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Li XT. Alzheimer's disease therapy based on acetylcholinesterase inhibitor/blocker effects on voltage-gated potassium channels. Metab Brain Dis 2022; 37:581-587. [PMID: 35098414 DOI: 10.1007/s11011-022-00921-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/24/2022] [Indexed: 01/11/2023]
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder with progressive loss of memory and other cognitive functions. The pathogenesis of this disease is complex and multifactorial, and remains obscure until now. To enhance the declined level of acetylcholine (ACh) resulting from loss of cholinergic neurons, acetylcholinesterase (AChE) inhibitors are developed and successfully approved for AD treatment in the clinic, with a limited therapeutic effectiveness. At present, it is generally accepted that multi-target strategy is potently useful for designing novel drugs for AD. Accumulated evidence reveals that Kv channels, which are broadly expressed in brain and possess crucial functions in modulating the neuronal activity, are inhibited by several acetylcholinesterase (AChE) inhibitors, such as tacrine, bis(7)-tacrine, donepezil and galantamine. Inhibition of Kv channels by these AChE inhibitors can generate neuroprotective effects by either mitigating Aβ toxicity and neuronal apoptosis, or facilitating cell proliferation. These inhibitory effects provide additional explanations for clinical beneficial effectiveness of AChE inhibitors, meaning that Kv channel is a promising candidate target for novel drugs for AD therapy.
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Affiliation(s)
- Xian-Tao Li
- Department of Neuroscience, South-Central University for Nationalities, 182 Minyuan Road, Wuhan, 430074, China.
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2
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Genistein Inhibits Aβ 25-35-Induced Neuronal Death with Changes in the Electrophysiological Properties of Voltage-Gated Sodium and Potassium Channels. Cell Mol Neurobiol 2019; 39:809-822. [PMID: 31037516 DOI: 10.1007/s10571-019-00680-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 04/25/2019] [Indexed: 01/07/2023]
Abstract
We established a model of Alzheimer's disease in vitro by exposing primary hippocampal neurons of neonatal Wistar rats to the β-Amyloid peptide fragment 25-35, Aβ25-35. We then observed the effects of genistein, a type of soybean isoflavone, on Aβ25-35-incubated hippocampal neuron viability, and the electrophysiological properties of voltage-gated sodium channels (NaV) and potassium channels (KV) in the hippocampal neurons. Aβ25-35 exposure reduced the viability of hippocampal neurons, decreased the peak amplitude of voltage-activated sodium channel currents (INa), and significantly reduced INa at different membrane potentials. Moreover, Aβ25-35 shifted the activation curve toward depolarization, shifted the inactivation curve toward hyperpolarization, and increased the time constant of recovery from inactivation. Aβ25-35 exposure significantly shifted the inactivation curve of transient outward K+ currents (IA) toward hyperpolarization and increased its time constant of recovery from inactivation. In addition, Aβ25-35 significantly decreased the peak density of outward-delayed rectifier potassium channel currents (IDR) and significantly reduced IDR value at different membrane potentials. We found that genistein partially reversed the decrease in hippocampal neuron viability, and the alterations in electrophysiological properties of NaV and KV induced by Aβ25-35. Our results suggest that genistein could inhibit Aβ25-35-induced neuronal damage with changes in the electrophysiological properties of NaV and KV.
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Coppi E, Lana D, Cherchi F, Fusco I, Buonvicino D, Urru M, Ranieri G, Muzzi M, Iovino L, Giovannini MG, Pugliese AM, Chiarugi A. Dexpramipexole enhances hippocampal synaptic plasticity and memory in the rat. Neuropharmacology 2018; 143:306-316. [PMID: 30291939 DOI: 10.1016/j.neuropharm.2018.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 09/19/2018] [Accepted: 10/02/2018] [Indexed: 01/22/2023]
Abstract
Even though pharmacological approaches able to counteract age-dependent cognitive impairment have been highly investigated, drugs improving cognition and memory are still an unmet need. It has been hypothesized that sustaining energy dynamics within the aged hippocampus can boost memory storage by sustaining synaptic functioning and long term potentiation (LTP). Dexpramipexole (DEX) is the first-in-class compound able to sustain neuronal bioenergetics by interacting with mitochondrial F1Fo-ATP synthase. In the present study, for the first time we evaluated the effects of DEX on synaptic fatigue, LTP induction, learning and memory retention. We report that DEX improved LTP maintenance in CA1 neurons of acute hippocampal slices from aged but not young rats. However, we found no evidence that DEX counteracted two classic parameters of synaptic fatigue such as fEPSP reduction or the train area during the high frequency stimulation adopted to induce LTP. Interestingly, patch-clamp recordings in rat hippocampal neurons revealed that DEX dose-dependently inhibited (IC50 814 nM) the IA current, a rapidly-inactivating K+ current that negatively regulates neuronal excitability as well as cognition and memory processes. In keeping with this, DEX counteracted both scopolamine-induced spatial memory loss in rats challenged in Morris Water Maze test and memory retention in rats undergoing Novel Object Recognition. Overall, the present study discloses the ability of DEX to boost hippocampal synaptic plasticity, learning and memory. In light of the good safety profile of DEX in humans, our findings may have a realistic translational potential to treatment of cognitive disorders.
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Affiliation(s)
- Elisabetta Coppi
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Italy.
| | - Daniele Lana
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Federica Cherchi
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Italy
| | - Irene Fusco
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Italy
| | - Daniela Buonvicino
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Matteo Urru
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Giuseppe Ranieri
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Mirko Muzzi
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Ludovica Iovino
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Italy
| | - Maria Grazia Giovannini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Anna Maria Pugliese
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Italy
| | - Alberto Chiarugi
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
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Kulikova AA, Makarov AA, Kozin SA. Roles of zinc ions and structural polymorphism of β-amyloid in the development of Alzheimer’s disease. Mol Biol 2015. [DOI: 10.1134/s0026893315020065] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Ping Y, Hahm ET, Waro G, Song Q, Vo-Ba DA, Licursi A, Bao H, Ganoe L, Finch K, Tsunoda S. Linking aβ42-induced hyperexcitability to neurodegeneration, learning and motor deficits, and a shorter lifespan in an Alzheimer's model. PLoS Genet 2015; 11:e1005025. [PMID: 25774758 PMCID: PMC4361604 DOI: 10.1371/journal.pgen.1005025] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 01/25/2015] [Indexed: 11/19/2022] Open
Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly. β-amyloid (Aβ) accumulation in the brain is thought to be a primary event leading to eventual cognitive and motor dysfunction in AD. Aβ has been shown to promote neuronal hyperactivity, which is consistent with enhanced seizure activity in mouse models and AD patients. Little, however, is known about whether, and how, increased excitability contributes to downstream pathologies of AD. Here, we show that overexpression of human Aβ42 in a Drosophila model indeed induces increased neuronal activity. We found that the underlying mechanism involves the selective degradation of the A-type K+ channel, Kv4. An age-dependent loss of Kv4 leads to an increased probability of AP firing. Interestingly, we find that loss of Kv4 alone results in learning and locomotion defects, as well as a shortened lifespan. To test whether the Aβ42-induced increase in neuronal excitability contributes to, or exacerbates, downstream pathologies, we transgenically over-expressed Kv4 to near wild-type levels in Aβ42-expressing animals. We show that restoration of Kv4 attenuated age-dependent learning and locomotor deficits, slowed the onset of neurodegeneration, and partially rescued premature death seen in Aβ42-expressing animals. We conclude that Aβ42-induced hyperactivity plays a critical role in the age-dependent cognitive and motor decline of this Aβ42-Drosophila model, and possibly in AD.
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Affiliation(s)
- Yong Ping
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Girma Waro
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Qian Song
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Dai-An Vo-Ba
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ashley Licursi
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Han Bao
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Logan Ganoe
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Kelly Finch
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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Gomes GM, Dalmolin GD, Cordeiro MDN, Gomez MV, Ferreira J, Rubin MA. The selective A-type K+ current blocker Tx3-1 isolated from the Phoneutria nigriventer venom enhances memory of naïve and Aβ(25-35)-treated mice. Toxicon 2013; 76:23-7. [PMID: 23994427 DOI: 10.1016/j.toxicon.2013.08.059] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/07/2013] [Accepted: 08/13/2013] [Indexed: 11/15/2022]
Abstract
Potassium channels regulate many neuronal functions, including neuronal excitability and synaptic plasticity, contributing, by these means, to mnemonic processes. In particular, A-type K(+) currents (IA) play a key role in hippocampal synaptic plasticity. Therefore, we evaluated the effect of the peptidic toxin Tx3-1, a selective blocker of IA currents, extracted from the venom of the spider Phoneutria nigriventer, on memory of mice. Administration of Tx3-1 (i.c.v., 300 pmol/site) enhanced both short- and long-term memory consolidation of mice tested in the novel object recognition task. In comparison, 4-aminopyridine (4-AP; i.c.v., 30-300 pmol/site), a non-selective K(+) channel blocker did not alter long-term memory and caused toxic side effects such as circling, freezing and tonic-clonic seizures. Moreover, Tx3-1 (i.c.v., 10-100 pmol/site) restored memory of Aβ25-35-injected mice, and exhibited a higher potency to improve memory of Aβ25-35-injected mice when compared to control group. These results show the effect of the selective blocker of IA currents Tx3-1 in both short- and long-term memory retention and in memory impairment caused by Aβ25-35, reinforcing the role of IA in physiological and pathological memory processes.
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Affiliation(s)
- Guilherme M Gomes
- Graduation Program in Biological Sciences, Toxicological Biochemistry, Building 18, Room 2203, Center of Exact and Natural Sciences, Federal University of Santa Maria, Santa Maria, RS 97105-900, Brazil
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7
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Leão RN, Colom LV, Borgius L, Kiehn O, Fisahn A. Medial septal dysfunction by Aβ-induced KCNQ channel-block in glutamatergic neurons. Neurobiol Aging 2012; 33:2046-61. [DOI: 10.1016/j.neurobiolaging.2011.07.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 11/30/2022]
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8
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Culmone V, Migliore M. Progressive effect of beta amyloid peptides accumulation on CA1 pyramidal neurons: a model study suggesting possible treatments. Front Comput Neurosci 2012; 6:52. [PMID: 22837746 PMCID: PMC3402026 DOI: 10.3389/fncom.2012.00052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 07/05/2012] [Indexed: 12/24/2022] Open
Abstract
Several independent studies show that accumulation of β-amyloid (Aβ) peptides, one of the characteristic hallmark of Alzheimer's Disease (AD), can affect normal neuronal activity in different ways. However, in spite of intense experimental work to explain the possible underlying mechanisms of action, a comprehensive and congruent understanding is still lacking. Part of the problem might be the opposite ways in which Aβ have been experimentally found to affect the normal activity of a neuron; for example, making a neuron more excitable (by reducing the A- or DR-type K+ currents) or less excitable (by reducing synaptic transmission and Na+ current). The overall picture is therefore confusing, since the interplay of many mechanisms makes it difficult to link individual experimental findings with the more general problem of understanding the progression of the disease. This is an important issue, especially for the development of new drugs trying to ameliorate the effects of the disease. We addressed these paradoxes through computational models. We first modeled the different stages of AD by progressively modifying the intrinsic membrane and synaptic properties of a realistic model neuron, while accounting for multiple and different experimental findings and by evaluating the contribution of each mechanism to the overall modulation of the cell's excitability. We then tested a number of manipulations of channel and synaptic activation properties that could compensate for the effects of Aβ. The model predicts possible therapeutic treatments in terms of pharmacological manipulations of channels' kinetic and activation properties. The results also suggest how and which mechanisms can be targeted by a drug to restore the original firing conditions.
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Affiliation(s)
- Viviana Culmone
- Institute of Biophysics, National Research Council Palermo, Italy
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9
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D'Amelio M, Rossini PM. Brain excitability and connectivity of neuronal assemblies in Alzheimer's disease: from animal models to human findings. Prog Neurobiol 2012; 99:42-60. [PMID: 22789698 DOI: 10.1016/j.pneurobio.2012.07.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 06/08/2012] [Accepted: 07/02/2012] [Indexed: 10/28/2022]
Abstract
The human brain contains about 100 billion neurons forming an intricate network of innumerable connections, which continuously adapt and rewire themselves following inputs from external and internal environments as well as the physiological synaptic, dendritic and axonal sculpture during brain maturation and throughout the life span. Growing evidence supports the idea that Alzheimer's disease (AD) targets selected and functionally connected neuronal networks and, specifically, their synaptic terminals, affecting brain connectivity well before producing neuronal loss and compartmental atrophy. The understanding of the molecular mechanisms underlying the dismantling of neuronal circuits and the implementation of 'clinically oriented' methods to map-out the dynamic interactions amongst neuronal assemblies will enhance early/pre-symptomatic diagnosis and monitoring of disease progression. More important, this will open the avenues to innovative treatments, bridging the gap between molecular mechanisms and the variety of symptoms forming disease phenotype. In the present review a set of evidence supports the idea that altered brain connectivity, exhausted neural plasticity and aberrant neuronal activity are facets of the same coin linked to age-related neurodegenerative dementia of Alzheimer type. Investigating their respective roles in AD pathophysiology will help in translating findings from basic research to clinical applications.
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Affiliation(s)
- Marcello D'Amelio
- IRCCS S. Lucia Foundation, Via del Fosso di Fiorano 65, 00143 Rome, Italy.
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10
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Solntseva EI, Bukanova JV, Marchenko EV, Skrebitsky VG. Impact of amyloid-β peptide (1-42) on voltage-gated ion currents in molluscan neurons. Bull Exp Biol Med 2012; 151:671-4. [PMID: 22485204 DOI: 10.1007/s10517-011-1412-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Different types of voltage-gated ion currents were recorded in isolated neurons of snail Helix pomatia using the two-microelectrode voltage-clamp technique. Application of amyloid-β peptide (1-42, 1-10 μM) in the bathing solution did not change delayed rectifier K(+)-current and leakage current, but enhanced inactivation of Ca(2+)-current and blocked Ca(2+)-dependent K(+)-current.
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Affiliation(s)
- E I Solntseva
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia.
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Garrido-Sanabria ER, Perez-Cordova MG, Colom LV. Differential expression of voltage-gated K+ currents in medial septum/diagonal band complex neurons exhibiting distinct firing phenotypes. Neurosci Res 2011; 70:361-9. [PMID: 21624401 PMCID: PMC3150140 DOI: 10.1016/j.neures.2011.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 04/22/2011] [Accepted: 05/09/2011] [Indexed: 01/28/2023]
Abstract
The medial septum/diagonal band complex (MSDB) controls hippocampal excitability, rhythms and plastic processes. Medial septal neuronal populations display heterogeneous firing patterns. In addition, some of these populations degenerate during age-related disorders (e.g. cholinergic neurons). Thus, it is particularly important to examine the intrinsic properties of theses neurons in order to create new agents that effectively modulate hippocampal excitability and enhance memory processes. Here, we have examined the properties of voltage-gated, K(+) currents in electrophysiologically-identified neurons. These neurons were taken from young rat brain slices containing the MS/DB complex. Whole-cell, patch recordings of outward currents were obtained from slow firing, fast-spiking, regular-firing and burst-firing neurons. Slow firing neurons showed depolarization-activated K(+) current peaks and densities larger than in other neuronal subtypes. Slow firing total current exhibited an inactivating A-type current component that activates at subthreshold depolarization and was reliably blocked by high concentrations of 4-AP. In addition, slow firing neurons expressed a low-threshold delayed rectifier K(+) current component with slow inactivation and intermediate sensitivity to tetraethylammonium. Fast-spiking neurons exhibited the smaller I(K) and I(A) current densities. Burst and regular firing neurons displayed an intermediate firing phenotype with I(K) and I(A) current densities that were larger than the ones observed in fast-spiking neurons but smaller than the ones observed in slow-firing neurons. In addition, the prevalence of each current differed among electrophysiological groups with slow firing and regular firing neurons expressing mostly I(A) and fast spiking and bursting neurons exhibiting mostly delayer rectifier K(+) currents with only minimal contributions of the I(A). The pharmacological or genetic modulations of these currents constitute an important target for the treatment of age-related disorders.
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Affiliation(s)
- Emilio R. Garrido-Sanabria
- Department of Biological Sciences, The Center for Biomedical Studies, The University of Texas at Brownsville, 80 Fort Brown, Brownsville, Texas 78520
| | - Miriam G. Perez-Cordova
- Department of Biological Sciences, The Center for Biomedical Studies, The University of Texas at Brownsville, 80 Fort Brown, Brownsville, Texas 78520
| | - Luis V. Colom
- Department of Biological Sciences, The Center for Biomedical Studies, The University of Texas at Brownsville, 80 Fort Brown, Brownsville, Texas 78520
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12
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Changes in the physiology of CA1 hippocampal pyramidal neurons in preplaque CRND8 mice. Neurobiol Aging 2011; 33:1609-23. [PMID: 21676499 DOI: 10.1016/j.neurobiolaging.2011.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 04/19/2011] [Accepted: 05/03/2011] [Indexed: 12/16/2022]
Abstract
Amyloid-β protein (Aβ) is thought to play a central pathogenic role in Alzheimer's disease. Aβ can impair synaptic transmission, but little is known about the effects of Aβ on intrinsic cellular properties. Here we compared the cellular properties of CA1 hippocampal pyramidal neurons in acute slices from preplaque transgenic (Tg+) CRND8 mice and wild-type (Tg-) littermates. CA1 pyramidal neurons from Tg+ mice had narrower action potentials with faster decays than neurons from Tg- littermates. Action potential-evoked intracellular Ca(2+) transients in the apical dendrite were smaller in Tg+ than in Tg- neurons. Resting calcium concentration was higher in Tg+ than in Tg- neurons. The difference in action potential waveform was eliminated by low concentrations of tetraethylammonium ions and of 4-aminopyridine, implicating a fast delayed-rectifier potassium current. Consistent with this suggestion, there was a small increase in immunoreactivity for Kv3.1b in stratum radiatum in Tg+ mice. These changes in intrinsic properties may affect information flow through the hippocampus and contribute to the behavioral deficits observed in mouse models and patients with early-stage Alzheimer's disease.
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Ray S, Howells C, Eaton ED, Butler CW, Shabala L, Adlard PA, West AK, Bennett WR, Guillemin GJ, Chung RS. Tg2576 cortical neurons that express human Ab are susceptible to extracellular Aβ-induced, K+ efflux dependent neurodegeneration. PLoS One 2011; 6:e19026. [PMID: 21556141 PMCID: PMC3083396 DOI: 10.1371/journal.pone.0019026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 03/13/2011] [Indexed: 11/25/2022] Open
Abstract
Background One of the key pathological features of AD is the formation of insoluble amyloid plaques. The major constituent of these extracellular plaques is the beta-amyloid peptide (Aβ), although Aβ is also found to accumulate intraneuronally in AD. Due to the slowly progressive nature of the disease, it is likely that neurons are exposed to sublethal concentrations of both intracellular and extracellular Aβ for extended periods of time. Results In this study, we report that daily exposure to a sublethal concentration of Aβ1-40 (1 µM) for six days induces substantial apoptosis of cortical neurons cultured from Tg2576 mice (which express substantial but sublethal levels of intracellular Aβ). Notably, untreated Tg2576 neurons of similar age did not display any signs of apoptosis, indicating that the level of intracellular Aβ present in these neurons was not the cause of toxicity. Furthermore, wildtype neurons did not become apoptotic under the same chronic Aβ1-40 treatment. We found that this apoptosis was linked to Tg2576 neurons being unable to maintain K+ homeostasis following Aβ treatment. Furthermore, blocking K+ efflux protected Tg2576 neurons from Aβ-induced neurotoxicity. Interestingly, chronic exposure to 1 µM Aβ1-40 caused the generation of axonal swellings in Tg2576 neurons that contained dense concentrations of hyperphosphorylated tau. These were not observed in wildtype neurons under the same treatment conditions. Conclusions Our data suggest that when neurons are chronically exposed to sublethal levels of both intra- and extra-cellular Aβ, this causes a K+-dependent neurodegeneration that has pathological characteristics similar to AD.
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Affiliation(s)
- Shannon Ray
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - Claire Howells
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - Emma D. Eaton
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - Chris W. Butler
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - Lana Shabala
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - Paul A. Adlard
- Synaptic Neurobiology Lab, Mental Health Research Institute, Melbourne, Victoria, Australia
| | - Adrian K. West
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - William R. Bennett
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
| | - Gilles J. Guillemin
- Neuroinflammation Group, University of New South Wales, Sydney, New South Wales, Australia
| | - Roger S. Chung
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
- * E-mail:
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Ziyatdinova S, Gurevicius K, Kutchiashvili N, Bolkvadze T, Nissinen J, Tanila H, Pitkänen A. Spontaneous epileptiform discharges in a mouse model of Alzheimer's disease are suppressed by antiepileptic drugs that block sodium channels. Epilepsy Res 2011; 94:75-85. [DOI: 10.1016/j.eplepsyres.2011.01.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 01/03/2011] [Accepted: 01/08/2011] [Indexed: 11/30/2022]
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Shabala L, Howells C, West AK, Chung RS. Prolonged Abeta treatment leads to impairment in the ability of primary cortical neurons to maintain K+ and Ca2+ homeostasis. Mol Neurodegener 2010; 5:30. [PMID: 20704753 PMCID: PMC2927593 DOI: 10.1186/1750-1326-5-30] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Accepted: 08/13/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterised by the formation of insoluble amyloidogenic plaques and neurofibrillary tangles. Beta amyloid (Abeta) peptide is one of the main constituents in Abeta plaques, and is thought to be a primary causative agent in AD. Neurons are likely to be exposed to chronic, sublethal doses of Abeta over an extended time during the pathogenesis of AD, however most studies published to date using in vitro models have focussed on acute studies. To experimentally model the progressive pathogenesis of AD, we exposed primary cortical neurons daily to 1 muM of Abeta1-40 over 7 days and compared their survival with age-similar untreated cells. We also investigated whether chronic Abeta exposure affects neuronal susceptibility to the subsequent acute excitotoxicity induced by 10 muM glutamate and assessed how Ca2+ and K+ homeostasis were affected by either treatment. RESULTS We show that continuous exposure to 1 muM Abeta1-40 for seven days decreased survival of cultured cortical neurons by 20%. This decrease in survival correlated with increased K+ efflux from the cells. One day treatment with 1 muM Abeta followed by glutamate led to a substantially higher K+ efflux than in the age-similar untreated control. This difference further increased with the duration of the treatment. K+ efflux also remained higher in Abeta treated cells 20 min after glutamate application leading to 2.8-fold higher total K+ effluxed from the cells compared to controls. Ca2+ uptake was significantly higher only after prolonged Abeta treatment with 2.5-fold increase in total Ca2+ uptake over 20 min post glutamate application after six days of Abeta treatment or longer (P < 0.05). CONCLUSIONS Our data suggest that long term exposure to Abeta is detrimental because it reduces the ability of cortical neurons to maintain K+ and Ca2+ homeostasis in response to glutamate challenge, a response that might underlie the early symptoms of AD. The observed inability to maintain K+ homeostasis might furthermore be useful in future studies as an early indicator of pathological changes in response to Abeta.
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Affiliation(s)
- Lana Shabala
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Private Bag 23, Hobart, Tasmania, 7001, Australia.
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16
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Randall AD, Witton J, Booth C, Hynes-Allen A, Brown JT. The functional neurophysiology of the amyloid precursor protein (APP) processing pathway. Neuropharmacology 2010; 59:243-67. [PMID: 20167227 DOI: 10.1016/j.neuropharm.2010.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Amyloid beta (Abeta) peptides derived from proteolytic cleavage of amyloid precursor protein (APP) are thought to be a pivotal toxic species in the pathogenesis of Alzheimer's disease (AD). Furthermore, evidence has been accumulating that components of APP processing pathway are involved in non-pathological normal function of the CNS. In this review we aim to cover the extensive body of research aimed at understanding how components of this pathway contribute to neurophysiological function of the CNS in health and disease. We briefly outline changes to clinical neurophysiology seen in AD patients before discussing functional changes in mouse models of AD which range from changes to basal synaptic transmission and synaptic plasticity through to abnormal synchronous network activity. We then describe the various neurophysiological actions that are produced by application of exogenous Abeta in various forms, and finally discuss a number or other neurophysiological aspects of the APP pathway, including functional activities of components of secretase complexes other than Abeta production.
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Affiliation(s)
- A D Randall
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol School of Medical Sciences, Bristol, UK.
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