactic and therapeutic treatment against AD and other neurodegenerative diseases, as well as systemic amyloid diseases. A common emerging theme throughout many studies is the anti-oxidant and anti-inflammatory properties of the compounds or herbal extracts under investigation, within the context of the inhibition of cyto/neurotoxicity and anti-amyloid activity.
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Affiliation(s)
- Suresh Kumar
- University School of Biotechnology, GGS Indraprastha University, Sector 16C, 10075, Dwarka, Delhi, India,
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89
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D'Onofrio G, Panza F, Frisardi V, Solfrizzi V, Imbimbo BP, Paroni G, Cascavilla L, Seripa D, Pilotto A. Advances in the identification of γ-secretase inhibitors for the treatment of Alzheimer's disease. Expert Opin Drug Discov 2011; 7:19-37. [DOI: 10.1517/17460441.2012.645534] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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90
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Spines, plasticity, and cognition in Alzheimer's model mice. Neural Plast 2011; 2012:319836. [PMID: 22203915 PMCID: PMC3238410 DOI: 10.1155/2012/319836] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 10/27/2011] [Indexed: 01/03/2023] Open
Abstract
The pathological hallmarks of Alzheimer's disease (AD)--widespread synaptic and neuronal loss and the pathological accumulation of amyloid-beta peptide (Aβ) in senile plaques, as well as hyperphosphorylated tau in neurofibrillary tangles--have been known for many decades, but the links between AD pathology and dementia and effective therapeutic strategies remain elusive. Transgenic mice have been developed based on rare familial forms of AD and frontotemporal dementia, allowing investigators to test in detail the structural, functional, and behavioral consequences of AD-associated pathology. Here, we review work on transgenic AD models that investigate the degeneration of dendritic spine structure, synaptic function, and cognition. Together, these data support a model of AD pathogenesis in which soluble Aβ initiates synaptic dysfunction and loss, as well as pathological changes in tau, which contribute to both synaptic and neuronal loss. These changes in synapse structure and function as well as frank synapse and neuronal loss contribute to the neural system dysfunction which causes cognitive deficits. Understanding the underpinnings of dementia in AD will be essential to develop and evaluate therapeutic approaches for this widespread and devastating disease.
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91
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γ-secretase inhibitors for treating Alzheimer’s disease: rationale and clinical data. ACTA ACUST UNITED AC 2011. [DOI: 10.4155/cli.11.86] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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92
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Wesson DW, Nixon RA, Levy E, Wilson DA. Mechanisms of neural and behavioral dysfunction in Alzheimer's disease. Mol Neurobiol 2011; 43:163-79. [PMID: 21424679 DOI: 10.1007/s12035-011-8177-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 03/03/2011] [Indexed: 10/18/2022]
Abstract
This review critically examines progress in understanding the link between Alzheimer's disease (AD) molecular pathogenesis and behavior, with an emphasis on the impact of amyloid-β. We present the argument that the AD research field requires more multifaceted analyses into the impacts of Alzheimer's pathogenesis which combine simultaneous molecular-, circuit-, and behavior-level approaches. Supporting this argument is a review of particular research utilizing similar, "systems-level" methods in mouse models of AD. Related to this, a critique of common physiological and behavioral models is made-highlighting the likely usefulness of more refined and specific tools in understanding the relationship between candidate molecular pathologies and behavioral dysfunction. Finally, we propose challenges for future research which, if met, may greatly extend our current understanding of how AD molecular pathology impacts neural network function and behavior and possibly may lead to refinements in disease therapeutics.
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Affiliation(s)
- Daniel W Wesson
- Emotional Brain Institute, Nathan S. Kline Institute for Psychiatric Research, New York University School of Medicine, Orangeburg, NY 10962, USA.
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93
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Sambamurti K, Greig NH, Utsuki T, Barnwell EL, Sharma E, Mazell C, Bhat NR, Kindy MS, Lahiri DK, Pappolla MA. Targets for AD treatment: conflicting messages from γ-secretase inhibitors. J Neurochem 2011; 117:359-74. [PMID: 21320126 DOI: 10.1111/j.1471-4159.2011.07213.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Current evidence suggests that Alzheimer's disease (AD) is a multi-factorial disease that starts with accumulation of multiple proteins. We have previously proposed that inhibition of γ-secretase may impair membrane recycling causing neurodegeneration starting at synapses (Sambamurti K., Suram A., Venugopal C., Prakasam A., Zhou Y., Lahiri D. K. and Greig N. H. A partial failure of membrane protein turnover may cause Alzheimer's disease: a new hypothesis. Curr. Alzheimer Res., 3, 2006, 81). We also proposed familal AD mutations increase Aβ42 by inhibiting γ-secretase. Herein, we discuss the failure of Eli Lilly's γ-secretase inhibitor, semagacestat, in clinical trials in the light of our hypothesis, which extends the problem beyond toxicity of Aβ aggregates. We elaborate that γ-secretase inhibitors lead to accumulation of amyloid precursor protein C-terminal fragments that can later be processed by γ-secretase to yields bursts of Aβ to facilitate aggregation. Although we do not exclude a role for toxic Aβ aggregates, inhibition of γ-secretase can affect numerous substrates other than amyloid precursor protein to affect multiple pathways and the combined accumulation of multiple peptides in the membrane may impair its function and turnover. Taken together, protein processing and turnover pathways play an important role in maintaining cellular homeostasis and unless we clearly see consistent disease-related increase in their levels or activity, we need to focus on preserving their function rather than inhibiting them for treatment of AD and similar diseases.
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Affiliation(s)
- Kumar Sambamurti
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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94
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Terry AV, Callahan PM, Hall B, Webster SJ. Alzheimer's disease and age-related memory decline (preclinical). Pharmacol Biochem Behav 2011; 99:190-210. [PMID: 21315756 DOI: 10.1016/j.pbb.2011.02.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 01/21/2011] [Accepted: 02/01/2011] [Indexed: 01/05/2023]
Abstract
An unfortunate result of the rapid rise in geriatric populations worldwide is the increasing prevalence of age-related cognitive disorders such as Alzheimer's disease (AD). AD is a devastating neurodegenerative illness that is characterized by a profound impairment of cognitive function, marked physical disability, and an enormous economic burden on the afflicted individual, caregivers, and society in general. The rise in elderly populations is also resulting in an increase in individuals with related (potentially treatable) conditions such as "Mild Cognitive Impairment" (MCI) which is characterized by a less severe (but abnormal) level of cognitive impairment and a high-risk for developing dementia. Even in the absence of a diagnosable disorder of cognition (e.g., AD and MCI), the perception of increased forgetfulness and declining mental function is a clear source of apprehension in the elderly. This is a valid concern given that even a modest impairment of cognitive function is likely to be associated with significant disability in a rapidly evolving, technology-based society. Unfortunately, the currently available therapies designed to improve cognition (i.e., for AD and other forms of dementia) are limited by modest efficacy and adverse side effects, and their effects on cognitive function are not sustained over time. Accordingly, it is incumbent on the scientific community to develop safer and more effective therapies that improve and/or sustain cognitive function in the elderly allowing them to remain mentally active and productive for as long as possible. As diagnostic criteria for memory disorders evolve, the demand for pro-cognitive therapeutic agents is likely to surpass AD and dementia to include MCI and potentially even less severe forms of memory decline. The purpose of this review is to provide an overview of the contemporary therapeutic targets and preclinical pharmacologic approaches (with representative drug examples) designed to enhance memory function.
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Affiliation(s)
- Alvin V Terry
- Department of Pharmacology and Toxicology and Small Animal Behavior Core, Medical College of Georgia, Augusta, GA 30912, USA.
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95
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Reduction of β-amyloid deposits by γ-secretase inhibitor is associated with the attenuation of secondary damage in the ipsilateral thalamus and sensory functional improvement after focal cortical infarction in hypertensive rats. J Cereb Blood Flow Metab 2011; 31:572-9. [PMID: 20683452 PMCID: PMC3049512 DOI: 10.1038/jcbfm.2010.127] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Abnormal β-amyloid (Aβ) deposits in the thalamus have been reported after cerebral cortical infarction. In this study, we investigated the association of Aβ deposits, with the secondary thalamic damage after focal cortical infarction in rats. Thirty-six stroke-prone renovascular hypertensive rats were subjected to distal middle cerebral artery occlusion (MCAO) and then randomly divided into MCAO, vehicle, and N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) groups and 12 sham-operated rats as control. The DAPT was administered orally at 72 hours after MCAO. Seven days after MCAO, sensory function, neuron loss, and glial activation and proliferation were evaluated using adhesive removal test, Nissl staining, and immunostaining, respectively. Thalamic Aβ accumulation was evaluated using immunostaining and enzyme-linked immunosorbent assay (ELISA). Compared with vehicle group, the ipsilateral thalamic Aβ, neuronal loss, glial activation and proliferation, and the mean time to remove the stimulus from right forepaw significantly decreased in DAPT group. The mean time to remove the stimulus from the right forepaw and thalamic Aβ burden were both negatively correlated with the number of thalamic neurons. These findings suggest that Aβ deposits are associated with the secondary thalamic damage. Reduction of thalamic Aβ by γ-secretase inhibitor may attenuate the secondary damage and improve sensory function after cerebral cortical infarction.
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96
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Imbimbo BP, Panza F, Frisardi V, Solfrizzi V, D'Onofrio G, Logroscino G, Seripa D, Pilotto A. Therapeutic intervention for Alzheimer's disease with γ-secretase inhibitors: still a viable option? Expert Opin Investig Drugs 2011; 20:325-41. [DOI: 10.1517/13543784.2011.550572] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Bruno P Imbimbo
- Research & Development Department, Chiesi Farmaceutici, Via Palermo 26/A, 43100 Parma, Italy ;
| | - Francesco Panza
- Geriatric Unit and Gerontology-Geriatrics Research Laboratory, Department of Medical Sciences, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Vincenza Frisardi
- University of Bari, Center for Aging Brain, Department of Geriatrics, Memory Unit, Bari, Italy
| | - Vincenzo Solfrizzi
- University of Bari, Center for Aging Brain, Department of Geriatrics, Memory Unit, Bari, Italy
| | - Grazia D'Onofrio
- Geriatric Unit and Gerontology-Geriatrics Research Laboratory, Department of Medical Sciences, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Giancarlo Logroscino
- University of Bari, Department of Neurological and Psychiatric Sciences, Bari, Italy
| | - Davide Seripa
- Geriatric Unit and Gerontology-Geriatrics Research Laboratory, Department of Medical Sciences, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Alberto Pilotto
- Geriatric Unit and Gerontology-Geriatrics Research Laboratory, Department of Medical Sciences, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
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Piau A, Nourhashémi F, Hein C, Caillaud C, Vellas B. Progress in the development of new drugs in Alzheimer's disease. J Nutr Health Aging 2011; 15:45-57. [PMID: 21267520 DOI: 10.1007/s12603-011-0012-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disease with a global prevalence estimated at 26.55 million in 2006. During the past decades, several agents have been approved that enhance cognition of AD patients. However, the effectiveness of these treatments are limited or controversial and they do not modify disease progression. Recent advances in understanding AD pathogenesis have led to the development of numerous compounds that might modify the disease process. AD is mainly characterized neuropathologically by the presence of two kinds of protein aggregates: extracellular plaques of Abeta-peptide and intracellular neurofibrillary tangles. Abeta and tau could interfere in an original way contributing to a cascade of events leading to neuronal death and transmitter deficits. Investigation for novel therapeutic approaches targeting the presumed underlying pathogenic mechanisms is major focus of research. Antiamyloid agents targeting production, accumulation, clearance, or toxicity associated with Abeta peptide, are some approaches under investigation to limit extracellular plaques of Abeta-peptide accumulation. We can state as an example: Abeta passive and active immunization, secretases modulation, Abeta degradation enhancement, or antiaggregation and antifibrillization agents. Tau-related therapies are also under clinical investigation but few compounds are available. Another alternative approach under development is neuroprotective agents such as antioxidants, anti-inflammatory drugs, compounds acting against glutamate mediated neurotoxicity. Neurorestorative approaches through neurotrophin or cell therapy also represent a minor avenue in AD research. Finally, statins, receptor for advanced glycation end products inhibitors, thiazolidinediones, insulin, and hormonal therapies are some other ways of research for a therapeutic approach of Alzheimer's disease. Taking into account AD complexity, it becomes clear that polypharmacology with drugs targeting different sites could be the future treatment approach and a majority of the recent drugs under evaluation seems to act on multiple targets. This article exposes general classes of disease-modifying therapies under investigation.
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Basi GS, Hemphill S, Brigham EF, Liao A, Aubele DL, Baker J, Barbour R, Bova M, Chen XH, Dappen MS, Eichenbaum T, Goldbach E, Hawkinson J, Lawler-Herbold R, Hu K, Hui T, Jagodzinski JJ, Keim PS, Kholodenko D, Latimer LH, Lee M, Marugg J, Mattson MN, McCauley S, Miller JL, Motter R, Mutter L, Neitzel ML, Ni H, Nguyen L, Quinn K, Ruslim L, Semko CM, Shapiro P, Smith J, Soriano F, Szoke B, Tanaka K, Tang P, Tucker JA, Ye XM, Yu M, Wu J, Xu YZ, Garofalo AW, Sauer JM, Konradi AW, Ness D, Shopp G, Pleiss MA, Freedman SB, Schenk D. Amyloid precursor protein selective gamma-secretase inhibitors for treatment of Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2010; 2:36. [PMID: 21190552 PMCID: PMC3031881 DOI: 10.1186/alzrt60] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 12/16/2010] [Accepted: 12/29/2010] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Inhibition of gamma-secretase presents a direct target for lowering Aβ production in the brain as a therapy for Alzheimer's disease (AD). However, gamma-secretase is known to process multiple substrates in addition to amyloid precursor protein (APP), most notably Notch, which has limited clinical development of inhibitors targeting this enzyme. It has been postulated that APP substrate selective inhibitors of gamma-secretase would be preferable to non-selective inhibitors from a safety perspective for AD therapy. METHODS In vitro assays monitoring inhibitor potencies at APP γ-site cleavage (equivalent to Aβ40), and Notch ε-site cleavage, in conjunction with a single cell assay to simultaneously monitor selectivity for inhibition of Aβ production vs. Notch signaling were developed to discover APP selective gamma-secretase inhibitors. In vivo efficacy for acute reduction of brain Aβ was determined in the PDAPP transgene model of AD, as well as in wild-type FVB strain mice. In vivo selectivity was determined following seven days x twice per day (b.i.d.) treatment with 15 mg/kg/dose to 1,000 mg/kg/dose ELN475516, and monitoring brain Aβ reduction vs. Notch signaling endpoints in periphery. RESULTS The APP selective gamma-secretase inhibitors ELN318463 and ELN475516 reported here behave as classic gamma-secretase inhibitors, demonstrate 75- to 120-fold selectivity for inhibiting Aβ production compared with Notch signaling in cells, and displace an active site directed inhibitor at very high concentrations only in the presence of substrate. ELN318463 demonstrated discordant efficacy for reduction of brain Aβ in the PDAPP compared with wild-type FVB, not observed with ELN475516. Improved in vivo safety of ELN475516 was demonstrated in the 7d repeat dose study in wild-type mice, where a 33% reduction of brain Aβ was observed in mice terminated three hours post last dose at the lowest dose of inhibitor tested. No overt in-life or post-mortem indications of systemic toxicity, nor RNA and histological end-points indicative of toxicity attributable to inhibition of Notch signaling were observed at any dose tested. CONCLUSIONS The discordant in vivo activity of ELN318463 suggests that the potency of gamma-secretase inhibitors in AD transgenic mice should be corroborated in wild-type mice. The discovery of ELN475516 demonstrates that it is possible to develop APP selective gamma-secretase inhibitors with potential for treatment for AD.
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Affiliation(s)
- Guriqbal S Basi
- Elan Pharmaceuticals, Inc, 180 Oyster Point Blvd, S, San Francisco, CA 94080, USA.
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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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Ricobaraza A, Cuadrado-Tejedor M, Marco S, Pérez-Otaño I, García-Osta A. Phenylbutyrate rescues dendritic spine loss associated with memory deficits in a mouse model of Alzheimer disease. Hippocampus 2010; 22:1040-50. [PMID: 21069780 DOI: 10.1002/hipo.20883] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2010] [Indexed: 01/16/2023]
Abstract
Alzheimer's disease (AD) and ageing are associated with impaired learning and memory, and recent findings point toward modulating chromatin remodeling through histone acetylation as a promising therapeutic strategy. Here we report that systemic administration of the HDAC inhibitor 4-phenylbutyrate (PBA) reinstated fear learning in the Tg2576 mouse model of AD. Tg2576 mice develop age-dependent amyloid pathology and cognitive decline that closely mimics disease progression in humans. Memory reinstatement by PBA was observed independently of the disease stage: both in 6-month-old Tg2576 mice, at the onset of the first symptoms, but also in aged, 12- to 16-month-old mice, when amyloid plaque deposition and major synaptic loss has occurred. Reversal of learning deficits was associated to a PBA-induced clearance of intraneuronal Aβ accumulation, which was accompanied by mitigation of endoplasmic reticulum (ER) stress, and to restoration of dendritic spine densities of hippocampal CA1 pyramidal neurons to control levels. Furthermore, the expression of plasticity-related proteins such as the NMDA receptor subunit NR2B and the synaptic scaffold SAP102 was significantly increased by PBA. Our data suggest that the beneficial effects of PBA in memory are mediated both via its chemical chaperone-like activity and via the transcriptional activation of a cluster of proteins required for the induction of synaptic plasticity and structural remodeling.
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Affiliation(s)
- Ana Ricobaraza
- Neuropharmacology and Behaviour, Neuroscience Department, Centro de Investigación Médica Aplicada (CIMA) y Universidad de Navarra, 31008 Pamplona, Spain
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