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Alzu'bi A, Lindsay SJ, Harkin LF, McIntyre J, Lisgo SN, Clowry GJ. The Transcription Factors COUP-TFI and COUP-TFII have Distinct Roles in Arealisation and GABAergic Interneuron Specification in the Early Human Fetal Telencephalon. Cereb Cortex 2017; 27:4971-4987. [PMID: 28922831 PMCID: PMC5903418 DOI: 10.1093/cercor/bhx185] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/12/2017] [Accepted: 07/03/2017] [Indexed: 12/13/2022] Open
Abstract
In human telencephalon at 8-12 postconceptional weeks, ribonucleic acid quantitative sequencing and immunohistochemistry revealed cortical chicken ovalbumin upstream promotor-transcription factor 1 (COUP-TFI) expression in a high ventro-posterior to low anterior gradient except for raised immunoreactivity in the anterior ventral pallium. Unlike in mouse, COUP-TFI and SP8 were extensively co-expressed in dorsal sensory neocortex and dorsal hippocampus whereas COUPTFI/COUPTFII co-expression defined ventral temporal cortex and ventral hippocampus. In the ganglionic eminences (GEs) COUP-TFI immunoreactivity demarcated the proliferative zones of caudal GE (CGE), dorsal medial GE (MGE), MGE/lateral GE (LGE) boundary, and ventral LGE whereas COUP-TFII was limited to ventral CGE and the MGE/LGE boundary. Co-labeling with gamma amino butyric acidergic interneuron markers revealed that COUP-TFI was expressed in subpopulations of either MGE-derived (SOX6+) or CGE-derived (calretinin+/SP8+) interneurons. COUP-TFII was mainly confined to CGE-derived interneurons. Twice as many GAD67+ cortical cells co-labeled for COUP-TFI than for COUP-TFII. A fifth of COUP-TFI cells also co-expressed COUP-TFII, and cells expressing either transcription factor followed posterior or anterio-lateral pathways into the cortex, therefore, a segregation of migration pathways according to COUP-TF expression as proposed in mouse was not observed. In cultures differentiated from isolated human cortical progenitors, many cells expressed either COUP-TF and 30% also co-expressed GABA, however no cells expressed NKX2.1. This suggests interneurons could be generated intracortically from progenitors expressing either COUP-TF.
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Affiliation(s)
- Ayman Alzu'bi
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Susan J Lindsay
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Lauren F Harkin
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
- Present address: School of Healthcare Science, Manchester Metropolitan University, UK
| | - Jack McIntyre
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Steven N Lisgo
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Gavin J Clowry
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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2
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Brandão JA, Romcy-Pereira RN. Interplay of environmental signals and progenitor diversity on fate specification of cortical GABAergic neurons. Front Cell Neurosci 2015; 9:149. [PMID: 25972784 PMCID: PMC4412069 DOI: 10.3389/fncel.2015.00149] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 04/01/2015] [Indexed: 12/19/2022] Open
Abstract
Cortical GABAergic interneurons constitute an extremely diverse population of cells organized in a well-defined topology of precisely interconnected cells. They play a crucial role regulating inhibitory-excitatory balance in brain circuits, gating sensory perception, and regulating spike timing to brain oscillations during distinct behaviors. Dysfunctions in the establishment of proper inhibitory circuits have been associated to several brain disorders such as autism, epilepsy, and schizophrenia. In the rodent adult cortex, inhibitory neurons are generated during the second gestational week from distinct progenitor lineages located in restricted domains of the ventral telencephalon. However, only recently, studies have revealed some of the mechanisms generating the heterogeneity of neuronal subtypes and their modes of integration in brain networks. Here we will discuss some the events involved in the production of cortical GABAergic neuron diversity with focus on the interaction between intrinsically driven genetic programs and environmental signals during development.
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Affiliation(s)
- Juliana A Brandão
- Brain Institute, Federal University of Rio Grande do Norte Natal, Brazil
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3
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Sequerra EB, Costa MR, Menezes JRL, Hedin-Pereira C. Adult neural stem cells: plastic or restricted neuronal fates? Development 2013; 140:3303-9. [PMID: 23900539 DOI: 10.1242/dev.093096] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
During embryonic development, the telencephalon is specified along its axis through morphogenetic gradients, leading to the positional-dependent generation of multiple neuronal types. After embryogenesis, however, the fate of neuronal progenitors becomes more restricted, and they generate only a subset of neurons. Here, we review studies of postnatal and adult neurogenesis, challenging the notion that fixed genetic programs restrict neuronal fate. We hypothesize that the adult brain maintains plastic neural stem cells that are capable of responding to changes in environmental cues and generating diverse neuronal types. Thus, the limited diversity of neurons generated under normal conditions must be actively maintained by the adult milieu.
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Affiliation(s)
- Eduardo B Sequerra
- Department of Physiology and Membrane Biology, University of California Davis, Shriners Hospital for Children Northern California, Sacramento, CA 95817, USA.
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4
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Abstract
The mechanisms involved in Alzheimer's disease are not completely understood and how glial cells contribute to this neurodegenerative disease remains to be elucidated. Because inflammatory treatments and products released from activated microglia increase glial hemichannel activity, we investigated whether amyloid-β peptide (Aβ) could regulate these channels in glial cells and affect neuronal viability. Microglia, astrocytes, or neuronal cultures as well as acute hippocampal slices made from GFAP-eGFP transgenic mice were treated with the active fragment of Aβ. Hemichannel activity was monitored by single-channel recordings and by time-lapse ethidium uptake, whereas neuronal death was assessed by Fluoro-Jade C staining. We report that low concentrations of Aβ(25-35) increased hemichannel activity in all three cell types and microglia initiate these effects triggered by Aβ. Finally, neuronal damage occurs by activation of neuronal hemichannels induced by ATP and glutamate released from Aβ(25-35)-activated glia. These responses were observed in the presence of external calcium and were differently inhibited by hemichannel blockers, whereas the Aβ(25-35)-induced neuronal damage was importantly reduced in acute slices made from Cx43 knock-out mice. Thus, Aβ leads to a cascade of hemichannel activation in which microglia promote the release of glutamate and ATP through glial (microglia and astrocytes) hemichannels that induces neuronal death by triggering hemichannels in neurons. Consequently, this work opens novel avenues for alternative treatments that target glial cells and neurons to maintain neuronal survival in the presence of Aβ.
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Dorsal radial glial cells have the potential to generate cortical interneurons in human but not in mouse brain. J Neurosci 2011; 31:2413-20. [PMID: 21325508 DOI: 10.1523/jneurosci.5249-10.2011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Radial glial (RG) cells, in the neocortical ventricular/subventricular zone (VZ/SVZ), generate cortical projection neurons both in rodents and humans, but whether they can also generate cortical interneurons is not clear. We demonstrated both on cryosections and in cell cultures that in the human VZ/SVZ, cells can be double labeled with RG markers and calretinin (CalR) and GABA, markers that suggest interneuronal lineage. We examined in more detail the cell fate of human RG cells isolated from the VZ/SVZ at midterm. After 24 h, no CalR(+) or GABA(+) cells were seen in cultures, whereas 5-10% cells expressed Nkx2.1 and Dlx, two ventral transcription factors. CalR(+) and GABA(+) cells were apparent for the first time after 3 d in vitro, and their number increased in subsequent days, consistent with the gradual transition of RG cells into CalR(+) or GABA(+) cells. Indeed, the progeny of genetically labeled RG cells could be immunolabeled with antibodies to CalR and GABA or ventral transcription factors (Nkx2.1(+), Dlx(+)). In contrast to humans, in the embryonic mouse, similar experiments showed that only RG cells isolated from the subpallium (ganglionic eminence) generate CalR(+) or GABA(+) cells, whereas this was not the case with RG cells isolated from the pallium. These findings support the idea that human, but not mouse, dorsal RG cells have the potential to generate various subtypes of neocortical interneurons. Multiple progenitors and sites of cortical interneuron origin in human might be an evolutionary adaptation underlying brain expansion and the increased complexity of cortical circuitry in humans.
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Corner MA. Spontaneous neuronal burst discharges as dependent and independent variables in the maturation of cerebral cortex tissue cultured in vitro: a review of activity-dependent studies in live 'model' systems for the development of intrinsically generated bioelectric slow-wave sleep patterns. ACTA ACUST UNITED AC 2008; 59:221-44. [PMID: 18722470 DOI: 10.1016/j.brainresrev.2008.08.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 08/01/2008] [Accepted: 08/05/2008] [Indexed: 10/21/2022]
Abstract
A survey is presented of recent experiments which utilize spontaneous neuronal spike trains as dependent and/or independent variables in developing cerebral cortex cultures when synaptic transmission is interfered with for varying periods of time. Special attention is given to current difficulties in selecting suitable preparations for carrying out biologically relevant developmental studies, and in applying spike-train analysis methods with sufficient resolution to detect activity-dependent age and treatment effects. A hierarchy of synchronized nested burst discharges which approximate early slow-wave sleep patterns in the intact organism is established as a stable basis for isolated cortex function. The complexity of reported long- and short-term homeostatic responses to experimental interference with synaptic transmission is reviewed, and the crucial role played by intrinsically generated bioelectric activity in the maturation of cortical networks is emphasized.
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Affiliation(s)
- Michael A Corner
- Netherlands Institute for Brain Research, Amsterdam, The Netherlands.
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7
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Price J, Williams BP, Götz M. The generation of cellular diversity in the cerebral cortex. CIBA FOUNDATION SYMPOSIUM 2007; 193:71-84; discussion 117-26. [PMID: 8727487 DOI: 10.1002/9780470514795.ch4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have used retroviral vectors to study cell lineage in the embryonic rat cerebral cortex both in vivo and in dissociated cell culture. We provide evidence that during the late phase of corticogenesis, most precursor cells of the ventricular zone are specified for the production of a single cell type, either neurons or one of the glial cell types. Although specified, the precursor cells that generate neurons can apparently generate both pyramidal and non-pyramidal cells. Earlier stages of development are dominated by a different type of precursor cell with a number of properties that lead us to believe that it is the founding, multipotential precursor cell of the cerebral cortex. We discuss a possible model of cell lineage which unifies these various observations.
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Affiliation(s)
- J Price
- SmithKline Beecham Pharmaceuticals, Harlow, Essex, UK
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8
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Ventura RE, Goldman JE. Dorsal radial glia generate olfactory bulb interneurons in the postnatal murine brain. J Neurosci 2007; 27:4297-302. [PMID: 17442813 PMCID: PMC6672317 DOI: 10.1523/jneurosci.0399-07.2007] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During embryogenesis, dorsal radial glia generate pyramidal cell neurons but not interneurons, and are thought to degenerate or transform into astrocytes in the postnatal brain. Ventral radial glia, in contrast, retract their processes to form GFAP+ subventricular zone (SVZ) astrocytes that continue to generate interneurons into adulthood. We sought to fate map dorsal radial glia by codelivering an adenovirus expressing Cre recombinase and a lentivirus expressing dsRedExpress to the dorsal cortical surface of ROSA26R-YFP mice. Whereas the adenovirus is retrogradely transported to the cell body, the VSV-G (vesicular stomatitis virus G) pseudotyped lentivirus is not and allows us to control for viral diffusion from the site of infection. We found that dorsal radial glia give rise to gray and white matter astrocytes and oligodendrocytes. In addition, the dorsal radial glia fate map to astrocytes lining the dorsal aspect of the SVZ that persist at least 8 weeks postnatally. Finally, we found that dorsal radial glial-derived cells generate granule cell and periglomerular interneurons in the olfactory bulb and continue to form interneuronal precursors into adulthood.
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Affiliation(s)
| | - James E. Goldman
- Center for Neurobiology and Behavior and
- Department of Pathology, Columbia University, New York, New York 10032
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9
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Stromal derived factor-1 exerts differential regulation on distinct cortical cell populations in vitro. BMC DEVELOPMENTAL BIOLOGY 2007; 7:31. [PMID: 17425785 PMCID: PMC1854892 DOI: 10.1186/1471-213x-7-31] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 04/10/2007] [Indexed: 11/10/2022]
Abstract
BACKGROUND Stromal derived factor (SDF-1), an alpha chemokine, is a widely known chemoattractant in the immune system. A growing body of evidence now suggests multiple regulatory roles for SDF-1 in the developing nervous system. RESULTS To investigate the role of SDF-1 signaling in the growth and differentiation of cortical cells, we performed numerous in vitro experiments, including gene chip and quantitative RT-PCR analysis. Using SDF-1 medium and AMD3100, a receptor antagonist, we demonstrate that the chemokine signaling regulates key events during early cortical development. First, SDF-1 signaling maintains cortical progenitors in proliferation, possibly through a mechanism involving connexin 43 mediated intercellular coupling. Second, SDF-1 signaling upregulates the differentiation of cortical GABAergic neurons, independent of sonic signaling pathway. Third, SDF-1 enables the elongation and branching of axons of cortical glutamatergic neurons. Finally, cortical cultures derived from CXCR4-/- mutants show a close parallel to AMD3100 treatment with reduced cell proliferation and differentiation of GABAergic neurons. CONCLUSION Results from this study show that SDF-1 regulates distinct cortical cell populations in vitro.
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Trinh HH, Reid J, Shin E, Liapi A, Parnavelas JG, Nadarajah B. Secreted factors from ventral telencephalon induce the differentiation of GABAergic neurons in cortical cultures. Eur J Neurosci 2007; 24:2967-77. [PMID: 17156358 DOI: 10.1111/j.1460-9568.2006.05194.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is widely believed that the pyramidal cells and interneurons of the cerebral cortex are distinct in their origin, lineage and genetic make up. In view of these findings, the current thesis is that the phenotype determination of cortical neurons is primarily directed by genetic mechanisms. Using in vitro assays, the present study demonstrates that secreted factors from ganglionic eminence (GE) of the ventral telencephalon have the potency to induce the differentiation of a subset of cortical neurons towards gamma-aminobutyric acid (GABA)ergic lineage. Characterization of cortical cultures that were exposed to medium derived from GE illustrated a significant increase in the number of GABA-, calretinin- and calbindin-positive neurons. Calcium imaging together with pharmacological studies showed that the application of exogenous medium significantly elevated the intracellular calcium transients in cortical neurons through the activation of ionotropic glutamate receptors. The increase in GABA+ neurons appeared to be associated with the elevated calcium activity; treatment with blockers specific for glutamate receptors abolished both the synchronized transients and reduced the differentiation of GABAergic neurons. Such studies demonstrate that although intrinsic mechanisms determine the fate of cortical interneurons, extrinsic factors have the potency to influence their neurochemical differentiation and contribute towards their molecular diversity.
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Affiliation(s)
- H-h Trinh
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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11
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Bianchi C, Marani L, Marino S, Barbieri M, Nazzaro C, Beani L, Siniscalchi A. Serotonin modulation of cell excitability and of [3H]GABA and [3H]D-aspartate efflux in primary cultures of rat cortical neurons. Neuropharmacology 2006; 52:995-1002. [PMID: 17156800 DOI: 10.1016/j.neuropharm.2006.10.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 10/25/2006] [Accepted: 10/28/2006] [Indexed: 11/25/2022]
Abstract
The effects of 5-hydroxytryptamine (5-HT) on neuronal excitability, evaluated as depolarization-induced firing rate, and on amino acid release, measured as electrically-evoked [(3)H]GABA and [(3)H]d-aspartate efflux, were investigated in rat primary cortical neuronal cultures. 5-HT displayed a concentration-dependent, bimodal effect on neuronal excitability: at 3-10microM it increased excitability through 5-HT(2A) receptors, and was blocked by the selective 5-HT(2A) antagonist MDL 100907, whereas at 30-100microM it reduced excitability through 5-HT(1A) receptors, and was, in turn, blocked by the selective 5-HT(1A) antagonist WAY 100135. The electrically-evoked [(3)H]GABA efflux was concentration-dependently inhibited by 5-HT (pEC(50)=4.74) and such inhibition was prevented by WAY 100135, but not by GR 55562, a selective 5-HT(1D/B) receptor antagonist. Conversely, 5-HT concentration-dependently increased stimulus-evoked [(3)H]d-aspartate efflux (pEC(50)=4.71). The increase was facilitated by methiothepin and was reversed into inhibition by ICS 205930, a selective 5-HT(3) receptor antagonist. In the presence of ICS 205930, the inhibition induced by 5-HT was prevented by the selective 5-HT(1D/B) receptor antagonist GR 55562, but not by WAY 100135. These findings suggest that 5-HT inhibits GABA release through 5-HT(1A) receptors and exerts a dual modulation on glutamate release, mostly facilitatory (through 5-HT(3) receptors) but also inhibitory (through 5-HT(1D/B) receptors), leading to a prevalently positive modulation of the excitatory signal by amino acid neurotransmitter containing neurons.
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Affiliation(s)
- C Bianchi
- Department of Clinical and Experimental Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy
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12
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Allain AE, Meyrand P, Branchereau P. Ontogenic changes of the spinal GABAergic cell population are controlled by the serotonin (5-HT) system: implication of 5-HT1 receptor family. J Neurosci 2006; 25:8714-24. [PMID: 16177041 PMCID: PMC6725515 DOI: 10.1523/jneurosci.2398-05.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During the development of the nervous system, the acquisition of the GABA neurotransmitter phenotype is crucial for neural networks operation. Although both intrinsic and extrinsic signals such as transcription factors and growth factors have been demonstrated to govern the acquisition of GABA, few data are available concerning the effects of modulatory transmitters expressed by axons that progressively invade emerging neuronal networks. Among such transmitters, serotonin (5-HT) is a good candidate because serotonergic axons innervate the entire CNS at very early stages of development. We have shown previously that descending 5-HT slows the maturation of inhibitory synaptic transmission in the embryonic mouse spinal cord. We now report that 5-HT also regulates the spatiotemporal changes of the GABAergic neuronal population in the mouse spinal cord. Using a quantitative confocal study performed on acute and cultured spinal cords, we find that the GABAergic population matures according to a similar rostrocaudal temporal gradient both in utero and in organotypic culture. Moreover, we show that 5-HT delays the appearance of the spinal GABAergic system. Indeed, in the absence of 5-HT descending inputs or exogenous 5-HT, the GABAergic population matures earlier. In the presence of exogenous 5-HT, the GABA population matures later. Finally, using a pharmacological approach, we show that 5-HT exerts its action via the 5-HT1 receptor family. Together, our data suggest that, during the course of the embryonic development, 5-HT descending inputs delay the maturation of lumbar spinal motor networks relative to brachial networks.
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Affiliation(s)
- Anne-Emilie Allain
- Laboratoire de Neurobiologie des Réseaux, Université Bordeaux 1, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5816, 33405 Talence cedex, France
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13
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Siniscalchi A, Marino S, Marani L, Piubello C, Bianchi C, Selvatici R. Early and delayed glutamate effects in rat primary cortical neurons. Neurochem Int 2005; 46:117-25. [PMID: 15627512 DOI: 10.1016/j.neuint.2004.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2004] [Revised: 08/10/2004] [Accepted: 08/12/2004] [Indexed: 01/29/2023]
Abstract
Glutamate-induced changes in the subcellular distribution of protein kinase C isoforms and in the intracellular calcium concentration were investigated in rat primary cortical neurons. Western blot analysis of protein kinase C isoforms (alpha, beta1, beta2, gamma, delta, epsilon, zeta and theta), performed 30 min after a 10 min treatment with 30 microM glutamate, revealed a decrease in the total beta1 (-24%) and beta2 (-40%) isoform levels, without any significant change in any of the other isozymes. All conventional isoforms translocated to the membrane compartment, while delta, epsilon, zeta and theta; maintained their initial subcellular distribution. Twenty-four hours after glutamate treatment, the total protein kinase C labelling had increased, particularly the epsilon isoform, which accounted for 34% of the total densitometric signal. At this time, protein kinase C beta1, delta, epsilon and zeta isoforms were mainly detected in the membrane compartment, while gamma and theta; signals were displayed almost solely in the cytosol. Basal intracellular calcium concentration (FURA 2 assay) was concentration-dependently increased (maximum effect +77%) 30 min, but not 24h after a 10 min glutamate (10-100 microM) treatment, while the net increase induced by electrical stimulation (10 Hz, 10s) was consistently reduced (maximum effect -64%). The N-methyl-d-aspartate receptor antagonist, MK-801, 1 microM, prevented glutamate action both 30 min and 24 h after treatment, while non-selective protein kinase C inhibitors, ineffective at 30 min, potentiated it at 24 h. These findings show that protein kinase C isoforms are differently activated and involved in the early and delayed glutamate actions, and that the prevailing effect of their activation is neuroprotective.
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Affiliation(s)
- Anna Siniscalchi
- Department of Clinical and Experimental Medicine, Section of Pharmacology, University of Ferrara, 17, Via Fossato di Mortara, 44100 Ferrara, Italy.
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14
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Kawaguchi A, Ogawa M, Saito K, Matsuzaki F, Okano H, Miyata T. Differential expression of Pax6 and Ngn2 between pair-generated cortical neurons. J Neurosci Res 2004; 78:784-95. [PMID: 15523634 DOI: 10.1002/jnr.20347] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Progenitor cells that generate neuron pairs ("pair progenitor cells") are implicated in mammalian cortical development, and their division has been thought to be "symmetric." However, asymmetric growth of two sister neurons generated by the division of a pair progenitor cell would lead to more efficient generation of neuronal diversity in the cortex. To explore mechanisms by which pair progenitor cells provide neuronal diversity, we examined molecular differences between a pair of neurons generated in clonal-density culture. Time-course analysis for the acquisition of neuronal markers and the disappearance of Pax6 and Neurogenin2 (Ngn2) demonstrated that 1) these transcription factors are expressed transiently in some but not all young neurons and 2) some neuron pairs showed uneven/asymmetric expression of Pax6 (19.5%) or Ngn2 (23.8%), whereas other pairs were either symmetrically positive or negative. Asymmetric Pax6 distribution in neuron pairs was not associated with asymmetric distribution of Numb, which raises an intriguing possibility, that Pax6 asymmetry in neuron pairs is produced by an alternative mode of the cell autonomous mechanisms. Stage-dependent changes were noted in the pattern of Ngn2 retention in daughter neurons, reflecting qualitative changes in the pair progenitor population. We suggest that pair progenitor cells contribute to the generation of neuronal diversity through cell-intrinsic heterogeneity and asymmetric division.
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Affiliation(s)
- Ayano Kawaguchi
- Laboratory for Cell Culture Development, Brain Science Institute, RIKEN, Wako, Saitama, Japan.
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15
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Bianchi C, Marani L, Barbieri M, Marino S, Beani L, Siniscalchi A. Effects of nociceptin/orphanin FQ and endomorphin-1 on glutamate and GABA release, intracellular [Ca2+] and cell excitability in primary cultures of rat cortical neurons. Neuropharmacology 2004; 47:873-83. [PMID: 15527821 DOI: 10.1016/j.neuropharm.2004.06.017] [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: 02/04/2004] [Revised: 05/19/2004] [Accepted: 06/23/2004] [Indexed: 11/30/2022]
Abstract
The effects of nociceptin/orphanin FQ (N/OFQ) and endomorphin-1 (EM-1) on glutamate and GABA release, intracellular calcium, neuronal excitability and glutamate current were investigated in rat primary cortical neuronal cultures. Through their specific receptors N/OFQ and EM-1 (0.02-1 microM) inhibited the electrically evoked outflow of [3H]D-aspartate at most to -50% and that of [3H]GABA to -30%. In addition, at 1 microM, both peptides induced a decrease of the firing rate caused by electrical depolarization. N/OFQ 1-10 microM did not influence either the electrically evoked calcium influx or the glutamate-evoked currents, whereas EM-1 1 microM significantly inhibited them. Thus, in cortical neurons in culture, both N/OFQ and EM-1 inhibited the secretory process and neuronal excitability but EM-1 also affected calcium influx and cell body responsiveness to glutamate. Consequently, EM-1 appeared to dampen this excitatory signal more then N/OFQ did.
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Affiliation(s)
- C Bianchi
- Department of Clinical and Experimental Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, via Fossato di Mortara 17-19, Ferrara 44100, Italy.
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16
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Spitzer NC, Root CM, Borodinsky LN. Orchestrating neuronal differentiation: patterns of Ca2+ spikes specify transmitter choice. Trends Neurosci 2004; 27:415-21. [PMID: 15219741 DOI: 10.1016/j.tins.2004.05.003] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Appropriate specification of neurotransmitters is a key feature of neuronal network assembly. There is much evidence that genetic programs are responsible for this aspect of cell fate and neuronal differentiation. Are there additional ways in which these processes are shaped? Recent findings demonstrate that altering patterned Ca(2+) spike activity that is spontaneously generated by different classes of embryonic spinal neurons in vivo changes expression of neurotransmitters in a homeostatic manner, as if to achieve a constant level of excitation. Activity-dependent changes in presynaptic transmitter expression pose a matching problem: are there corresponding changes in postsynaptic transmitter receptor expression, or are axons rerouted to novel targets with which functional synapses can be formed?
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Affiliation(s)
- Nicholas C Spitzer
- Neurobiology Section and Center for Molecular Genetics, Division of Biological Sciences, UCSD, La Jolla, CA 92093, USA.
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17
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Sonic hedgehog and bone morphogenetic protein regulate interneuron development from dorsal telencephalic progenitors in vitro. J Neurosci 2003. [PMID: 14586015 DOI: 10.1523/jneurosci.23-30-09862.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cortical progenitors are competent to produce interneurons, but do not generate large numbers of interneurons in vivo under normal circumstances. This could reflect the absence of an inductive signal in the environment of the dorsal telencephalon and/or the presence of an inhibitory signal. To determine whether either or both mechanisms regulate interneuron generation, progenitors in dorsomedial and dorsolateral wall explants of mouse telencephalon were marked with a retrovirus and cultured under several conditions. When cultured separately, progenitors in dorsomedial wall explants produced fewer GABAergic interneurons than progenitors in dorsolateral wall explants. When cocultured with ventral telencephalic cells, however, dorsomedial wall progenitors produced more GABAergic interneurons than in dorsomedial wall explants alone. The inductive effect of ventral telencephalon depended on sonic hedgehog (Shh) and could be mimicked by exogenous Shh. In contrast, exogenous bone morphogenetic protein 4 (BMP4) reduced the production of interneurons in dorsolateral wall explants and inhibited the induction by exogenous Shh. Moreover, inhibiting BMP signaling in dorsomedial wall progenitors with a dominant-negative BMP receptor Ib (dnBMPIb) virus increased their production of interneurons, even if Shh was blocked. Shh and dnBMPRIb increased proliferation and the generation of interneurons, but FGF2 did not induce interneurons, although it increased proliferation. This suggests that proliferation per se does not control the production of interneurons. Our findings suggest that the generation of interneurons by dorsal telencephalic progenitors is normally limited by excess levels of BMPs. Shh may promote the generation of interneurons by antagonizing BMP, but may not be required directly for the generation of interneurons.
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Corner MA, van Pelt J, Wolters PS, Baker RE, Nuytinck RH. Physiological effects of sustained blockade of excitatory synaptic transmission on spontaneously active developing neuronal networks--an inquiry into the reciprocal linkage between intrinsic biorhythms and neuroplasticity in early ontogeny. Neurosci Biobehav Rev 2002; 26:127-85. [PMID: 11856557 DOI: 10.1016/s0149-7634(01)00062-8] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spontaneous bioelectric activity (SBA) taking the form of extracellularly recorded spike trains (SBA) has been quantitatively analyzed in organotypic neonatal rat visual cortex explants at different ages in vitro, and the effects investigated of both short- and long-term pharmacological suppression of glutamatergic synaptic transmission. In the presence of APV, a selective NMDA receptor blocker, 1-2- (but not 3-)week-old cultures recovered their previous SBA levels in a matter of hours, although in imitation of the acute effect of the GABAergic inhibitor picrotoxin (PTX), bursts of action potentials were abnormally short and intense. Cultures treated either overnight or chronically for 1-3 weeks with APV, the AMPA/kainate receptor blocker DNQX, or a combination of the two were found to display very different abnormalities in their firing patterns. NMDA receptor blockade for 3 weeks produced the most severe deviations from control SBA, consisting of greatly prolonged and intensified burst firing with a strong tendency to be broken up into trains of shorter spike clusters. This pattern was most closely approximated by acute GABAergic disinhibition in cultures of the same age, but this latter treatment also differed in several respects from the chronic-APV effect. In 2-week-old explants, in contrast, it was the APV+DNQX treated group which showed the most exaggerated spike bursts. Functional maturation of neocortical networks, therefore, may specifically require NMDA receptor activation (not merely a high level of neuronal firing) which initially is driven by endogenous rather than afferent evoked bioelectric activity. Putative cellular mechanisms are discussed in the context of a thorough review of the extensive but scattered literature relating activity-dependent brain development to spontaneous neuronal firing patterns.
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Affiliation(s)
- M A Corner
- Academic Medical Centre, Meibergdreef 33, Netherlands Institute for Brain Research, 1105 AZ Amsterdam, The Netherlands.
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19
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Corbin JG, Nery S, Fishell G. Telencephalic cells take a tangent: non-radial migration in the mammalian forebrain. Nat Neurosci 2001; 4 Suppl:1177-82. [PMID: 11687827 DOI: 10.1038/nn749] [Citation(s) in RCA: 219] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During development of the mammalian telencephalon, cells migrate via diverse pathways to reach their final destinations. In the developing neocortex, projection neurons are generated from cells that migrate radially from the underlying ventricular zone. In contrast, subsets of cells that populate the ventral piriform cortex and olfactory bulb reach these sites by migrating long distances. Additionally, it has been recently established that cells migrate tangentially from the ventral ganglionic eminences to the developing cortex. These tangentially migrating cells are a significant source of cortical interneurons and possibly other cell types such as oligodendrocytes. Here we summarize the known routes of migration in the developing telencephalon, with a particular focus on tangential migration. We also review recent genetic and transplantation studies that have given greater insight into the understanding of these processes and the molecular cues that may guide these migrating cells.
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Affiliation(s)
- J G Corbin
- Developmental Genetics Program and the Department of Cell Biology, The Skirball Institute of Biomolecular Medicine, New York University Medical Center, 540 First Avenue, New York, New York, 10016, USA
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Drian MJ, Bardoul M, König N. Blockade of AMPA/kainate receptors can either decrease or increase the survival of cultured neocortical cells depending on the stage of maturation. Neurochem Int 2001; 38:509-17. [PMID: 11248399 DOI: 10.1016/s0197-0186(00)00103-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neurotoxicity has often been associated with glutamate receptor stimulation and neuroprotection with glutamate receptor blockade. However, the relationship may be much more complex. We dissociated cells from the rat neocortical anlage at an early stage of prenatal development (embryonic day 14). The cells were exposed in vitro to agonists and antagonists of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA)/kainate and N-methyl-D-aspartate (NMDA) receptors and the effects on differentiation and survival have been quantitatively and qualitatively evaluated. NMDA and the non-competitive antagonist (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine hydrogen maleate (MK-801) had the expected effects (the agonist decreasing and the antagonist increasing neuronal survival) when applied at a relatively advanced stage of in vitro maturation, but no significant effect in either direction at earlier stages. Kainate also had an effect on cell survival only at an advanced stage (where it decreased the number of cells). However, this cannot be attributed to the absence of functional AMPA/kainate receptors at earlier stages, since: (1) cells could be loaded with cobalt; and (2) early application of kainate dramatically reduced the number of cobalt-positive cells. Furthermore, exposure at early stages to 6,7-dinitroquinoxaline-2,3-dione (DNQX), or GYKI 53655, (competitive and non-competitive AMPA receptor antagonists, respectively) strongly reduced cell survival. The effects were concentration- and time-dependent with a complex time--curve. The decrease in cell number was maximal after antagonist application from 2 to 5 days in vitro. The effects of DNQX could be cancelled by co-application of kainate. When exposed to an antagonist at later stages of development, the number of surviving cells gradually approached control values and finally became significantly higher. Our results suggest that cells of the developing neocortex (and perhaps newly generated cells in the adult brain) require at different stages of their development, an appropriate level of AMPA/kainate receptor activation.
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Affiliation(s)
- M J Drian
- EPHE Quantitative Cell Biology/INSERM U 336, University Montpellier 2, Case Courier 106, Place E. Bataillon, 34095 Montpellier, Cedex 05, France
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Chenn A, Levin ME, McConnell SK. Temporally and spatially regulated expression of a candidate G-protein-coupled receptor during cerebral cortical development. JOURNAL OF NEUROBIOLOGY 2001; 46:167-77. [PMID: 11169503 DOI: 10.1002/1097-4695(20010215)46:3<167::aid-neu1000>3.0.co;2-j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Genes expressed in layer-specific patterns in the mammalian cerebral cortex may play a role in specifying the identity of different cortical layers. Using PCR-differential display, we identified a cDNA that encodes rCNL3, a gene cloned previously by sequence homology to G-protein-coupled receptors. rCNL3 is expressed predominantly in layers 2-4 of the young rat cortex and in the developing and adult striatum. Cortical expression of rCNL3 begins postnatally at P3 and continues at high levels until around P15, while striatal expression begins at E20 and continues through adulthood. rCNL3 expression is not detectable in the ventricular zone precursors that generate the neurons of layers 2-4. The expression pattern of rCNL3 in the developing cortex suggests that rCNL3 is not involved in the initial specification of laminar fate, but rather may be involved with later differentiation events within the superficial cortical layers.
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Affiliation(s)
- A Chenn
- Department of Biological Sciences, Stanford University, 385 Serra Mall, Stanford, California 94305, USA
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Abstract
Thalamic afferents are known to exert a control over the differentiation of cortical areas at late stages of development. Here, we show that thalamic afferents also influence early stages of corticogenesis at the level of the ventricular zone. Using an in vitro approach, we show that embryonic day 14 mouse thalamic axons release a diffusable factor that promotes the proliferation of cortical precursors over a restricted developmental window. The thalamic mitogenic effect on cortical precursors (1) shortens the total cell-cycle duration via a reduction of the G(1) phase; (2) facilitates the G(1)/S transition leading to an increase in proliferative divisions; (3) is significantly reduced by antibodies directed against bFGF; and (4) influences the proliferation of both glial and neuronal precursors and does not preclude the action of signals that induce differentiation in these two lineages. We have related these in vitro findings to the in vivo condition: the organotypic culture of cortical explants in which anatomical thalamocortical innervation is preserved shows significantly increased proliferation rates compared with cortical explants devoid of subcortical afferents. These results are in line with a number of studies at subcortical levels showing the control of neurogenesis via afferent fibers in both vertebrates and invertebrates. Specifically, they indicate the mechanisms whereby embryonic thalamic afferents contribute to the known early regionalization of the ventricular zone, which plays a major role in the specification of neocortical areas.
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Wahle P, Gorba T, Wirth MJ, Obst-Pernberg K. Specification of neuropeptide Y phenotype in visual cortical neurons by leukemia inhibitory factor. Development 2000; 127:1943-51. [PMID: 10751182 DOI: 10.1242/dev.127.9.1943] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Building the complex mammalian neocortex requires appropriate numbers of neurochemically specified neurons. It is not clear how the highly diverse cortical interneurons acquire their distinctive phenotypes. The lack of genetic determination implicates environmental factors in this selection and specification process. We analysed, in organotypic visual cortex cultures, the specification of neurons expressing neuropeptide Y (NPY), a potent anticonvulsant. Endogenous brain-derived neurotrophic factor and neurotrophin 4/5 play no role in early NPY phenotype specification. Rather, the decision to express NPY is made during a period of molecular plasticity during which differentiating neurons with the potential to express NPY compete for the cytokine leukemia inhibitory factor which is produced in the cortex, but is negatively regulated by thalamic afferences. The neurons that fail in this competition are parvalbuminergic basket and chandelier neurons, which express NPY transiently, but will not acquire a permanent NPY expression. They switch into a facultative NPY expression mode, and remain responsive to the neurotrophins which modulate NPY expression later in development.
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Affiliation(s)
- P Wahle
- AG Entwicklungsneurobiologie, Ruhr-Universität, ND 7/31, Germany.
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Brooker GJ, Kalloniatis M, Russo VC, Murphy M, Werther GA, Bartlett PF. Endogenous IGF-1 regulates the neuronal differentiation of adult stem cells. J Neurosci Res 2000; 59:332-41. [PMID: 10679768 DOI: 10.1002/(sici)1097-4547(20000201)59:3<332::aid-jnr6>3.0.co;2-2] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Stem cells from the adult forebrain of mice were stimulated to form clones in vitro using fibroblast growth factor-2 (FGF-2). At concentrations above 10 ng/ml of FGF-2, very few clones gave rise to neurons; however, if FGF-2 was removed after 5 days, 20-30% of clones subsequently gave rise to neurons. The number of neuron-containing clones and the number of neurons per clone was significantly enhanced, if insulin-like growth factor (IGF)-1 or heparin were added subsequent to FGF-2 removal. The spontaneous production of neurons after FGF-2 removal was shown to be due to endogenous IGF-1, since antibodies to IGF-1 and an IGF-1 binding protein totally inhibited neuronal production. Similarly, these reagents also abrogated the neuron-promoting effects of heparin. Thus, it appears that endogenous IGF-1 may be a major regulator of stem cell differentiation into neurons. Furthermore, it was found that high levels of IGF-1 or insulin promoted the maturation and affected the neurotransmitter phenotype of the neurons generated.
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Affiliation(s)
- G J Brooker
- The Walter and Eliza Hall Institute of Medical Research, The Royal Melbourne Hospital, Parkville, Victoria, Australia
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25
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Fode C, Ma Q, Casarosa S, Ang SL, Anderson DJ, Guillemot F. A role for neural determination genes in specifying the dorsoventral identity of telencephalic neurons. Genes Dev 2000. [DOI: 10.1101/gad.14.1.67] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Neurogenin1 (Ngn1), Neurogenin2(Ngn2), and Mash1 encode bHLH transcription factors with neuronal determination functions. In the telencephalon, theNgns and Mash1 are expressed at high levels in complementary dorsal and ventral domains, respectively. We found thatNgn function is required to maintain these two separate expression domains, as Mash1 expression is up-regulated in the dorsal telencephalon of Ngn mutant embryos. We have taken advantage of the replacement of the Ngns by Mash1 in dorsal progenitors to address the role of the neural determination genes in neuronal-type specification in the telencephalon. InNgn2 single and Ngn1; Ngn2 double mutants, a population of early born cortical neurons lose expression of dorsal-specific markers and ectopically express a subset of ventral telencephalic-specific markers. Analysis of Mash1; Ngn2double mutant embryos and of embryos carrying a Ngn2 toMash1 replacement mutation demonstrated that ectopic expression of Mash1 is required and sufficient to confer these ventral characteristics to cortical neurons. Our results indicate that in addition to acting as neuronal determinants, Mash1 andNgns play a role in the specification of dorsal-ventral neuronal identity, directly linking pathways of neurogenesis and regional patterning in the forebrain.
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Gorba T, Wahle P. Expression of TrkB and TrkC but not BDNF mRNA in neurochemically identified interneurons in rat visual cortex in vivo and in organotypic cultures. Eur J Neurosci 1999; 11:1179-90. [PMID: 10103114 DOI: 10.1046/j.1460-9568.1999.00551.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The mammalian visual cortex contains morphologically diverse populations of interneurons whose neurochemical properties are believed to be regulated by neurotrophic factors. This requires the expression of neurotrophin receptors. We have analysed whether brain-derived neurotrophic factor (BDNF), its receptor trkB and the NT-3 receptor trkC are expressed in interneurons of rat visual cortex in vivo, and in organotypic visual cortex cultures, paying particular attention to the subsets of neuropeptidergic neurons. In situ hybridization in combination with immunofluorescence for calcium-binding proteins and neuropeptides revealed that BDNF is not expressed in interneurons in vivo or in vitro. For the neurotrophin receptors we found in vivo at postnatal day 70 (P70) that approximately 80% of the parvalbumin-immunoreactive (-ir), but only 50% of the intensely calbindin-ir, and only 20% of the calretinin-ir neurons express trkB. Double labelling with neuropeptides revealed that approximately 50% of the neuropeptide Y-ir and approximately 50% of the somatostatin-ir neurons express trkB in a laminar-specific way. Only 25% of the vasoactive intestinal polypeptide (VIP)-ir neurons coexpress trkB. The coexpression of neuropeptide Y with trkB, but not with BDNF or trkC, was confirmed with a double in situ hybridization. In contrast, the percentages differed in the immature cortex; at P14 70% of the NPY-ir neurons and 46% of the calretinin-ir neurons revealed trkB expression, while the ratio for calbindin-ir cells was fairly constant (59%). From the interneuron populations studied, only 12% of the parvalbumin-ir neurons expressed trkC. A triple labelling revealed that some neurons coexpressed both trk mRNAs, while others had only trkC. The analysis of interneurons in organotypic cultures yielded very similar results. The results indicate that trkB ligands synthesized by pyramidal neurons influence neuropeptide or calcium-binding protein expression in a paracrine or transsynaptic manner. However, in contrast to current belief, in the adult only about half of all interneurons appear responsive to trkB ligands. Although the proportion is higher in the immature cortex, not all of the interneurons appear neurotrophin-receptive. With regard to the presence or absence of neurotrophin receptors, the molecular heterogeneity of GABAergic interneurons in the visual cortex is higher than currently assumed, and the responsiveness to neurotrophins changes with development in a cell type-specific way.
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Affiliation(s)
- T Gorba
- AG Entwicklungsneurobiologie, Fakultät für Biologie, Ruhr-Universit at, Bochum, Germany
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27
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Döbrössy MD, Dunnett SB. Striatal grafts alleviate deficits in response execution in a lateralised reaction time task. Brain Res Bull 1998; 47:585-93. [PMID: 10078616 DOI: 10.1016/s0361-9230(98)00129-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It has been reported that homotopic neural transplants can ameliorate behavioural impairments induced by striatal lesions in a reaction time (RT) task. In the present study we seek to replicate and extend this observation in a new lateralised choice RT task based on the conventional Skinner box apparatus. Rats were trained to make rapid lateralised lever press responses to a visual stimulus presented on either the left or the right side of the animal. The RTs required to initiate and execute correct responses were recorded, along with other accuracy and performance indices. Following unilateral lesions of the dorsal striatum, the rats exhibited an increased number of error trials, a bias to respond towards the ipsilateral side, a decreased accuracy on the contralateral side, and an increase of the execution time to respond correctly to contralateral stimuli. Striatal grafts alleviated the lateralised response deficits, prevented the development of lateral disparity, and restored the speed of responding back to pre-lesion levels. Control grafts of cortical tissues also increased task accuracy and reduced the ipsilateral bias in responding, but were without effect on the RT deficit.
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Affiliation(s)
- M D Döbrössy
- MRC Cambridge Centre for Brain Repair and Department of Experimental Psychology, University of Cambridge, UK.
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28
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Dual action of a ligand for Eph receptor tyrosine kinases on specific populations of axons during the development of cortical circuits. J Neurosci 1998. [PMID: 9614241 DOI: 10.1523/jneurosci.18-12-04663.1998] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The structural basis of cortical columns are radially oriented axon collaterals that form precise connections between distinct cortical layers. During development, these connections are highly specified from the initial outgrowth of collateral branches. Our previous work provided evidence for positional cues confined to individual layers that induce and/or prevent the formation of axon collaterals in specific populations of cortical neurons. Here we demonstrated with in situ hybridization techniques that mRNA of the Eph receptor tyrosine kinase EphA5 and one of its ligands, ephrin-A5, are present in distinct cortical layers, at a time when intrinsic connections are being formed in the cortex. Axonal guidance assays indicate that ephrin-A5 is a repellent signal for a populations of axons that in vivo avoid the cortical layer expressing ephrin-A5. In contrast to its established role as a repulsive axonal guidance signal, ephrin-A5 specifically mediates sprouting of those cortical axons that target the ephrin-A5-expressing layer in vivo. These results identify a novel function of ephrin-A5 on axonal arbor formation. The laminar distribution and the dual action on specific populations of axons suggest that ephrin-A5 plays a role in the assembly of local cortical circuits.
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Obst K, Bronzel M, Wahle P. Visual activity is required to maintain the phenotype of supragranular NPY neurons in rat area 17. Eur J Neurosci 1998; 10:1422-8. [PMID: 9749796 DOI: 10.1046/j.1460-9568.1998.00146.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Visual activity governs the functional maturation of the mammalian visual cortex. We report here, that visual experience is required for stabilizing the phenotype of a subset of cortical interneurons. Neurons expressing neuropeptide Y mRNA (NPY neurons) display a transiently higher expression in the early postnatal visual areas 18a and 17 that is followed by a phenotype restriction during the second postnatal month: about 50% of the NPY neurons in supragranular and infragranular layers of area 18a, and in infragranular layers of area 17 gradually stop the NPY expression. In contrast, the expression remains unchanged in supragranular layers of area 17. Dark rearing rats from birth to up to 100 days does neither prevent the developmental onset of NPY mRNA expression, nor does it prevent the phenotype restriction from occurring. In contrast, in dark reared animals NPY neurons in supragranular layers of area 17 now also undergo a phenotype restriction. Returning animals to light after variable periods of darkness results in an upregulation of NPY mRNA expression selectively in neurons in supragranular layers of area 17. These neurons acquire a constitutive expression during the second postnatal month. This suggests that the phenotypic specification of a distinct subset of cortical interneurons is regulated by visual experience which thus influences on the maturation of the neurochemical architecture of area 17.
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Affiliation(s)
- K Obst
- AG Entwicklungsneurobiologie, Fakultät für Biologie, Ruhr-Universität, Bochum, Germany
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Vogt Weisenhorn DM, Celio MR, Rickmann M. The onset of parvalbumin-expression in interneurons of the rat parietal cortex depends upon extrinsic factor(s). Eur J Neurosci 1998; 10:1027-36. [PMID: 9753170 DOI: 10.1046/j.1460-9568.1998.00120.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Parvalbumin (PV) belongs to the large family of EF-hand calcium-binding proteins and is an excellent marker for a subpopulation of GABAergic neocortical interneurons. During cortical development, PV first appears on postnatal day (P)8, in the infragranular layers; after P14, it also becomes apparent within the supragranular layers. However, nothing is known about the factors controlling its expression, which could involve functional activity, neuronal connectivity and/or neurotrophic factors. It being difficult to manipulate these parameters in vivo, their role may be more readily assessed in organotypic cultures, which are deprived of their subcortical afferents and efferents, and hence of subcortically derived neurotrophic factors and extrinsic functional activity. We prepared slices of the rat brain on P3, P5, P7 and P9, maintained them in culture for 2-5 weeks, and compared the temporal and spatial distribution pattern of PV-immunoreactivity within these slices with the in vivo situation. We found, first, that during late postnatal in vivo development and ageing, the number of PV-immunoreactive neurons in the parietal cortex decreases significantly, and second, that the expression of PV-immunoreactivity in the parietal cortex was markedly influenced by the phase of postnatal development at which slice cultures were explanted. In those removed on P7 and P9, the number of PV-immunoreactive cells, as well as the temporal and spatial distribution pattern of PV-immunoreactivity corresponded to the in vivo situation, but in explants obtained on P3 or P5, PV-immunoreactivity remained confined to layer V of the cortex, reminiscent of the expression profile manifested at the end of the second postnatal week in vivo. Also, the number of PV-immunoreactive cells in these cultures was significantly lower than in explants at the later stages. Our results indicate that the onset of PV-expression in the parietal cortex depends upon extrinsic cortical factors subsisting prior to P7. Once the production of this protein has been initiated, such influences are no longer required.
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Affiliation(s)
- D M Vogt Weisenhorn
- Emory University, School of Medicine, Department of Pathology, Atlanta, GA 30329, USA.
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31
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De Lima AD, Voigt T. Identification of two distinct populations of ?-aminobutyric acidergic neurons in cultures of the rat cerebral cortex. J Comp Neurol 1997. [DOI: 10.1002/(sici)1096-9861(19971201)388:4<526::aid-cne2>3.0.co;2-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
The transient expression of neuropeptide transmitters is a common feature of the developing cortex. We have now analysed the role of cortical afferents in shaping the neurochemical architecture of rat visual cortex using organotypic cultures. Deafferented cortex monocultures prepared from newborn rats reveal a constant NPY mRNA expression in 6-8% of all cortical neurons up to 90 days in vitro (DIV). In contrast, afferent thalamocortical and corticocortical axonal innervation elicits a progressive reduction in the percentage of NPY mRNA expressing neurons from initially 6-8% in 30DIV cocultures to 2-3% and 3-4% respectively in 60DIV cocultures, which is maintained for up to 90DIV. This phenotype restriction is not observed in only efferently connected corticocollicular cocultures. Further, axonal innervation does not change the percentage of GAD mRNA-expressing neurons, which remains at 13% in mono- and cocultures. When feeding thalamocortical cocultures with monoculture-conditioned medium between 3-20DIV followed by normal medium up to 60DIV, the phenotype restriction fails to occur in the cocultured cortex. We conclude that cortex-derived factors secreted into the medium by a monoculture suppress the phenotype-restricting capacity of the afferents, but only when present within the first 14DIV during the period of formation of axonal connections. To elucidate the nature of the cortex-derived factors, brain-derived neurotrophic factor was applied to the medium. When applied for the first 14DIV, it does not prevent the phenotype restriction from occurring. This suggests that epigenetic factors such as axonal innervation and cortex-derived factors other than brain-derived neurotrophic factor govern a phenotype decision in neocortical neurons during a period of molecular plasticity.
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Affiliation(s)
- K Obst
- AG Entwicklungsneurobiologie, Fakultät für Biologie, Ruhr-Universität, Bochum, Germany
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Serotonin promotes the differentiation of glutamate neurons in organotypic slice cultures of the developing cerebral cortex. J Neurosci 1997. [PMID: 9315907 DOI: 10.1523/jneurosci.17-20-07872.1997] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The monoamines serotonin (5-HT), noradrenaline (NA), and dopamine (DA), which are present in the developing brain apparently before they assume their neurotransmitter functions, are regarded as strong candidates for a role in the maturation of the cerebral cortex. Here we sought to investigate their effects on the generation and differentiation of cortical cell types. Slice cultures, prepared from the cortices of embryonic day (E) 14, E16, and E19 rat fetuses, were kept in defined medium or in defined medium plus 5-HT for 7 d. E16 cortices were also exposed to NA or DA for the same period. At the end of this period, the proportions of the neuronal [glutamate (Glu)-, GABA-, calbindin-, calretinin-labeled], glial (GFAP), and neuroepithelial (nestin) cell types were estimated for all conditions. We found that in E16 cultures, application of 5-HT, but not of NA or DA, significantly increased the proportion of Glu-containing neurons without affecting the overall neuronal population or the proportions of any other cell types. A similar effect was observed in co-cultures of E16 cortex with slices through the midbrain raphe nuclei of E19 rats. The total amount of cortical Glu, as measured with HPLC, was also increased in these co-cultures. To investigate whether the effect of 5-HT was the result of changes in cell proliferation, we exposed slices to bromodeoxyuridine (BrdU) and found that the proportion of BrdU-labeled cells was similar in the 5-HT-treated and control slices. These results indicate that 5-HT promotes the differentiation of cortical Glu-containing neurons without affecting neuroepithelial cell proliferation.
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Echevarría D, Matute C, Albus K. Neurons in the rat occipital cortex co-expressing the substance P-receptor and GABA: a comparison between in vivo and organotypic cultures. Eur J Neurosci 1997; 9:1530-5. [PMID: 9240411 DOI: 10.1111/j.1460-9568.1997.tb01508.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The morphology and the distribution of neurons expressing the NK1-receptor (NK1R) and the co-expression of gamma-aminobutyric acid (GABA) in these neurons were studied in the rat occipital cortex and in organotypic cultures (OTCs) derived from this structure. By employing immunohistochemistry, we demonstrate that the NK1R-expressing neurons are non-pyramidal neurons and co-express GABA. Some differences were noted between in vivo and OTCs. NK1R-expressing neurons in OTCs had larger somata and longer dendrites and the proportion stained with an anti-GABA-antibody (approximately 50%) was smaller than in vivo (90%). The preferential location of NK1R-expressing neurons in layers II/III and VI, seen in vivo is not present in OTCs where these neurons distribute rather homogeneously through layers II-VI. Our findings imply that in contrast to the cat and monkey, in the rat occipital cortex the effects of substance P are almost exclusively mediated via inhibitory interneurons.
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Affiliation(s)
- D Echevarría
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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35
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Brain-derived neurotrophic factor mediates the activity-dependent regulation of inhibition in neocortical cultures. J Neurosci 1997. [PMID: 9169513 DOI: 10.1523/jneurosci.17-12-04527.1997] [Citation(s) in RCA: 255] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The excitability of cortical circuits is modulated by interneurons that release the inhibitory neurotransmitter GABA. In primate and rodent visual cortex, activity deprivation leads to a decrease in the expression of GABA. This suggests that activity is able to adjust the strength of cortical inhibition, but this has not been demonstrated directly. In addition, the nature of the signal linking activity to GABA expression has not been determined. Activity is known to regulate the expression of the neurotrophin brain-derived neurotrophic factor (BDNF), and BDNF has been shown to influence the phenotype of GABAergic interneurons. We use a culture system from postnatal rat visual cortex to test the hypothesis that activity is regulating the strength of cortical inhibition through the regulation of BDNF. Cultures were double-labeled against GABA and the neuronal marker MAP2, and the percentage of neurons that were GABA-positive was determined. Blocking spontaneous activity in these cultures reversibly decreased the number of GABA-positive neurons without affecting neuronal survival. Voltage-clamp analysis of inhibitory currents demonstrated that activity blockade also decreased GABA-mediated inhibition onto pyramidal neurons and raised pyramidal neuron firing rates. All of these effects were prevented by incubation with BDNF during activity blockade, but not by neurotrophin 3 or nerve growth factor. Additionally, blockade of neurotrophin signaling mimicked the effects of activity blockade on GABA expression. These data suggest that activity regulates cortical inhibition through a BDNF-dependent mechanism and that this neurotrophin plays an important role in the control of cortical excitability.
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Castellani V, Bolz J. Membrane-associated molecules regulate the formation of layer-specific cortical circuits. Proc Natl Acad Sci U S A 1997; 94:7030-5. [PMID: 9192686 PMCID: PMC21279 DOI: 10.1073/pnas.94.13.7030] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The columnar organization of the mammalian neocortex is based on radially oriented axon collaterals which precisely link cells from distinct cortical layers. During development, these interlaminar connections are specific from their initial outgrowth: collaterals form only in the target layers and there are no transient axonal collaterals in the nontarget layers. To examine whether positional cues within individual cortical layers regulate the laminar specificity of collateral formation, explants of cells destined for different cortical layers were cultured on membranes prepared from target and nontarget layers. Axonal growth and branching were examined on homogeneous membrane substrates and on alternating stripes of membranes from different layers. Results show that axons branch preferentially on membrane substrates from those layers that they would target in vivo. In addition, when cortical axons were given a choice to grow on membranes from either their target or their nontarget layer, they exhibited a clear preference for the target layers. This indicates that membrane-associated cues confined to individual layers regulate the formation of collaterals of cortical axons and restrict their growth to their target layers. Heat inactivation of membranes from target layers resulted in reduced axonal branching. The same manipulation of membranes from nontarget layers increased axonal branching for one population of cortical neurons. Taken together, these results suggest that membrane-associated molecules confined to individual layers induce and prevent the formation of axon collaterals in distinct populations of cortical neurons. Thus, the expression of layer-specific cues provides important constraints for the remodeling of local circuits during cortical development.
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Affiliation(s)
- V Castellani
- Institut National de la Santé et de la Recherche Médicale Unité 371 'Cerveau et Vision', 69500 Bron, France
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37
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de Lima AD, Merten MD, Voigt T. Neuritic differentiation and synaptogenesis in serum-free neuronal cultures of the rat cerebral cortex. J Comp Neurol 1997; 382:230-46. [PMID: 9183691 DOI: 10.1002/(sici)1096-9861(19970602)382:2<230::aid-cne7>3.0.co;2-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To better understand the dynamics of the cellular processes involved in early neocortical development, we studied the neuritic differentiation and synaptogenesis of dispersed neurons grown in serum-free cultures under a wide variety of culture conditions. Microtubule-associated protein (MAP2), phosphorylated neurofilament (SMI 31) and synaptophysin immunocytochemistry was complemented with time-lapse studies. During the first week in vitro dissociated cortical neurons developed from roundish cells without processes to neurons with axons and differentiated dendrites, going through five distinct phases. The sequence of these phases was unaltered in a wide range of culturing methods, but the timing of the steps varied among cultures started with different cell densities. Synaptic terminals were first observed after 3-4 days in vitro, coincident with the beginning of dendritic differentiation. Synaptogenesis progressed at least until the end of the third week in vitro, despite a decline in cell density during the second week in vitro. The process of cellular differentiation of cerebral cortical neurons in vitro resembled the development of these cells in the intact tissue, suggesting that organized cell migration is not a prerequisite for the differentiation of single cortical neurons.
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Affiliation(s)
- A D de Lima
- Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
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38
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Micheva KD, Beaulieu C. Development and plasticity of the inhibitory neocortical circuitry with an emphasis on the rodent barrel field cortex: a review. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-032] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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39
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Herrmann K. Differential distribution of AMPA receptors and glutamate during pre- and postnatal development in the visual cortex of ferrets. J Comp Neurol 1996; 375:1-17. [PMID: 8913890 DOI: 10.1002/(sici)1096-9861(19961104)375:1<1::aid-cne1>3.0.co;2-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Immunohistochemical methods were used to study the distribution and time-course of appearance of cells expressing glutamate and alpha-amino-3-hydroxy-5-methyl-4-isoaxazole propionic acid (AMPA)-type glutamate receptors (GluR1 and GluR2/3) during development of the ferret visual cortex. Glutamate is present in many neurons in the ventricular zone, intermediate zone, developing cortical plate, and marginal zone as early as embryonic day (E) 34 (birth is at E41 in ferrets). Glutamate attains its adult distribution coincident with the completion of cellular migration. By contrast, GluR1 immunoreactivity emerges more slowly. By birth, GluR1 immunoreactivity is present only in a few neurons in the marginal zone and ventricular zone but is abundant in the marginal zone and subplate, where synaptogenesis commences. The number and staining intensity of GluR1-positive cells increases dramatically during the first two postnatal weeks and is maximal between the second and third week, before slowly declining to adult levels. Cortical cells immunopositive for GluR2/3 follow a similar pattern, although their distribution differs: GluR2/3-positive cells are mainly pyramidal cells. During the first postnatal week, GluR2/3 is also transiently present in fibers in the intermediate zone, which at this stage contains many thalamocortical and callosal and corticofugal axons. The abundance of glutamate at fetal stages, especially in the ventricular zone, is consistent with the previously proposed role of glutamate in mediating trophic effects in vivo, as previously demonstrated in vitro. The expression of AMPA receptors, as well as their transient overexpression, confirms the results of in situ hybridization studies and may imply a developmental role in neuronal differentiation for these receptors, in addition to their mature role in mediating cortical transmission.
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Affiliation(s)
- K Herrmann
- Laboratory of Neurophysiology, National Institute of Mental Health, NIHAC, Poolesville, Maryland 20837, USA.
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40
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Wilkemeyer MF, Angelides KJ. Adenovirus-mediated expression of a reporter gene in thalamocortical cocultures. Brain Res 1995; 703:129-38. [PMID: 8719624 DOI: 10.1016/0006-8993(95)01101-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Organotypic cocultures of thalamic and cortical explants have recently been used to study the development of the thalamocortical axonal network in the mammalian neocortex. To explore the possibility of genetically manipulating organotypic explants, rat thalamocortical (TC) cocultures were infected with the recombinant adenovirus, Adv/RSV beta gal. Infection of the cortical explants resulted in long-term expression (2 weeks) of the reporter gene (beta-galactosidase) with no significant alterations to the structural integrity of the explants. By micro-injecting the adenoviruses into cortical explants a significant degree of spatial control over reporter gene expression was obtained. DiI-labeled axonal projections from thalamic explants into infected (n = 116) and control cortical (n = 120) explants were also analyzed. There was no significant difference in the extent or degree of TC ingrowth into infected or control cortical explants. Thalamic explants were also efficiently infected with the Adv/RSV beta gal virus. While the pattern and extent of TC ingrowth from infected thalamic explants was similar to controls, the percentage of viable, infected thalamic explants was decreased. These experiments were necessary precursors for future studies using recombinant adenoviruses and organotypic cocultures. Genetic manipulation of these cocultures should enable the dissection of proteins involved in the development of axonal networks in the mammalian neocortex, using a system amenable to direct manipulation and observation.
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Affiliation(s)
- M F Wilkemeyer
- Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
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41
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Obst K, Wahle P. Areal differences of NPY mRNA-expressing neurons are established in the late postnatal rat visual cortex in vivo, but not in organotypic cultures. Eur J Neurosci 1995; 7:2139-58. [PMID: 8542071 DOI: 10.1111/j.1460-9568.1995.tb00636.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In order to learn about the factors regulating the postnatal development of neocortical peptidergic neuron populations, we have analysed neurons expressing neuropeptide Y (NPY) by immunohistochemistry and in situ hybridization in developing and adult rat visual cortical areas 17 and 18a in vivo, and in organotypic slice cultures of rat visual cortex. For quantitative analysis, the percentage of NPY mRNA-expressing neurons was determined in supragranular layers I-IV, in infragranular layers V and VI and in the white matter. In vivo, this percentage increased in visual areas 17 and 18a until postnatal day 21 in supra- and infragranular layers. Initially, in both areas the neurons were about equally distributed in supra- and infragranular layers (a ratio of 1:1). During the second postnatal month, the percentage of NPY mRNA-expressing neurons in area 18a declined by approximately 50% in both supra- and infragranular layers, so that the ratio of 1:1 remained constant. In contrast, in area 17 the percentage of neurons in supragranular layers remained fairly constant, but it declined to 50% in infragranular layers, so that by postnatal day 70 the ratio was gradually shifted to 2:1. Throughout development, area 18a contained significantly more NPY mRNA-expressing neurons than area 17. In organotypic slice cultures, a high density of NPY mRNA-expressing neurons had appeared by 10 days in vitro. A much higher percentage of neurons expressed NPY mRNA. The ratio of labelled neurons in supra- versus infragranular layers was 1:1. Both ratio and percentage remained constant from 10-85 days in vitro. The decline in vivo was not caused by an elimination of transient cell types. All cell types persisted into adulthood. Four NPY peptide-immunoreactive neuronal types were classified by axonal morphology in organotypic slice cultures and in vivo; they include (i) cells in layer VI/white matter with horizontal axons and ascending collaterals, (ii) cells in layers V/VI with descending axon and horizontal collaterals, (iii) Martinotti cells in layers V/VI with ascending axons, and (iv) cells in layers III-V with columnar axons. Two further types, bipolar cells with axons descending from dendrites and small basket cells with short horizontal axons, both found in vivo in layers II/III, could not be unequivocally identified in organotypic slice cultures. The NPY-immunoreactive neuron types had already formed a dense innervation of the cultures by 10 days in vitro, which remained stable for up to 85 days in vitro, and resembled the innervation observed in vivo. NPY peptide-immunoreactive neurons in organotypic slice cultures and in vivo were distributed in cortical layers II/III, V and VI and the white matter, but rarely in layers I and IV, which corresponded to the distribution of NPY mRNA-expressing neurons. However, with in situ hybridization more neurons were detectable, especially in layers II/III. A majority of NPY mRNA-expressing neurons co-localized NPY peptide, somatostatin and calbindin. We conclude that intrinsic cues were sufficient to drive the molecular expression of the NPY phenotype, the morphological differentiation and the stabilization of an organotypic NPY innervation in organotypic slice cultures. However, the area- and lamina-specific changes observed in vivo were not observed under monoculture conditions.
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Affiliation(s)
- K Obst
- Fakultät für Biologie, Lehrstuhl für Allgemeine Zoologie und Neurobiologie, Ruhr-Universität, Bochum, Germany
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42
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Abstract
Adult rat sympathetic neurons can possess specific neuropeptides utilized as cotransmitters along with norepinephrine, but the factors that regulate their expression remain unknown. 60% of adult rat superior cervical ganglion (SCG) neurons express neuropeptide Y (NPY) in vivo. To determine whether the restricted expression was an intrinsic property of sympathetic ganglia, we examined if embryonic sympathetic precursors gave rise to NPY immunoreactive (-IR) neurons in vitro. After one week in culture, 60% of neurons derived from the E14.5 rat SCG were NPY-IR. Thus, ganglia isolated before peripheral target contact or preganglionic innervation were capable of regulating NPY expression both in the number of neurons with NPY and in the developmental timing of NPY expression. To determine if the restricted expression of NPY was a reflection of neuroblasts committed to an NPY fate, SCG precursors were labeled with a replication incompetent retrovirus carrying lacZ, and NPY expression in lacZ-labeled clones examined after one week. Two thirds of neuronal clones obtained were uniformly NPY-IR; that is, all neurons in a clone either possessed or lacked NPY. One-third of the neuronal clones were mixed and contained both neurons with and without NPY. We provide a novel demonstration that both lineage and environmental cues contribute to neuropeptide phenotype.
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Affiliation(s)
- A K Hall
- Department of Neuroscience, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
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43
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Götz M, Williams BP, Bolz J, Price J. The specification of neuronal fate: a common precursor for neurotransmitter subtypes in the rat cerebral cortex in vitro. Eur J Neurosci 1995; 7:889-98. [PMID: 7613625 DOI: 10.1111/j.1460-9568.1995.tb01076.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Neurotransmitter choice is a crucial step in neural development. In the cerebral cortex, pyramidal neurons use the excitatory neurotransmitter glutamate, whereas non-pyramidal cells use the inhibitory neurotransmitter GABA. We are interested in how these two neuronal types are generated. We labelled precursor cells from embryonic rat cerebral cortex with a retroviral vector in dissociated cell cultures, and examined the neurotransmitter phenotype of their progeny immunohistochemically after 2 weeks in vitro. We discovered, first, that precursor cells in culture generate glutamatergic and GABAergic neurons in proportions similar to those in vivo. Second, we found that neuronal precursor cells gave rise to both GABAergic and glutamatergic neurons. These results suggest that neuronal precursor cells in the cerebral cortex have the potential to generate both neuronal subtypes. Moreover, these data are consistent with a stochastic model of neurotransmitter specification.
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Affiliation(s)
- M Götz
- National Institute for Medical Research, London, UK
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44
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Abstract
The mammalian neocortex is composed of functional areas that are specified to process particular aspects of information. How is this specification achieved during development? Since cells migrate to their final positions in the developing nervous system, a central issue is the relation between cellular migration and positional information. This review combines evidence for early positional specification in the developing cortex with evidence for cellular dispersion during migration. A model is suggested whereby stable cues provide positional information and minorities of 'displaced' cells are respecified accordingly. Comparison with other parts of the CNS reveals that cellular dispersal is ubiquitous and has to be included in any mechanism relaying positional specification. Ontogenetic and phylogenetic considerations suggest that radial glial cells might provide the positional information in the developing nervous system.
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Affiliation(s)
- M Götz
- SmithKline Beecham, Harlow, Essex, England, UK
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45
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Paysan J, Bolz J, Mohler H, Fritschy JM. GABAA receptor alpha 1 subunit, an early marker for area specification in developing rat cerebral cortex. J Comp Neurol 1994; 350:133-49. [PMID: 7860797 DOI: 10.1002/cne.903500110] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Changes in the expression of neurotransmitter receptors in developing cerebral cortex may be related to the functional maturation of distinct areas. In the present study, we have tested whether GABAA receptor expression in neonatal rats reflects the differentiation of cortical areas. Specifically, the alpha 1 subunit, one of the most prevalent GABAA receptor subunits in adult cerebral cortex, is up-regulated postnatally, suggesting a link with the establishment of inhibitory circuits. Using immunohistochemistry with a subunit-specific antiserum, we observed a striking area- and lamina-specific increase in staining for GABAA receptors containing the alpha 1 subunit (alpha 1-GABAA receptors), from low levels in neonates to an intense and uniform staining in adults. Already at birth, the alpha 1-subunit immunoreactivity selectively demarcated the boundaries of certain cortical areas. In particular, the primary somatosensory (S1) and visual (V1) areas were distinctly delineated with a band of alpha 1-subunit immunoreactivity located in the developing layers III and IV. The staining ended abruptly at the presumptive boundaries of S1 and V1, adjacent areas being unstained at this age. Around postnatal day 3, clusters of alpha 1-subunit positive cells were seen in layers III-IV of S1 and V1 extending their dendrites up to layer I, where they arborized profusely. In addition, the distribution of alpha 1-GABAA receptors in S1 revealed in detail the differentiation of the barrel field during early postnatal development. Although staining was observed in all areas by postnatal day 6, differences in the laminar distribution of alpha 1-GABAA receptors persisted for at least 1 more week. Our results provide evidence for the existence of area-specific boundaries in neocortex of newborn rats before layers III-IV are fully differentiated and innervated by cortical afferents. Furthermore, the area- and lamina-specific maturation of alpha 1-GABAA receptor staining demonstrates the value of this marker for investigating the cytoarchitectonic differentiation of cortical areas during development.
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Affiliation(s)
- J Paysan
- Institute of Pharmacology, University of Zurich, Switzerland
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46
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Abstract
In the mammalian neocortex, local connections as well as projections to and from the cortex are organized in cortical layers. Recent studies have demonstrated that the formation of the patterns of afferent and efferent cortical connections in organotypic co-cultures are similar to those observed in vivo. These findings provide some insights into the cellular strategies that operate during the development of layer-specific cortical connections.
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Affiliation(s)
- J Bolz
- INSERM U.371, Bron, France
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