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Caya-Bissonnette L, Béïque JC. Half a century legacy of long-term potentiation. Curr Biol 2024; 34:R640-R662. [PMID: 38981433 DOI: 10.1016/j.cub.2024.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
In 1973, two papers from Bliss and Lømo and from Bliss and Gardner-Medwin reported that high-frequency synaptic stimulation in the dentate gyrus of rabbits resulted in a long-lasting increase in synaptic strength. This form of synaptic plasticity, commonly referred to as long-term potentiation (LTP), was immediately considered as an attractive mechanism accounting for the ability of the brain to store information. In this historical piece looking back over the past 50 years, we discuss how these two landmark contributions directly motivated a colossal research effort and detail some of the resulting milestones that have shaped our evolving understanding of the molecular and cellular underpinnings of LTP. We highlight the main features of LTP, cover key experiments that defined its induction and expression mechanisms, and outline the evidence supporting a potential role of LTP in learning and memory. We also briefly explore some ramifications of LTP on network stability, consider current limitations of LTP as a model of associative memory, and entertain future research orientations.
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Affiliation(s)
- Léa Caya-Bissonnette
- Graduate Program in Neuroscience, University of Ottawa, 451 ch. Smyth Road (3501N), Ottawa, ON K1H 8M5, Canada; Brain and Mind Research Institute's Centre for Neural Dynamics and Artificial Intelligence, 451 ch. Smyth Road (3501N), Ottawa, ON K1H 8M5, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, 451 ch. Smyth Road (3501N), Ottawa, ON K1H 8M5, Canada
| | - Jean-Claude Béïque
- Brain and Mind Research Institute's Centre for Neural Dynamics and Artificial Intelligence, 451 ch. Smyth Road (3501N), Ottawa, ON K1H 8M5, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, 451 ch. Smyth Road (3501N), Ottawa, ON K1H 8M5, Canada.
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2
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Gall CM, Le AA, Lynch G. Sex differences in synaptic plasticity underlying learning. J Neurosci Res 2023; 101:764-782. [PMID: 33847004 PMCID: PMC10337639 DOI: 10.1002/jnr.24844] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 03/23/2021] [Indexed: 11/09/2022]
Abstract
Although sex differences in learning behaviors are well documented, sexual dimorphism in the synaptic processes of encoding is only recently appreciated. Studies in male rodents have built upon the discovery of long-term potentiation (LTP), and acceptance of this activity-dependent increase in synaptic strength as a mechanism of encoding, to identify synaptic receptors and signaling activities that coordinate the activity-dependent remodeling of the subsynaptic actin cytoskeleton that is critical for enduring potentiation and memory. These molecular substrates together with other features of LTP, as characterized in males, have provided an explanation for a range of memory phenomena including multiple stages of consolidation, the efficacy of spaced training, and the location of engrams at the level of individual synapses. In the present report, we summarize these findings and describe more recent results from our laboratories showing that in females the same actin regulatory mechanisms are required for hippocampal LTP and memory but, in females only, the engagement of both modulatory receptors such as TrkB and synaptic signaling intermediaries including Src and ERK1/2 requires neuron-derived estrogen and signaling through membrane-associated estrogen receptor α (ERα). Moreover, in association with the additional ERα involvement, females exhibit a higher threshold for hippocampal LTP and spatial learning. We propose that the distinct LTP threshold in females contributes to as yet unappreciated sex differences in information processing and features of learning and memory.
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Affiliation(s)
- Christine M. Gall
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
- Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - Aliza A. Le
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Gary Lynch
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA
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3
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Yin C, Harms AC, Hankemeier T, Kindt A, de Lange ECM. Status of Metabolomic Measurement for Insights in Alzheimer's Disease Progression-What Is Missing? Int J Mol Sci 2023; 24:ijms24054960. [PMID: 36902391 PMCID: PMC10003384 DOI: 10.3390/ijms24054960] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/24/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Alzheimer's disease (AD) is an aging-related neurodegenerative disease, leading to the progressive loss of memory and other cognitive functions. As there is still no cure for AD, the growth in the number of susceptible individuals represents a major emerging threat to public health. Currently, the pathogenesis and etiology of AD remain poorly understood, while no efficient treatments are available to slow down the degenerative effects of AD. Metabolomics allows the study of biochemical alterations in pathological processes which may be involved in AD progression and to discover new therapeutic targets. In this review, we summarized and analyzed the results from studies on metabolomics analysis performed in biological samples of AD subjects and AD animal models. Then this information was analyzed by using MetaboAnalyst to find the disturbed pathways among different sample types in human and animal models at different disease stages. We discuss the underlying biochemical mechanisms involved, and the extent to which they could impact the specific hallmarks of AD. Then we identify gaps and challenges and provide recommendations for future metabolomics approaches to better understand AD pathogenesis.
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Affiliation(s)
- Chunyuan Yin
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
- Division of Systems Pharmacology and Pharmacy, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Amy C. Harms
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Thomas Hankemeier
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Alida Kindt
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Elizabeth C. M. de Lange
- Division of Systems Pharmacology and Pharmacy, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
- Correspondence:
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4
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Brown TE, Sorg BA. Net gain and loss: influence of natural rewards and drugs of abuse on perineuronal nets. Neuropsychopharmacology 2023; 48:3-20. [PMID: 35568740 PMCID: PMC9700711 DOI: 10.1038/s41386-022-01337-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 12/26/2022]
Abstract
Overindulgence, excessive consumption, and a pattern of compulsive use of natural rewards, such as certain foods or drugs of abuse, may result in the development of obesity or substance use disorder, respectively. Natural rewards and drugs of abuse can trigger similar changes in the neurobiological substrates that drive food- and drug-seeking behaviors. This review examines the impact natural rewards and drugs of abuse have on perineuronal nets (PNNs). PNNs are specialized extracellular matrix structures that ensheathe certain neurons during development over the critical period to provide synaptic stabilization and a protective microenvironment for the cells they surround. This review also analyzes how natural rewards and drugs of abuse impact the density and maturation of PNNs within reward-associated circuitry of the brain, which may contribute to maladaptive food- and drug-seeking behaviors. Finally, we evaluate the relatively few studies that have degraded PNNs to perturb reward-seeking behaviors. Taken together, this review sheds light on the complex way PNNs are regulated by natural rewards and drugs and highlights a need for future studies to delineate the molecular mechanisms that underlie the modification and maintenance of PNNs following exposure to rewarding stimuli.
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Affiliation(s)
- Travis E Brown
- Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164, USA.
| | - Barbara A Sorg
- R.S. Dow Neurobiology, Legacy Research Institute, Portland, OR, 97232, USA
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5
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Dong TN, Kramár EA, Beardwood JH, Al-Shammari A, Wood MA, Keiser AA. Temporal endurance of exercise-induced benefits on hippocampus-dependent memory and synaptic plasticity in female mice. Neurobiol Learn Mem 2022; 194:107658. [PMID: 35811066 PMCID: PMC9901197 DOI: 10.1016/j.nlm.2022.107658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/20/2022] [Accepted: 07/04/2022] [Indexed: 02/08/2023]
Abstract
Exercise facilitates hippocampal neurogenesis and neuroplasticity that in turn, promotes cognitive function. Our previous studies have demonstrated that in male mice, voluntary exercise enables hippocampus-dependent learning in conditions that are normally subthreshold for long-term memory formation in sedentary animals. Such cognitive enhancement can be maintained long after exercise has ceased and can be re-engaged by a subsequent subthreshold exercise session, suggesting exercise-induced benefits are temporally dynamic. In females, the extent to which the benefits of exercise can be maintained and the mechanisms underlying this maintenance have yet to be defined. Here, we examined the exercise parameters required to initiate and maintain the benefits of exercise in female C57BL/6J mice. Using a subthreshold version of the hippocampus-dependent task called object-location memory (OLM) task, we show that 14d of voluntary exercise enables learning under subthreshold acquisition conditions in female mice. Following the initial exercise, a 7d sedentary delay results in diminished performance, which can be re-facilitated when animals receive 2d of reactivating exercise following the sedentary delay. Assessment of estrous cycle reveals enhanced wheel running activity during the estrus phase relative to the diestrus phase, whereas estrous phase on training or test had no effect on OLM performance. Utilizing the same exercise parameters, we demonstrate that 14d of exercise enhances long-term potentiation (LTP) in the CA1 region of the hippocampus, an effect that persists throughout the sedentary delay and following the reactivating exercise session. Previous studies have proposed exercise-induced BDNF upregulation as the mechanism underlying exercise-mediated benefits on synaptic plasticity and cognition. However, our assessment of hippocampal Bdnf mRNA expression following memory retrieval reveals no difference between exercise conditions and control, suggesting that persistent Bdnf upregulation may not be required for maintenance of exercise-induced benefits. Together, our data indicate that 14d of voluntary exercise can initiate long-lasting benefits on neuroplasticity and cognitive function in female mice, establishing the first evidence on the temporal endurance of exercise-induced benefits in females.
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Affiliation(s)
- T N Dong
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - E A Kramár
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - J H Beardwood
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - A Al-Shammari
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - M A Wood
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - A A Keiser
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States.
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6
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Thakre PP, Sunshine MD, Fuller DD. Spinally delivered ampakine CX717 increases phrenic motor output in adult rats. Respir Physiol Neurobiol 2022; 296:103814. [PMID: 34775071 PMCID: PMC9235873 DOI: 10.1016/j.resp.2021.103814] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/01/2021] [Accepted: 11/07/2021] [Indexed: 02/03/2023]
Abstract
Ampakines are synthetic molecules that allosterically modulate AMPA-type glutamate receptors. We tested the hypothesis that delivery of ampakines to the intrathecal space could stimulate neural drive to the diaphragm. Ampakine CX717 (20 mM, dissolved in 10 % HPCD) or an HPCD vehicle solution were delivered via a catheter placed in the intrathecal space at the fourth cervical segment in urethane-anesthetized, mechanically ventilated adult male Sprague-Dawley rats. The electrical activity of the phrenic nerve was recorded for 60-minutes following drug application. Intrathecal application of CX717 produced a gradual and sustained increase in phrenic inspiratory burst amplitude (n = 10). In contrast, application of HPCD (n = 10) caused no sustained change in phrenic motor output. Phrenic burst rate, heart rate, and mean arterial pressure were similar between CX717 and HPCD treated rats. We conclude that intrathecally delivered ampakines can modulate phrenic motor output. This approach may have value for targeted induction of spinal neuroplasticity in the context of neurorehabiliation.
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Affiliation(s)
- Prajwal P. Thakre
- Department of Physical Therapy, University of Florida, Gainesville, FL,Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL,McKnight Brain Institute, University of Florida, Gainesville, FL
| | - Michael D. Sunshine
- Department of Physical Therapy, University of Florida, Gainesville, FL,Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL,McKnight Brain Institute, University of Florida, Gainesville, FL
| | - David D. Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL,Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL,McKnight Brain Institute, University of Florida, Gainesville, FL,Corresponding author: David D. Fuller, Department of Physical Therapy, University of Florida, 1149 Newell Drive, Gainesville, FL 32611
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7
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Grande V, Hathazi D, O'Connor E, Marteau T, Schara-Schmidt U, Hentschel A, Gourdon G, Nikolenko N, Lochmüller H, Roos A. Dysregulation of GSK3β-Target Proteins in Skin Fibroblasts of Myotonic Dystrophy Type 1 (DM1) Patients. J Neuromuscul Dis 2021; 8:603-619. [PMID: 33682722 DOI: 10.3233/jnd-200558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is the most common monogenetic muscular disorder of adulthood. This multisystemic disease is caused by CTG repeat expansion in the 3'-untranslated region of the DM1 protein kinase gene called DMPK. DMPK encodes a myosin kinase expressed in skeletal muscle cells and other cellular populations such as smooth muscle cells, neurons and fibroblasts. The resultant expanded (CUG)n RNA transcripts sequester RNA binding factors leading to ubiquitous and persistent splicing deregulation. The accumulation of mutant CUG repeats is linked to increased activity of glycogen synthase kinase 3 beta (GSK3β), a highly conserved and ubiquitous serine/threonine kinase with functions in pathways regulating inflammation, metabolism, oncogenesis, neurogenesis and myogenesis. As GSK3β-inhibition ameliorates defects in myogenesis, muscle strength and myotonia in a DM1 mouse model, this kinase represents a key player of DM1 pathobiochemistry and constitutes a promising therapeutic target. To better characterise DM1 patients, and monitor treatment responses, we aimed to define a set of robust disease and severity markers linked to GSK3βby unbiased proteomic profiling utilizing fibroblasts derived from DM1 patients with low (80- 150) and high (2600- 3600) CTG-repeats. Apart from GSK3β increase, we identified dysregulation of nine proteins (CAPN1, CTNNB1, CTPS1, DNMT1, HDAC2, HNRNPH3, MAP2K2, NR3C1, VDAC2) modulated by GSK3β. In silico-based expression studies confirmed expression in neuronal and skeletal muscle cells and revealed a relatively elevated abundance in fibroblasts. The potential impact of each marker in the myopathology of DM1 is discussed based on respective function to inform potential uses as severity markers or for monitoring GSK3β inhibitor treatment responses.
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Affiliation(s)
- Valentina Grande
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Denisa Hathazi
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Emily O'Connor
- Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Theo Marteau
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Ulrike Schara-Schmidt
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Andreas Hentschel
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany
| | - Genevieve Gourdon
- Centre de Recherche en Myologie, Association Institut de Myologie, Sorbonne Université, Inserm UMR 974, Paris, France
| | - Nikoletta Nikolenko
- National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, UK
| | - Hanns Lochmüller
- Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Centro Nacional de AnálisisGenómico, Center for Genomic Regulation (CNAG-CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Andreas Roos
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany.,Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
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8
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Keiser AA, Kramár EA, Dong T, Shanur S, Pirodan M, Ru N, Acharya MM, Baulch JE, Limoli CL, Wood MA. Systemic HDAC3 inhibition ameliorates impairments in synaptic plasticity caused by simulated galactic cosmic radiation exposure in male mice. Neurobiol Learn Mem 2021; 178:107367. [PMID: 33359392 PMCID: PMC8456980 DOI: 10.1016/j.nlm.2020.107367] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/05/2020] [Accepted: 12/15/2020] [Indexed: 12/18/2022]
Abstract
Deep space travel presents a number of measurable risks including exposure to a spectrum of radiations of varying qualities, termed galactic cosmic radiation (GCR) that are capable of penetrating the spacecraft, traversing through the body and impacting brain function. Using rodents, studies have reported that exposure to simulated GCR leads to cognitive impairments associated with changes in hippocampus function that can persist as long as one-year post exposure with no sign of recovery. Whether memory can be updated to incorporate new information in mice exposed to GCR is unknown. Further, mechanisms underlying long lasting impairments in cognitive function as a result of GCR exposure have yet to be defined. Here, we examined whether whole body exposure to simulated GCR using 6 ions and doses of 5 or 30 cGy interfered with the ability to update an existing memory or impact hippocampal synaptic plasticity, a cellular mechanism believed to underlie memory processes, by examining long term potentiation (LTP) in acute hippocampal slices from middle aged male mice 3.5-5 months after radiation exposure. Using a modified version of the hippocampus-dependent object location memory task developed by our lab termed "Objects in Updated Locations" (OUL) task we find that GCR exposure impaired hippocampus-dependent memory updating and hippocampal LTP 3.5-5 months after exposure. Further, we find that impairments in LTP are reversed through one-time systemic subcutaneous injection of the histone deacetylase 3 inhibitor RGFP 966 (10 mg/kg), suggesting that long lasting impairments in cognitive function may be mediated at least in part, through epigenetic mechanisms.
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Affiliation(s)
- A A Keiser
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - E A Kramár
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - T Dong
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - S Shanur
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - M Pirodan
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States
| | - N Ru
- Department of Radiation Oncology, University of California, Irvine 92697-2695, United States
| | - M M Acharya
- Department of Radiation Oncology, University of California, Irvine 92697-2695, United States
| | - J E Baulch
- Department of Radiation Oncology, University of California, Irvine 92697-2695, United States
| | - C L Limoli
- Department of Radiation Oncology, University of California, Irvine 92697-2695, United States.
| | - M A Wood
- Department of Neurobiology and Behavior, School of Biological Sciences University of California, Irvine 92697-2695, United States; Center for the Neurobiology of Learning and Memory (CNLM), University of California, Irvine 92697-2695, United States; Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine 92697-2695, United States.
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9
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Matthews DB, Scaletty S, Schreiber A, Trapp S. Acute ethanol administration produces larger spatial and nonspatial memory impairments in 29-33 month old rats compared to adult and 18-24 month old rats. Pharmacol Biochem Behav 2020; 199:173074. [PMID: 33212145 DOI: 10.1016/j.pbb.2020.173074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 01/11/2023]
Abstract
The average age of the population in many countries is continuing to increase. Older people continue to consume alcohol, often in a binge like fashion. Previous research has demonstrated that older human subjects and aged animal subjects have an increased sensitivity to the effects of ethanol on a variety of behaviors. However, it has yet to be determined if acute ethanol exposure impairs spatial and/or nonspatial memory to a greater extent in aged rats compared to adult rats. In the current studies we trained male rats ranging in age from young adult (2 months of age) to aged rats (29-33 months of age) in the standard nonspatial task followed by the standard spatial task in the Morris water maze. Only animals deemed "cognitively-spared", that is aged animals that learn as well as young animals, were administered one of two doses of moderate ethanol and had their memory tested 30 min later. Acute ethanol administration produced similar performance impairments in spatial and nonspatial memory in all cognitively-spared animals except for the 29-33 month old animals which showed a significantly greater cognitive impairment in both tasks. In addition, blood ethanol levels were similar across all ages. The present work adds to the growing literature on the selective effects of acute ethanol exposure in aged animals.
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Affiliation(s)
- Douglas B Matthews
- Department of Psychology, University of Wisconsin - Eau Claire, Eau Claire, WI 54701, United States of America.
| | - Samantha Scaletty
- Department of Psychology, University of Wisconsin - Eau Claire, Eau Claire, WI 54701, United States of America
| | - Areonna Schreiber
- Department of Psychology, University of Wisconsin - Eau Claire, Eau Claire, WI 54701, United States of America
| | - Sarah Trapp
- Department of Psychology, University of Wisconsin - Eau Claire, Eau Claire, WI 54701, United States of America
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10
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Vithayathil J, Pucilowska J, Friel D, Landreth GE. Chronic impairment of ERK signaling in glutamatergic neurons of the forebrain does not affect spatial memory retention and LTP in the same manner as acute blockade of the ERK pathway. Hippocampus 2017; 27:1239-1249. [PMID: 28833860 DOI: 10.1002/hipo.22769] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 06/29/2017] [Accepted: 07/31/2017] [Indexed: 11/10/2022]
Abstract
The ERK/MAPK signaling pathway has been extensively studied in the context of learning and memory. Defects in this pathway underlie genetic diseases associated with intellectual disability, including impaired learning and memory. Numerous studies have investigated the impact of acute ERK/MAPK inhibition on long-term potentiation and spatial memory. However, genetic knockouts of the ERKs have not been utilized to determine whether developmental perturbations of ERK/MAPK signaling affect LTP and memory formation in postnatal life. In this study, two different ERK2 conditional knockout mice were generated that restrict loss of ERK2 to excitatory neurons in the forebrain, but at different time-points (embryonically and post-natally). We found that embryonic loss of ERK2 had minimal effect on spatial memory retention and novel object recognition, while loss of ERK2 post-natally had more pronounced effects in these behaviors. Loss of ERK2 in both models showed intact LTP compared to control animals, while loss of both ERK1 and ERK2 impaired late phase LTP. These findings indicate that ERK2 is not necessary for LTP and spatial memory retention and provide new insights into the functional deficits associated with the chronic impairment of ERK signaling.
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Affiliation(s)
- Joseph Vithayathil
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
| | - Joanna Pucilowska
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
| | - David Friel
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
| | - Gary E Landreth
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
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11
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HUANG J, ZHU X. The Molecular Mechanisms of Calpains Action on Skeletal Muscle Atrophy. Physiol Res 2016; 65:547-560. [DOI: 10.33549/physiolres.933087] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle atrophy is associated with a loss of muscle protein which may result from both increased proteolysis and decreased protein synthesis. Investigations on cell signaling pathways that regulate muscle atrophy have promoted our understanding of this complicated process. Emerging evidence implicates that calpains play key roles in dysregulation of proteolysis seen in muscle atrophy. Moreover, studies have also shown that abnormally activated calpain results muscle atrophy via its downstream effects on ubiquitin-proteasome pathway (UPP) and Akt phosphorylation. This review will discuss the role of calpains in regulation of skeletal muscle atrophy mainly focusing on its collaboration with either UPP or Akt in atrophy conditions in hope to stimulate the interest in development of novel therapeutic interventions for skeletal muscle atrophy.
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Affiliation(s)
| | - X. ZHU
- Department of Respiratory Diseases, YangPu Hospital of Tongji University, Shanghai, China
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12
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Abstract
INTRODUCTION Calpain is a family of cysteine proteases found in eukaryotes and a few bacteria. There is considerable interest in the search for calpain inhibitors because the enzyme has been implicated in several diseases including ocular disorders, neurodegenerative disorders, metabolic disorders and cancer. AREAS COVERED An overview of calpain inhibitors disclosed between 2012 and 2014 is presented. Among these are epoxysuccinates, dipeptide imaging agents, macrocyclic inhibitors, α-helical peptidomimetic inhibitors, carboxamides, 5-azolones and α-mercaptoacrylates. Additionally, preclinical studies of calpain inhibitors in pathologies such blood disorders, ocular disorders, neurological disorders and muscle disorders are discussed. EXPERT OPINION Major advances made in calpain inhibitor research between 2012 and 2014 include: i) the discovery of cytosolic-stable carboxamide calpain inhibitors; ii) synthesis of epoxysuccinates with excellent bioavailability; iii) disclosure of the X-ray crystal structures of novel α-mercaptoacrylates bound to the pentaEF hand region from human calpain; and iv) disclosure of calpain inhibitors as anti-sickling agents. Several calpain inhibitors were reported but limited effort was directed towards the discovery of calpain isoform selective agents, which continues to dampen the therapeutic potential of calpain inhibitors.
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Affiliation(s)
- Isaac O Donkor
- The University of Tennessee Health Science Center , Memphis, TN , USA
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13
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Posner MI, Tang YY, Lynch G. Mechanisms of white matter change induced by meditation training. Front Psychol 2014; 5:1220. [PMID: 25386155 PMCID: PMC4209813 DOI: 10.3389/fpsyg.2014.01220] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/08/2014] [Indexed: 12/12/2022] Open
Abstract
Training can induce changes in specific brain networks and changes in brain state. In both cases it has been found that the efficiency of white matter as measured by diffusion tensor imaging is increased, often after only a few hours of training. In this paper we consider a plausible molecular mechanism for how state change produced by meditation might lead to white matter change. According to this hypothesis frontal theta induced by meditation produces a molecular cascade that increases myelin and improves connectivity.
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Affiliation(s)
| | - Yi-Yuan Tang
- Department of Psychological Sciences, Texas Tech University Lubbock, TX, USA
| | - Gary Lynch
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine Irvine, CA, USA
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Neuhof C, Neuhof H. Calpain system and its involvement in myocardial ischemia and reperfusion injury. World J Cardiol 2014; 6:638-652. [PMID: 25068024 PMCID: PMC4110612 DOI: 10.4330/wjc.v6.i7.638] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 01/26/2014] [Accepted: 05/29/2014] [Indexed: 02/06/2023] Open
Abstract
Calpains are ubiquitous non-lysosomal Ca2+-dependent cysteine proteases also present in myocardial cytosol and mitochondria. Numerous experimental studies reveal an essential role of the calpain system in myocardial injury during ischemia, reperfusion and postischemic structural remodelling. The increasing Ca2+-content and Ca2+-overload in myocardial cytosol and mitochondria during ischemia and reperfusion causes an activation of calpains. Upon activation they are able to injure the contractile apparatus and impair the energy production by cleaving structural and functional proteins of myocytes and mitochondria. Besides their causal involvement in acute myocardial dysfunction they are also involved in structural remodelling after myocardial infarction by the generation and release of proapoptotic factors from mitochondria. Calpain inhibition can prevent or attenuate myocardial injury during ischemia, reperfusion, and in later stages of myocardial infarction.
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Lynch G, Cox CD, Gall CM. Pharmacological enhancement of memory or cognition in normal subjects. Front Syst Neurosci 2014; 8:90. [PMID: 24904313 PMCID: PMC4033242 DOI: 10.3389/fnsys.2014.00090] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 04/30/2014] [Indexed: 12/14/2022] Open
Abstract
The possibility of expanding memory or cognitive capabilities above the levels in high functioning individuals is a topic of intense discussion among scientists and in society at large. The majority of animal studies use behavioral endpoint measures; this has produced valuable information but limited predictability for human outcomes. Accordingly, several groups are pursuing a complementary strategy with treatments targeting synaptic events associated with memory encoding or forebrain network operations. Transcription and translation figure prominently in substrate work directed at enhancement. Notably, the question of why new proteins would be needed for a now-forming memory given that learning-driven synthesis presumably occurred throughout the immediate past has been largely ignored. Despite this conceptual problem, and some controversy, recent studies have reinvigorated the idea that selective gene manipulation is a plausible route to enhancement. Efforts to improve memory by facilitating synaptic encoding of information have also progressed, in part due of breakthroughs on mechanisms that stabilize learning-related, long-term potentiation (LTP). These advances point to a reductionistic hypothesis for a diversity of experimental results on enhancement, and identify under-explored possibilities. Cognitive enhancement remains an elusive goal, in part due to the difficulty of defining the target. The popular view of cognition as a collection of definable computations seems to miss the fluid, integrative process experienced by high functioning individuals. The neurobiological approach obviates these psychological issues to directly test the consequences of improving throughput in networks underlying higher order behaviors. The few relevant studies testing drugs that selectively promote excitatory transmission indicate that it is possible to expand cortical networks engaged by complex tasks and that this is accompanied by capabilities not found in normal animals.
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Affiliation(s)
- Gary Lynch
- Department of Psychiatry and Human Behavior, University of California Irvine, CA, USA ; Department of Anatomy and Neurobiology, University of California Irvine, CA, USA
| | - Conor D Cox
- Department of Anatomy and Neurobiology, University of California Irvine, CA, USA
| | - Christine M Gall
- Department of Anatomy and Neurobiology, University of California Irvine, CA, USA
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16
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Watterson LR, Olive MF. Are AMPA receptor positive allosteric modulators potential pharmacotherapeutics for addiction? Pharmaceuticals (Basel) 2013; 7:29-45. [PMID: 24380895 PMCID: PMC3915193 DOI: 10.3390/ph7010029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/13/2013] [Accepted: 12/24/2013] [Indexed: 01/01/2023] Open
Abstract
Positive allosteric modulators (PAMs) of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF) in an activity-dependent manner. Through these mechanisms, AMPA PAMs have shown promise as broad spectrum pharmacotherapeutics in preclinical and clinical studies for various neurodegenerative and psychiatric disorders. In recent years, a small collection of preclinical animal studies has also shown that AMPA PAMs may have potential as pharmacotherapeutic adjuncts to extinction-based or cue-exposure therapies for the treatment of drug addiction. The present paper will review this preclinical literature, discuss novel data collected in our laboratory, and recommend future research directions for the possible development of AMPA PAMs as anti-addiction medications.
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Affiliation(s)
- Lucas R Watterson
- Department of Psychology, Behavioral Neuroscience Area, Arizona State University, Tempe, AZ 85287, USA.
| | - M Foster Olive
- Department of Psychology, Behavioral Neuroscience Area, Arizona State University, Tempe, AZ 85287, USA
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17
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Dubiela FP, Queiroz CM, Moreira KDM, Nobrega JN, Sita LV, Tufik S, Hipolide DC. AMPA receptors mediate passive avoidance deficits induced by sleep deprivation. Behav Brain Res 2013; 257:189-96. [PMID: 24079994 DOI: 10.1016/j.bbr.2013.09.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/18/2013] [Accepted: 09/21/2013] [Indexed: 01/31/2023]
Abstract
The present study addressed the effects of sleep deprivation (SD) on AMPA receptor (AMPAR) binding in brain regions associated with learning and memory, and investigated whether treatment with drugs acting on AMPAR could prevent passive avoidance deficits in sleep deprived animals. [(3)H]AMPA binding and GluR1 in situ hybridization signals were quantified in different brain regions of male Wistar rats either immediately after 96 h of sleep deprivation or after 24h of sleep recovery following 96 h of sleep deprivation. Another group of animals were sleep deprived and then treated with either the AMPAR potentiator, aniracetam (25, 50 and 100mg/kg, acute administration) or the AMPAR antagonist GYKI-52466 (5 and 10mg/kg, acute and chronic administration) before passive avoidance training. Task performance was evaluated 2h and 24h after training. A significant reduction in [(3)H]AMPA binding was found in the hippocampal formation of SD animals, while no alterations were observed in GluR1 mRNA levels. The highest dose of aniracetam (100mg/kg) reverted SD-induced impairment of passive avoidance performance in both retention tests, whereas GYKI-52466 treatment had no effect. Pharmacological enhancement of AMPAR function may revert hippocampal-dependent learning impairments produced after SD. We argue that such effects might be associated with reduced AMPAR binding in the hippocampus of sleep deprived animals.
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18
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Kudryashova IV, Onufriev MV. The synchronous and reciprocal regulation of the activities of cysteine proteases associated with long-term plasticity. NEUROCHEM J+ 2013. [DOI: 10.1134/s1819712413010054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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19
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Samartgis JR, Schachte L, Hazi A, Crowe SF. Piracetam, an AMPAkine drug, facilitates memory consolidation in the day-old chick. Pharmacol Biochem Behav 2012; 103:353-8. [PMID: 22940587 DOI: 10.1016/j.pbb.2012.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 08/13/2012] [Accepted: 08/19/2012] [Indexed: 10/28/2022]
Abstract
Piracetam is an AMPAkine drug that may have a range of different mechanisms at the cellular level, and which has been shown to facilitate memory, amongst its other effects. This series of experiments demonstrated that a 10mg/kg dose of piracetam facilitated memory consolidation in the day-old chick when injected from immediately until 120min after weak training (i.e. using a 20% v/v concentration of methyl anthranilate) with the passive avoidance learning task. Administration of piracetam immediately after training led to memory facilitation which lasted for up to 24h following training. This dose of the AMPAkine was not shown to facilitate memory reconsolidation. These findings support the contention that application of the AMPAkine piracetam facilitates memory using a weak training task, and extend the range of actions previously noted with NMDA-related agents to those which also facilitate the AMPA receptor.
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Affiliation(s)
- Jodi R Samartgis
- School of Psychological Science, Faculty of Science, Technology and Engineering, La Trobe University, Bundoora, Victoria 3086, Australia
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20
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Cognitive enhancers: focus on modulatory signaling influencing memory consolidation. Pharmacol Biochem Behav 2011; 99:155-63. [PMID: 21236291 DOI: 10.1016/j.pbb.2010.12.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/20/2010] [Accepted: 12/22/2010] [Indexed: 12/24/2022]
Abstract
Biological research has unraveled many of the molecular and cellular mechanisms involved in the formation of long-lasting memory, providing new opportunities for the development of cognitive-enhancing drugs. Studies of drug enhancement of cognition have benefited from the use of pharmacological treatments given after learning, allowing the investigation of mechanisms regulating the consolidation phase of memory. Modulatory systems influencing consolidation processes include stress hormones and several neurotransmitter and neuropeptide systems. Here, we review some of the findings on memory enhancement by drug administration in animal models, and discuss their implications for the development of cognitive enhancers.
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21
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Wright JW, Harding JW. Contributions of matrix metalloproteinases to neural plasticity, habituation, associative learning and drug addiction. Neural Plast 2010; 2009:579382. [PMID: 20169175 PMCID: PMC2821634 DOI: 10.1155/2009/579382] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 11/22/2009] [Accepted: 12/15/2009] [Indexed: 12/13/2022] Open
Abstract
The premise of this paper is that increased expression of matrix metalloproteinases (MMPs) permits the reconfiguration of synaptic connections (i.e., neural plasticity) by degrading cell adhesion molecules (CAMs) designed to provide stability to those extracellular matrix (ECM) proteins that form scaffolding supporting neurons and glia. It is presumed that while these ECM proteins are weakened, and/or detached, synaptic connections can form resulting in new neural pathways. Tissue inhibitors of metalloproteinases (TIMPs) are designed to deactivate MMPs permitting the reestablishment of CAMs, thus returning the system to a reasonably fixed state. This review considers available findings concerning the roles of MMPs and TIMPs in reorganizing ECM proteins thus facilitating the neural plasticity underlying long-term potentiation (LTP), habituation, and associative learning. We conclude with a consideration of the influence of these phenomena on drug addiction, given that these same processes may be instrumental in the formation of addiction and subsequent relapse. However, our knowledge concerning the precise spatial and temporal relationships among the mechanisms of neural plasticity, habituation, associative learning, and memory consolidation is far from complete and the possibility that these phenomena mediate drug addiction is a new direction of research.
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Affiliation(s)
- John W Wright
- Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA.
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22
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Panza F, Solfrizzi V, Frisardi V, Imbimbo BP, Capurso C, D'Introno A, Colacicco AM, Seripa D, Vendemiale G, Capurso A, Pilotto A. Beyond the neurotransmitter-focused approach in treating Alzheimer's disease: drugs targeting beta-amyloid and tau protein. Aging Clin Exp Res 2009; 21:386-406. [PMID: 20154508 DOI: 10.1007/bf03327445] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Drugs currently used to treat Alzheimer's Disease (AD) have limited therapeutic value and do not affect the main neuropathological hallmarks of the disease, i.e., senile plaques and neurofibrillar tangles. Senile plaques are mainly formed of beta-amyloid (Abeta), a 42-aminoacid peptide. Neurofibrillar tangles are composed of paired helical filaments of hyperphosphorylated tau protein. New, potentially disease-modifying, therapeutic approaches are targeting Abeta and tau protein. Drugs directed against Abeta include active and passive immunization, that have been found to accelerate Abeta clearance from the brain. The most developmentally advanced monoclonal antibody directly targeting Abeta is bapineuzumab, now being studied in a large Phase III clinical trial. Compounds that interfere with proteases regulating Abeta formation from amyloid precursor protein (APP) are also actively pursued. The discovery of inhibitors of beta-secretase, the enzyme that regulates the first step of the amyloidogenic metabolism of APP, has been revealed to be particularly difficult due to inherent medicinal chemistry problems, and only one compound (CTS-21166) has reached clinical testing. Conversely, several compounds that inhibit gamma-secretase, the pivotal enzyme that generates Abeta, have been identified, the most advanced being LY-450139 (semagacestat), now in Phase III clinical development. Compounds that stimulate alpha-secretase, the enzyme responsible for the non-amyloidogenic metabolism of APP, are also being developed, and one of them, EHT-0202, has recently entered Phase II testing. Potent inhibitors of Abeta aggregation have also been identified, and one of such compounds, PBT-2, has provided encouraging neuropsychological results in a recently completed Phase II study. Therapeutic approaches directed against tau protein include inhibitors of glycogen synthase kinase- 3 (GSK-3), the enzyme responsible for tau phosphorylation and tau protein aggregation inhibitors. NP-12, a promising GSK-3 inhibitor, is being tested in a Phase II study, and methylthioninium chloride, a tau protein aggregation inhibitor, has given initial encouraging results in a 50-week study. With all these approaches on their way, the hope for disease-modifying therapy in this devastating disease may become a reality in the next 5 years.
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Affiliation(s)
- Francesco Panza
- Department of Geriatrics, Center for Aging Brain, Memory Unit, University of Bari, 70124, Bari, Italy.
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Turpin FR, Potier B, Dulong JR, Sinet PM, Alliot J, Oliet SHR, Dutar P, Epelbaum J, Mothet JP, Billard JM. Reduced serine racemase expression contributes to age-related deficits in hippocampal cognitive function. Neurobiol Aging 2009; 32:1495-504. [PMID: 19800712 DOI: 10.1016/j.neurobiolaging.2009.09.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 08/25/2009] [Accepted: 09/06/2009] [Indexed: 12/18/2022]
Abstract
To gain insight into the contribution of d-serine to impaired cognitive aging, we compared the metabolic pathway and content of the amino acid as well as d-serine-dependent synaptic transmission and plasticity in the hippocampus of young and old rats of the Wistar and Lou/C/Jall strains. Wistar rats display cognitive impairments with aging that are not found in the latter strain, which is therefore considered a model of healthy aging. Both mRNA and protein levels of serine racemase, the d-serine synthesizing enzyme, were decreased in the hippocampus but not in the cerebral cortex or cerebellum of aged Wistar rats, whereas the expression of d-amino acid oxidase, which degrades the amino acid, was not affected. Consequently, hippocampal levels of endogenous d-serine were significantly lower. In contrast, serine racemase expression and d-serine levels were not altered in the hippocampus of aged Lou/C/Jall rats. Ex vivo electrophysiological recordings in hippocampal slices showed a marked reduction in N-methyl-d-aspartate-receptor (NMDA-R)-mediated synaptic potentials and theta-burst-induced long-term potentiation (LTP) in the CA1 area of aged Wistar rats, which were restored by exogenous d-serine. In contrast, NMDA-R activation, LTP induction and responses to d-serine were not altered in aged Lou/C/Jall rats. These results further strengthen the notion that the serine racemase-dependent pathway is a prime target of hippocampus-dependent cognitive deficits with aging. Understanding the processes that specifically affect serine racemase during aging could thus provide key insights into the treatment of memory deficits in the elderly.
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Affiliation(s)
- F R Turpin
- Centre de Psychiatrie et Neurosciences, INSERM, UMR 894, Université Paris Descartes, Faculté de Médecine René Descartes, Paris, F-75014, France.
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24
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Bostrom N, Sandberg A. Cognitive enhancement: methods, ethics, regulatory challenges. SCIENCE AND ENGINEERING ETHICS 2009; 15:311-341. [PMID: 19543814 DOI: 10.1007/s11948-009-9142-5] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Accepted: 03/25/2009] [Indexed: 05/27/2023]
Abstract
Cognitive enhancement takes many and diverse forms. Various methods of cognitive enhancement have implications for the near future. At the same time, these technologies raise a range of ethical issues. For example, they interact with notions of authenticity, the good life, and the role of medicine in our lives. Present and anticipated methods for cognitive enhancement also create challenges for public policy and regulation.
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Affiliation(s)
- Nick Bostrom
- Future of Humanity Institute, Faculty of Philosophy & James Martin 21st Century School, Oxford University, Littlegate House, Oxford OX1 1PT, UK.
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25
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Bartus RT, Dean RL. Pharmaceutical treatment for cognitive deficits in Alzheimer's disease and other neurodegenerative conditions: exploring new territory using traditional tools and established maps. Psychopharmacology (Berl) 2009; 202:15-36. [PMID: 19011839 DOI: 10.1007/s00213-008-1365-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 10/02/2008] [Indexed: 12/21/2022]
Abstract
RATIONALE Over 30 years ago, we began to develop a nonhuman primate model to study cognitive deficits of age-related neurodegenerative diseases and their neuroanatomical-neurochemical underpinnings for purposes of translating this work toward first pharmacotherapies. This effort produced several notable findings that eventually received consensus support, which we have been asked to review. OBJECTIVES A discussion of these findings, in the context of issues and obstacles confronted and principles applied, might facilitate the development of even more effective models and treatments, not only for Alzheimer's disease (AD) but for many other disorders involving cognitive deficits. RESULTS Collectively, our research provided first evidence of the following: aged primates can be used as 'models' for human age-related neurodegenerative diseases; key cognitive deficits in early AD share important conceptual similarities to deficits in both aged monkeys as well as non-demented humans (e.g., age-associated memory impairment and mild cognitive impairment); pharmacological intervention can reduce age-related cognitive impairments in animals that are conceptually similar to those seen in human diseases, including AD; cholinergics would likely be the first approved therapeutics for AD; and that many other classes of drugs would not likely succeed. CONCLUSIONS Despite the early promise shown by behavioral/functional approaches to develop treatment strategies, the dramatic shift in focus away from behavioral outcomes in animal neurodegenerative research that began 20 years ago has compromised further progress and continues to impede our ability to understand how these diseases impair human cognition and what pathways might lead to effective therapies. Principles applied successfully in the past should provide guidance for facilitating efforts in the future.
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Affiliation(s)
- Raymond T Bartus
- Ceregene, Inc., 9381 Judicial Dr., Suite 130, San Diego, CA 92121, USA.
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26
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Gao XM, Elmer GI, Adams-Huet B, Tamminga CA. Social memory in mice: disruption with an NMDA antagonist and attenuation with antipsychotic drugs. Pharmacol Biochem Behav 2008; 92:236-42. [PMID: 19103218 DOI: 10.1016/j.pbb.2008.11.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 11/23/2008] [Accepted: 11/26/2008] [Indexed: 10/21/2022]
Abstract
Social recognition reflects the ability of one animal to learn and remember the identity of another. Animal models of social learning and memory are pertinent to several different CNS diseases involving disruptions in cognition. Moreover, the increased understanding of the basic biology of memory increases the likelihood of discovery of memory-enhancing treatments in these human diseases. In the present study, we investigated the effects of the non-competitive NMDA antagonist ketamine on social recognition in mice across a broad dose range (5-30 mg/kg) and time-course (60 min-7 days). We also tested the ability of two antipsychotic drugs, haloperidol and olanzapine, to block the ketamine effect. Our results show that mice demonstrate social recognition over a several day period, with loss of recognition between 3-7 days. Ketamine disrupts social memory at doses which do not affect task performance. Chronic oral administration of haloperidol or olanzapine attenuates these ketamine-induced effects on social recognition, tending to normalize the memory behavior. The neural mechanisms of these actions are not known, although medial temporal lobe memory systems have been implicated.
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Affiliation(s)
- Xue-Min Gao
- Department of Psychiatry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9127, United States
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27
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Brown TE, Wilson AR, Cocking DL, Sorg BA. Inhibition of matrix metalloproteinase activity disrupts reconsolidation but not consolidation of a fear memory. Neurobiol Learn Mem 2008; 91:66-72. [PMID: 18824238 DOI: 10.1016/j.nlm.2008.09.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 01/18/2023]
Abstract
The reconsolidation hypothesis posits that memories that have been reactivated can be either enhanced or disrupted by pharmacological manipulation. Synaptic plasticity is presumed to underlie the reconsolidation process. Matrix metalloproteinases are proteins that regulate the extracellular matrix involved in plasticity events, and these proteins have recently been shown to influence learning and memory. However, all studies on the role of matrix metalloproteinases in learning and memory have employed tasks that rely on contextual cues. The goal of this study was to determine the extent to which FN-439 would disrupt the consolidation and/or reconsolidation of a fear memory associated with a conditioned stimulus that signaled tone-shock pairings and that was independent of contextual cues. Male Sprague-Dawley rats were given infusions of FN-439 (35 microg intracerebroventricular) 30 min prior to conditioning (tone-shock paired association) or 30 min prior to a single reactivation session given 24h after conditioning. Administration of FN-439 did not disrupt consolidation of the freezing response when the tone (conditioned stimulus) was presented. In contrast, FN-439 infusion disrupted reconsolidation of the fear memory in a reactivation-dependent manner. The reduced freezing behavior was not due to a decrease in general anxiety levels, since FN-439 had no effect on the percent of open-arm time or open-arm entries in an elevated-plus maze task. Thus, we demonstrated for the first time that matrix metalloproteinase inhibition in the brain is capable of disrupting the reconsolidation of a tone-shock association memory that does not depend on contextual cues. The finding that a fear response to a previously paired conditioned stimulus can be disrupted by treatment with an MMP inhibitor during a single reactivation session suggests that this class of compounds may have therapeutic potential for posttraumatic stress disorder and/or simple phobias.
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Affiliation(s)
- Travis E Brown
- Alcohol and Drug Abuse Research Program and Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Stadium Way, Pullman, WA 99164-6520, USA
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28
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Francis PT. Glutamatergic approaches to the treatment of cognitive and behavioural symptoms of Alzheimer's disease. NEURODEGENER DIS 2008; 5:241-3. [PMID: 18322401 DOI: 10.1159/000113713] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The glutamatergic system has long been recognised for its role in learning and memory and recent studies indicate an early loss of glutamatergic synapses in Alzheimer's disease (AD). Efforts to produce drugs which address changes in the glutamatergic system in AD are well advanced (e.g. memantine and drugs in development such as ampakines). Much less is known about the possible role of glutamate in non-cognitive behavioural changes; however, recent data from clinical trials suggest that memantine reduces agitation and aggressive behaviour in AD patients. In this context, it is important to help identify new treatment approaches to replace the use of antipsychotics in this vulnerable population.
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Affiliation(s)
- Paul T Francis
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK.
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29
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Das SR, Magnusson KR. Relationship between mRNA expression of splice forms of the zeta1 subunit of the N-methyl-D-aspartate receptor and spatial memory in aged mice. Brain Res 2008; 1207:142-54. [PMID: 18374315 DOI: 10.1016/j.brainres.2008.02.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 02/05/2008] [Accepted: 02/17/2008] [Indexed: 10/22/2022]
Abstract
Age-related changes in the protein and mRNA expression of some of the splice forms of the zeta1 (NR1) subunit of the NMDA receptor have been seen in mice and rats. The present study was designed to determine whether individual splice forms of the zeta1 subunit of the NMDA receptor within prefrontal/frontal cortical regions contribute to memory deficits during aging and whether experience in learning tasks can influence the expression of the splice forms. mRNA expression of 4 splice forms (zeta1-1, zeta1-3, zeta1-a and zeta1-b) and mRNA for all known splice forms (zeta1-pan) were examined by in situ hybridization. mRNA for C-terminal splice forms, zeta1-1 (+ C1 and + C2 cassettes) and zeta1-3 (+ C1 and + C2'), showed significant declines during aging in several brain regions even though overall zeta1-pan mRNA expression was not significantly affected by aging. This suggests that these splice forms are more influenced by aging than the subunit as a whole. There was an increase in the expression of zeta1-a (-N1 cassette) splice form in the behaviorally-experienced old mice relative to the younger groups. Old mice with high levels of mRNA expression for the zeta1-a splice form in orbital cortex showed the best performances in the working memory task, but the poorest performances in the cued, associative learning task. These results suggest that there is a complex interaction between zeta1 splice form expression and performance of memory tasks during aging.
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Affiliation(s)
- Siba R Das
- Molecular and Cellular Biology Program and Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
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Wezenberg E, Verkes RJ, Ruigt GSF, Hulstijn W, Sabbe BGC. Acute effects of the ampakine farampator on memory and information processing in healthy elderly volunteers. Neuropsychopharmacology 2007; 32:1272-83. [PMID: 17119538 DOI: 10.1038/sj.npp.1301257] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ampakines act as positive allosteric modulators of AMPA-type glutamate receptors and facilitate hippocampal long-term potentiation (LTP), a mechanism associated with memory storage and consolidation. The present study investigated the acute effects of farampator, 1-(benzofurazan-5-ylcarbonyl) piperidine, on memory and information processes in healthy elderly volunteers. A double-blind, placebo-controlled, randomized, cross-over study was performed in 16 healthy, elderly volunteers (eight male, eight female; mean age 66.1, SD 4.5 years). All subjects received farampator (500 mg) and placebo. Testing took place 1 h after drug intake, which was around Tmax for farampator. Subjects performed tasks assessing episodic memory (wordlist learning and picture memory), working and short-term memory (N-back, symbol recall) and motor learning (maze task, pursuit rotor). Information processing was assessed with a tangled lines task, the symbol digit substitution test (SDST) and the continuous trail making test (CTMT). Farampator (500 mg) unequivocally improved short-term memory but appeared to impair episodic memory. Furthermore, it tended to decrease the number of switching errors in the CTMT. Drug-induced side effects (SEs) included headache, somnolence and nausea. Subjects with SEs had significantly higher plasma levels of farampator than subjects without SEs. Additional analyses revealed that in the farampator condition the group without SEs showed a significantly superior memory performance relative to the group with SEs. The positive results on short-term memory and the favorable trends in the trail making test (CTMT) are interesting in view of the development of ampakines in the treatment of Alzheimer's disease and schizophrenia.
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Affiliation(s)
- Elke Wezenberg
- Department of Psychiatry (966), Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
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31
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Abstract
Cognitive enhancement, the amplification or extension of core capacities of the mind, has become a major topic in bioethics. But cognitive enhancement is a prime example of a converging technology where individual disciplines merge and issues transcend particular local discourses. This article reviews currently available methods of cognitive enhancement and their likely near-term prospects for convergence.
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Affiliation(s)
- Anders Sandberg
- Oxford Uehiro Centre for Practical Ethics, Faculty of Philosophy, Oxford University, Littlegate House, 16/17 St. Ebbe's St. Oxford, OX1 1PT, United Kingdom.
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Wright JW, Brown TE, Harding JW. Inhibition of hippocampal matrix metalloproteinase-3 and -9 disrupts spatial memory. Neural Plast 2006; 2007:73813. [PMID: 17502908 PMCID: PMC1838960 DOI: 10.1155/2007/73813] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 09/21/2006] [Accepted: 09/26/2006] [Indexed: 11/24/2022] Open
Abstract
Memory consolidation requires synaptic reconfiguration dependent upon extracellular matrix (ECM) molecules interacting with cell adhesion molecules. Matrix metalloproteinase (MMP) activity is responsible for transient alterations in the ECM that may be prerequisite to hippocampal-dependent learning. In support of this hypothesis we have measured increases in MMP-3 and MMP-9 levels within the hippocampus and
prefrontal cortex during Morris water maze training. The present investigation extends these findings by determining that infusion of an MMP inhibitor (FN-439) into the dorsal hippocampus disrupted acquisition of this task. In vitro fluorescence enzyme assays to determine the specificity of FN-439 against the catalytic domains of MMP-3 and MMP-9 indicated mean ± SEM IC50s of 16.2 ± 7.8 and 210.5 ± 37.8 μM, respectively, while in situ zymography using hippocampal sections treated with FN-439 indicated significant reductions in MMP gelatinase activity. These results suggest that compromising the ability of the dorsal hippocampus to reconfigure ECM molecules by inhibiting MMP activity interferes with appropriate spatial
memory acquisition, and support a role for hippocampal MMPs in the phenomena of spatial memory acquisition and storage.
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Affiliation(s)
- John W. Wright
- Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University,
Pullman, WA 99164-6520, USA
- Programs in Neuroscience and Biotechnology, Washington State University, Pullman, WA 99164-6520, USA
- *John W. Wright:
| | - Travis E. Brown
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University,
Pullman, WA 99164-6520, USA
- Programs in Neuroscience and Biotechnology, Washington State University, Pullman, WA 99164-6520, USA
| | - Joseph W. Harding
- Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University,
Pullman, WA 99164-6520, USA
- Programs in Neuroscience and Biotechnology, Washington State University, Pullman, WA 99164-6520, USA
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Coitinho AS, Freitas ARO, Lopes MH, Hajj GNM, Roesler R, Walz R, Rossato JI, Cammarota M, Izquierdo I, Martins VR, Brentani RR. The interaction between prion protein and laminin modulates memory consolidation. Eur J Neurosci 2006; 24:3255-64. [PMID: 17156386 DOI: 10.1111/j.1460-9568.2006.05156.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cellular prion protein (PrPc) has a pivotal role in prion diseases. PrPc is a specific receptor for laminin (LN) gamma1 peptide and several lines of evidence indicate that it is also involved in neural plasticity. Here we investigated whether the interaction between PrPc and LN plays a role in rat memory formation. We found that post-training intrahippocampal infusion of PrPc-derived peptides that contain the LN binding site (PrPc163-182 and PrPc173-192) or of anti-PrPc or anti-LN antibodies that inhibit PrPc-LN interaction impaired inhibitory avoidance memory retention. The amnesic effect of anti-PrPc antibodies and PrPc173-192 peptide was reversed by co-infusion of a LN gamma1 chain-derived peptide containing the PrPc-binding site, suggesting that PrPc-LN interaction is indeed crucial for memory consolidation. In addition, PrPc173-192 peptide and anti-PrPc or anti-LN antibodies also inhibited the activation of hippocampal cAMP-dependent protein kinase A (PKA) and extracellular regulated kinase (ERK1/2), two kinases that mediate the up-regulation of signaling pathways needed for consolidation of inhibitory avoidance memory. Our findings show that, through its interaction with LN, hippocampal PrPc plays a critical role in memory processing and suggest that this role is mediated by activation of both PKA and ERK1/2 signaling pathways.
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Affiliation(s)
- Adriana S Coitinho
- Centro Universitário Feevale, Instituto de Ciências da Saúde, RS 239, 2755, 93352-000, Novo Hamburgo, RS, and Centro de Cirurgia de Epilepsia do Estado de Santa Catarina, Hospital Governador Celso Ramos, SC, Brazil
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Kudryashova IV, Kudryashov IE, Gulyaeva NV. Long-term potentiation in the hippocampus in conditions of inhibition of caspase-3: Analysis of facilitation in paired-pulse stimulation. ACTA ACUST UNITED AC 2006; 36:817-24. [PMID: 16964458 DOI: 10.1007/s11055-006-0092-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Indexed: 11/25/2022]
Abstract
Treatment of hippocampal slices with the caspase-3 inhibitor Z-DEVD-FMK led to a decrease in the magnitude of long-term potentiation (LTP), which developed over time. Testing with paired stimuli separated by an interval of 70 msec showed that after caspase-3 inhibition, as compared with control slices, the second response in the pair showed no increase in amplitude in conditions of LTP. In these conditions, the magnitude of LTP depended on differences in the amplitudes of the first and second responses before induction of LTP. LTP was absent in slices with initially highly efficient afferent stimulation and correspondingly low levels of facilitation in paired-pulse stimulation. It is suggested that inhibition of caspase-3 prevents the structural rearrangements in LTP associated with the involvement of new synapses and neurons in the response.
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Affiliation(s)
- I V Kudryashova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerov Street, 117485 Moscow, Russia
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35
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Lee JC, Hwang IK, Yoo KY, Kim DS, Kim WK, Won MH. Degradation of spectrin via calpains in the ventral horn after transient spinal cord ischemia in rabbits. Neurochem Res 2006; 31:989-98. [PMID: 16847592 DOI: 10.1007/s11064-006-9104-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2006] [Indexed: 11/27/2022]
Abstract
In the present study, we investigated chronological changes of mu-calpain, m-calpain and cleaved spectrin alphaII immunoreactivity in the ventral horn after transient spinal cord ischemia to investigate relationship between calpains and vulnerability to ischemia using abdominal aorta occlusion model in rabbits. Spinal cord sections at the level of L(7) were immunostained with calpains and cleaved spectrin alphaII monoclonal antibodies. mu-Calpain and m-calpain immunoreactivity was significantly increased in the ischemic ventral horn at 30 min and 1 h after ischemia/reperfusion, respectively. Thereafter, they were decreased with time after ischemia/reperfusion: at 48 h after ischemia, their immunoreactivities nearly disappeared in the ischemic ventral horn. Cleaved spectrin alphaII immunoreactivity was significantly increased in the ventral horn of spinal cord at 12 h after ischemia/reperfusion, and thereafter, its immunoreactivity was decreased with time after ischemia/reperfusion. In addition, spectrin alphaII protein level (280 kDa) was decreased from 12 h after ischemia/reperfusion; in contrast, cleaved spectrin alphaII protein level (150 kDa) was significantly increased at 12 h after ischemia/reperfusion. In conclusion, our observations in this study indicate that calpain is associated with neuronal degeneration in the ventral horn at early time after transient spinal cord ischemia via the proteolysis of spectrin alphaII.
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Affiliation(s)
- Jae-Chul Lee
- Department of Pharmacology, Ewha Medical School and Institute of Neuroscience, Ewha Womans University, Seoul 110-783, South Korea
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36
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Schechter LE, Ring RH, Beyer CE, Hughes ZA, Khawaja X, Malberg JE, Rosenzweig-Lipson S. Innovative approaches for the development of antidepressant drugs: current and future strategies. NeuroRx 2006; 2:590-611. [PMID: 16489368 PMCID: PMC1201318 DOI: 10.1602/neurorx.2.4.590] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Depression is a highly debilitating disorder that has been estimated to affect up to 21% of the world population. Despite the advances in the treatment of depression with selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs), there continue to be many unmet clinical needs with respect to both efficacy and side effects. These needs range from efficacy in treatment resistant patients, to improved onset, to reductions in side effects such as emesis or sexual dysfunction. To address these needs, there are numerous combination therapies and novel targets that have been identified that may demonstrate improvements in one or more areas. There is tremendous diversity in the types of targets and approaches being taken. At one end of a spectrum is combination therapies that maintain the benefits associated with SSRIs but attempt to either improve efficacy or reduce side effects by adding additional mechanisms (5-HT1A, 5-HT1B, 5-HT1D, 5-HT2C, alpha-2A). At the other end of the spectrum are more novel targets, such as neurotrophins (BDNF, IGF), based on recent findings that antidepressants induce neurogenesis. In between, there are many approaches that range from directly targeting serotonin receptors (5-HT2C, 5-HT6) to targeting the multiplicity of potential mechanisms associated with excitatory (glutamate, NMDA, mGluR2, mGluR5) or inhibitory amino acid systems (GABA) or peptidergic systems (neurokinin 1, corticotropin-releasing factor 1, melanin-concentrating hormone 1, V1b). The present review addresses the most exciting approaches and reviews the localization, neurochemical and behavioral data that provide the supporting rationale for each of these targets or target combinations.
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Affiliation(s)
- Lee E Schechter
- Discovery Neuroscience, Wyeth Research, CN 8000, Princeton, New Jersey 08543, USA.
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37
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Robilotto A, Baust J, Buskirk RV, Baust J. Involvement of the Cysteine Protease Calpain Family in Cell Death After Cryopreservation. ACTA ACUST UNITED AC 2006. [DOI: 10.1089/cpt.2006.4.17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- A.T. Robilotto
- Institute of Biomedical Technologies, State University of New York, Binghamton, New York
- Cell Preservation Services, Inc., Owego, New York
| | - J.M. Baust
- Institute of Biomedical Technologies, State University of New York, Binghamton, New York
- Cell Preservation Services, Inc., Owego, New York
| | - R. Van Buskirk
- Institute of Biomedical Technologies, State University of New York, Binghamton, New York
- Cell Preservation Services, Inc., Owego, New York
| | - J.G. Baust
- Institute of Biomedical Technologies, State University of New York, Binghamton, New York
- Biolife Solutions, Inc., Owego, New York
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38
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Meighan SE, Meighan PC, Choudhury P, Davis CJ, Olson ML, Zornes PA, Wright JW, Harding JW. Effects of extracellular matrix-degrading proteases matrix metalloproteinases 3 and 9 on spatial learning and synaptic plasticity. J Neurochem 2006; 96:1227-41. [PMID: 16464240 DOI: 10.1111/j.1471-4159.2005.03565.x] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Rats learning the Morris water maze exhibit hippocampal changes in synaptic morphology and physiology that manifest as altered synaptic efficacy. Learning requires structural changes in the synapse, and multiple cell adhesion molecules appear to participate. The activity of these cell adhesion molecules is, in large part, dependent on their interaction with the extracellular matrix (ECM). Given that matrix metalloproteinases (MMPs) are responsible for transient alterations in the ECM, we predicted that MMP function is critical for hippocampal-dependent learning. In support of this, it was observed that hippocampal MMP-3 and -9 increased transiently during water maze acquisition as assessed by western blotting and mRNA analysis. The ability of the NMDA receptor channel blocker MK801 to attenuate these changes indicated that the transient MMP changes were in large part dependent upon NMDA receptor activation. Furthermore, inhibition of MMP activity with MMP-3 and -9 antisense oligonucleotides and/or MMP inhibitor FN-439 altered long-term potentiation and prevented acquisition in the Morris water maze. The learning-dependent MMP alterations were shown to modify the stability of the actin-binding protein cortactin, which plays an essential role in regulating the dendritic cytoskeleton and synaptic efficiency. Together these results indicate that changes in MMP function are critical to synaptic plasticity and hippocampal-dependent learning.
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Affiliation(s)
- Starla E Meighan
- Department of Veterinary Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164, USA.
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39
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Abstract
Fragile X syndrome (FXS) is caused by the transcriptional silencing of the Fmr1 gene, which encodes a protein (FMRP) that can act as a translational suppressor in dendrites, and is characterized by a preponderance of abnormally long, thin and tortuous dendritic spines. According to a current theory of FXS, the loss of FMRP expression leads to an exaggeration of translation responses linked to group I metabotropic glutamate receptors. Such responses are involved in the consolidation of a form of long-term depression that is enhanced in Fmr1 knockout mice and in the elongation of dendritic spines, resembling synaptic phenotypes over-represented in fragile X brain. These observations place fragile X research at the heart of a long-standing issue in neuroscience. The consolidation of memory, and several distinct forms of synaptic plasticity considered to be substrates of memory, requires mRNA translation and is associated with changes in spine morphology. A recent convergence of research on FXS and on the involvement of translation in various forms of synaptic plasticity has been very informative on this issue and on mechanisms underlying FXS. Evidence suggests a general relationship in which the receptors that induce distinct forms of efficacy change differentially regulate translation to produce unique spine shapes involved in their consolidation. We discuss several potential mechanisms for differential translation and the notion that FXS represents an exaggeration of one 'channel' in a set of translation-dependent consolidation responses.
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Affiliation(s)
- P W Vanderklish
- Department of Neurobiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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40
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Suzuki E, Kessler M, Arai AC. C-terminal truncation affects kinetic properties of GluR1 receptors. Mol Cell Neurosci 2005; 29:1-10. [PMID: 15866042 DOI: 10.1016/j.mcn.2005.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 12/30/2004] [Accepted: 01/13/2005] [Indexed: 11/25/2022] Open
Abstract
GluR1flop receptors in which the C-terminal 52 amino acids had been recombinantly removed were characterized with whole-cell recording and binding assays. Compared to wildtype GluR1, truncated receptors showed faster desensitization and deactivation and they recovered more slowly from desensitization. The EC50 for glutamate was increased 2-fold. In binding tests, K(D)s for [3H]fluorowillardiine were 1.5 times larger for truncated receptors. According to receptor simulations, most differences can be explained if the C-terminal domain is assumed to stabilize the ligand-bound closed and open states. The effects on response waveforms are different from those caused by phosphorylation, suggesting that the C-terminus influences receptor function in multiple ways. Truncated forms of GluR1 identical or similar to the one examined here may also be generated by calcium-activated proteases during intense synaptic activity. The lowered affinity and faster inactivation of these receptors suggests that their presence does not represent a risk for neuronal viability.
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Affiliation(s)
- Erika Suzuki
- Department of Pharmacology, Southern Illinois University School of Medicine, MC 9629, 801 N. Rutledge, Room 3275, Springfield, IL 62702, USA
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41
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Pellerin L, Magistretti PJ. Ampakine CX546 bolsters energetic response of astrocytes: a novel target for cognitive-enhancing drugs acting as alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor modulators. J Neurochem 2005; 92:668-77. [PMID: 15659236 DOI: 10.1111/j.1471-4159.2004.02905.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutamate was previously shown to enhance aerobic glycolysis i.e. increase glucose utilization and lactate production with no change in oxygen levels, in mouse cortical astrocytes by a mechanism involving glutamate uptake. It is reported here that a similar response is produced in both hippocampal and cerebellar astrocytes. Application of the cognitive-enhancing drug CX546 promoted further enhancement of glucose utilization by astrocytes from each brain area following glutamate exposure. alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors represent the purported molecular target of cognitive-enhancing drugs such as CX546, and the presence of AMPA receptor subunits GluR1-4 was evidenced in astrocytes from all three regions by immunocytochemistry. AMPA itself did not stimulate aerobic glycolysis, but in the presence of CX546, a strong enhancement of glucose utilization and lactate production was obtained in cortical, hippocampal and cerebellar astrocytes. The effect of CX546 was concentration-dependent, with an EC(50) of 93.2 microm in cortical astrocytes. AMPA-induced glucose utilization in the presence of CX546 was prevented by the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the negative modulator GYKI 52466. In addition, the metabolic effect of CX546 in the presence of AMPA was mimicked by the AMPA receptor modulator cyclothiazide. Our data suggest that astrocyte energetics represents a novel target for cognitive-enhancing drugs acting as AMPA receptor modulators.
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Affiliation(s)
- Luc Pellerin
- Department of Physiology, University of Lausanne, 7 rue du Bugnon, 1005 Lausanne, Switzerland.
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42
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Wright JW, Harding JW. The brain angiotensin system and extracellular matrix molecules in neural plasticity, learning, and memory. Prog Neurobiol 2004; 72:263-93. [PMID: 15142685 DOI: 10.1016/j.pneurobio.2004.03.003] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2003] [Accepted: 03/18/2004] [Indexed: 01/25/2023]
Abstract
The brain renin-angiotensin system (RAS) has long been known to regulate several classic physiologies including blood pressure, sodium and water balance, cyclicity of reproductive hormones and sexual behaviors, and pituitary gland hormones. These physiologies are thought to be under the control of the angiotensin II (AngII)/AT1 receptor subtype system. The AT2 receptor subtype is expressed during fetal development and is less abundant in the adult. This receptor appears to oppose growth responses facilitated by the AT1 receptor, as well as growth factor receptors. Recent evidence points to an important contribution by the brain RAS to non-classic physiologies mediated by the newly discovered angiotensin IV (AngIV)/AT4 receptor subtype system. These physiologies include the regulation of blood flow, modulation of exploratory behavior, and a facilitory role in learning and memory acquisition. This system appears to interact with brain matrix metalloproteinases in order to modify extracellular matrix molecules thus permitting the synaptic remodeling critical to the neural plasticity presumed to underlie memory consolidation, reconsolidation, and retrieval. There is support for an inhibitory influence by AngII activation of the AT1 subtype, and a facilitory role by AngIV activation of the AT4 subtype, on neuronal firing rate, long-term potentiation, associative and spatial learning. The discovery of the AT4 receptor subtype, and its facilitory influence upon learning and memory, suggest an important role for the brain RAS in normal cognitive processing and perhaps in the treatment of dysfunctional memory disease states.
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Affiliation(s)
- John W Wright
- Department of Psychology, Washington State University, P.O. Box 644820, Pullman, WA 99164-4820, USA.
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43
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Abstract
Age-related memory impairment, a cognitive decline not clearly related to any gross pathology, is progressive and widespread in the population, although not universal. While the mechanisms of learning and memory remain incompletely understood, the study of their molecular mechanisms is already yielding promising approaches toward therapy for such "normal" declines in the efficiency of learning. This review presents the rationale and results for two such approaches. One approach, partial inhibition of the type IV cAMP specific phosphodiesterase, appears to act indirectly. Although little evidence supports an age-related decline in this system, considerable evidence indicates that this approach can facilitate the transition from short-term to long-term memory and thus counterbalance defects in long-term memory, which may be due to other causes. A second approach, inhibition of l-type voltage gated calcium channels (LVGCCs) may be a specific corrective for a molecular pathology of aging, as substantial evidence indicates that an ongoing increase occurs throughout the lifespan in the density of these channels in hippocampal pyramidal cells, with a concomitant reduction in cellular excitability. Because LVGCCs are also crucial to extinction, a paradigm of inhibitory learning, age-related memory impairment may be an unfortunate side effect of a developmental process necessary to the maturation of the ability to suppress inappropriate behavior, an interpretation consistent with the antagonistic pleiotropy theory of aging.
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Affiliation(s)
- Mark Barad
- Department of Psychiatry and Biobehavioral Sciences, Brain Research Institute, and Neuropsychiatric Institute, UCLA, Los Angeles, California, USA.
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44
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Hong SJ, Li H, Becker KG, Dawson VL, Dawson TM. Identification and analysis of plasticity-induced late-response genes. Proc Natl Acad Sci U S A 2004; 101:2145-50. [PMID: 14766980 PMCID: PMC357066 DOI: 10.1073/pnas.0305170101] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The excitatory neurotransmitter, glutamate, activates N-methyl-d-aspartate (NMDA) receptors to induce long-lasting synaptic changes through alterations in gene expression. It is believed that these long-lasting changes contribute to learning and memory, drug tolerance, and ischemic preconditioning. To identify NMDA-induced late-response genes, we used a powerful gene-identification method, differential analysis of primary cDNA library expression (DAzLE), and cDNA microarray from primary cortical neurons. We report here that a variety of genes, which we have named plasticity-induced genes (PLINGs), are up-regulated with differential expression patterns after NMDA receptor activation, indicating that there is a broad and dynamic range of long-lasting neuronal responses that occur through NMDA receptor activation. Our results provide a molecular dissection of the activity-dependent long-lasting neuronal responses induced by NMDA receptor activation.
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Affiliation(s)
- Suk Jin Hong
- Department of Neurology, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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45
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Sargsyan AR, Melkonyan AA, Papatheodoropoulos C, Mkrtchian HH, Kostopoulos GK. A model synapse that incorporates the properties of short- and long-term synaptic plasticity. Neural Netw 2003; 16:1161-77. [PMID: 13678620 DOI: 10.1016/s0893-6080(03)00135-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We propose a general computer model of a synapse, which incorporates mechanisms responsible for the realization of both short- and long-term synaptic plasticity-the two forms of experimentally observed plasticity that seem to be very significant for the performance of neuronal networks. The model consists of a presynaptic part based on the earlier 'double barrier synapse' model, and a postsynaptic compartment which is connected to the presynaptic terminal via a feedback, the sign and magnitude of which depend on postsynaptic Ca(2+) concentration. The feedback increases or decreases the amount of neurotransmitter which is in a ready for release state. The model adequately reproduced the phenomena of short- and long-term plasticity observed experimentally in hippocampal slices for CA3-CA1 synapses. The proposed model may be used in the investigation of certain real synapses to estimate their physiological parameters, and in the construction of realistic neuronal networks.
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Affiliation(s)
- Armen R Sargsyan
- Neuronal Systems Mathematical Modelling Laboratory, Orbeli Institute of Physiology, Yerevan, Armenia
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46
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The glycine transporter type 1 inhibitor N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine potentiates NMDA receptor-mediated responses in vivo and produces an antipsychotic profile in rodent behavior. J Neurosci 2003. [PMID: 12930797 DOI: 10.1523/jneurosci.23-20-07586.2003] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Glycine acts as a necessary coagonist for glutamate at the NMDA receptor (NMDAR) complex by binding to the strychnine-insensitive glycine-B binding site on the NR1 subunit. The fact that glycine is normally found in the brain and spinal cord at concentrations that exceed those required to saturate this site has led to the speculation that glycine normally saturates NMDAR-containing synapses in vivo. However, additional lines of evidence suggest that synaptic glycine may be efficiently regulated in synaptic areas by the glycine transporter type 1 (GlyT1). The recent description of a potent and selective GlyT1 inhibitor (N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine [NFPS]) provides a tool for evaluation of the hypothesis that inhibition of GlyT1 may increase synaptic glycine and thereby potentiate NMDAR function in vivo. In the present study, we found that (+)-NFPS demonstrated >10-fold greater activity in an in vitro functional glycine reuptake assay relative to the racemic compound. In vivo, (+/-)-NFPS significantly enhanced long-term potentiation in the hippocampal dentate gyrus induced by high-frequency electrical stimulation of the afferent perforant pathway. Furthermore, (+)-NFPS induced a pattern of c-Fos immunoreactivity comparable with the atypical antipsychotic clozapine and enhanced prepulse inhibition of the acoustic startle response in DBA/2J mice, a strain with low basal levels of prepulse inhibition. Collectively, these data suggest that selective inhibition of GlyT1 can enhance NMDAR-sensitive activity in vivo and also support the idea that GlyT1 may represent a novel target for developing therapeutics to treat disorders associated with NMDAR hypofunction.
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47
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Gulyaeva NV, Kudryashov IE, Kudryashova IV. Caspase activity is essential for long-term potentiation. J Neurosci Res 2003; 73:853-64. [PMID: 12949912 DOI: 10.1002/jnr.10730] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Slices from rat hippocampus were incubated with the caspase-3 inhibitor N-benzyloxycarbonyl-Asp-Glu-Val-Asp fluoromethylketone (Z-DEVD-FMK) or with the inactive peptide N-benzyloxycarbonyl-Phe-Ala fluoromethylketone (Z-Phe-Ala-FMK) for 30 min. The peptides changed neither input-output curves nor paired-pulse effects at 70-msec interpulse intervals, nor amplitudes of pop spikes in the CA1 region 1.0-6.9 hr after the incubation. Slices taken 1.0-1.4 hr after Z-DEVD-FMK or inactive peptide treatment demonstrated similar long-term potentiation (LTP) curves; however, LTP was suppressed significantly (P<0.001) 1.5-3.4 hr after Z-DEVD-FMK treatment when compared to the corresponding inactive peptide group. LTP magnitude correlated with time after Z-DEVD-FMK (r= -0.74; P<0.02) but did not depend on time after the inactive peptide treatment. After 3.5 hr, LTP was blocked completely. Z-DEVD-FMK did not have a significant effect on presynaptic function. The results are the first evidence that inhibition of caspase-3 significantly decreases or fully blocks LTP in the CA1 region and suggest that caspase-3 is essential for LTP. Candidate caspase-3 substrates that may be cleaved for LTP induction and maintenance are discussed.
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Affiliation(s)
- Natalia V Gulyaeva
- Department of Functional Biochemistry of the Nervous System, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia.
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48
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Abstract
Glutamate is the major transmitter of the brain and is involved in all aspects of cognitive function since it is the transmitter of cortical and hippocampal pyramidal neurones. Furthermore, glutamate and glutamate receptors are involved in long-term potentiation, a process believed to underlie learning and memory. Histological studies indicate loss of pyramidal neurones and their synapses in Alzheimer's disease (AD), this together with biochemical evidence suggests presynaptic (and postsynaptic) glutamatergic hypoactivity. This represents a 'double blow' as the activity of glutamatergic neurones is heavily influenced by the cholinergic system, which is also dysfunctional in AD. The clinical relevance of these changes is emphasised because glutamatergic and cholinergic dysfunction are strong correlates of cognitive decline in AD. The mechanism by which glutamatergic (and cholinergic) cells die is likely to be a combination of necrosis and apoptosis caused by a range of factors which include tangle formation and the effects of too much and too little glutamatergic neurotransmission.
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Affiliation(s)
- Paul T Francis
- Centre for Neuroscience Research, King's College London, London, UK.
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49
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Abstract
The calpain system originally comprised three molecules: two Ca2+-dependent proteases, mu-calpain and m-calpain, and a third polypeptide, calpastatin, whose only known function is to inhibit the two calpains. Both mu- and m-calpain are heterodimers containing an identical 28-kDa subunit and an 80-kDa subunit that shares 55-65% sequence homology between the two proteases. The crystallographic structure of m-calpain reveals six "domains" in the 80-kDa subunit: 1). a 19-amino acid NH2-terminal sequence; 2). and 3). two domains that constitute the active site, IIa and IIb; 4). domain III; 5). an 18-amino acid extended sequence linking domain III to domain IV; and 6). domain IV, which resembles the penta EF-hand family of polypeptides. The single calpastatin gene can produce eight or more calpastatin polypeptides ranging from 17 to 85 kDa by use of different promoters and alternative splicing events. The physiological significance of these different calpastatins is unclear, although all bind to three different places on the calpain molecule; binding to at least two of the sites is Ca2+ dependent. Since 1989, cDNA cloning has identified 12 additional mRNAs in mammals that encode polypeptides homologous to domains IIa and IIb of the 80-kDa subunit of mu- and m-calpain, and calpain-like mRNAs have been identified in other organisms. The molecules encoded by these mRNAs have not been isolated, so little is known about their properties. How calpain activity is regulated in cells is still unclear, but the calpains ostensibly participate in a variety of cellular processes including remodeling of cytoskeletal/membrane attachments, different signal transduction pathways, and apoptosis. Deregulated calpain activity following loss of Ca2+ homeostasis results in tissue damage in response to events such as myocardial infarcts, stroke, and brain trauma.
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Affiliation(s)
- Darrell E Goll
- Muscle Biology Group, University of Arizona, Tucson, AZ 85721, USA.
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50
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Leever JD, Clark S, Weeks AM, Partin KM. Identification of a site in GluR1 and GluR2 that is important for modulation of deactivation and desensitization. Mol Pharmacol 2003; 64:5-10. [PMID: 12815155 DOI: 10.1124/mol.64.1.5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid subtype of ionotropic glutamate receptors consists of rapidly gating ion channels. Positive modulation of channel gating may slow gating kinetics through at least two distinct mechanisms, evidenced by the predominant slowing of either the rate of receptor desensitization or the rate of offset after agonist withdrawal (deactivation). This study compares the actions of two positive allosteric modulators [cyclothiazide, which modulates desensitization, and 1-(1,4-benzodioxan-6-ylcarbonyl)piperidine (CX546), which modulates deactivation] in a mutant shown previously to impede modulation by cyclothiazide. These experiments test the hypothesis that the point mutation, GluR1(S493T), would also cause a loss of modulation by CX546. Wild-type GluR1 through -4 receptors were modulated by CX546, as assayed by the potentiation of steady-state currents in the Xenopus laevis oocyte expression system. CX546 potentiated steady-state currents of both splice isoforms of GluR1. Modulation by CX546 was completely abolished in GluR1(S493T) and its homolog, GluR2(S497T), although this mutation did not affect apparent agonist affinity in the absence of CX546. Thus, the GluR1(S493T) mutation has a similar impairment of modulation by either cyclothiazide or CX546, indicating that some residues at the subunit interface of glutamate receptors play an important role in channel deactivation and desensitization.
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Affiliation(s)
- J Duncan Leever
- Department of Biomedical Sciences, Colorado State University, 200 West Lake Street, Fort Collins, CO 80523-1617, USA
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