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King MK, Pardo M, Cheng Y, Downey K, Jope RS, Beurel E. Glycogen synthase kinase-3 inhibitors: Rescuers of cognitive impairments. Pharmacol Ther 2014; 141:1-12. [PMID: 23916593 PMCID: PMC3867580 DOI: 10.1016/j.pharmthera.2013.07.010] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 07/18/2013] [Indexed: 01/02/2023]
Abstract
Impairment of cognitive processes is a devastating outcome of many diseases, injuries, and drugs affecting the central nervous system (CNS). Most often, very little can be done by available therapeutic interventions to improve cognitive functions. Here we review evidence that inhibition of glycogen synthase kinase-3 (GSK3) ameliorates cognitive deficits in a wide variety of animal models of CNS diseases, including Alzheimer's disease, Fragile X syndrome, Down syndrome, Parkinson's disease, spinocerebellar ataxia type 1, traumatic brain injury, and others. GSK3 inhibitors also improve cognition following impairments caused by therapeutic interventions, such as cranial irradiation for brain tumors. These findings demonstrate that GSK3 inhibitors are able to ameliorate cognitive impairments caused by a diverse array of diseases, injury, and treatments. The improvements in impaired cognition instilled by administration of GSK3 inhibitors appear to involve a variety of different mechanisms, such as supporting long-term potentiation and diminishing long-term depression, promotion of neurogenesis, reduction of inflammation, and increasing a number of neuroprotective mechanisms. The potential for GSK3 inhibitors to repair cognitive deficits associated with many conditions warrants further investigation of their potential for therapeutic interventions, particularly considering the current dearth of treatments available to reduce loss of cognitive functions.
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Affiliation(s)
- Margaret K King
- Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Marta Pardo
- Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Yuyan Cheng
- Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Kimberlee Downey
- Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Richard S Jope
- Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Eléonore Beurel
- Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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Ikrar T, Guo N, He K, Besnard A, Levinson S, Hill A, Lee HK, Hen R, Xu X, Sahay A. Adult neurogenesis modifies excitability of the dentate gyrus. Front Neural Circuits 2013; 7:204. [PMID: 24421758 PMCID: PMC3872742 DOI: 10.3389/fncir.2013.00204] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 12/10/2013] [Indexed: 01/24/2023] Open
Abstract
Adult-born dentate granule neurons contribute to memory encoding functions of the dentate gyrus (DG) such as pattern separation. However, local circuit-mechanisms by which adult-born neurons partake in this process are poorly understood. Computational, neuroanatomical and electrophysiological studies suggest that sparseness of activation in the granule cell layer (GCL) is conducive for pattern separation. A sparse coding scheme is thought to facilitate the distribution of similar entorhinal inputs across the GCL to decorrelate overlapping representations and minimize interference. Here we used fast voltage-sensitive dye (VSD) imaging combined with laser photostimulation and electrical stimulation to examine how selectively increasing adult DG neurogenesis influences local circuit activity and excitability. We show that DG of mice with more adult-born neurons exhibits decreased strength of neuronal activation and more restricted excitation spread in GCL while maintaining effective output to CA3c. Conversely, blockade of adult hippocampal neurogenesis changed excitability of the DG in the opposite direction. Analysis of GABAergic inhibition onto mature dentate granule neurons in the DG of mice with more adult-born neurons shows a modest readjustment of perisomatic inhibitory synaptic gain without changes in overall inhibitory tone, presynaptic properties or GABAergic innervation pattern. Retroviral labeling of connectivity in mice with more adult-born neurons showed increased number of excitatory synaptic contacts of adult-born neurons onto hilar interneurons. Together, these studies demonstrate that adult hippocampal neurogenesis modifies excitability of mature dentate granule neurons and that this non-cell autonomous effect may be mediated by local circuit mechanisms such as excitatory drive onto hilar interneurons. Modulation of DG excitability by adult-born dentate granule neurons may enhance sparse coding in the GCL to influence pattern separation.
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Affiliation(s)
- Taruna Ikrar
- Department of Anatomy and Neurobiology, School of Medicine, University of California Irvine, CA, USA
| | - Nannan Guo
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA
| | - Kaiwen He
- Department of Biology, University of Maryland College Park, MD, USA ; The Solomon H. Snyder Department of Neuroscience, The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University Baltimore, MD, USA
| | - Antoine Besnard
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA
| | - Sally Levinson
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA
| | - Alexis Hill
- Division of Integrative Neuroscience, Departments of Neuroscience and Psychiatry, Department of Pharmacology, Columbia University New York, NY, USA
| | - Hey-Kyoung Lee
- Department of Biology, University of Maryland College Park, MD, USA ; The Solomon H. Snyder Department of Neuroscience, The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University Baltimore, MD, USA
| | - Rene Hen
- Division of Integrative Neuroscience, Departments of Neuroscience and Psychiatry, Department of Pharmacology, Columbia University New York, NY, USA
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California Irvine, CA, USA ; Department of Biomedical Engineering, University of California Irvine, CA, USA
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA ; Harvard Stem Cell Institute, Harvard University Boston, MA, USA ; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA
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Tapia-González S, Muñoz MD, Cuartero MI, Sánchez-Capelo A. Smad3 is required for the survival of proliferative intermediate progenitor cells in the dentate gyrus of adult mice. Cell Commun Signal 2013; 11:93. [PMID: 24330661 PMCID: PMC4029396 DOI: 10.1186/1478-811x-11-93] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 12/06/2013] [Indexed: 12/16/2022] Open
Abstract
Background New neurons are continuously being generated in the adult hippocampus, a phenomenon that is regulated by external stimuli, such as learning, memory, exercise, environment or stress. However, the molecular mechanisms underlying neuron production and how they are integrated into existing circuits under such physiological conditions remain unclear. Indeed, the intracellular modulators that transduce the extracellular signals are not yet fully understood. Results We show that Smad3, an intracellular molecule involved in the transforming growth factor (TGF)-β signaling cascade, is strongly expressed by granule cells in the dentate gyrus (DG) of adult mice, although the loss of Smad3 in null mutant mice does not affect their survival. Smad3 is also expressed by adult progenitor cells in the subgranular zone (SGZ) and more specifically, it is first expressed by Type 2 cells (intermediate progenitor cells). Its expression persists through the distinct cell stages towards that of the mature neuron. Interestingly, proliferative intermediate progenitor cells die in Smad3 deficiency, which is associated with a large decrease in the production of newborn neurons in Smad3 deficient mice. Smad3 signaling appears to influence adult neurogenesis fulfilling distinct roles in the rostral and mid-caudal regions of the DG. In rostral areas, Smad3 deficiency increases proliferation and promotes the cell cycle exit of undifferentiated progenitor cells. By contrast, Smad3 deficiency impairs the survival of newborn neurons in the mid-caudal region of the DG at early proliferative stages, activating apoptosis of intermediate progenitor cells. Furthermore, long-term potentiation (LTP) after high frequency stimulation (HFS) to the medial perforant path (MPP) was abolished in the DG of Smad3-deficient mice. Conclusions These data show that endogenous Smad3 signaling is central to neurogenesis and LTP induction in the adult DG, these being two forms of hippocampal brain plasticity related to learning and memory that decline with aging and as a result of neurological disorders.
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Affiliation(s)
| | | | | | - Amelia Sánchez-Capelo
- CIBERNED - Ser, Neurobiología-Investigación, Hospital Universitario Ramón y Cajal-IRYCIS, Ctra, Colmenar Viejo Km 9, 28034 Madrid, Spain.
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Abstract
In the adult mammalian brain, newly generated neurons are continuously incorporated into two networks: interneurons born in the subventricular zone migrate to the olfactory bulb, whereas the dentate gyrus (DG) of the hippocampus integrates locally born principal neurons. That the rest of the mammalian brain loses significant neurogenic capacity after the perinatal period suggests that unique aspects of the structure and function of DG and olfactory bulb circuits allow them to benefit from the adult generation of neurons. In this review, we consider the distinctive features of the DG that may account for it being able to profit from this singular form of neural plasticity. Approaches to the problem of neurogenesis are grouped as "bottom-up," where the phenotype of adult-born granule cells is contrasted to that of mature developmentally born granule cells, and "top-down," where the impact of altering the amount of neurogenesis on behavior is examined. We end by considering the primary implications of these two approaches and future directions.
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Affiliation(s)
- Liam J Drew
- Division of Integrative Neuroscience, Research Foundation for Mental Hygiene, New York State Psychiatric Institute, New York 10032, USA
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Canovas-Jorda D, Louisse J, Pistollato F, Zagoura D, Bremer S. Regenerative toxicology: the role of stem cells in the development of chronic toxicities. Expert Opin Drug Metab Toxicol 2013; 10:39-50. [PMID: 24102433 DOI: 10.1517/17425255.2013.844228] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Human stem cell lines and their derivatives, as alternatives to the use of animal cells or cancer cell lines, have been widely discussed as cellular models in predictive toxicology. However, the role of stem cells in the development of long-term toxicities and carcinogenesis has not received great attention so far, despite growing evidence indicating the relationship of stem cell damage to adverse effects later in life. However, testing this in vitro is a scientific/technical challenge in particular due to the complex interplay of factors existing under physiological conditions. Current major research programs in stem cell toxicity are not aiming to demonstrate that stem cells can be targeted by toxicants. Therefore, this knowledge gap needs to be addressed in additional research activities developing technical solutions and defining appropriate experimental designs. AREAS COVERED The current review describes selected examples of the role of stem cells in the development of long-term toxicities in the brain, heart or liver and in the development of cancer. EXPERT OPINION The presented examples illustrate the need to analyze the contribution of stem cells to chronic toxicity in order to make a final conclusion whether stem cell toxicities are an underestimated risk in mechanism-based safety assessments. This requires the development of predictive in vitro models allowing the assessment of adverse effects to stem cells on chronic toxicity and carcinogenicity.
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Affiliation(s)
- David Canovas-Jorda
- Institute for Health and Consumer Protection, DG Joint Research Centre (JRC), European Commission, Systems Toxicology Unit , Via E. Fermi 2749, TP 580, 21027 Ispra (VA) , Italy +39 0332 785914 ; +39 0332 785336 ;
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Sultan S, Gebara EG, Moullec K, Toni N. D-serine increases adult hippocampal neurogenesis. Front Neurosci 2013; 7:155. [PMID: 24009551 PMCID: PMC3756301 DOI: 10.3389/fnins.2013.00155] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/12/2013] [Indexed: 12/16/2022] Open
Abstract
Adult hippocampal neurogenesis results in the continuous formation of new neurons and is a process of brain plasticity involved in learning and memory. The neurogenic niche regulates the stem cell proliferation and the differentiation and survival of new neurons and a major contributor to the neurogenic niche are astrocytes. Among the molecules secreted by astrocytes, D-serine is an important gliotransmitter and is a co-agonist of the glutamate, N-methyl-D-aspartate (NMDA) receptor. D-serine has been shown to enhance the proliferation of neural stem cells in vitro, but its effect on adult neurogenesis in vivo is unknown. Here, we tested the effect of exogenous administration of D-serine on adult neurogenesis in the mouse dentate gyrus. We found that 1 week of treatment with D-serine increased cell proliferation in vivo and in vitro and increased the density of neural stem cells and transit amplifying progenitors. Furthermore, D-serine increased the survival of newborn neurons. Together, these results indicate that D-serine treatment resulted in the improvement of several steps of adult neurogenesis in vivo.
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Affiliation(s)
- Sebastien Sultan
- Department of Fundamental Neurosciences, University of Lausanne Lausanne, Switzerland
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Sultan S, Gebara E, Toni N. Doxycycline increases neurogenesis and reduces microglia in the adult hippocampus. Front Neurosci 2013; 7:131. [PMID: 23898238 PMCID: PMC3722480 DOI: 10.3389/fnins.2013.00131] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/08/2013] [Indexed: 11/13/2022] Open
Abstract
Adult hippocampal neurogenesis results in the continuous formation of new neurons and is a process of brain plasticity involved in learning and memory. Although inducible-reversible transgenic mouse models are increasingly being used to investigate adult neurogenesis, transgene control requires the administration of an activator, doxycycline (Dox), with unknown effects on adult neurogenesis. Here, we tested the effect of Dox administration on adult neurogenesis in vivo. We found that 4 weeks of Dox treatment at doses commonly used for gene expression control, resulted in increased neurogenesis. Furthermore, the dendrites of new neurons displayed increased spine density. Concomitantly, Iba1-expressing microglia was reduced by Dox treatment. These results indicate that Dox treatment may interfere with parameters of relevance for the use of inducible transgenic mice in studies of adult neurogenesis or brain inflammation.
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Affiliation(s)
- Sebastien Sultan
- Department of Fundamental Neurosciences, University of Lausanne Lausanne, Switzerland
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Konefal S, Elliot M, Crespi B. The adaptive significance of adult neurogenesis: an integrative approach. Front Neuroanat 2013; 7:21. [PMID: 23882188 PMCID: PMC3712125 DOI: 10.3389/fnana.2013.00021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 06/18/2013] [Indexed: 01/15/2023] Open
Abstract
Adult neurogenesis in mammals is predominantly restricted to two brain regions, the dentate gyrus (DG) of the hippocampus and the olfactory bulb (OB), suggesting that these two brain regions uniquely share functions that mediate its adaptive significance. Benefits of adult neurogenesis across these two regions appear to converge on increased neuronal and structural plasticity that subserves coding of novel, complex, and fine-grained information, usually with contextual components that include spatial positioning. By contrast, costs of adult neurogenesis appear to center on potential for dysregulation resulting in higher risk of brain cancer or psychological dysfunctions, but such costs have yet to be quantified directly. The three main hypotheses for the proximate functions and adaptive significance of adult neurogenesis, pattern separation, memory consolidation, and olfactory spatial, are not mutually exclusive and can be reconciled into a simple general model amenable to targeted experimental and comparative tests. Comparative analysis of brain region sizes across two major social-ecological groups of primates, gregarious (mainly diurnal haplorhines, visually-oriented, and in large social groups) and solitary (mainly noctural, territorial, and highly reliant on olfaction, as in most rodents) suggest that solitary species, but not gregarious species, show positive associations of population densities and home range sizes with sizes of both the hippocampus and OB, implicating their functions in social-territorial systems mediated by olfactory cues. Integrated analyses of the adaptive significance of adult neurogenesis will benefit from experimental studies motivated and structured by ecologically and socially relevant selective contexts.
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Affiliation(s)
- Sarah Konefal
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montreal General HospitalMontreal, QC, Canada
| | - Mick Elliot
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, BC, Canada
| | - Bernard Crespi
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, BC, Canada
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Cardenas-Aguayo MDC, Kazim SF, Grundke-Iqbal I, Iqbal K. Neurogenic and neurotrophic effects of BDNF peptides in mouse hippocampal primary neuronal cell cultures. PLoS One 2013; 8:e53596. [PMID: 23320097 PMCID: PMC3539976 DOI: 10.1371/journal.pone.0053596] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/30/2012] [Indexed: 12/11/2022] Open
Abstract
The level of brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, is down regulated in Alzheimer’s disease (AD), Parkinson’s disease (PD), depression, stress, and anxiety; conversely the level of this neurotrophin is increased in autism spectrum disorders. Thus, modulating the level of BDNF can be a potential therapeutic approach for nervous system pathologies. In the present study, we designed five different tetra peptides (peptides B-1 to B-5) corresponding to different active regions of BDNF. These tetra peptides were found to be non-toxic, and they induced the expression of neuronal markers in mouse embryonic day 18 (E18) primary hippocampal neuronal cultures. Additionally, peptide B-5 induced the expression of BDNF and its receptor, TrkB, suggesting a positive feedback mechanism. The BDNF peptides induced only a moderate activation (phosphorylation at Tyr 706) of the TrkB receptor, which could be blocked by the Trk’s inhibitor, K252a. Peptide B-3, when combined with BDNF, potentiated the survival effect of this neurotrophin on H2O2-treated E18 hippocampal cells. Peptides B-3 and B-5 were found to work as partial agonists and as partial antagonists competing with BDNF to activate the TrkB receptor in a dose-dependent manner. Taken together, these results suggest that the described BDNF tetra peptides are neurotrophic, can modulate BDNF signaling in a partial agonist/antagonist way, and offer a novel therapeutic approach to neural pathologies where BDNF levels are dysregulated.
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Affiliation(s)
- Maria del Carmen Cardenas-Aguayo
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Syed Faraz Kazim
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
- Neural and Behavioral Science Graduate Program, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America
| | - Inge Grundke-Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Khalid Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
- * E-mail:
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Shipman SL, Nicoll RA. A subtype-specific function for the extracellular domain of neuroligin 1 in hippocampal LTP. Neuron 2012; 76:309-16. [PMID: 23083734 DOI: 10.1016/j.neuron.2012.07.024] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2012] [Indexed: 12/27/2022]
Abstract
At neuronal excitatory synapses, two major subtypes of the synaptic adhesion molecule neuroligin are present. These subtypes, neuroligin 1 and neuroligin 3, have roles in synaptogenesis and synaptic maintenance that appear largely overlapping. In this study, we combine electrophysiology with molecular deletion and replacement of these proteins to identify similarities and differences between these subtypes. In doing so, we identify a subtype-specific role in LTP for neuroligin 1 in young CA1, which persists into adulthood in the dentate gyrus. As neuroligin 3 showed no requirement for LTP, we constructed chimeric proteins of the two excitatory neuroligin subtypes to identify the molecular determinants particular to the unique function of neuroligin 1. Using in vivo molecular replacement experiments, we find that these unique functions depend on a region in its extracellular domain containing the B site splice insertion previously shown to determine specificity of neurexin binding.
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Affiliation(s)
- Seth L Shipman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
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Gu Z, Liu Y, Zhang Y, Jin S, Chen Q, Goltzman D, Karaplis A, Miao D. Absence of PTHrP nuclear localization and carboxyl terminus sequences leads to abnormal brain development and function. PLoS One 2012; 7:e41542. [PMID: 22844494 PMCID: PMC3402381 DOI: 10.1371/journal.pone.0041542] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 06/22/2012] [Indexed: 11/18/2022] Open
Abstract
We assessed whether the nuclear localization sequences (NLS) and C terminus of parathyroid hormone-related protein (PTHrP) play critical roles in brain development and function. We used histology, immunohistochemistry, histomorphometry, Western blots and electrophysiological recordings to compare the proliferation and differentiation of neural stem cells, neuronal hippocampal synaptic transmission, and brain phenotypes including shape and structures, in Pthrp knock-in mice, which express PTHrP (1–84), a truncated form of the protein that is missing the NLS and the C-terminal region of the protein, and their wild-type littermates. Results showed that Pthrp knock-in mice display abnormal brain shape and structures; decreased neural cell proliferative capacity and increased apoptosis associated with up-regulation of cyclin dependent kinase inhibitors p16, p21, p27 and p53 and down-regulation of the Bmi-1 oncogene; delayed neural cell differentiation; and impaired hippocampal synaptic transmission and plasticity. These findings provide in vivo experimental evidence that the NLS and C-terminus of PTHrP are essential not only for the regulation of neural cell proliferation and differentiation, but also for the maintenance of normal neuronal synaptic transmission and plasticity.
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Affiliation(s)
- Zhen Gu
- State Key Laboratory of Reproductive Medicine, The Research Center for Bone and Stem Cells, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
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Nuclear factor of activated T cells (NFATc4) is required for BDNF-dependent survival of adult-born neurons and spatial memory formation in the hippocampus. Proc Natl Acad Sci U S A 2012; 109:E1499-508. [PMID: 22586092 DOI: 10.1073/pnas.1202068109] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
New neurons generated in the adult dentate gyrus are constantly integrated into the hippocampal circuitry and activated during encoding and recall of new memories. Despite identification of extracellular signals that regulate survival and integration of adult-born neurons such as neurotrophins and neurotransmitters, the nature of the intracellular modulators required to transduce those signals remains elusive. Here, we provide evidence of the expression and transcriptional activity of nuclear factor of activated T cell c4 (NFATc4) in hippocampal progenitor cells. We show that NFATc4 calcineurin-dependent activity is required selectively for survival of adult-born neurons in response to BDNF signaling. Indeed, cyclosporin A injection and stereotaxic delivery of the BDNF scavenger TrkB-Fc in the mouse dentate gyrus reduce the survival of hippocampal adult-born neurons in wild-type but not in NFATc4(-/-) mice and do not affect the net rate of neural precursor proliferation and their fate commitment. Furthermore, associated with the reduced survival of adult-born neurons, the absence of NFATc4 leads to selective defects in LTP and in the encoding of hippocampal-dependent spatial memories. Thus, our data demonstrate that NFATc4 is essential in the regulation of adult hippocampal neurogenesis and identify NFATc4 as a central player of BDNF-driven prosurvival signaling in hippocampal adult-born neurons.
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Abstract
Adult neurogenesis occurs in the dentate gyrus of the hippocampus, which is a key structure in learning and memory. It is believed that adult-born neurons exert their unique role in information processing due to their high plasticity during immature stage that renders them malleable in response to environmental demands. Here, we demonstrate that, in rats, there is no critical time window for experience-induced dendritic plasticity of adult-born neurons as spatial learning in the water maze sculpts the dendritic arbor of adult-born neurons even when they are several months of age. By ablating neurogenesis within a specific period of time, we found that learning was disrupted when the delay between ablation and learning was extended to several months. Together, these results show that mature adult-born neurons are still plastic when they are functionally integrated into dentate network. Our results suggest a new perspective with regard to the role of neo-neurons by highlighting that even mature ones can provide an additional source of plasticity to the brain to process memory information.
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Oudin MJ, Hobbs C, Doherty P. DAGL-dependent endocannabinoid signalling: roles in axonal pathfinding, synaptic plasticity and adult neurogenesis. Eur J Neurosci 2012; 34:1634-46. [PMID: 22103420 DOI: 10.1111/j.1460-9568.2011.07831.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Until recently, endocannabinoid (eCB) signalling was largely studied in the context of synaptic plasticity in the postnatal brain in the absence of detailed knowledge of the nature of the enzyme(s) responsible for the synthesis of the eCBs. However, the identification of two diacylglycerol lipases (DAGLα and DAGLβ) responsible for the synthesis of 2-arachidonoylglycerol (2-AG) has increased the understanding of where this eCB is synthesised in relationship to the expression of cannabinoid receptor (CB)1 and CB2. Furthermore, the generation of knockout animals for each enzyme has allowed for the direct testing of their importance for established and emerging eCB functions. Based on this, we now know that DAGLα is enriched in dendritic spines that appose CB1-positive synaptic terminals, and that 2-AG functions as a retrograde signal controlling synaptic strength throughout the nervous system. Consequently, we have built on the principle that expression of eCB components dictates function to identify additional physiological functions of this signalling cassette. A number of studies have now provided support for DAGL-dependent eCB signalling playing important roles in brain development and in cellular plasticity in the adult nervous system. In this article, we will review evidence based on the localisation of the enzymes, as well as from genetic and pharmacological studies, that show DAGL-dependent eCB signalling to play an important role in axonal growth and guidance during development, in retrograde synaptic signalling at mature synapses, and in the control of adult neurogenesis in the hippocampus and subventricular zone.
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Affiliation(s)
- Madeleine J Oudin
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
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Ekdahl CT. Microglial activation - tuning and pruning adult neurogenesis. Front Pharmacol 2012; 3:41. [PMID: 22408626 PMCID: PMC3297835 DOI: 10.3389/fphar.2012.00041] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 02/23/2012] [Indexed: 01/23/2023] Open
Abstract
NEW NEURONS ARE CONTINUOUSLY GENERATED IN TWO ADULT BRAIN REGIONS: the subgranular zone of the hippocampus and the subependyma by the lateral ventricles, referred to as the neurogenic niches. During their development from neural stem cells to mature functionally integrated neurons numerous choices are made, such as proliferation or quiescence, cell survival or death, migration or establishment, growth or retraction of processes, synaptic assembly or pruning, or tuning of synaptic transmission. The process is altered by physiological stimuli as well as several brain diseases. Microglia are located within the neurogenic niches and have become interesting candidates for modulating neurogenesis in both the healthy and injured brain. They become activated by foreign antigens or changes in the brain homeostasis and transform this innate immunity into an adaptive immune response by recruiting systemic immune cells. Most studies report an acute decrease in the survival of new neurons following this classically activated microglia reaction. The long-term effects are more complex. In neurodegenerative diseases, microglial activation is more heterogeneous and the transformation from a pro- to an anti-inflammatory cytokine profile and the deactivation of microglia is not well defined. The diversity is reflected by numerous reports describing both beneficial and detrimental effects on neurogenesis, primarily on the proliferation, survival, and cell fate. However, relatively few studies have investigated alterations at later stages of neurogenesis including the functional integration. Though likely, it is not established how a fine-tuned cross-talk between microglia and adult-born neurons would work and how it changes upon microglia activation. This review will therefore launch three hypotheses for how microglia might direct synaptic integration of newborn neurons, currently a fast expanding research field.
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Affiliation(s)
- Christine T Ekdahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Wallenberg Neuroscience Center, Department of Clinical Sciences, Lund University and Skåne University Hospital Lund, Sweden
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Zhang X, Gong Q, Zhang S, Wang L, Hu Y, Shen H, Dong S. 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1, 2, 5-thiadiazol-4-yl]-1, 2, 5, 6-tetrahydro-1- methylpyridine oxalate, a novel xanomeline derivative, improves neural cells proliferation and survival in adult mice. Neural Regen Res 2012; 7:24-30. [PMID: 25806054 PMCID: PMC4354111 DOI: 10.3969/j.issn.1673-5374.2012.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 11/12/2011] [Indexed: 11/25/2022] Open
Abstract
The present study analyzed the influence of 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1, 2, 5-thiadiazol-4-yl]-1, 2, 5, 6-tetrahydro-1-methylpyridine oxalate (EUK1001), a novel xanomeline derivative of the M1/M4 receptor agonist, on hippocampal neurogenesis in adult C57BL6 mice. Results showed that 15-day EUK1001 treatment via intraperitoneal injection promoted neural cell proliferation in the dentate gyrus, although cell differentiation did not change. The majority of bromodeoxyuridine-positive cells co-expressed the immature neuronal marker doublecortin. In addition, the level of neurogenesis in the subventricular zone was not altered. Brain-derived neurotrophic factor mRNA expression was up-regulated following EUK1001 treatment, but no change was observed in expression of camp-responsive element binding protein 1, paired box gene 6, vascular endothelial growth factor alpha, neurogenic differentiation factor 1, and wingless-related mouse mammary tumor virus integration site 3A mRNA. These experimental findings indicated that EUK1001 enhanced proliferation and survival of hippocampal cells, possibly by increasing brain-derived neurotrophic factor expression.
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Affiliation(s)
- Xiaoliang Zhang
- Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, Shanghai 200062, China
| | - Qiang Gong
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Shuang Zhang
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Lin Wang
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Yinghe Hu
- Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, Shanghai 200062, China ; Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
| | - Haiming Shen
- Institute of Aviation Medicine, Civil Aviation University of China, Tianjin 300300, China
| | - Suzhen Dong
- Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, Shanghai 200062, China ; Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China
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68
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Bolognin S, Blanchard J, Wang X, Basurto-Islas G, Tung YC, Kohlbrenner E, Grundke-Iqbal I, Iqbal K. An experimental rat model of sporadic Alzheimer's disease and rescue of cognitive impairment with a neurotrophic peptide. Acta Neuropathol 2012; 123:133-51. [PMID: 22083255 DOI: 10.1007/s00401-011-0908-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/30/2011] [Accepted: 11/05/2011] [Indexed: 10/15/2022]
Abstract
Alzheimer's disease (AD) is multifactorial and, to date, no single cause of the sporadic form of this disease, which accounts for over 99% of the cases, has been established. In AD brain, protein phosphatase-2A (PP2A) activity is known to be compromised due to the cleavage and translocation of its potent endogenous inhibitor, I2PP2A, from the neuronal nucleus to the cytoplasm. Here, we show that adeno-associated virus vector-induced expression of the N-terminal I2NTF and C-terminal I2CTF halves of I2PP2A , also called SET, in brain reproduced key features of AD in Wistar rats. The I2NTF-CTF rats showed a decrease in brain PP2A activity, abnormal hyperphosphorylation and aggregation of tau, a loss of neuronal plasticity and impairment in spatial reference and working memories. To test whether early pharmacologic intervention with a neurotrophic molecule could rescue neurodegeneration and behavioral deficits, 2.5-month-old I2NTF-CTF rats and control littermates were treated for 40 days with Peptide 6, an 11-mer peptide corresponding to an active region of the ciliary neurotrophic factor. Peripheral administration of Peptide 6 rescued neurodegeneration and cognitive deficit in I2NTF-CTF animals by increasing dentate gyrus neurogenesis and mRNA level of brain derived neurotrophic factor. Moreover, Peptide 6-treated I2NTF-CTF rats showed a significant increase in dendritic and synaptic density as reflected by increased expression of synapsin I, synaptophysin and MAP2, especially in the pyramidal neurons of CA1 and CA3 of the hippocampus.
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Kameda M, Taylor CJ, Walker TL, Black DM, Abraham WC, Bartlett PF. Activation of latent precursors in the hippocampus is dependent on long-term potentiation. Transl Psychiatry 2012; 2:e72. [PMID: 22832734 PMCID: PMC3309542 DOI: 10.1038/tp.2011.70] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The recent discovery of a large latent population of precursor cells in the dentate gyrus of adult mice led us to investigate whether activation of this population is regulated by synaptic activity, thereby explaining the observation that environmental signals can affect neurogenesis. Using a variety of stimulation protocols, we found that only a long-term potentiation (LTP)-inducing protocol activated the latent precursor pool, leading to increased neurogenesis in the dentate gyrus. LTP induced by high-frequency stimulation (HFS) of the perforant pathway in vivo produced a two-fold increase in the number of neurospheres cultured from the stimulated hippocampus, compared with the unstimulated hippocampus. No increase in neurosphere number or neurogenesis was observed when the HFS failed to induce LTP. These results show that LTP can activate latent neural precursor cells in the adult mouse dentate gyrus, thereby providing a direct mechanism for regulating activity-driven neurogenesis. In the future, it may be possible to utilize such learning- or stimulation-induced neurogenesis to overcome disorders characterized by neuronal loss.
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Affiliation(s)
- M Kameda
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - C J Taylor
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - T L Walker
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - D M Black
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - W C Abraham
- Department of Psychology and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - P F Bartlett
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia. E-mail:
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70
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Petrik D, Lagace DC, Eisch AJ. The neurogenesis hypothesis of affective and anxiety disorders: are we mistaking the scaffolding for the building? Neuropharmacology 2011; 62:21-34. [PMID: 21945290 DOI: 10.1016/j.neuropharm.2011.09.003] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 09/03/2011] [Accepted: 09/06/2011] [Indexed: 01/22/2023]
Abstract
Hypotheses are scaffoldings erected in front of a building and then dismantled when the building is finished. They are indispensable for the workman; but you mustn't mistake the scaffolding for the building. Johann Wolfgang von Goethe. The neurogenesis hypothesis of affective disorders - in its simplest form - postulates that the generation of neurons in the postnatal hippocampal dentate gyrus is involved in the etiology and treatment efficacy of major depressive disorder (MDD). The hypothesis was established in the 1990s but was built on a broad foundation of earlier research on the hippocampus, serotonin and MDD. It has gone through several growth phases fueled by discoveries both correlative and causative in nature. Recently, the hypothesis has also been broadened to also include potential relevance for anxiety disorders, like post-traumatic stress disorder (PTSD). As any hypothesis should be, it has been tested and challenged, sometimes vigorously. Here we review the current standing of the neurogenesis hypothesis of affective and anxiety disorders, noting in particular how a central postulate - that decreased neurogenesis results in depression or anxiety - has, in general, been rejected. We also review the controversies on whether treatments for these disorders, like antidepressants, rely on intact neurogenesis for their efficacy, and the existence of neurogenesis-dependent and -independent effects of antidepressants. In addition, we review the implications that the hypothesis has for the response to stress, PTSD, and the neurobiology of resilience, and highlight our own work showing that adult-generated neurons are functionally important for the behavioral response to social stress. We conclude by emphasizing how advancements in transgenic mouse technology, rodent behavioral analyses, and our understanding of the neurogenesis process will allow us to refine our conclusions and perform ever more specific experiments. Such scrutiny is critical, since if we "mistake the scaffolding for the building" we could overlook opportunities for translational impact in the clinic. This article is part of a special Issue entitled 'Anxiety and Depression'.
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Affiliation(s)
- David Petrik
- Department of Psychiatry, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9070, USA
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Bie B, Brown DL, Naguib M. Synaptic plasticity and pain aversion. Eur J Pharmacol 2011; 667:26-31. [PMID: 21699892 DOI: 10.1016/j.ejphar.2011.05.080] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 05/12/2011] [Accepted: 05/22/2011] [Indexed: 12/11/2022]
Abstract
Negative affective emotions are defined as the conceptual feature of pain. A number of clinical and animal studies have indicated that the limbic system including the anterior cingulate cortex (ACC) and amygdala plays a critical role in the processing of affective components of pain. Glutamatergic transmission plays an important role in the processing of affective aspects of pain. Long-term changes on glutamatergic synapses contribute to the expression of aversion behavior induced by pain. In this article, the neurocircuits involved in the processing of affective aspects of pain, the glutamatergic synaptic plasticity in these brain regions, and the epigenetic mechanisms underlying pain-related synaptic plasticity will be reviewed and discussed. New discoveries regarding the interaction between the synaptic plasticity and affective components of pain may advance our understanding on the pain mechanism, and lead to new strategies for pain treatment.
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Affiliation(s)
- Bihua Bie
- Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio 44195, United States
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