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Alderman PJ, Saxon D, Torrijos-Saiz LI, Sharief M, Page CE, Baroudi JK, Biagiotti SW, Butyrkin VA, Melamed A, Kuo CT, Vicini S, García-Verdugo JM, Herranz-Pérez V, Corbin JG, Sorrells SF. Delayed maturation and migration of excitatory neurons in the juvenile mouse paralaminar amygdala. Neuron 2024; 112:574-592.e10. [PMID: 38086370 PMCID: PMC10922384 DOI: 10.1016/j.neuron.2023.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 05/05/2023] [Accepted: 11/09/2023] [Indexed: 02/12/2024]
Abstract
The human amygdala paralaminar nucleus (PL) contains many immature excitatory neurons that undergo prolonged maturation from birth to adulthood. We describe a previously unidentified homologous PL region in mice that contains immature excitatory neurons and has previously been considered part of the amygdala intercalated cell clusters or ventral endopiriform cortex. Mouse PL neurons are born embryonically, not from postnatal neurogenesis, despite a subset retaining immature molecular and morphological features in adults. During juvenile-adolescent ages (P21-P35), the majority of PL neurons undergo molecular, structural, and physiological maturation, and a subset of excitatory PL neurons migrate into the adjacent endopiriform cortex. Alongside these changes, PL neurons develop responses to aversive and appetitive olfactory stimuli. The presence of this homologous region in both humans and mice points to the significance of this conserved mechanism of neuronal maturation and migration during adolescence, a key time period for amygdala circuit maturation and related behavioral changes.
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Affiliation(s)
- Pia J Alderman
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - David Saxon
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC 20011, USA; Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Lucía I Torrijos-Saiz
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Comparative Neurobiology, University of Valencia, CIBERNED-ISCIII, Valencia 46980, Spain
| | - Malaz Sharief
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Chloe E Page
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Jude K Baroudi
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Sean W Biagiotti
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Vladimir A Butyrkin
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC 20011, USA; Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA
| | - Anna Melamed
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Chay T Kuo
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Stefano Vicini
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20007, USA; Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Jose M García-Verdugo
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Comparative Neurobiology, University of Valencia, CIBERNED-ISCIII, Valencia 46980, Spain; Department of Cell Biology, Functional Biology and Physical Anthropology, University of Valencia, Burjassot 46100, Spain
| | - Vicente Herranz-Pérez
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Comparative Neurobiology, University of Valencia, CIBERNED-ISCIII, Valencia 46980, Spain; Department of Cell Biology, Functional Biology and Physical Anthropology, University of Valencia, Burjassot 46100, Spain
| | - Joshua G Corbin
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC 20011, USA
| | - Shawn F Sorrells
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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2
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Bonfanti L, La Rosa C, Ghibaudi M, Sherwood CC. Adult neurogenesis and "immature" neurons in mammals: an evolutionary trade-off in plasticity? Brain Struct Funct 2023:10.1007/s00429-023-02717-9. [PMID: 37833544 DOI: 10.1007/s00429-023-02717-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023]
Abstract
Neuronal plasticity can vary remarkably in its form and degree across animal species. Adult neurogenesis, namely the capacity to produce new neurons from neural stem cells through adulthood, appears widespread in non-mammalian vertebrates, whereas it is reduced in mammals. A growing body of comparative studies also report variation in the occurrence and activity of neural stem cell niches between mammals, with a general trend of reduction from small-brained to large-brained species. Conversely, recent studies have shown that large-brained mammals host large amounts of neurons expressing typical markers of neurogenesis in the absence of cell division. In layer II of the cerebral cortex, populations of prenatally generated, non-dividing neurons continue to express molecules indicative of immaturity throughout life (cortical immature neurons; cINs). After remaining in a dormant state for a very long time, these cINs retain the potential of differentiating into mature neurons that integrate within the preexisting neural circuits. They are restricted to the paleocortex in small-brained rodents, while extending into the widely expanded neocortex of highly gyrencephalic, large-brained species. The current hypothesis is that these populations of non-newly generated "immature" neurons might represent a reservoir of developmentally plastic cells for mammalian species that are characterized by reduced stem cell-driven adult neurogenesis. This indicates that there may be a trade-off between various forms of plasticity that coexist during brain evolution. This balance may be necessary to maintain a "reservoir of plasticity" in brain regions that have distinct roles in species-specific socioecological adaptations, such as the neocortex and olfactory structures.
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Affiliation(s)
- Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy.
- Department of Veterinary Sciences, University of Turin, Largo Braccini 2, 10095, Turin, Grugliasco, Italy.
| | - Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy
| | - Marco Ghibaudi
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, Largo Braccini 2, 10095, Turin, Grugliasco, Italy
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, USA.
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Mendez-David I, David DJ, Deloménie C, Tritschler L, Beaulieu JM, Colle R, Corruble E, Gardier AM, Hen R. A complex relation between levels of adult hippocampal neurogenesis and expression of the immature neuron marker doublecortin. Hippocampus 2023; 33:1075-1093. [PMID: 37421207 DOI: 10.1002/hipo.23568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 05/08/2023] [Accepted: 06/20/2023] [Indexed: 07/10/2023]
Abstract
We investigated the mechanisms underlying the effects of the antidepressant fluoxetine on behavior and adult hippocampal neurogenesis (AHN). After confirming our earlier report that the signaling molecule β-arrestin-2 (β-Arr2) is required for the antidepressant-like effects of fluoxetine, we found that the effects of fluoxetine on proliferation of neural progenitors and survival of adult-born granule cells are absent in the β-Arr2 knockout (KO) mice. To our surprise, fluoxetine induced a dramatic upregulation of the number of doublecortin (DCX)-expressing cells in the β-Arr2 KO mice, indicating that this marker can be increased even though AHN is not. We discovered two other conditions where a complex relationship occurs between the number of DCX-expressing cells compared to levels of AHN: a chronic antidepressant model where DCX is upregulated and an inflammation model where DCX is downregulated. We concluded that assessing the number of DCX-expressing cells alone to quantify levels of AHN can be complex and that caution should be applied when label retention techniques are unavailable.
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Affiliation(s)
- Indira Mendez-David
- Université Paris-Saclay, UVSQ, Centre de recherche en Epidémiologie et Santé des Populations (CESP), UMR 1018, CESP-Inserm, Team Moods, Faculté de Pharmacie, Bâtiment Henri MOISSAN, Orsay, France
- Department of Psychiatry, Columbia University, New York, New York, USA
- Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, New York, USA
| | - Denis Joseph David
- Université Paris-Saclay, UVSQ, Centre de recherche en Epidémiologie et Santé des Populations (CESP), UMR 1018, CESP-Inserm, Team Moods, Faculté de Pharmacie, Bâtiment Henri MOISSAN, Orsay, France
- Department of Psychiatry, Columbia University, New York, New York, USA
- Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, New York, USA
| | - Claudine Deloménie
- UMS-IPSIT ACTAGen, Inserm, CNRS, Ingénierie et Plateformes au Service de l'Innovation Thérapeutique, Université Paris-Saclay, Bâtiment Henri MOISSAN, Orsay, France
| | - Laurent Tritschler
- Université Paris-Saclay, UVSQ, Centre de recherche en Epidémiologie et Santé des Populations (CESP), UMR 1018, CESP-Inserm, Team Moods, Faculté de Pharmacie, Bâtiment Henri MOISSAN, Orsay, France
| | - Jean-Martin Beaulieu
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Romain Colle
- CESP, MOODS Team, INSERM UMR 1018, Faculté de Médecine, Univ Paris-Saclay, Le Kremlin Bicêtre, France
- Service Hospitalo-Universitaire de Psychiatrie de Bicêtre, Hôpitaux Universitaires Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Hôpital de Bicêtre, Le Kremlin Bicêtre, France
| | - Emmanuelle Corruble
- CESP, MOODS Team, INSERM UMR 1018, Faculté de Médecine, Univ Paris-Saclay, Le Kremlin Bicêtre, France
- Service Hospitalo-Universitaire de Psychiatrie de Bicêtre, Hôpitaux Universitaires Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Hôpital de Bicêtre, Le Kremlin Bicêtre, France
| | - Alain Michel Gardier
- Université Paris-Saclay, UVSQ, Centre de recherche en Epidémiologie et Santé des Populations (CESP), UMR 1018, CESP-Inserm, Team Moods, Faculté de Pharmacie, Bâtiment Henri MOISSAN, Orsay, France
| | - René Hen
- Department of Psychiatry, Columbia University, New York, New York, USA
- Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, New York, USA
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Ghibaudi M, Marchetti N, Vergnano E, La Rosa C, Benedetti B, Couillard-Despres S, Farioli-Vecchioli S, Bonfanti L. Age-related changes in layer II immature neurons of the murine piriform cortex. Front Cell Neurosci 2023; 17:1205173. [PMID: 37576566 PMCID: PMC10416627 DOI: 10.3389/fncel.2023.1205173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/14/2023] [Indexed: 08/15/2023] Open
Abstract
The recent identification of a population of non-newly born, prenatally generated "immature" neurons in the layer II of the piriform cortex (cortical immature neurons, cINs), raises questions concerning their maintenance or depletion through the lifespan. Most forms of brain structural plasticity progressively decline with age, a feature that is particularly prominent in adult neurogenesis, due to stem cell depletion. By contrast, the entire population of the cINs is produced during embryogenesis. Then these cells simply retain immaturity in postnatal and adult stages, until they "awake" to complete their maturation and ultimately integrate into neural circuits. Hence, the question remains open whether the cINs, which are not dependent on stem cell division, might follow a similar pattern of age-related reduction, or in alternative, might leave a reservoir of young, undifferentiated cells in the adult and aging brain. Here, the number and features of cINs were analyzed in the mouse piriform cortex from postnatal to advanced ages, by using immunocytochemistry for the cytoskeletal marker doublecortin. The abundance and stage of maturation of cINs, along with the expression of other markers of maturity/immaturity were investigated. Despite a marked decrease in this neuronal population during juvenile stages, reminiscent of that observed in hippocampal neurogenesis, a small amount of highly immature cINs persisted up to advanced ages. Overall, albeit reducing in number with increasing age, we report that the cINs are present through the entire animal lifespan.
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Affiliation(s)
- Marco Ghibaudi
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Nicole Marchetti
- Institute of Biochemistry and Cell Biology, National Research Council, Rome, Italy
| | - Elena Vergnano
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Bruno Benedetti
- Institute of Experimental Neuroregeneration, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center Salzburg (SCI-TReCS), Salzburg, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Sebastien Couillard-Despres
- Institute of Experimental Neuroregeneration, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center Salzburg (SCI-TReCS), Salzburg, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | | | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, Turin, Italy
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5
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Ghibaudi M, Amenta A, Agosti M, Riva M, Graïc JM, Bifari F, Bonfanti L. Consistency and Variation in Doublecortin and Ki67 Antigen Detection in the Brain Tissue of Different Mammals, including Humans. Int J Mol Sci 2023; 24:2514. [PMID: 36768845 PMCID: PMC9916846 DOI: 10.3390/ijms24032514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/10/2023] [Accepted: 01/12/2023] [Indexed: 01/31/2023] Open
Abstract
Recently, a population of "immature" neurons generated prenatally, retaining immaturity for long periods and finally integrating in adult circuits has been described in the cerebral cortex. Moreover, comparative studies revealed differences in occurrence/rate of different forms of neurogenic plasticity across mammals, the "immature" neurons prevailing in gyrencephalic species. To extend experimentation from laboratory mice to large-brained mammals, including humans, it is important to detect cell markers of neurogenic plasticity in brain tissues obtained from different procedures (e.g., post-mortem/intraoperative specimens vs. intracardiac perfusion). This variability overlaps with species-specific differences in antigen distribution or antibody species specificity, making it difficult for proper comparison. In this work, we detect the presence of doublecortin and Ki67 antigen, markers for neuronal immaturity and cell division, in six mammals characterized by widely different brain size. We tested seven commercial antibodies in four selected brain regions known to host immature neurons (paleocortex, neocortex) and newly born neurons (hippocampus, subventricular zone). In selected human brains, we confirmed the specificity of DCX antibody by performing co-staining with fluorescent probe for DCX mRNA. Our results indicate that, in spite of various types of fixations, most differences were due to the use of different antibodies and the existence of real interspecies variation.
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Affiliation(s)
- Marco Ghibaudi
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy
| | - Alessia Amenta
- Laboratory of Cell Metabolism and Regenerative Medicine, Department of Medical Biotechnology and Translational Medicine, University of Milan, 20133 Milan, Italy
| | - Miriam Agosti
- Laboratory of Cell Metabolism and Regenerative Medicine, Department of Medical Biotechnology and Translational Medicine, University of Milan, 20133 Milan, Italy
| | - Marco Riva
- Department of Biomedical Sciences, Humanitas University, 20090 Pieve Emanuele, Italy
- IRCCS Humanitas Research Hospital, 20089 Rozzano, Italy
| | - Jean-Marie Graïc
- Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro, Italy
| | - Francesco Bifari
- Laboratory of Cell Metabolism and Regenerative Medicine, Department of Medical Biotechnology and Translational Medicine, University of Milan, 20133 Milan, Italy
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy
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6
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Porter DDL, Henry SN, Ahmed S, Rizzo AL, Makhlouf R, Gregg C, Morton PD. Neuroblast migration along cellular substrates in the developing porcine brain. Stem Cell Reports 2022; 17:2097-2110. [PMID: 35985331 PMCID: PMC9481921 DOI: 10.1016/j.stemcr.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 07/22/2022] [Accepted: 07/23/2022] [Indexed: 11/27/2022] Open
Abstract
In the past decade it has become evident that neuroblasts continue to supply the human cortex with interneurons via unique migratory streams shortly following birth. Owing to the size of the human brain, these newborn neurons must migrate long distances through complex cellular landscapes to reach their final locations. This process is poorly understood, largely because of technical difficulties in acquiring and studying neurotypical postmortem human samples along with diverging developmental features of well-studied mouse models. We reasoned that migratory streams of neuroblasts utilize cellular substrates, such as blood vessels, to guide their trek from the subventricular zone to distant cortical targets. Here, we evaluate the association between young interneuronal migratory streams and their preferred cellular substrates in gyrencephalic piglets during the developmental equivalent of human birth, infancy, and toddlerhood. Migratory streams of neuroblasts are preserved through postnatal swine development Evidence of young neocortical interneurons within migratory streams Neuroblasts are tightly associated with vascular and astrocytic cellular substrates Harm to migratory interneurons or their substrates may have lifelong consequences
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Affiliation(s)
- Demisha D L Porter
- Virginia Tech Graduate Program in Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA; Department of Biological Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Sara N Henry
- Department of Biological Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Sadia Ahmed
- Department of Biological Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Amy L Rizzo
- Office of the University Veterinarian & Animal Resources, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Rita Makhlouf
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Collin Gregg
- Virginia Tech Graduate Program in Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - Paul D Morton
- Department of Biological Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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Immature excitatory neurons in the amygdala come of age during puberty. Dev Cogn Neurosci 2022; 56:101133. [PMID: 35841648 PMCID: PMC9289873 DOI: 10.1016/j.dcn.2022.101133] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/23/2022] [Accepted: 07/08/2022] [Indexed: 11/21/2022] Open
Abstract
The human amygdala is critical for emotional learning, valence coding, and complex social interactions, all of which mature throughout childhood, puberty, and adolescence. Across these ages, the amygdala paralaminar nucleus (PL) undergoes significant structural changes including increased numbers of mature neurons. The PL contains a large population of immature excitatory neurons at birth, some of which may continue to be born from local progenitors. These progenitors disappear rapidly in infancy, but the immature neurons persist throughout childhood and adolescent ages, indicating that they develop on a protracted timeline. Many of these late-maturing neurons settle locally within the PL, though a small subset appear to migrate into neighboring amygdala subnuclei. Despite its prominent growth during postnatal life and possible contributions to multiple amygdala circuits, the function of the PL remains unknown. PL maturation occurs predominately during late childhood and into puberty when sex hormone levels change. Sex hormones can promote developmental processes such as neuron migration, dendritic outgrowth, and synaptic plasticity, which appear to be ongoing in late-maturing PL neurons. Collectively, we describe how the growth of late-maturing neurons occurs in the right time and place to be relevant for amygdala functions and neuropsychiatric conditions.
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Benedetti B, Couillard-Despres S. Why Would the Brain Need Dormant Neuronal Precursors? Front Neurosci 2022; 16:877167. [PMID: 35464307 PMCID: PMC9026174 DOI: 10.3389/fnins.2022.877167] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 03/11/2022] [Indexed: 12/13/2022] Open
Abstract
Dormant non-proliferative neuronal precursors (dormant precursors) are a unique type of undifferentiated neuron, found in the adult brain of several mammalian species, including humans. Dormant precursors are fundamentally different from canonical neurogenic-niche progenitors as they are generated exquisitely during the embryonic development and maintain a state of protracted postmitotic immaturity lasting up to several decades after birth. Thus, dormant precursors are not pluripotent progenitors, but to all effects extremely immature neurons. Recently, transgenic models allowed to reveal that with age virtually all dormant precursors progressively awaken, abandon the immature state, and become fully functional neurons. Despite the limited common awareness about these cells, the deep implications of recent discoveries will likely lead to revisit our understanding of the adult brain. Thus, it is timely to revisit and critically assess the essential evidences that help pondering on the possible role(s) of these cells in relation to cognition, aging, and pathology. By highlighting pivoting findings as well as controversies and open questions, we offer an exciting perspective over the field of research that studies these mysterious cells and suggest the next steps toward the answer of a crucial question: why does the brain need dormant neuronal precursors?
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Affiliation(s)
- Bruno Benedetti
- Institute of Experimental Neuroregeneration, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Sebastien Couillard-Despres
- Institute of Experimental Neuroregeneration, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
- *Correspondence: Sebastien Couillard-Despres,
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9
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Bonfanti L, Seki T. The PSA-NCAM-Positive "Immature" Neurons: An Old Discovery Providing New Vistas on Brain Structural Plasticity. Cells 2021; 10:2542. [PMID: 34685522 PMCID: PMC8534119 DOI: 10.3390/cells10102542] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/14/2021] [Accepted: 09/24/2021] [Indexed: 01/18/2023] Open
Abstract
Studies on brain plasticity have undertaken different roads, tackling a wide range of biological processes: from small synaptic changes affecting the contacts among neurons at the very tip of their processes, to birth, differentiation, and integration of new neurons (adult neurogenesis). Stem cell-driven adult neurogenesis is an exception in the substantially static mammalian brain, yet, it has dominated the research in neurodevelopmental biology during the last thirty years. Studies of comparative neuroplasticity have revealed that neurogenic processes are reduced in large-brained mammals, including humans. On the other hand, large-brained mammals, with respect to rodents, host large populations of special "immature" neurons that are generated prenatally but express immature markers in adulthood. The history of these "immature" neurons started from studies on adhesion molecules carried out at the beginning of the nineties. The identity of these neurons as "stand by" cells "frozen" in a state of immaturity remained un-detected for long time, because of their ill-defined features and because clouded by research ef-forts focused on adult neurogenesis. In this review article, the history of these cells will be reconstructed, and a series of nuances and confounding factors that have hindered the distinction between newly generated and "immature" neurons will be addressed.
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Affiliation(s)
- Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy
| | - Tatsunori Seki
- Department of Histology and Neuroanatomy, Tokyo Medical University, Tokyo 160-8402, Japan
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 160-8402, Japan
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10
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Bonfanti L, Charvet CJ. Brain Plasticity in Humans and Model Systems: Advances, Challenges, and Future Directions. Int J Mol Sci 2021; 22:9358. [PMID: 34502267 PMCID: PMC8431131 DOI: 10.3390/ijms22179358] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/20/2022] Open
Abstract
Plasticity, and in particular, neurogenesis, is a promising target to treat and prevent a wide variety of diseases (e.g., epilepsy, stroke, dementia). There are different types of plasticity, which vary with age, brain region, and species. These observations stress the importance of defining plasticity along temporal and spatial dimensions. We review recent studies focused on brain plasticity across the lifespan and in different species. One main theme to emerge from this work is that plasticity declines with age but that we have yet to map these different forms of plasticity across species. As part of this effort, we discuss our recent progress aimed to identify corresponding ages across species, and how this information can be used to map temporal variation in plasticity from model systems to humans.
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Affiliation(s)
- Luca Bonfanti
- Department of Veterinary Sciences, University of Turin, Largo Braccini 2, 10095 Grugliasco, TO, Italy
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Regione Gonzole 10, 10043 Orbassano, TO, Italy
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11
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Early Life Stress and Metabolic Plasticity of Brain Cells: Impact on Neurogenesis and Angiogenesis. Biomedicines 2021; 9:biomedicines9091092. [PMID: 34572278 PMCID: PMC8470044 DOI: 10.3390/biomedicines9091092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/15/2021] [Accepted: 08/23/2021] [Indexed: 12/15/2022] Open
Abstract
Early life stress (ELS) causes long-lasting changes in brain plasticity induced by the exposure to stress factors acting prenatally or in the early postnatal ontogenesis due to hyperactivation of hypothalamic-pituitary-adrenal axis and sympathetic nervous system, development of neuroinflammation, aberrant neurogenesis and angiogenesis, and significant alterations in brain metabolism that lead to neurological deficits and higher susceptibility to development of brain disorders later in the life. As a key component of complex pathogenesis, ELS-mediated changes in brain metabolism associate with development of mitochondrial dysfunction, loss of appropriate mitochondria quality control and mitochondrial dynamics, deregulation of metabolic reprogramming. These mechanisms are particularly critical for maintaining the pool and development of brain cells within neurogenic and angiogenic niches. In this review, we focus on brain mitochondria and energy metabolism related to tightly coupled neurogenic and angiogenic events in healthy and ELS-affected brain, and new opportunities to develop efficient therapeutic strategies aimed to restore brain metabolism and reduce ELS-induced impairments of brain plasticity.
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Life and Death of Immature Neurons in the Juvenile and Adult Primate Amygdala. Int J Mol Sci 2021; 22:ijms22136691. [PMID: 34206571 PMCID: PMC8268704 DOI: 10.3390/ijms22136691] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/11/2021] [Accepted: 06/18/2021] [Indexed: 12/12/2022] Open
Abstract
In recent years, a large population of immature neurons has been documented in the paralaminar nucleus of the primate amygdala. A substantial fraction of these immature neurons differentiate into mature neurons during postnatal development or following selective lesion of the hippocampus. Notwithstanding a growing number of studies on the origin and fate of these immature neurons, fundamental questions about the life and death of these neurons remain. Here, we briefly summarize what is currently known about the immature neurons present in the primate ventral amygdala during development and in adulthood, as well as following selective hippocampal lesions. We provide evidence confirming that the distribution of immature neurons extends to the anterior portions of the entorhinal cortex and layer II of the perirhinal cortex. We also provide novel arguments derived from stereological estimates of the number of mature and immature neurons, which support the view that the migration of immature neurons from the lateral ventricle accompanies neuronal maturation in the primate amygdala at all ages. Finally, we propose and discuss the hypothesis that increased migration and maturation of neurons in the amygdala following hippocampal dysfunction may be linked to behavioral alterations associated with certain neurodevelopmental disorders.
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13
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Implications of Extended Inhibitory Neuron Development. Int J Mol Sci 2021; 22:ijms22105113. [PMID: 34066025 PMCID: PMC8150951 DOI: 10.3390/ijms22105113] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 05/05/2021] [Accepted: 05/06/2021] [Indexed: 12/23/2022] Open
Abstract
A prolonged developmental timeline for GABA (γ-aminobutyric acid)-expressing inhibitory neurons (GABAergic interneurons) is an amplified trait in larger, gyrencephalic animals. In several species, the generation, migration, and maturation of interneurons take place over several months, in some cases persisting after birth. The late integration of GABAergic interneurons occurs in a region-specific pattern, especially during the early postnatal period. These changes can contribute to the formation of functional connectivity and plasticity, especially in the cortical regions responsible for higher cognitive tasks. In this review, we discuss GABAergic interneuron development in the late gestational and postnatal forebrain. We propose the protracted development of interneurons at each stage (neurogenesis, neuronal migration, and network integration), as a mechanism for increased complexity and cognitive flexibility in larger, gyrencephalic brains. This developmental feature of interneurons also provides an avenue for environmental influences to shape neural circuit formation.
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La Rosa C, Cavallo F, Pecora A, Chincarini M, Ala U, Faulkes CG, Nacher J, Cozzi B, Sherwood CC, Amrein I, Bonfanti L. Phylogenetic variation in cortical layer II immature neuron reservoir of mammals. eLife 2020; 9:55456. [PMID: 32690132 PMCID: PMC7373429 DOI: 10.7554/elife.55456] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 06/03/2020] [Indexed: 12/22/2022] Open
Abstract
The adult mammalian brain is mainly composed of mature neurons. A limited amount of stem cell-driven neurogenesis persists in postnatal life and is reduced in large-brained species. Another source of immature neurons in adult brains is cortical layer II. These cortical immature neurons (cINs) retain developmentally undifferentiated states in adulthood, though they are generated before birth. Here, the occurrence, distribution and cellular features of cINs were systematically studied in 12 diverse mammalian species spanning from small-lissencephalic to large-gyrencephalic brains. In spite of well-preserved morphological and molecular features, the distribution of cINs was highly heterogeneous, particularly in neocortex. While virtually absent in rodents, they are present in the entire neocortex of many other species and their linear density in cortical layer II generally increased with brain size. These findings suggest an evolutionary developmental mechanism for plasticity that varies among mammalian species, granting a reservoir of young cells for the cerebral cortex. To acquire new skills or recover after injuries, the mammalian brain relies on plasticity, the ability for the brain to change its architecture and its connections during the lifetime of an animal. Creating new nerve cells is one way to achieve plasticity, but this process is rarer in humans than it is in mammals with smaller brains. In particular, it is absent in the human cortex: this region is enlarged in species with large brains, where it carries out complex tasks such as learning and memory. Producing new cells in the cortex would threaten the stability of the structures that retain long-term memories. Another route to plasticity is to reshape the connections between existing, mature nerve cells. This process takes place in the human brain during childhood and adolescence, as some connections are strengthened and others pruned away. An alternative mechanism relies on keeping some nerve cells in an immature, ‘adolescent’ state. When needed, these nerve cells emerge from their state of arrested development and ‘grow up’, connecting with the appropriate brain circuits. This mechanism does not involve producing new nerve cells, and so it would be suitable to maintain plasticity in the cortex. Consistent with this idea, in mice some dormant nerve cells are present in a small, primitive part of the cortex. La Rosa et al. therefore wanted to determine if the location and number of immature cells in the cortex differed between mammals, and if so, whether these differences depended on brain size. The study spanned 12 mammal species, from small-brained species like mice to larger-brained animals including sheep and non-human primates. Microscopy imaging was used to identify immature nerve cells in brain samples, which revealed that the cortex in larger-brained species contained more adolescent cells than its mouse counterpart. The difference was greatest in a region called the neocortex, which has evolved most recently. This area is most pronounced in primates – especially humans – where it carries out high-level cognitive tasks. These results identify immature nerve cells as a potential mechanism for plasticity in the cortex. La Rosa et al. hope that the work will inspire searches for similar reservoirs of young cells in humans, which could perhaps lead to new treatments for brain disorders like dementia.
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Affiliation(s)
- Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy.,Department of Veterinary Sciences, University of Turin, Torino, Italy
| | - Francesca Cavallo
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Alessandra Pecora
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Matteo Chincarini
- Università degli Studi di Teramo, Facoltà di Medicina Veterinaria, Teramo, Italy
| | - Ugo Ala
- Department of Veterinary Sciences, University of Turin, Torino, Italy
| | - Chris G Faulkes
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Juan Nacher
- Neurobiology Unit, BIOTECMED, Universitat de València, and Spanish Network for Mental Health Research CIBERSAM, València, Spain
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington DC, United States
| | - Irmgard Amrein
- D-HEST, ETH, Zurich, Switzerland.,Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy.,Department of Veterinary Sciences, University of Turin, Torino, Italy
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15
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La Rosa C, Parolisi R, Bonfanti L. Brain Structural Plasticity: From Adult Neurogenesis to Immature Neurons. Front Neurosci 2020; 14:75. [PMID: 32116519 PMCID: PMC7010851 DOI: 10.3389/fnins.2020.00075] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/20/2020] [Indexed: 12/21/2022] Open
Abstract
Brain structural plasticity is an extraordinary tool that allows the mature brain to adapt to environmental changes, to learn, to repair itself after lesions or disease, and to slow aging. A long history of neuroscience research led to fascinating discoveries of different types of plasticity, involving changes in the genetically determined structure of nervous tissue, up to the ultimate dream of neuronal replacement: a stem cell-driven “adult neurogenesis” (AN). Yet, this road does not seem a straight one, since mutable dogmas, conflicting results and conflicting interpretations continue to warm the field. As a result, after more than 10,000 papers published on AN, we still do not know its time course, rate or features with respect to other kinds of structural plasticity in our brain. The solution does not appear to be behind the next curve, as differences among mammals reveal a very complex landscape that cannot be easily understood from rodents models alone. By considering evolutionary aspects, some pitfalls in the interpretation of cell markers, and a novel population of undifferentiated cells that are not newly generated [immature neurons (INs)], we address some conflicting results and controversies in order to find the right road forward. We suggest that considering plasticity in a comparative framework might help assemble the evolutionary, anatomical and functional pieces of a very complex biological process with extraordinary translational potential.
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Affiliation(s)
- Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy.,Department of Veterinary Sciences, University of Turin, Turin, Italy
| | | | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy.,Department of Veterinary Sciences, University of Turin, Turin, Italy
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16
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La Rosa C, Ghibaudi M, Bonfanti L. Newly Generated and Non-Newly Generated "Immature" Neurons in the Mammalian Brain: A Possible Reservoir of Young Cells to Prevent Brain Aging and Disease? J Clin Med 2019; 8:jcm8050685. [PMID: 31096632 PMCID: PMC6571946 DOI: 10.3390/jcm8050685] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 01/21/2023] Open
Abstract
Brain plasticity is important for translational purposes since most neurological disorders and brain aging problems remain substantially incurable. In the mammalian nervous system, neurons are mostly not renewed throughout life and cannot be replaced. In humans, the increasing life expectancy explains the increase in brain health problems, also producing heavy social and economic burden. An exception to the “static” brain is represented by stem cell niches leading to the production of new neurons. Such adult neurogenesis is dramatically reduced from fish to mammals, and in large-brained mammals with respect to rodents. Some examples of neurogenesis occurring outside the neurogenic niches have been reported, yet these new neurons actually do not integrate in the mature nervous tissue. Non-newly generated, “immature” neurons (nng-INs) are also present: Prenatally generated cells continuing to express molecules of immaturity (mostly shared with the newly born neurons). Of interest, nng-INs seem to show an inverse phylogenetic trend across mammals, being abundant in higher-order brain regions not served by neurogenesis and providing structural plasticity in rather stable areas. Both newly generated and nng-INs represent a potential reservoir of young cells (a “brain reserve”) that might be exploited for preventing the damage of aging and/or delay the onset/reduce the impact of neurological disorders.
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Affiliation(s)
- Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy.
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy.
| | - Marco Ghibaudi
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy.
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy.
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy.
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17
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Oppenheim RW. Adult Hippocampal Neurogenesis in Mammals (and Humans): The Death of a Central Dogma in Neuroscience and its Replacement by a New Dogma. Dev Neurobiol 2019; 79:268-280. [DOI: 10.1002/dneu.22674] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 01/31/2023]
Affiliation(s)
- Ronald W. Oppenheim
- Department of Neurobiology and Anatomy, The Neuroscience Program Wake Forest School of Medicine Medical Center Blvd. Winston‐Salem NC 27157‐1010
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18
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La Rosa C, Bonfanti L. Brain Plasticity in Mammals: An Example for the Role of Comparative Medicine in the Neurosciences. Front Vet Sci 2018; 5:274. [PMID: 30443551 PMCID: PMC6221904 DOI: 10.3389/fvets.2018.00274] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 10/15/2018] [Indexed: 12/11/2022] Open
Abstract
Comparative medicine deals with similarities and differences between veterinary and human medicine. All mammals share most basic cellular and molecular mechanisms, thus justifying murine animal models in a translational perspective; yet “mice are not men,” thus some biases can emerge when complex biological processes are concerned. Brain plasticity is a cutting-edge, expanding topic in the field of Neurosciences with important translational implications, yet, with remarkable differences among mammals, as emerging from comparative studies. In particular, adult neurogenesis (the genesis of new neurons from brain stem cell niches) is a life-long process in laboratory rodents but a vestigial, mostly postnatal remnant in humans and dolphins. Another form of “whole cell” plasticity consisting of a population of “immature” neurons which are generated prenatally but continue to express markers of immaturity during adulthood has gained interest more recently, as a reservoir of young neurons in the adult brain. The distribution of the immature neurons also seems quite heterogeneous among different animal species, being confined within the paleocortex in rodents while extending into neocortex in other mammals. A recent study carried out in sheep, definitely showed that gyrencephalic, large-sized brains do host higher amounts of immature neurons, also involving subcortical, white, and gray matter regions. Hence, “whole cell” plasticity such as adult neurogenesis and immature neurons are biological processes which, as a whole, cannot be studied exclusively in laboratory rodents, but require investigation in comparative medicine, involving large-sized, long-living mammals, in order to gain insights for translational purposes.
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Affiliation(s)
- Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi, Turin, Italy.,Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi, Turin, Italy.,Department of Veterinary Sciences, University of Turin, Turin, Italy
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Parolisi R, Cozzi B, Bonfanti L. Humans and Dolphins: Decline and Fall of Adult Neurogenesis. Front Neurosci 2018; 12:497. [PMID: 30079011 PMCID: PMC6062615 DOI: 10.3389/fnins.2018.00497] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/02/2018] [Indexed: 02/06/2023] Open
Abstract
Pre-clinical research is carried out on animal models, mostly laboratory rodents, with the ultimate aim of translating the acquired knowledge to humans. In the last decades, adult neurogenesis (AN) has been intensively studied since it is viewed as a tool for fostering brain plasticity, possibly repair. Yet, occurrence, location, and rate of AN vary among mammals: the capability for constitutive neuronal production is substantially reduced when comparing small-brained, short living (laboratory rodents) and large-brained, long-living species (humans, dolphins). Several difficulties concerning scarce availability of fresh tissues, technical limits and ethical concerns did contribute in delaying and diverting the achievement of the picture of neurogenic plasticity in large-brained mammals. Some reports appeared in the last few years, starting to shed more light on this issue. Despite technical limits, data from recent studies mostly converge to indicate that neurogenesis is vestigial, or possibly absent, in regions of the adult human brain where in rodents neuronal addition continues into adult life. Analyses carried out in dolphins, mammals devoid of olfaction, but descendant of ancestors provided with olfaction, has shown disappearance of neurogenesis in both neonatal and adult individuals. Heterogeneity in mammalian structural plasticity remains largely underestimated by scientists focusing their research in rodents. Comparative studies are the key to understand the function of AN and the possible translational significance of neuronal replacement in humans. Here, we summarize comparative studies on AN and discuss the evolutionary implications of variations on the recruitment of new neurons in different regions and different species.
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Affiliation(s)
- Roberta Parolisi
- NICO - Neuroscience Institute Cavalieri Ottolenghi, Turin, Italy
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padua, Padua, Italy
| | - Luca Bonfanti
- NICO - Neuroscience Institute Cavalieri Ottolenghi, Turin, Italy.,Department of Veterinary Sciences, University of Turin, Turin, Italy
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20
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Abstract
The brain is a dynamic organ of the biological renaissance due to the existence of neuroplasticity. Adult neurogenesis abides by every aspect of neuroplasticity in the intact brain and contributes to neural regeneration in response to brain diseases and injury. The occurrence of adult neurogenesis has unequivocally been witnessed in human subjects, experimental and wildlife research including rodents, bats and cetaceans. Adult neurogenesis is a complex cellular process, in which generation of neuroblasts namely, neuroblastosis appears to be an integral process that occur in the limbic system and basal ganglia in addition to the canonical neurogenic niches. Neuroblastosis can be regulated by various factors and contributes to different functions of the brain. The characteristics and fate of neuroblasts have been found to be different among mammals regardless of their cognitive functions. Recently, regulation of neuroblastosis has been proposed for the sensorimotor interface and regenerative neuroplasticity of the adult brain. Hence, the understanding of adult neurogenesis at the functional level of neuroblasts requires a great scientific attention. Therefore, this mini-review provides a glimpse into the conceptual development of neuroplasticity, discusses the possible role of different types of neuroblasts and signifies neuroregenerative failure as a potential cause of dementia.
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Affiliation(s)
- Mahesh Kandasamy
- Laboratory of Stem Cells and Neuroregeneration, Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu; Faculty Recharge Programme, University Grants Commission (UGC-FRP), New Delhi, India
| | - Ludwig Aigner
- Institute of Molecular Regenerative Medicine, Salzburg, Paracelsus Medical University; Spinal Cord Injury and Tissue Regeneration Center, Salzburg, Paracelsus Medical University, Salzburg, Austria
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