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Gingras M, Champigny MF, Berthod F. Differentiation of human adult skin-derived neuronal precursors into mature neurons. J Cell Physiol 2007; 210:498-506. [PMID: 17111366 DOI: 10.1002/jcp.20889] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The isolation of autologous neuronal precursors from skin-derived precursor cells extracted from adult human skin would be a very efficient source of neurons for the treatment of various neurodegenerative diseases. The purpose of this study was to demonstrate that these neuronal precursors were able to differentiate into mature neurons. We isolated neuronal precursors from breast skin and expanded them in vitro for over ten passages. We showed that 48% of these cells were proliferating after the first passage, while this growth rate decreased after the second passage. We demonstrated that 70% of these cells were nestin-positive after the third passage, while only 17% were neurofilament M-positive after 7 days of differentiation. These neuronal precursors expressed betaIII tubulin, the dendritic marker MAP2 and the presynaptic marker synaptophysin after 7 days of in vitro maturation. They also expressed the postsynaptic marker PSD95 and the late neuronal markers NeuN and neurofilament H after 21 days of differentiation, demonstrating they became terminally differentiated neurons. These markers were still expressed after 50 days of culture. The generation of autologous neurons from an accessible adult human source opens many potential therapeutic applications and has a great potential for the development of experimental studies on normal human neurons.
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Affiliation(s)
- Marie Gingras
- Laboratoire d'Organogénèse Expérimentale (LOEX), Centre Hospitalier Affilié Universitaire de Québec, Hôpital du St-Sacrement and Département de Chirurgie, Faculté de Médecine, Université Laval, Québec, Canada
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52
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Wenzel HJ, Tamse CT, Schwartzkroin PA. Dentate development in organotypic hippocampal slice cultures from p35 knockout mice. Dev Neurosci 2007; 29:99-112. [PMID: 17148953 DOI: 10.1159/000096215] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 04/14/2006] [Indexed: 11/19/2022] Open
Abstract
Abnormal brain development, induced by genetic influences or resulting from a perinatal trauma, has been recognized as a cause of seizure disorders. To understand how and when these structural abnormalities form, and how they are involved in epileptogenesis, it is important to generate and investigate animal models. We have studied one such model, a mouse in which deletion of the p35 gene (p35-/-) gives rise to both structural disorganization and seizure-like function. We now report that aberrant dentate development can be recognized in the organotypic hippocampal slice culture preparation generated from p35-/- mouse pups. In these p35-/- cultures, an abnormally high proportion of dentate granule cells migrates into the hilus and molecular layer, and develops aberrant dendritic and axonal morphology. In addition, astrocyte formation in the dentate gyrus is disturbed, as is the distribution of GABAergic interneurons. Although the p35-/- brain shows widespread abnormalities, the disorganization of the hippocampal dentate region is particularly intriguing since a similar pathology is often found in hippocampi of temporal lobe epilepsy patients. The abnormal granule cell features occur early in development, and are independent of seizure activity. Further, these aberrant patterns and histopathological features of p35-/- culture preparations closely resemble those observed in p35 knockout mice in vivo. This culture preparation thus provides an experimentally accessible window for studying abnormal developmental factors that can result in seizure propensity.
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Affiliation(s)
- H Jurgen Wenzel
- Department of Neurological Surgery, University of California at Davis, Davis, CA 95616, USA
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53
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Abstract
Major depressive disorder (MDD) is a debilitating and complex psychiatric disorder that involves multiple neural circuits and genetic and non-genetic risk factors. In the quest for elucidating the neurobiological basis of MDD, hippocampal neurogenesis has emerged as a candidate substrate, both for the etiology as well as treatment of MDD. This chapter critiques the advances made in the study of hippocampal neurogenesis as they relate to the neurogenic hypothesis of MDD. While an involvement of neurogenesis in the etiology of depression remains highly speculative, preclinical studies have revealed a novel and previously unrecognized role for hippocampal neurogenesis in mediating some of the behavioral effects of antidepressants. The implications of these findings are discussed to reevaluate the role of hippocampal neurogenesis in MDD.
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Affiliation(s)
- Amar Sahay
- Department of Neuroscience, Columbia University, New York, NY 10032, USA.
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54
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Schloesser RJ, Chen G, Manji HK. Neurogenesis and Neuroenhancement in the Pathophysiology and Treatment of Bipolar Disorder. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 77:143-78. [PMID: 17178474 DOI: 10.1016/s0074-7742(06)77005-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Robert J Schloesser
- Laboratory of Molecular Pathophysiology, Mood and Anxiety Disorders Research Program National Institute of Mental Health, Bethesda, Maryland 20892, USA
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55
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Abstract
Opiate drugs alter cognitive performance and influence hippocampal excitability, including long-term potentiation (LTP) and seizure activity. The dentate gyrus (DG) contains two major opioid peptides, enkephalins and dynorphins, which have opposing effects on excitability. Enkephalins preferentially bind to delta- and mu-opioid receptors (DORs and MORs) while dynorphins preferentially bind to kappa-opioid receptors (KORs). Opioid receptors can also be activated by exogenous opiate drugs such as the MOR agonist morphine. Enkephalins are contained in the mossy fiber pathway, in the lateral perforant path (PP) and in scattered GABAergic interneurons. MORs and DORs are predominantly in distinct subpopulations of GABAergic interneurons known to inhibit granule cells, and are present at low levels within granule cells. MOR and DOR agonists increase excitability and facilitate LTP in the molecular layer. Anatomical and physiological evidence is consistent with somatodendritic and axon terminal targeting of both MORs and DORs. Dynorphins are in the granule cells, most abundantly in mossy fibers but also in dendrites. KORs have been localized to granule cell mossy fibers, supramammillary afferents to granule cells, and PP terminals. KOR agonists, including endogenous dynorphins, diminish the induction of LTP. Recent evidence indicates that opiates and opioids also modulate other processes in the hippocampal formation, including adult neurogenesis, the actions of gonadal hormones, and development of neonatal transmitter systems.
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Affiliation(s)
- Carrie T Drake
- Division of Neurobiology, Department of Neurology and Neuroscience, Weill-Cornell Medical College, 411 East 69th Street, New York, NY 10021, USA
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56
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Bruel-Jungerman E, Rampon C, Laroche S. Adult Hippocampal Neurogenesis, Synaptic Plasticity and Memory: Facts and Hypotheses. Rev Neurosci 2007; 18:93-114. [PMID: 17593874 DOI: 10.1515/revneuro.2007.18.2.93] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The demonstration that progenitor cells in regions of the adult mammalian brain such as the dentate gyrus of the hippocampus can undergo mitosis and generate new cells that differentiate into functionally integrated neurons throughout life has marked a new era in neuroscience. In recent years, a wide range of investigations has been directed at understanding the physiological mechanisms and functional relevance of this form of brain plasticity. Our current knowledge of adult hippocampal neurogenesis indicates that the production of new cells in the brain follows a multi-step process during which newborn cells are submitted to various regulatory factors that influence cell proliferation, maturation, fate determination and survival. As details of the dynamics of morphological maturation and functional integration of newborn neurons in corticohippocampal circuits have become clearer, an increasing number of studies have examined how environmental and/or behavioural factors can modulate neurogenesis and affect hippocampal-dependent learning and memory. In this article we present an overview of recent literature that relates neurogenesis to hippocampal function on the basis of correlative studies investigating the modulation of neurogenesis by learning and behavioural experience, and the consequences of the loss of hippocampal neurogenesis for memory function. We also highlight experimental evidence that immature neurons exhibit unique electrophysiological characteristics and therefore may constitute a specific cell population particularly inclined to undergo activity-dependent plasticity. Moreover, we review recent work that reveals an unsuspected mechanistic link between synaptic plasticity and the proliferation and survival of new hippocampal neurons. From the present background of research, we argue that the incorporation of functional adult-generated neurons into existing neural networks provides a higher capacity for plasticity, which may favour the encoding and storage of certain types of memories. Depending on their birth date and maturation stage, new neurons might be implicated in the encoding/storage process of the task at hand or may help future learning experience. Finally, we highlight critical issues to be addressed in order to decipher the exact contribution of newly generated neurons to cognitive functions.
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Affiliation(s)
- Elodie Bruel-Jungerman
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, CNRS UMR 8620, University Paris-Sud, Orsay, France.
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57
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Smith PD, McLean KJ, Murphy MA, Turnley AM, Cook MJ. Functional dentate gyrus neurogenesis in a rapid kindling seizure model. Eur J Neurosci 2006; 24:3195-203. [PMID: 17156380 DOI: 10.1111/j.1460-9568.2006.05205.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Neurogenesis in the adult mammalian hippocampus resulting in long-term persistence of new neurons with features of capacity for functional activation is recognized. Many stimuli are capable of increasing the rate of neurogenesis, including seizure activity. Whether these insults result in an increased number of new functionally active neurons over and above the baseline rate of neurogenesis is not known. The rapid electrical amygdala kindling (REAK) model of seizures isolates the effects of seizures alone in the absence of neuronal death and the resulting seizures induce expression of c-Fos in the vast majority of dentate gyrus (DG) granule cells. C57BL/6 mice were exposed to REAK then injected with bromodeoxyuridine (BrDU) to label dividing cells, then re-exposed to REAK after a delay period to allow detection of functional activation in new neurons by measurement c-Fos expression in response to seizures. Adult subgranular zone cells migrated into the DG granule cell layer (GCL), assumed a neuronal phenotype and demonstrated seizure-dependent responsiveness. Larger absolute numbers of new neurons demonstrating seizure-dependent activation were found in the GCL of previously kindled mice. Seizures are capable of increasing the number of new neurons with the capacity for functional activation laid down in the postseizure period and incorporated into seizure-activated circuitry.
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Affiliation(s)
- Paul D Smith
- Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital, University of Melbourne, VIC, Australia 3065.
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58
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Herrick SP, Waters EM, Drake CT, McEwen BS, Milner TA. Extranuclear estrogen receptor beta immunoreactivity is on doublecortin-containing cells in the adult and neonatal rat dentate gyrus. Brain Res 2006; 1121:46-58. [PMID: 17026970 DOI: 10.1016/j.brainres.2006.08.084] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2006] [Revised: 08/03/2006] [Accepted: 08/22/2006] [Indexed: 12/17/2022]
Abstract
In adult female rats, estrogen receptor (ER) activation, particularly of ERbeta, promotes hippocampal neurogenesis. We previously reported that extranuclear ERbeta immunoreactivity (ir) in adult rats is on cellular profiles in or near the granule cell layer, which is the location of newly generated cells. During development, cells in or near the granule cell layer transiently express high levels of estrogen binding and nuclear ERs. Thus, we sought to determine if extranuclear ERbeta is in newly generated cells in adult and neonatal rat dentate gyrus. Sections from the dentate gyrus of adult proestrus or postnatal day 7 and 14 female rats were dual-labeled for ERbeta and the new-cell marker doublecortin (DCX) and examined by electron microscopy. DCX-containing neurons were found in the subgranular hilus in adult rats and were more widespread throughout the granule cell layer and hilus of neonatal rats. In both adults and neonatal rats, ERbeta immunoreactivity was found in a subset of DCX-labeled neurons. Electron microscopic examination of the adult dentate gyrus revealed that most perikarya with DCX-ir had the morphological characteristics of granule cells, although a few resembled interneurons. Dendrites with DCX-ir also were observed. In both adults and neonates, DCX-labeled neuronal perikarya and dendrites contained ERbeta-ir; ERbeta-ir usually was aggregated near the plasma membrane, mitochondria or endoplasmic reticula. ERbeta-ir was in glial profiles that apposed DCX-labeled perikarya and dendrites. These findings are consistent with data showing that estrogens can exert non-genomic effects directly and indirectly on newly generated cells in neonatal and adult rat dentate gyrus.
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Affiliation(s)
- Scott P Herrick
- Department of Neurology and Neuroscience, Weill-Cornell Medical College, New York, NY 10021, USA
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59
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Arshavsky YI. “The seven sins” of the Hebbian synapse: Can the hypothesis of synaptic plasticity explain long-term memory consolidation? Prog Neurobiol 2006; 80:99-113. [PMID: 17074430 DOI: 10.1016/j.pneurobio.2006.09.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 09/25/2006] [Accepted: 09/26/2006] [Indexed: 11/16/2022]
Abstract
Memorizing new facts and events means that entering information produces specific physical changes within the brain. According to the commonly accepted view, traces of memory are stored through the structural modifications of synaptic connections, which result in changes of synaptic efficiency and, therefore, in formations of new patterns of neural activity (the hypothesis of synaptic plasticity). Most of the current knowledge on learning and initial stages of memory consolidation ("synaptic consolidation") is based on this hypothesis. However, the hypothesis of synaptic plasticity faces a number of conceptual and experimental difficulties when it deals with potentially permanent consolidation of declarative memory ("system consolidation"). These difficulties are rooted in the major intrinsic self-contradiction of the hypothesis: stable declarative memory is unlikely to be based on such a non-stable foundation as synaptic plasticity. Memory that can last throughout an entire lifespan should be "etched in stone." The only "stone-like" molecules within living cells are DNA molecules. Therefore, I advocate an alternative, genomic hypothesis of memory, which suggests that acquired information is persistently stored within individual neurons through modifications of DNA, and that these modifications serve as the carriers of elementary memory traces.
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Affiliation(s)
- Yuri I Arshavsky
- Institute for Nonlinear Science, University of California San Diego, La Jolla, CA 92093-0402, USA.
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60
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Müller GJ, Dogonowski AM, Finsen B, Johansen FF. Expression of glutamic acid decarboxylase and identification of GABAergic cells in the ischemic rat dentate gyrus. Exp Brain Res 2006; 175:556-66. [PMID: 16906421 DOI: 10.1007/s00221-006-0572-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 05/24/2006] [Indexed: 11/26/2022]
Abstract
We have investigated the glutamic acid dexcarboxylase (GAD) mRNA and protein isoforms as markers for ischemic loss of GABAergic neurons in the dentate hilus. Stereological counts of these neurons were performed in rats surviving 8 days after 10 min of transient forebrain ischemia, and in control rats (sham-operated and naïve). GAD65 and GAD67 were detected by both in situ hybridization and immunocytochemistry. No differences (three-way ANOVA, P > 0.05) were found between treatments (ischemia, sham-operated or naïve) when cell counts of identical GAD isoforms were compared at the same level (mRNA or protein). However, irrespective of treatments, the number of neurons expressing GAD65 mRNA was significantly higher than the number of neurons expressing GAD65 protein, and the number of neurons expressing GAD67 mRNA was significantly lower than the number of neurons expressing GAD67 protein. In parallel, we investigated the colocalization of the cell death marker Fluorojade B (FJB) with somatostatin- or GAD67-immunoreactivity in hilus of control and ischemic rats. Although the majority of FJB positive cells also contained somatostatin, a small number of GAD67 immunoreactive neurons contained FJB, suggesting that a small number of GABAergic neurons die after ischemia. In conclusion, this study provides direct evidence that a small proportion of GABAergic hilar neurons succumbs to ischemia. Stereological counts of neurons identified from their expression of either GAD isoform of mRNA or protein revealed a high inter-animal variation at any detection level in both naïve, sham-operated and ischemic rats. Therefore, counts of GABAergic neurons should be carefully interpreted in accordance with the marker used for identification.
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Affiliation(s)
- Georg Johannes Müller
- Molecular Neuropathology Group, Institute of Molecular Pathology, University of Copenhagen, 11, Frederik V vej, 2100 Copenhagen, Denmar
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61
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Mori T, Tanaka K, Buffo A, Wurst W, Kühn R, Götz M. Inducible gene deletion in astroglia and radial glia--a valuable tool for functional and lineage analysis. Glia 2006; 54:21-34. [PMID: 16652340 DOI: 10.1002/glia.20350] [Citation(s) in RCA: 296] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Astrocytes are thought to play a variety of key roles in the adult brain, such as their participation in synaptic transmission, in wound healing upon brain injury, and adult neurogenesis. However, to elucidate these functions in vivo has been difficult because of the lack of astrocyte-specific gene targeting. Here we show that the inducible form of Cre (CreERT2) expressed in the locus of the astrocyte-specific glutamate transporter (GLAST) allows precisely timed gene deletion in adult astrocytes as well as radial glial cells at earlier developmental stages. Moreover, postnatal and adult neurogenesis can be targeted at different stages with high efficiency as it originates from astroglial cells. Taken together, this mouse line will allow dissecting the molecular pathways regulating the diverse functions of astrocytes as precursors, support cells, repair cells, and cells involved in neuronal information processing.
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Affiliation(s)
- Tetsuji Mori
- Institute of Stem Cell Research, GSF-National Research Center for Environment and Health, Neuherberg/Munich, Germany
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62
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Talos DM, Fishman RE, Park H, Folkerth RD, Follett PL, Volpe JJ, Jensen FE. Developmental regulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor subunit expression in forebrain and relationship to regional susceptibility to hypoxic/ischemic injury. I. Rodent cerebral white matter and cortex. J Comp Neurol 2006; 497:42-60. [PMID: 16680782 PMCID: PMC4313670 DOI: 10.1002/cne.20972] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This is the first part of a two-part study to investigate the cellular distribution and temporal regulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor (AMPAR) subunits in the developing white matter and cortex in rat (part I) and human (part II). Western blot and immunocytochemistry were used to evaluate the differential expression of AMPAR subunits on glial and neuronal subtypes during the first 3 postnatal weeks in the Long Evans and Sprague Dawley rat strains. In Long Evans rats during the first postnatal week, GluR2-lacking AMPARs were expressed predominantly on white matter cells, including radial glia, premyelinating oligodendrocytes, and subplate neurons, whereas, during the second postnatal week, these AMPARs were highly expressed on cortical neurons, coincident with decreased expression on white matter cells. Immunocytochemical analysis revealed that cell-specific developmental changes in AMPAR expression occurred 2-3 days earlier by chronological age in Sprague Dawley rats compared with Long Evans rats, despite overall similar temporal sequencing. In both white and gray matter, the periods of high GluR2 deficiency correspond to those of regional susceptibility to hypoxic/ischemic injury in each of the two rat strains, supporting prior studies suggesting a critical role for Ca2+-permeable AMPARs in excitotoxic cellular injury and epileptogenesis. The developmental regulation of these receptor subunits strongly suggests that Ca2+ influx through GluR2-lacking AMPARs may play an important role in neuronal and glial development and injury in the immature brain. Moreover, as demonstrated in part II, there are striking similarities between rat and human in the regional and temporal maturational regulation of neuronal and glial AMPAR expression.
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Affiliation(s)
- Delia M. Talos
- Department of Neurology, Children’s Hospital, Boston, Massachusetts 02115
- Harvard Medical School, Boston, Massachusetts 02115
| | - Rachel E. Fishman
- Department of Neurology, Children’s Hospital, Boston, Massachusetts 02115
| | - Hyunkyung Park
- Department of Neurology, Children’s Hospital, Boston, Massachusetts 02115
- Harvard Medical School, Boston, Massachusetts 02115
| | - Rebecca D. Folkerth
- Harvard Medical School, Boston, Massachusetts 02115
- Department of Pathology (Neuropathology), Children’s Hospital, Boston, Massachusetts 02115
- Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts 02115
| | - Pamela L. Follett
- Department of Neurology, Children’s Hospital, Boston, Massachusetts 02115
- Harvard Medical School, Boston, Massachusetts 02115
| | - Joseph J. Volpe
- Department of Neurology, Children’s Hospital, Boston, Massachusetts 02115
- Harvard Medical School, Boston, Massachusetts 02115
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115
| | - Frances E. Jensen
- Department of Neurology, Children’s Hospital, Boston, Massachusetts 02115
- Harvard Medical School, Boston, Massachusetts 02115
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115
- Correspondence to: Frances E. Jensen, Enders 348, Department of Neurology, Children’s Hospital, 300 Longwood Avenue, Boston, MA 02115.
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63
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Zhu XJ, Hua Y, Jiang J, Zhou QG, Luo CX, Han X, Lu YM, Zhu DY. Neuronal nitric oxide synthase-derived nitric oxide inhibits neurogenesis in the adult dentate gyrus by down-regulating cyclic AMP response element binding protein phosphorylation. Neuroscience 2006; 141:827-836. [PMID: 16735094 DOI: 10.1016/j.neuroscience.2006.04.032] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 04/13/2006] [Accepted: 04/14/2006] [Indexed: 12/27/2022]
Abstract
Neuronal nitric oxide synthase, the major nitric oxide synthase isoform in the mammalian brain, is implicated in some developmental processes, including neuronal survival, precursor proliferation and differentiation. However, reports about the role of neuronal nitric oxide synthase in neurogenesis in the adult dentate gyrus are conflicting. Here we show that 5-bromodeoxyuridine-labeled dividing progenitor cells in the dentate gyrus were significantly increased in mice receiving 7-nitroindazole, a selective neuronal nitric oxide synthase inhibitor, and in null mutant mice lacking neuronal nitric oxide synthase gene (nNOS-/-) 6 h and 4 weeks after 5-bromodeoxyuridine incorporation. The increase in 5-bromodeoxyuridine positive cells in 7-nitroindazole-treated mice was accompanied by activation of cyclic AMP response element binding protein phosphorylation in the dentate gyrus. Pretreatment with N-methyl-D-aspartate receptor antagonist MK-801 fully abolished the effects of 7-nitroindazole on neurogenesis and cyclic AMP response element binding protein phosphorylation. Furthermore, neuronal nitric oxide synthase inhibition significantly enhanced the survival of newborn cells and the number of 5-bromodeoxyuridine positive/NeuN positive cells in the dentate gyrus. These results indicate that neuronal nitric oxide synthase-derived nitric oxide suppresses neurogenesis in the adult dentate gyrus, in which N-methyl-D-aspartate receptor functions and cyclic AMP response element binding protein phosphorylation may be involved.
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Affiliation(s)
- X J Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, 140 Road Hanzhong, Nanjing, China 210029
| | - Y Hua
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, 140 Road Hanzhong, Nanjing, China 210029
| | - J Jiang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, 140 Road Hanzhong, Nanjing, China 210029
| | - Q G Zhou
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, 140 Road Hanzhong, Nanjing, China 210029
| | - C X Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, 140 Road Hanzhong, Nanjing, China 210029
| | - X Han
- Laboratory of Mammalian Genes, Nanjing Medical University, Nanjing, China 210029
| | - Y M Lu
- Biomolecular Science Center, Burnet College of Biomedical Science, University of Florida, Room 324/BMS, 4000 Central Florida Boulevard, Orlando, FL 32816, USA
| | - D Y Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, 140 Road Hanzhong, Nanjing, China 210029; Laboratory of Mammalian Genes, Nanjing Medical University, Nanjing, China 210029.
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64
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Bonde S, Ekdahl CT, Lindvall O. Long-term neuronal replacement in adult rat hippocampus after status epilepticus despite chronic inflammation. Eur J Neurosci 2006; 23:965-74. [PMID: 16519661 DOI: 10.1111/j.1460-9568.2006.04635.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dentate gyrus (DG) neurogenesis is transiently increased during the first weeks after status epilepticus (SE). Survival of the new neurons is initially compromised by an acute inflammatory response, but the long-term fate of the remaining ones in the post-SE environment is unknown. Here adult rats were subjected to 2 h electrically evoked self-sustained SE and perfused after 5 weeks or 6 months. Rats exhibited partial or generalized SE followed by spontaneous behavioural seizures and abnormal electroencephalographic activity during 6 months. Numbers of activated microglia in the dentate subgranular zone (SGZ)-granule cell layer (GCL) and in the hilus declined after 5 weeks, but were still elevated at 6 months after SE, with no differences between the milder partial and the more severe generalized SE. At 6 months, partial and generalized SE rats showed a seven-fold increase in the number of mature SGZ-GCL neurons formed during the first 2 weeks along with aberrant neurons in the hilus. Total numbers of mature neurons in SGZ-GCL were unaltered, indicating that SE-generated neurons replaced dead granule cells. Neuroblast formation had returned to normal levels in SGZ-GCL but generation of aberrant neurons in the hilus was still ongoing at 6 months. Our data indicate that long-term impairment of neurogenesis, as reported previously after kainic acid-induced SE, is not a general feature of chronic epilepsy. We have found that a substantial proportion of the mature granule cells at 6 months are generated during the first 2 weeks after SE and survive despite chronic inflammation, and that SE triggers continuous production of aberrant hilar neurons.
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Affiliation(s)
- Sara Bonde
- Laboratory of Neurogenesis and Cell Therapy, Section of Restorative Neurology, Wallenberg Neuroscience Center, University Hospital, SE-221 84, Lund, Sweden
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65
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Peng PL, Zhong X, Tu W, Soundarapandian MM, Molner P, Zhu D, Lau L, Liu S, Liu F, Lu Y. ADAR2-dependent RNA editing of AMPA receptor subunit GluR2 determines vulnerability of neurons in forebrain ischemia. Neuron 2006; 49:719-33. [PMID: 16504947 DOI: 10.1016/j.neuron.2006.01.025] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Revised: 12/09/2005] [Accepted: 01/25/2006] [Indexed: 01/09/2023]
Abstract
ADAR2 is a nuclear enzyme essential for GluR2 pre-mRNA editing at Q/R site-607, which gates Ca2+ entry through AMPA receptor channels. Here, we show that forebrain ischemia in adult rats selectively reduces expression of ADAR2 enzyme and, hence, disrupts RNA Q/R site editing of GluR2 subunit in vulnerable neurons. Recovery of GluR2 Q/R site editing by expression of exogenous ADAR2b gene or a constitutively active CREB, VP16-CREB, which induces expression of endogenous ADAR2, protects vulnerable neurons in the rat hippocampus from forebrain ischemic insult. Generation of a stable ADAR2 gene silencing by delivering small interfering RNA (siRNA) inhibits GluR2 Q/R site editing, leading to degeneration of ischemia-insensitive neurons. Direct introduction of the Q/R site edited GluR2 gene, GluR2(R607), rescues ADAR2 degeneration. Thus, ADAR2-dependent GluR2 Q/R site editing determines vulnerability of neurons in the rat hippocampus to forebrain ischemia.
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Affiliation(s)
- Peter L Peng
- Biomolecular Science Center, College of Biomedical Sciences, University of Central Florida, Orlando, Florida 32816, USA
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66
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Lledo PM, Alonso M, Grubb MS. Adult neurogenesis and functional plasticity in neuronal circuits. Nat Rev Neurosci 2006; 7:179-93. [PMID: 16495940 DOI: 10.1038/nrn1867] [Citation(s) in RCA: 1017] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The adult brain is a plastic place. To ensure that the mature nervous system's control of behaviour is flexible in the face of a varying environment, morphological and physiological changes are possible at many levels, including that of the entire cell. In two areas of the adult brain - the olfactory bulb and the dentate gyrus - new neurons are generated throughout life and form an integral part of the normal functional circuitry. This process is not fixed, but highly modulated, revealing a plastic mechanism by which the brain's performance can be optimized for a given environment. The functional benefits of this whole-cell plasticity, however, remain a matter for debate.
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Affiliation(s)
- Pierre-Marie Lledo
- Laboratory of Perception and Memory, Institut Pasteur, Centre National de la Recherche Scientifique Unit de Recherche Associée 2182, 25, rue du Docteur Roux, 75724 Paris cedex 15, France.
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67
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Scott BW, Burnham WM. Kindled seizures enhance young neuron survival in the adult rat dentate gyrus. Acta Neuropathol 2006; 111:364-71. [PMID: 16520968 DOI: 10.1007/s00401-006-0039-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2005] [Revised: 11/20/2005] [Accepted: 12/22/2005] [Indexed: 10/24/2022]
Abstract
New neurons continue to be generated throughout adulthood in the dentate gyrus of mammals. This process of neurogenesis is believed to play a role in some forms of learning and memory. Hippocampal-dependent learning tasks have been shown to specifically enhance the survival of new granule neurons. The present study examined the effects of kindled seizures in rats on the survival of young neurons born before the kindling began. Kindled seizures within the perforant path input to the dentate gyrus triggered between 1 and 2 weeks following the injection of bromodeoxyuridine (BrdU), were found to increase the number of BrdU and NeuN co-labeled cells in the granule cell layer by 128% 1 month later. The number of co-labeled cells was not correlated with measures of seizure severity. These results demonstrate that kindled seizures enhance the survival of new born neurons in the adult rat dentate gyrus which may reflect the actions of an activity-dependent mechanism normally involved in hippocampal-dependent learning and memory.
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Affiliation(s)
- B W Scott
- University of Toronto Epilepsy Research Program, University of Toronto, M5S1A8, Toronto, Canada.
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68
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Liu JJ, Mohila CA, Gong Y, Govindarajan N, Onn SP. Chronic nicotine exposure during adolescence differentially influences calcium-binding proteins in rat anterior cingulate cortex. Eur J Neurosci 2006; 22:2462-74. [PMID: 16307589 DOI: 10.1111/j.1460-9568.2005.04423.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have recently shown that chronic amphetamine exposure selectively up-regulates parvalbumin (PV) calcium-binding proteins in the anterior cingulate cortex (ACC). In this study, we evaluated the effects of chronic nicotine (NIC) exposure on PV, calbindin D28k (CB) and calretinin (CR) calcium-binding protein immunostaining in ACC GABAergic interneurons. Chronic NIC exposure for 3 weeks in adolescent rats, either via drinking water (the oral group) or by twice daily subcutaneous injections (the injection group), resulted in the expression of high levels of CR proteins in the ACC but not in the parietal cortex. Larger increases in the density of CR-immunoreactive (ir) neurons were noted in the NIC-injected rats at 0-day withdrawal (45% increase) compared with the oral group (26% increase). The larger increases in CR-ir neuron density in the NIC-injected rats were also reflected by prominent CR-ir processes across cortical layers. The density of PV-ir neurons was also increased (37%) at 0-day withdrawal but only in the oral NIC group and no changes in CB-ir neuron density were observed in either NIC group. Combined dual-immunofluorescence and confocal microscopy revealed that somatodendritic alpha4 nicotinic acetylcholine receptors colocalized with cortical neurons stained positively for CR, PV or CB. These results suggest that CR- and/or PV-ir-containing GABA interneurons may be involved in channeling the effects of NIC in the ACC, which is closely associated with the ventral basal ganglia circuit that is linked to brain reward function.
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Affiliation(s)
- Jen-Jane Liu
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
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69
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Sun HS, Feng ZP, Miki T, Seino S, French RJ. Enhanced neuronal damage after ischemic insults in mice lacking Kir6.2-containing ATP-sensitive K+ channels. J Neurophysiol 2005; 95:2590-601. [PMID: 16354731 DOI: 10.1152/jn.00970.2005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, incorporating Kir6.x and sulfonylurea receptor subunits, are weak inward rectifiers that are thought to play a role in neuronal protection from ischemic insults. However, the involvement of Kir6.2-containing KATP channel in hippocampus and neocortex has not been tested directly. To delineate the physiological roles of Kir6.2 channels in the CNS, we used knockout (KO) mice that do not express Kir6.2. Immunocytochemical staining demonstrated that Kir6.2 protein was expressed robustly in hippocampal neurons of the wild-type (WT) mice and absent in the KO. To examine neuronal sensitivity to metabolic stress in vitro, and to ischemia in vivo, we 1) exposed hippocampal slices to transient oxygen and glucose deprivation (OGD) and 2) produced focal cerebral ischemia by middle cerebral artery occlusion (MCAO). Both slice and whole animal studies showed that neurons from the KO mice were severely damaged after anoxia or ischemia, whereas few injured neurons were observed in the WT, suggesting that Kir6.2 channels are necessary to protect neurons from ischemic insults. Membrane potential recordings from the WT CA1 pyramidal neurons showed a biphasic response to OGD; a brief hyperpolarization was followed by a small depolarization during OGD, with complete recovery within 30 min after returning to normoxic conditions. By contrast, CA1 pyramidal neurons from the KO mice were irreversibly depolarized by OGD exposure, without any preceding hyperpolarization. These data suggest that expression of Kir6.2 channels prevents prolonged depolarization of neurons resulting from acute hypoxic or ischemic insults, and thus protects these central neurons from the injury.
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Affiliation(s)
- Hong-Shuo Sun
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Alberta, Canada
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70
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Meltzer LA, Yabaluri R, Deisseroth K. A role for circuit homeostasis in adult neurogenesis. Trends Neurosci 2005; 28:653-60. [PMID: 16271403 DOI: 10.1016/j.tins.2005.09.007] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 08/25/2005] [Accepted: 09/20/2005] [Indexed: 11/24/2022]
Abstract
Insertion of new neurons into adult neural circuits could either promote or impair circuit function, depending on whether homeostatic mechanisms are in place to regulate the resulting changes in neural activity. In the hippocampus (a mammalian forebrain structure important in aspects of memory and mood) several lines of behavioral evidence suggest important adaptive roles for adult-generated neurons, indicating that there could be mechanisms to control the potentially adverse increase in excitation associated with new cells. Here, we delineate behavioral and computational models for the role of circuit homeostasis in enabling neuron insertion to modulate hippocampal function adaptively, and we describe molecular and cellular mechanisms for implementing this circuit-level adaptive regulation of hippocampal activity.
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Affiliation(s)
- Leslie A Meltzer
- Department of Bioengineering, Neuroscience Program, Stanford University, W083 Clark Center, 318 Campus Drive West, Stanford, CA 94305, USA
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71
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Abstract
Forty years since the initial discovery of neurogenesis in the postnatal rat hippocampus, investigators have now firmly established that active neurogenesis from neural progenitors continues throughout life in discrete regions of the central nervous systems (CNS) of all mammals, including humans. Significant progress has been made over the past few years in understanding the developmental process and regulation of adult neurogenesis, including proliferation, fate specification, neuronal maturation, targeting, and synaptic integration of the newborn neurons. The function of this evolutionarily conserved phenomenon, however, remains elusive in mammals. Adult neurogenesis represents a striking example of structural plasticity in the mature CNS environment. Advances in our understanding of adult neurogenesis will not only shed light on the basic principles of adult plasticity, but also may lead to strategies for cell replacement therapy after injury or degenerative neurological diseases.
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Affiliation(s)
- Guo-li Ming
- Institute for Cell Engineering, Departments of Neurology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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72
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Luo CX, Zhu XJ, Zhang AX, Wang W, Yang XM, Liu SH, Han X, Sun J, Zhang SG, Lu Y, Zhu DY. Blockade of L-type voltage-gated Ca channel inhibits ischemia-induced neurogenesis by down-regulating iNOS expression in adult mouse. J Neurochem 2005; 94:1077-86. [PMID: 16000159 DOI: 10.1111/j.1471-4159.2005.03262.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Neurogenesis in the adult mammalian hippocampus may contribute to repairing the brain after injury. The signals that regulate neurogenesis in the dentate gyrus following ischemic stroke insult are not well known. We have previously reported that inducible nitric oxide synthase (iNOS) expression is necessary for ischemia-stimulated neurogenesis in the adult dentate gyrus. Here, we show that mice subjected to 90 min of middle cerebral artery occlusion (MCAO) significantly increased the number of new neurons and up-regulated iNOS expression in the dentate gyrus. Blockade of the L-type voltage-gated Ca(2+) channel (L-VGCC) prevented neurogenesis in the dentate gyrus and subventricular zone (SVZ), and down-regulated iNOS expression in the dentate gyrus after cerebral ischemia. This study suggests that Ca(2+) influx through L-VGCC is involved in ischemia-induced neurogenesis by up-regulating iNOS expression.
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Affiliation(s)
- Chun Xia Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, China
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73
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Doetsch F, Hen R. Young and excitable: the function of new neurons in the adult mammalian brain. Curr Opin Neurobiol 2005; 15:121-8. [PMID: 15721754 DOI: 10.1016/j.conb.2005.01.018] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Adult neurogenesis occurs in most species and is regulated by a wide variety of environmental and pharmacological challenges. The functional integration of neurons generated in the adult was first demonstrated in songbirds more than two decades ago. In the adult mammalian brain, neurons are continuously generated in two structures, the olfactory bulb and the hippocampus. Current evidence suggests that adult-born immature neurons have distinct electrophysiological properties from old neurons, and proposed roles in a variety of functions including olfaction, learning and mood regulation.
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Affiliation(s)
- Fiona Doetsch
- Departments of Pathology, Neurology and Center for Neurobiology and Behavior, Columbia University, 630W 168th Street, NY, NY 10032, USA.
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74
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Abstract
The discovery that the adult mammalian brain creates new neurons from pools of stemlike cells was a breakthrough in neuroscience. Interestingly, this particular new form of structural brain plasticity seems specific to discrete brain regions, and most investigations concern the subventricular zone (SVZ) and the dentate gyrus (DG) of the hippocampal formation (HF). Overall, two main lines of research have emerged over the last two decades: the first aims to understand the fundamental biological properties of neural stemlike cells (and their progeny) and the integration of the newly born neurons into preexisting networks, while the second focuses on understanding its relevance in brain functioning, which has been more extensively approached in the DG. Here, we propose an overview of the current knowledge on adult neurogenesis and its functional relevance for the adult brain. We first present an analysis of the methodological issues that have hampered progress in this field and describe the main neurogenic sites with their specificities. We will see that despite considerable progress, the levels of anatomic and functional integration of the newly born neurons within the host circuitry have yet to be elucidated. Then the intracellular mechanisms controlling neuronal fate are presented briefly, along with the extrinsic factors that regulate adult neurogenesis. We will see that a growing list of epigenetic factors that display a specificity of action depending on the neurogenic site under consideration has been identified. Finally, we review the progress accomplished in implicating neurogenesis in hippocampal functioning under physiological conditions and in the development of hippocampal-related pathologies such as epilepsy, mood disorders, and addiction. This constitutes a necessary step in promoting the development of therapeutic strategies.
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Affiliation(s)
- Djoher Nora Abrous
- Laboratoire de Physiopathologie des Comportements, Institut National de la Sané et de la Recherche Médicale, U588, Université de Bordeaux, France.
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75
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Lind D, Franken S, Kappler J, Jankowski J, Schilling K. Characterization of the neuronal marker NeuN as a multiply phosphorylated antigen with discrete subcellular localization. J Neurosci Res 2005; 79:295-302. [PMID: 15605376 DOI: 10.1002/jnr.20354] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
NeuN (neuronal nuclei) is an antigen used widely in research and diagnostics to identify postmitotic neurons. The present study aims at an initial understanding of the molecular nature and functional significance of this as yet ill-defined antigen. Using isoelectric focusing, both the 46- and 48-kDa isoforms of NeuN can be separated in multiple spots spanning a pH range of 8-10.5, suggesting that they might be phosphorylated. Enzymatic dephosphorylation abolishes NeuN immunoreactivity, confirming that NeuN is indeed a phosphoprotein, and establishing that binding of the defining antibody depends on its state of phosphorylation. Combined biochemical and immunohistochemical analysis show that both the 46- and the 48-kDa NeuN isoforms can be localized to the cell nucleus as well as in the neuronal cytoplasm. Their relative concentration in these compartments is distinct, however, with the 48-kDa isoform being the predominant isoform in the cytoplasm. Within the nucleus, NeuN is found preferentially in areas of low chromatin density and virtually excluded from areas containing densely packed DNA. The present identification of multiple differentially phosphorylated isoforms of NeuN, together with recent reports on the dependence of NeuN immunoreactivity levels on a variety of physiologic or pathologic signals, suggests a previously unappreciated level of complexity in the regulation of this enigmatic, neuron-specific antigen.
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Affiliation(s)
- Daniela Lind
- Anatomisches Institut, Anatomie und Zellbiologie, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
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76
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Fuchs E, Czéh B, Flügge G. Preclinical approaches to examine novel concepts of the pathophysiology of depressive disorders: lessons learned from tree shrews. Drug Dev Res 2005. [DOI: 10.1002/ddr.20032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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77
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Czeh B, Simon M, van der Hart MG, Schmelting B, Hesselink MB, Fuchs E. Chronic stress decreases the number of parvalbumin-immunoreactive interneurons in the hippocampus: prevention by treatment with a substance P receptor (NK1) antagonist. Neuropsychopharmacology 2005; 30:67-79. [PMID: 15470372 DOI: 10.1038/sj.npp.1300581] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Previous studies have demonstrated that stress may affect the hippocampal GABAergic system. Here, we examined whether long-term psychosocial stress influenced the number of parvalbumin-containing GABAergic cells, known to provide the most powerful inhibitory input to the perisomatic region of principal cells. Adult male tree shrews were submitted to 5 weeks of stress, after which immunocytochemical and quantitative stereological techniques were used to estimate the total number of hippocampal parvalbumin-immunoreactive (PV-IR) neurons. Stress significantly decreased the number of PV-IR cells in the dentate gyrus (DG) (-33%), CA2 (-28%), and CA3 (-29%), whereas the CA1 was not affected. Additionally, we examined whether antidepressant treatment offered protection from this stress-induced effect. We administered fluoxetine (15 mg/kg per day) and SLV-323 (20 mg/kg per day), a novel neurokinin 1 receptor (NK1R) antagonist, because the NK1R has been proposed as a possible target for novel antidepressant therapies. Animals were subjected to a 7-day period of psychosocial stress before the onset of daily oral administration of the drugs, with stress continued throughout the 28-day treatment period. NK1R antagonist administration completely prevented the stress-induced reduction of the number of PV-IR interneurons, whereas fluoxetine attenuated this decrement in the DG, without affecting the CA2 and CA3. The effect of stress on interneuron numbers may reflect real cell loss; alternatively, parvalbumin concentration is diminished in the neurons, which might indicate a compensatory attempt. In either case, antidepressant treatment offered protection from the effect of stress and appears to modulate the hippocampal GABAergic system. Furthermore, the NK1R antagonist SLV-323 showed neurobiological efficacy similar to that of fluoxetine.
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Affiliation(s)
- Boldizsár Czeh
- Clinical Neurobiology Laboratory, German Primate Center, Göttingen, Germany.
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78
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Mori T, Buffo A, Götz M. The novel roles of glial cells revisited: the contribution of radial glia and astrocytes to neurogenesis. Curr Top Dev Biol 2005; 69:67-99. [PMID: 16243597 DOI: 10.1016/s0070-2153(05)69004-7] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Astroglial cells are the most frequent cell type in the adult mammalian brain, and the number and range of their diverse functions are still increasing. One of their most striking roles is their function as adult neural stem cells and contribution to neurogenesis. This chapter discusses first the role of the ubiquitous glial cell type in the developing nervous system, the radial glial cells. Radial glial cells share several features with neuroepithelial cells, but also with astrocytes in the mature brain, which led to the name "radial glia." At the end of neurogenesis in the mammalian brain, radial glial cells disappear, and a subset of them transforms into astroglial cells. Interestingly, only some astrocytes maintain their neurogenic potential and continue to generate neurons throughout life. We discuss the current knowledge about the differences between the adult astroglial cells that remain neurogenic and act as neural stem cells and the majority of other astroglial cells that have apparently lost the capacity to generate neurons. Additionally, we review the changes in glial cells upon brain lesion, their dedifferentiation and recapitulation of radial glial properties, and the conditions under which reactive glia may reinitiate some neurogenic potential. Given that the astroglial cells are not only the most frequent cell type in an adult mammalian brain, but also the key cell type in the wound reaction of the brain to injury, it is essential to further understand their heterogeneity and molecular specification, with the final aim of using this unique source for neuronal replacement. Therefore, one of the key advances in the field of neurobiology is the discovery that astroglial cells can generate neurons not only during development, but also throughout adult life and potentially even after brain lesion.
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Affiliation(s)
- Tetsuji Mori
- Institute for Stem Cell Research, GSF-National Research Center for Environment and Health, D-85764 Neuherberg/Munich, Germany
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79
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Seri B, García-Verdugo JM, Collado-Morente L, McEwen BS, Alvarez-Buylla A. Cell types, lineage, and architecture of the germinal zone in the adult dentate gyrus. J Comp Neurol 2004; 478:359-78. [PMID: 15384070 DOI: 10.1002/cne.20288] [Citation(s) in RCA: 494] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
New neurons continue to be born in the subgranular zone (SGZ) of the dentate gyrus in the hippocampus of adult mammals, including humans. Previous work has shown that astrocytes function as the progenitors of these new neurons through immature intermediate D cells. In the first part of the present study, we determined the structure of each of these progenitors and how they are organized in three dimensions. Serial-section reconstructions of the SGZ, using confocal and electron microscopy demonstrate that SGZ astrocytes form baskets that hold clusters of D cells, largely insulating them from the hilus. Two types of glial fibrillary acidic protein-expressing astrocytes (radial and horizontal) and three classes of doublecortin and PSA-NCAM-positive D cells (D1, D2, D3) were observed. Radial astrocytes appear to interact closely with clusters of D cells forming radial proliferative units. In the second part of this study, we show that retrovirally labeled radial astrocytes give rise to granule neurons. We also used bromodeoxyuridine and [3H]thymidine labeling to study the sequence of appearance of the different D cells after a 7-day treatment with anti-mitotics. This analysis, together with retroviral labeling data, suggest that radial astrocytes divide to generate D1 cells, which in turn divide once to form postmitotic D2 cells. D2 cells mature through a D3 stage to form new granule neurons. These observations provide a model of how the germinal zone of the adult hippocampus is organized and suggest a sequence of cellular stages in the generation of new granule neurons.
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Affiliation(s)
- Bettina Seri
- University of California, San Francisco, Department of Neurological Surgery and Program in Developmental and Stem Cell Research, San Francisco, California 94143, USA
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80
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Schinder AF, Gage FH. A hypothesis about the role of adult neurogenesis in hippocampal function. Physiology (Bethesda) 2004; 19:253-61. [PMID: 15381753 DOI: 10.1152/physiol.00012.2004] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The functional relevance of adult hippocampal neurogenesis has long been a matter of intense experimentation and debate, but the precise role of new neurons has not been sufficiently elaborated. Here we propose a hypothesis in which specific features of newly generated neurons contribute to hippocampal plasticity and function and discuss the most recent and relevant findings in the context of the proposed hypothesis.
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Affiliation(s)
- Alejandro F Schinder
- Laboratory of Neuronal Plasticity, Leloir Institute Foundation, 1405 Buenos Aires, Argentina.
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81
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Schouten JW, Fulp CT, Royo NC, Saatman KE, Watson DJ, Snyder EY, Trojanowski JQ, Prockop DJ, Maas AIR, McIntosh TK. A Review and Rationale for the Use of Cellular Transplantation as a Therapeutic Strategy for Traumatic Brain Injury. J Neurotrauma 2004; 21:1501-38. [PMID: 15684646 DOI: 10.1089/neu.2004.21.1501] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Experimental research during the past decade has greatly increased our understanding of the pathophysiology of traumatic brain injury (TBI) and allowed us to develop neuroprotective pharmacological therapies. Encouraging results of experimental pharmacological interventions, however, have not been translated into successful clinical trials, to date. Traumatic brain injury is now believed to be a progressive degenerative disease characterized by cell loss. The limited capacity for self-repair of the brain suggests that functional recovery following TBI is likely to require cellular transplantation of exogenous cells to replace those lost to trauma. Recent advances in central nervous system transplantation techniques involve technical and experimental refinements and the analysis of the feasibility and efficacy of transplantation of a range of stem cells, progenitor cells and postmitotic cells. Cellular transplantation has begun to be evaluated in several models of experimental TBI, with promising results. The following is a compendium of these new and exciting studies, including a critical discussion of the rationale and caveats associated with cellular transplantation techniques in experimental TBI research. Further refinements in future research are likely to improve results from transplantation-based treatments for TBI.
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Affiliation(s)
- Joost W Schouten
- Traumatic Brain Injury Laboratory, Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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82
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Rüttimann E, Vacher CM, Gassmann M, Kaupmann K, Van der Putten H, Bettler B. Altered hippocampal expression of calbindin-D-28k and calretinin in GABAB(1)-deficient mice. Biochem Pharmacol 2004; 68:1613-20. [PMID: 15451404 DOI: 10.1016/j.bcp.2004.07.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Accepted: 07/07/2004] [Indexed: 10/26/2022]
Abstract
Balb/c GABA(B(1))(-/-) mice develop complex epileptiform activity, including spontaneous and audiogenic generalized seizures, 6-8 weeks after birth. The neuronal systems involved in these epilepsies have not been identified yet. Because the hippocampus is critically involved in epileptiform activity, we now investigated whether this brain region exhibits seizure-related alterations. Using semi-quantitative immunohistochemistry, we studied the temporal and cellular hippocampal expression pattern of two seizure-sensitive calcium-binding proteins, calbindin-D-28k and calretinin, in GABA(B(1))(-/-) mice. One month after birth, before the onset of overt epileptiform activity, wild-type (WT) and GABA(B(1))(-/-) mice exhibit comparable expression profiles for the two calcium-binding proteins. Three months after birth, once the epileptic phenotype is established, we observe clear alterations in the expression of calcium-binding proteins in the dentate gyrus area. GABA(B(1))(-/-) mice exhibit a 50% decline in the staining intensity of calbindin-D-28k expressing neurons and a 70% increase in the number of calretinin-positive neurons when compared to WT littermates. Six months after birth, the down-regulation of calbindin-D-28k protein is even more pronounced, while the calretinin expression in GABA(B(1))(-/-) mice reverts to the pattern seen in WT littermates. Our data demonstrate that the absence of functional GABA(B) receptors causes epileptiform activity through a mechanism that crucially involves dentate gyrus granule cells, and that this pathological activity is accompanied by adaptive changes.
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Affiliation(s)
- Elisabeth Rüttimann
- Department of Clinical-Biological Sciences, Institute of Physiology, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
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83
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Aguirre AA, Chittajallu R, Belachew S, Gallo V. NG2-expressing cells in the subventricular zone are type C-like cells and contribute to interneuron generation in the postnatal hippocampus. ACTA ACUST UNITED AC 2004; 165:575-89. [PMID: 15159421 PMCID: PMC2172347 DOI: 10.1083/jcb.200311141] [Citation(s) in RCA: 210] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subventricular zone (SVZ) is a source of neural progenitors throughout brain development. The identification and purification of these progenitors and the analysis of their lineage potential are fundamental issues for future brain repair therapies. We demonstrate that early postnatal NG2-expressing (NG2+) progenitor cells located in the SVZ self-renew in vitro and display phenotypic features of transit-amplifier type C-like multipotent cells. NG2+ cells in the SVZ are highly proliferative and express the epidermal growth factor receptor, the transcription factors Dlx, Mash1, and Olig2, and the Lewis X (LeX) antigen. We show that grafted early postnatal NG2+ cells generate hippocampal GABAergic interneurons that propagate action potentials and receive functional glutamatergic synaptic inputs. Our work identifies Dlx+/Mash1+/LeX+/NG2+/GFAP-negative cells of the SVZ as a new class of postnatal multipotent progenitor cells that may represent a specific cellular reservoir for renewal of postnatal and adult inhibitory interneurons in the hippocampus.
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Affiliation(s)
- Adan A Aguirre
- Center for Neuroscience Research, Children's Research Institute, Rm. 5345, Children's National Medical Center, 111 Michigan Ave., N.W., Washington, DC 20010, USA
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84
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Keilhoff G, Bernstein HG, Becker A, Grecksch G, Wolf G. Increased neurogenesis in a rat ketamine model of schizophrenia. Biol Psychiatry 2004; 56:317-22. [PMID: 15336513 DOI: 10.1016/j.biopsych.2004.06.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Revised: 04/20/2004] [Accepted: 06/07/2004] [Indexed: 11/23/2022]
Abstract
BACKGROUND Growing evidence implicates abnormal neurodevelopment in schizophrenia, which manifests itself, for example, in reduced volume and cellular disarray of the hippocampus. This prompted us to investigate if there are indications of an altered neurodevelopment in this brain region. While neuron birth is largely completed by the end of gestation, granule neurons of the dentate gyrus are generated throughout life, thus offering an opportunity to investigate neurogenesis postnatally. METHODS We investigated whether repeated application of subanesthetic doses of the noncompetitive N-methyl-D-aspartate receptor antagonist ketamine, which has been shown to mimic model aspects of schizophrenia in animals, affects the hippocampal neurogenesis detected by bromodeoxyuridine incorporation. Cells were identified by immunocytochemistry. RESULTS Subanesthetic doses of ketamine applied subchronically enhance neurogenesis in the hippocampal subgranular zone. CONCLUSIONS In our animal model of schizophrenia, ketamine may evoke its stimulating effect on neurogenesis via a block of the N-methyl-D-aspartate receptor directly by reducing the c-Fos/c-Jun expression, resulting in a depression of the AP1 transcription factor complex and/or by a reduced nitric oxide production or an enhanced serotonergic activity. The newly formed neurons are not able to overcome the schizophrenia-related loss of parvalbumin expressing neurons and the behavioral abnormalities indicating that their functional integration is crucial.
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Affiliation(s)
- Gerburg Keilhoff
- Institute of Medical Neurobiology, University of Magdeburg, Magdeburg, Germany.
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85
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Jiang W, Wolfe K, Xiao L, Zhang ZJ, Huang YG, Zhang X. Ionotropic glutamate receptor antagonists inhibit the proliferation of granule cell precursors in the adult brain after seizures induced by pentylenetrazol. Brain Res 2004; 1020:154-60. [PMID: 15312797 DOI: 10.1016/j.brainres.2004.06.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2004] [Indexed: 11/27/2022]
Abstract
Seizures have been shown to promote the proliferation of granule cell precursors in the adult brain, but the underlying mechanisms remain largely unknown. Using systemic bromodeoxyuridine (BrdU) to label dividing cells, we examined the effects of selective ionotropic glutamate receptor antagonists on granule cell precursor proliferation in adult rats after pentylenetrazol (PTZ)-induced generalized clonic seizures. We found that the NMDA receptor antagonist MK-801 significantly inhibited behavioral and EEG seizures and completely blocked seizure-induced increase in the number of BrdU-labeled cells in the dentate gyrus. Although the AMPA/KA receptor antagonist DNQX was not observed to affect seizures, it significantly suppressed the number of BrdU-labeled cells in the dentate gyrus. Double immunohistochemical staining showed that both the mature granule cells and the majority of BrdU-labeled, mitotically active cells expressed the NMDA receptor subunit NR1 and the AMPA/KA receptor subunit GluR2. Because accumulated evidence showed that mild seizures are sufficient to promote precursor cell proliferation, the present findings that MK-801 inhibited seizures and completely blocked seizure-induced increase in precursor cell proliferation suggest that the direct blockade action of MK-801 on NMDA receptors on the granule cell precursors may play an important role in blocking seizure-induced precursor cell proliferation. The suppression of seizure-induced proliferation of granule cell precursors by DNQX may be achieved by the direct action of DNQX on AMPA/KA receptors on the granule cell precursors. Thus, our findings indicate that seizures may promote cell proliferation in the adult rat dentate gyrus through glutamatergic mechanisms acting on both NMDA and AMPA/KA receptors.
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Affiliation(s)
- Wen Jiang
- Neuropsychiatry Research Unit, Department of Psychiatry, A114 Medical Research Building, University of Saskatchewan, 103 Wiggins Road, Saskatoon, SK, Canada S7N5E4.
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86
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Liu S, Lau L, Wei J, Zhu D, Zou S, Sun HS, Fu Y, Liu F, Lu Y. Expression of Ca(2+)-permeable AMPA receptor channels primes cell death in transient forebrain ischemia. Neuron 2004; 43:43-55. [PMID: 15233916 DOI: 10.1016/j.neuron.2004.06.017] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2004] [Revised: 04/07/2004] [Accepted: 06/01/2004] [Indexed: 11/15/2022]
Abstract
CA1 pyramidal neurons degenerate after transient global ischemia, whereas neurons in other regions of the hippocampus remain intact. A step in this selective injury is Ca(2+) and/or Zn(2+) entry through Ca(2+)-permeable AMPA receptor channels; reducing Ca(2+) permeability of AMPA receptors via expression of Ca(2+)-impermeable GluR2(R) channels or activation of CRE transcription in the hippocampus of adult rats in vivo using shutoff-deficient pSFV-based vectors rescues vulnerable CA1 pyramidal neurons from forebrain ischemic injury. Conversely, the induction of Ca(2+) and/or Zn(2+) influx through AMPA receptors by expressing functional Ca(2+)-permeable GluR2(Q) channels causes the postischemic degeneration of hippocampal granule neurons that otherwise are insensitive to ischemic insult. Thus, the AMPA receptor subunit GluR2 gates entry of Ca(2+) and/or Zn(2+) that leads to cell death following transient forebrain ischemia.
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MESH Headings
- Animals
- Animals, Newborn
- Calcium/metabolism
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Channels, Q-Type/genetics
- Calcium Channels, Q-Type/metabolism
- Calcium Signaling/genetics
- Cell Death/genetics
- Cell Membrane Permeability/genetics
- Cyclic AMP Response Element-Binding Protein/genetics
- Cyclic AMP Response Element-Binding Protein/metabolism
- Cyclin-Dependent Kinase 5
- Cyclin-Dependent Kinases/genetics
- Cyclin-Dependent Kinases/metabolism
- Disease Models, Animal
- Hippocampus/metabolism
- Hippocampus/physiopathology
- In Vitro Techniques
- Integrases/genetics
- Integrases/metabolism
- Ion Channel Gating/genetics
- Ischemic Attack, Transient/genetics
- Ischemic Attack, Transient/metabolism
- Ischemic Attack, Transient/pathology
- Nerve Degeneration/genetics
- Nerve Degeneration/metabolism
- Nerve Degeneration/pathology
- Prosencephalon/metabolism
- Prosencephalon/pathology
- Protein Binding/genetics
- Pyramidal Cells/metabolism
- Pyramidal Cells/pathology
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/genetics
- Receptors, AMPA/metabolism
- Zinc/metabolism
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Affiliation(s)
- ShuHong Liu
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Calgary T2N 4N1, Canada
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87
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Santhakumar V, Soltesz I. Plasticity of interneuronal species diversity and parameter variance in neurological diseases. Trends Neurosci 2004; 27:504-10. [PMID: 15271499 DOI: 10.1016/j.tins.2004.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Interneuronal diversity reflects the division of labor between numerous highly specialized interneuronal species, each performing a set of specific functions in neuronal networks. The rich diversity of interneurons found in the normal healthy brain is often significantly altered in neurological and psychiatric diseases. In genetic and developmental disorders, the diversity of interneuronal networks is compromised because of disturbances in the generation, specification or migration of specific interneuronal subtypes. Following insults related to trauma and seizures, the relative abundance of interneuronal subtypes might change, and entire interneuronal species can be lost from the network. In addition to the complete or partial loss of interneuronal subgroups, heterogeneity can also be altered in more subtle ways, as a result of changes in cell-to-cell variance of a particular parameter within specific interneuronal populations. Computational and experimental studies show that alterations in cellular and synaptic GABAergic heterogeneity can significantly modulate both firing rates and network coherence, indicating that plasticity of interneuronal diversity is likely to be an important mechanistic component of malfunctioning cortical networks in many pathological states.
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Affiliation(s)
- Vijayalakshmi Santhakumar
- Department of Anatomy and Neurobiology, and Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92697-1280, USA
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88
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Zhu DY, Lau L, Liu SH, Wei JS, Lu YM. Activation of cAMP-response-element-binding protein (CREB) after focal cerebral ischemia stimulates neurogenesis in the adult dentate gyrus. Proc Natl Acad Sci U S A 2004; 101:9453-7. [PMID: 15197280 PMCID: PMC438997 DOI: 10.1073/pnas.0401063101] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Accepted: 05/10/2004] [Indexed: 12/19/2022] Open
Abstract
New neurons are generated in adult mammalians and may contribute to repairing the brain after injury. Here, we show that the number of new neurons in the dentate gyrus of adult rats increased in cerebral ischemic stroke and correlated with activation of the cAMP-response-element-binding protein (CREB). Inhibition of endogenous CREB by expression of a dominant-negative mutant of CREB (CREB-S133A or CREB-R287L) blocked ischemia-induced neurogenesis in the dentate gyrus of adult rats, whereas expression of constitutively active CREB, VP16-CREB, increased the number of new neurons. Thus, our findings provide roles and regulatory mechanisms for CREB in adult neurogenesis and possibly suggest a practical strategy for replacing dead neurons in brain injury.
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Affiliation(s)
- Dong Ya Zhu
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
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89
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Raineteau O, Rietschin L, Gradwohl G, Guillemot F, Gähwiler BH. Neurogenesis in hippocampal slice cultures. Mol Cell Neurosci 2004; 26:241-50. [PMID: 15207849 DOI: 10.1016/j.mcn.2004.01.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Revised: 12/17/2003] [Accepted: 01/06/2004] [Indexed: 11/21/2022] Open
Abstract
A major challenge in studying neurogenesis in the adult brain is gaining access to neural stem cells for experimental manipulation. We developed an approach utilizing mouse hippocampal organotypic cultures to characterize neurogenesis under controlled conditions. After 2 weeks in culture, double immunostaining using the mitotic marker BrdU and cell type-specific markers revealed persistent proliferation of various cell types. The birth of new neurons was restricted to a third subgranular germinal zone as shown by analysis of the expression pattern of the proneural transcription factor neurogenin-2 and colocalization of BrdU with neuronal phenotypic markers. The regional distribution of newly born neurons closely resembled that observed in vivo in the adult hippocampus. Furthermore, neurogenesis was increased by chronic application of epidermal growth factor (EGF) and abolished by adding serum to the culture medium. Our study therefore establishes the hippocampal slice culture as a promising ex vivo model for investigating neurogenesis.
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Affiliation(s)
- Olivier Raineteau
- Brain Research Institute, University of Zurich, CH-8057 Zurich, Switzerland.
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90
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Jiang W, Wang JC, Zhang Z, Sheerin AH, Zhang X. Response of seizure-induced newborn neurons in the dentate gyrus of adult rats to second episode of seizures. Brain Res 2004; 1006:248-52. [PMID: 15051529 DOI: 10.1016/j.brainres.2004.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 11/19/2022]
Abstract
In this study we examined the unknown issue of whether seizure-induced newborn hippocampal neurons in freely moving adult rats are able to respond to pathophysiological stimuli in the same way as their neighboring neurons do. Three days after pentylenetrazol (PTZ)-induced generalized seizures, rats received 5-bromodeoxyuridine (BrdU) injections to label dividing cells, followed 4 weeks later by the second PTZ injection to induce second episode of generalized seizures. We observed that the first episode of PTZ-induced seizures resulted in a significant increase in the number of newborn neurons in the adult hippocampal dentate gyrus. In comparison with vehicle-injected control rats that exhibited no Fos immunoreactivity and mild glutamic acid decarboxylase 67 (GAD67) expression in the dentate granule cells, rats killed 2-6 h following the second PTZ injection showed intensive Fos and GAD67 expression in virtually all granule cells with or without BrdU double-labeling. These findings provide important evidence indicating that seizure-induced newborn neurons in freely moving adult rats are able to respond to pathophysiological stimuli in the same way as neighboring neurons do.
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Affiliation(s)
- Wen Jiang
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
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91
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Kawai T, Takagi N, Miyake-Takagi K, Okuyama N, Mochizuki N, Takeo S. Characterization of BrdU-positive neurons induced by transient global ischemia in adult hippocampus. J Cereb Blood Flow Metab 2004; 24:548-55. [PMID: 15129187 DOI: 10.1097/00004647-200405000-00009] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neurogenesis in the brain continues throughout life and is promoted by brain insults including ischemia. There is no critical conclusion, however, about whether proliferated cells acquire neuronal function after ischemia. Transient global ischemia was produced by a four-vessel occlusion procedure in rats (n = 54). To label proliferative cells, rats were administrated with a single dose of 5-bromo-2'-deoxyuridine (BrdU) at 4, 6, 8, 10, 13, or 15 days after ischemia. Increases in BrdU-positive cells were detected in the hippocampal dentate gyrus at 5, 7, and 9 days after ischemia. To determine the phenotype of BrdU-positive cells, BrdU was administrated twice daily for 3 consecutive days during 6 to 8 days after ischemia. A basic helix-loop-helix transcription factor NeuroD at 7 and 14 days and an immature migrating neuronal marker doublecortin at 14 days after ischemia were expressed transiently in proliferative cells. These proliferative cells after ischemia differentiated to the phenotype of neuron at 28 days after ischemia. Furthermore, BrdU-positive neurons showed phosphorylation of extracellular signal-regulated kinase (ERK) by intracerebroventricular injection of N-methyl-D-aspartate (NMDA) at 28 and 56 days after ischemia as seen in surrounding mature neurons. The number of BrdU-positive neurons, which responded to NMDA stimulation, increased with time after ischemia and was greater than that of sham-operated animals. The present study provides evidence for in vivo ERK phosphorylation in response to NMDA stimulation of BrdU-positive neurons in the adult hippocampus after transient forebrain ischemia.
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Affiliation(s)
- Takayuki Kawai
- Department of Pharmacology, Tokyo University of Pharmacy and Life Science, Tokyo, Japan
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92
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Schmidt-Hieber C, Jonas P, Bischofberger J. Enhanced synaptic plasticity in newly generated granule cells of the adult hippocampus. Nature 2004; 429:184-7. [PMID: 15107864 DOI: 10.1038/nature02553] [Citation(s) in RCA: 943] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Accepted: 04/08/2004] [Indexed: 11/09/2022]
Abstract
Neural stem cells in various regions of the vertebrate brain continuously generate neurons throughout life. In the mammalian hippocampus, a region important for spatial and episodic memory, thousands of new granule cells are produced per day, with the exact number depending on environmental conditions and physical exercise. The survival of these neurons is improved by learning and conversely learning may be promoted by neurogenesis. Although it has been suggested that newly generated neurons may have specific properties to facilitate learning, the cellular and synaptic mechanisms of plasticity in these neurons are largely unknown. Here we show that young granule cells in the adult hippocampus differ substantially from mature granule cells in both active and passive membrane properties. In young neurons, T-type Ca2+ channels can generate isolated Ca2+ spikes and boost fast Na+ action potentials, contributing to the induction of synaptic plasticity. Associative long-term potentiation can be induced more easily in young neurons than in mature neurons under identical conditions. Thus, newly generated neurons express unique mechanisms to facilitate synaptic plasticity, which may be important for the formation of new memories.
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93
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Okamoto M, Sakiyama J, Mori S, Kurazono S, Usui S, Hasegawa M, Oohira A. Kainic acid-induced convulsions cause prolonged changes in the chondroitin sulfate proteoglycans neurocan and phosphacan in the limbic structures. Exp Neurol 2004; 184:179-95. [PMID: 14637091 DOI: 10.1016/s0014-4886(03)00251-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Systemic administration of kainic acid induces repeated convulsive seizures (KA convulsions) that result in neuropathological changes similar to temporal lobe epilepsy and the appearance of spontaneous recurrent seizures (SRS). The appearance of SRS is considered a result of the remodeling of neuronal networks following neuronal degeneration. We investigated the changes in chondroitin sulfate proteoglycans (CSPGs) in the limbic structures after KA convulsions in the rat using monoclonal antibodies 1G2, which recognizes full-length neurocan and the C-terminal half of neurocan, neurocan C, and 6B4, which recognize phosphacan and protein tyrosine phosphatase zeta. After KA convulsions, full-length neurocan appeared by 24 h and reached a peak by 48 to 72 h, whereas phosphacan decreased within 24 h in the hippocampus. In immunohistochemistry, neurocan increased in the limbic structures coincident with the appearance of reactive astrocytes. Phosphacan decreased coincident with pyramidal cell loss in the hippocampus, and the number of phosphacan-positive perineuronal nets around parvalbumin neurons decreased, whereas parvalbumin neurons were relatively conserved. In contrast, phosphacan increased in the entorhinal and piriform cortices in correlation with the severity of neuronal loss. Both neurocan and phosphacan recovered to the control level by 8 weeks after KA convulsions in some rats, but the changes in neurocan and phosphacan described above still persisted in more than half the rats. The results indicate that KA convulsions induce prolonged changes in neurocan and phosphacan similar to those in the developing rat brain and suggest a role of these CSPGs in the remodeling of neuronal networks related to the establishment or enhancement of epileptogenesis.
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Affiliation(s)
- Motoi Okamoto
- Faculty of Health Sciences, Okayama University Medical School, Okayama, Japan.
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94
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Montaron MF, Koehl M, Lemaire V, Drapeau E, Abrous DN, Le Moal M. Environmentally induced long-term structural changes: cues for functional orientation and vulnerabilities. Neurotox Res 2004; 6:571-80. [PMID: 15639789 DOI: 10.1007/bf03033453] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Environmental challenges profoundly modify phenotypes and disrupt inherent developmental programs both at functional and structural levels. As an example, we have studied the impact of these environmental influences on adult neurogenesis in the dentate gyrus. Neurogenesis results from an inherent program, participates to hippocampal network organization and, as a consequence, to the various functional abilities depending on this region, including memories. In preclinical studies of aging we have shown that phenotypes vulnerable to the development of spatial memory disorders are characterized by lower hippocampal neurogenesis. We have hypothesized that these interindividual variations in functional expression of neurogenesis in senescent subjects could be predicted early in life. Indeed, a behavioral response (novelty-induced locomotor reactivity) and a biological trait (hypothalamo-pituitary-adrenal axis activity), which are predictive of cognitive impairments later in life, are related to neurogenesis in young adult rats. This suggests that subjects starting off with an impaired neurogenesis, here rats that are high reactive to stress, are predisposed for the development of age-related cognitive disorders. We have further shown that these inter-individual differences result from early deleterious life events. Indeed, prenatal stress orients neurogenesis in pathological ways for the entire life, and precipitates age-related cognitive impairments. Altogether these data suggest first that hippocampal neurogenesis plays a pivotal role in environmentally-induced vulnerability to the development of pathological aging, and second that environmental challenges and life events orient structural developments, leading to different phenotypes.
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Affiliation(s)
- M F Montaron
- INSERM U588, Domaine de Carreire, Rue Camille Saint Saëns, University of Bordeaux II Bordeaux Cedex 33077, France
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95
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Belachew S, Gallo V. Synaptic and extrasynaptic neurotransmitter receptors in glial precursors' quest for identity. Glia 2004; 48:185-96. [PMID: 15390115 DOI: 10.1002/glia.20077] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It is widely established that neurotransmitter receptors are expressed in non-neuronal cells, and particularly in neural progenitor cells in the postnatal central nervous system. The functional role of these receptors during development is unclear, but it needs to be revisited now that cells previously considered restricted to glial lineages have been shown to generate neurons. The present review integrates recent advances, to shed new light on how neurotransmitter receptors may, alternatively, serve as excitable mediators of neuron-glia and neuron-neuroblast interactions.
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Affiliation(s)
- Shibeshih Belachew
- Center for Cellular and Molecular Neurobiology, University of Liège, Liège, Belgium
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96
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Okuyama N, Takagi N, Kawai T, Miyake-Takagi K, Takeo S. Phosphorylation of extracellular-regulating kinase in NMDA receptor antagonist-induced newly generated neurons in the adult rat dentate gyrus. J Neurochem 2003; 88:717-25. [PMID: 14720221 DOI: 10.1046/j.1471-4159.2003.02215.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Neurogenesis in the adult brain is promoted by various stimulations. NMDA receptor blockade enhances neurogenesis in the hippocampal dentate gyrus. There is no agreed conclusion, however, as to whether newly generated neurons after NMDA receptor blockade obtain functional properties. We investigated the functional maturation of newly generated neurons after NMDA receptor blockade. In the dentate gyrus, 80% of newly generated cells differentiated into the phenotype of mature neurons at 29 days after the single intraperitoneal injection of an NMDA receptor antagonist MK-801. The number of newly generated neurons after MK-801 treatment was significantly greater than that in the saline-treated group. The neurogenic basic helix-loop-helix transcription factor NeuroD protein in the dentate gyrus after MK-801 treatment was expressed transiently in proliferative cells, but not in mature neurons. To determine functional properties of newly generated neurons, we administered NMDA to the lateral ventricle. As an in vivo response, we assessed extracellular-regulating kinase (ERK) phosphorylation. The newly generated neurons showed ERK phosphorylation by NMDA administration as seen in surrounding mature neurons. The number of newly generated neurons, which responded to NMDA receptor stimulation, increased with time after MK-801 treatment. The present study provides evidence that newly generated neurons in the adult hippocampus after NMDA receptor blockade acquire biochemical function in vivo.
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Affiliation(s)
- Noriko Okuyama
- Faculty of Pharmaceutical Sciences, Department of Pharmacology, Tokyo University of Pharmacy & Life Science, Tokyo, Japan
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97
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Brandt MD, Jessberger S, Steiner B, Kronenberg G, Reuter K, Bick-Sander A, von der Behrens W, Kempermann G. Transient calretinin expression defines early postmitotic step of neuronal differentiation in adult hippocampal neurogenesis of mice. Mol Cell Neurosci 2003; 24:603-13. [PMID: 14664811 DOI: 10.1016/s1044-7431(03)00207-0] [Citation(s) in RCA: 397] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We here show that the early postmitotic stage of granule cell development during adult hippocampal neurogenesis is characterized by the transient expression of calretinin (CR). CR expression was detected as early as 1 day after labeling dividing cells with bromodeoxyuridine (BrdU), but not before. Staining for Ki-67 confirmed that no CR-expressing cells were in cell cycle. Early after BrdU, CR colocalized with immature neuronal marker doublecortin; and later with persisting neuronal marker NeuN. BrdU/CR-labeled cells were negative for GABA and GABAA1 receptor, but early on expressed granule cell marker Prox-1. After 6 weeks, no new neurons expressed CR, but all contained calbindin. Stimuli inducing adult neurogenesis have limited (enriched environment), strong (voluntary wheel running), and very strong effects on cell proliferation (kainate-induced seizures). In these models the induction of cell proliferation was paralleled by an increase of CR-positive cells, indicating the stimulus-dependent progression from cell division to a postmitotic stage.
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Affiliation(s)
- Moritz D Brandt
- Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
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98
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Wang J, Liu S, Fu Y, Wang JH, Lu Y. Cdk5 activation induces hippocampal CA1 cell death by directly phosphorylating NMDA receptors. Nat Neurosci 2003; 6:1039-47. [PMID: 14502288 DOI: 10.1038/nn1119] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2003] [Accepted: 07/21/2003] [Indexed: 12/31/2022]
Abstract
CA1 pyramidal neurons degenerate after transient forebrain ischemia, whereas neurons in other regions of the hippocampus remain intact. Here we show that in rat hippocampal CA1 neurons, forebrain ischemia induces the phosphorylation of the N-methyl-D-aspartate (NMDA) receptor 2A subunit at Ser1232 (phospho-Ser1232). Ser1232 phosphorylation is catalyzed by cyclin-dependent kinase 5 (Cdk5). Inhibiting endogenous Cdk5, or perturbing interactions between Cdk5 and NR2A subunits, abolished NR2A phosphorylation at Ser1232 and protected CA1 pyramidal neurons from ischemic insult. Thus, we conclude that modulation of NMDA receptors by Cdk5 is the primary intracellular event underlying the ischemic injury of CA1 pyramidal neurons.
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Affiliation(s)
- Jian Wang
- Department of Physiology and Biophysics, University of Calgary, Calgary T2N 4N1, Canada
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99
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Belachew S, Chittajallu R, Aguirre AA, Yuan X, Kirby M, Anderson S, Gallo V. Postnatal NG2 proteoglycan-expressing progenitor cells are intrinsically multipotent and generate functional neurons. J Cell Biol 2003; 161:169-86. [PMID: 12682089 PMCID: PMC2172886 DOI: 10.1083/jcb.200210110] [Citation(s) in RCA: 385] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurogenesis is known to persist in the adult mammalian central nervous system (CNS). The identity of the cells that generate new neurons in the postnatal CNS has become a crucial but elusive issue. Using a transgenic mouse, we show that NG2 proteoglycan-positive progenitor cells that express the 2',3'-cyclic nucleotide 3'-phosphodiesterase gene display a multipotent phenotype in vitro and generate electrically excitable neurons, as well as astrocytes and oligodendrocytes. The fast kinetics and the high rate of multipotent fate of these NG2+ progenitors in vitro reflect an intrinsic property, rather than reprogramming. We demonstrate in the hippocampus in vivo that a sizeable fraction of postnatal NG2+ progenitor cells are proliferative precursors whose progeny appears to differentiate into GABAergic neurons capable of propagating action potentials and displaying functional synaptic inputs. These data show that at least a subpopulation of postnatal NG2-expressing cells are CNS multipotent precursors that may underlie adult hippocampal neurogenesis.
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Affiliation(s)
- Shibeshih Belachew
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010-2970, USA
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