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Yang J, Wang M, Lv Y, Chen J. Cortical Layer Markers Expression and Increased Synaptic Density in Interstitial Neurons of the White Matter from Drug-Resistant Epilepsy Patients. Brain Sci 2023; 13:brainsci13040626. [PMID: 37190591 DOI: 10.3390/brainsci13040626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/29/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
The interstitial neurons in the white matter of the human and non-human primate cortex share a similar developmental origin with subplate neurons and deep-layer cortical neurons. A subset of interstitial neurons expresses the molecular markers of subplate neurons, but whether interstitial neurons express cortical layer markers in the adult human brain remains unexplored. Here we report the expression of cortical layer markers in interstitial neurons in the white matter of the adult human brain, supporting the hypothesis that interstitial neurons could be derived from cortical progenitor cells. Furthermore, we found increased non-phosphorylated neurofilament protein (NPNFP) expression in interstitial neurons in the white matter of drug-resistant epilepsy patients. We also identified the expression of glutamatergic and g-aminobutyric acid (GABAergic) synaptic puncta that were distributed in the perikarya and dendrites of interstitial neurons. The density of glutamatergic and GABAergic synaptic puncta was increased in interstitial neurons in the white matter of drug-resistant epilepsy patients compared with control brain tissues with no history of epilepsy. Together, our results provide important insights of the molecular identity of interstitial neurons in the adult human white matter. Increased synaptic density of interstitial neurons could result in an imbalanced synaptic network in the white matter and participate as part of the epileptic network in drug-resistant epilepsy.
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Affiliation(s)
- Jiachao Yang
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou 310058, China
| | - Mi Wang
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yang Lv
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou 310058, China
| | - Jiadong Chen
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou 310058, China
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2
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Kurki SN, Uvarov P, Pospelov AS, Trontti K, Hübner AK, Srinivasan R, Watanabe M, Hovatta I, Hübner CA, Kaila K, Virtanen MA. Expression patterns of NKCC1 in neurons and non-neuronal cells during cortico-hippocampal development. Cereb Cortex 2022; 33:5906-5923. [PMID: 36573432 PMCID: PMC10183754 DOI: 10.1093/cercor/bhac470] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/05/2022] [Accepted: 11/06/2022] [Indexed: 12/28/2022] Open
Abstract
Abstract
The Na-K-2Cl cotransporter NKCC1 is widely expressed in cells within and outside the brain. However, our understanding of its roles in brain functions throughout development, as well as in neuropsychiatric and neurological disorders, has been severely hindered by the lack of reliable data on its developmental and (sub)cellular expression patterns. We provide here the first properly controlled analysis of NKCC1 protein expression in various cell types of the mouse brain using custom-made antibodies and an NKCC1 knock-out validated immunohistochemical procedure, with parallel data based on advanced mRNA approaches. NKCC1 protein and mRNA are expressed at remarkably high levels in oligodendrocytes. In immature neurons, NKCC1 protein was located in the somata, whereas in adult neurons, only NKCC1 mRNA could be clearly detected. NKCC1 immunoreactivity is also seen in microglia, astrocytes, developing pericytes, and in progenitor cells of the dentate gyrus. Finally, a differential expression of NKCC1 splice variants was observed, with NKCC1a predominating in non-neuronal cells and NKCC1b in neurons. Taken together, our data provide a cellular basis for understanding NKCC1 functions in the brain and enable the identification of major limitations and promises in the development of neuron-targeting NKCC1-blockers.
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Affiliation(s)
- Samu N Kurki
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Pavel Uvarov
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Alexey S Pospelov
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Kalevi Trontti
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
- University of Helsinki SleepWell Research Program, Faculty of Medicine, , 00014 Helsinki , Finland
- University of Helsinki Department of Psychology and Logopedics, , 00014 Helsinki , Finland
| | - Antje K Hübner
- Jena University Hospital, Friedrich Schiller Universität Institute of Human Genetics, , 07747 Jena , Germany
| | - Rakenduvadhana Srinivasan
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Masahiko Watanabe
- Hokkaido University Department of Anatomy, Faculty of Medicine, , Sapporo 060–8638 , Japan
| | - Iiris Hovatta
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
- University of Helsinki SleepWell Research Program, Faculty of Medicine, , 00014 Helsinki , Finland
- University of Helsinki Department of Psychology and Logopedics, , 00014 Helsinki , Finland
| | - Christian A Hübner
- Jena University Hospital, Friedrich Schiller Universität Institute of Human Genetics, , 07747 Jena , Germany
| | - Kai Kaila
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Mari A Virtanen
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
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3
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Llorca A, Deogracias R. Origin, Development, and Synaptogenesis of Cortical Interneurons. Front Neurosci 2022; 16:929469. [PMID: 35833090 PMCID: PMC9272671 DOI: 10.3389/fnins.2022.929469] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
The mammalian cerebral cortex represents one of the most recent and astonishing inventions of nature, responsible of a large diversity of functions that range from sensory processing to high-order cognitive abilities, such as logical reasoning or language. Decades of dedicated study have contributed to our current understanding of this structure, both at structural and functional levels. A key feature of the neocortex is its outstanding richness in cell diversity, composed by multiple types of long-range projecting neurons and locally connecting interneurons. In this review, we will describe the great diversity of interneurons that constitute local neocortical circuits and summarize the mechanisms underlying their development and their assembly into functional networks.
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Affiliation(s)
- Alfredo Llorca
- Visual Neuroscience Laboratory, Centre for Discovery Brain Sciences, School of Biomedical Sciences, University of Edinburgh, Edinburg, United Kingdom
- *Correspondence: Alfredo Llorca
| | - Ruben Deogracias
- Neuronal Circuits Formation and Brain Disorders Laboratory, Institute of Neurosciences of Castilla y León (INCyL), University of Salamanca, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, Salamanca, Spain
- Department of Cell Biology and Pathology, School of Medicine, University of Salamanca, Salamanca, Spain
- Ruben Deogracias
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4
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Leung RF, George AM, Roussel EM, Faux MC, Wigle JT, Eisenstat DD. Genetic Regulation of Vertebrate Forebrain Development by Homeobox Genes. Front Neurosci 2022; 16:843794. [PMID: 35546872 PMCID: PMC9081933 DOI: 10.3389/fnins.2022.843794] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/14/2022] [Indexed: 01/19/2023] Open
Abstract
Forebrain development in vertebrates is regulated by transcription factors encoded by homeobox, bHLH and forkhead gene families throughout the progressive and overlapping stages of neural induction and patterning, regional specification and generation of neurons and glia from central nervous system (CNS) progenitor cells. Moreover, cell fate decisions, differentiation and migration of these committed CNS progenitors are controlled by the gene regulatory networks that are regulated by various homeodomain-containing transcription factors, including but not limited to those of the Pax (paired), Nkx, Otx (orthodenticle), Gsx/Gsh (genetic screened), and Dlx (distal-less) homeobox gene families. This comprehensive review outlines the integral role of key homeobox transcription factors and their target genes on forebrain development, focused primarily on the telencephalon. Furthermore, links of these transcription factors to human diseases, such as neurodevelopmental disorders and brain tumors are provided.
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Affiliation(s)
- Ryan F. Leung
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Ankita M. George
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
| | - Enola M. Roussel
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
| | - Maree C. Faux
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Department of Surgery, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Jeffrey T. Wigle
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - David D. Eisenstat
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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5
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Cossart R, Garel S. Step by step: cells with multiple functions in cortical circuit assembly. Nat Rev Neurosci 2022; 23:395-410. [DOI: 10.1038/s41583-022-00585-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2022] [Indexed: 12/23/2022]
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6
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Lopes LT, Canto-de-Souza L, Baptista-de-Souza D, de Souza RR, Nunes-de-Souza RL, Canto-de-Souza A. The interplay between 5-HT 2C and 5-HT 3A receptors in the dorsal periaqueductal gray mediates anxiety-like behavior in mice. Behav Brain Res 2022; 417:113588. [PMID: 34547341 DOI: 10.1016/j.bbr.2021.113588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 08/17/2021] [Accepted: 09/15/2021] [Indexed: 11/17/2022]
Abstract
The monoamine neurotransmitter serotonin (5-HT) modulates anxiety by its activity on 5-HT2C receptors (5-HT2CR) expressed in the dorsal periaqueductal gray (dPAG). Here, we investigated the presence of 5-HT3A receptors (5-HT3AR) in the dPAG, and the interplay between 5-HT2CR and 5-HT3AR in the dPAG in mediating anxiety-like behavior in mice. We found that 5-HT3AR is expressed in the dPAG and the blockade of these receptors using intra-dPAG infusion of ondansetron (5-HT3AR antagonist; 3.0 nmol) induced an anxiogenic-like effect. The activation of 5-HT3ABR by the infusion of mCPBG [1-(m-Chlorophenyl)-biguanide; 5-HT3R agonist] did not alter anxiety-like behaviors. In addition, blockade of 5-HT3AR (1.0 nmol) prevented the anxiolytic-like effect induced by the infusion of the 5-HT2CR agonist mCPP (1-(3-chlorophenyl) piperazine; 0.03 nmol). None of the treatment effects on anxiety-like behaviors altered the locomotor activity levels. The present results suggest that the anxiolytic-like effect exerted by serotonin activity on 5-HT2CR in the dPAG is modulated by 5-HT3AR expressed in same region.
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Affiliation(s)
- Luana Tenorio Lopes
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada.
| | - Lucas Canto-de-Souza
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista, UNESP, Araraquara, SP 14801-902, Brazil; Neuroscience and Behavioral Institute, Av. do Café, 2.450, 14050-220 Ribeirão Preto, SP, Brazil.
| | - Daniela Baptista-de-Souza
- Psychobiology Group/Department of Psychology/CECH-UFSCar, São Carlos, SP 13565-905, Brazil; Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista, UNESP, Araraquara, SP 14801-902, Brazil; Neuroscience and Behavioral Institute, Av. do Café, 2.450, 14050-220 Ribeirão Preto, SP, Brazil.
| | - Rimenez Rodrigues de Souza
- The University of Texas at Dallas, School of Behavior and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States.
| | - Ricardo L Nunes-de-Souza
- Psychobiology Group/Department of Psychology/CECH-UFSCar, São Carlos, SP 13565-905, Brazil; Joint Graduate Program in Physiological Sciences UFSCar/UNESP, Rod. Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil; Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista, UNESP, Araraquara, SP 14801-902, Brazil; Neuroscience and Behavioral Institute, Av. do Café, 2.450, 14050-220 Ribeirão Preto, SP, Brazil.
| | - Azair Canto-de-Souza
- Psychobiology Group/Department of Psychology/CECH-UFSCar, São Carlos, SP 13565-905, Brazil; Joint Graduate Program in Physiological Sciences UFSCar/UNESP, Rod. Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil; Graduate Program in Psychology UFSCar, Rod. Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil; Neuroscience and Behavioral Institute, Av. do Café, 2.450, 14050-220 Ribeirão Preto, SP, Brazil.
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7
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Swiegers J, Bhagwandin A, Maseko BC, Sherwood CC, Hård T, Bertelsen MF, Spocter MA, Molnár Z, Manger PR. The distribution, number, and certain neurochemical identities of infracortical white matter neurons in the brains of a southern lesser galago, a black-capped squirrel monkey, and a crested macaque. J Comp Neurol 2021; 529:3676-3708. [PMID: 34259349 DOI: 10.1002/cne.25216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/01/2021] [Accepted: 07/10/2021] [Indexed: 12/20/2022]
Abstract
In the current study, we examined the number, distribution, and aspects of the neurochemical identities of infracortical white matter neurons, also termed white matter interstitial cells (WMICs), in the brains of a southern lesser galago (Galago moholi), a black-capped squirrel monkey (Saimiri boliviensis boliviensis), and a crested macaque (Macaca nigra). Staining for neuronal nuclear marker (NeuN) revealed WMICs throughout the infracortical white matter, these cells being most dense close to inner cortical border, decreasing in density with depth in the white matter. Stereological analysis of NeuN-immunopositive cells revealed estimates of approximately 1.1, 10.8, and 37.7 million WMICs within the infracortical white matter of the galago, squirrel monkey, and crested macaque, respectively. The total numbers of WMICs form a distinct negative allometric relationship with brain mass and white matter volume when examined in a larger sample of primates where similar measures have been obtained. In all three primates studied, the highest densities of WMICs were in the white matter of the frontal lobe, with the occipital lobe having the lowest. Immunostaining revealed significant subpopulations of WMICs containing neuronal nitric oxide synthase (nNOS) and calretinin, with very few WMICs containing parvalbumin, and none containing calbindin. The nNOS and calretinin immunopositive WMICs represent approximately 21% of the total WMIC population; however, variances in the proportions of these neurochemical phenotypes were noted. Our results indicate that both the squirrel monkey and crested macaque might be informative animal models for the study of WMICs in neurodegenerative and psychiatric disorders in humans.
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Affiliation(s)
- Jordan Swiegers
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Busisiwe C Maseko
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Chet C Sherwood
- Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA
| | | | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Muhammad A Spocter
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Department of Anatomy, Des Moines University, Des Moines, Iowa, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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8
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Swiegers J, Bhagwandin A, Williams VM, Maseko BC, Sherwood CC, Hård T, Bertelsen MF, Rockland KS, Molnár Z, Manger PR. The distribution, number, and certain neurochemical identities of infracortical white matter neurons in a chimpanzee (Pan troglodytes) brain. J Comp Neurol 2021; 529:3429-3452. [PMID: 34180538 DOI: 10.1002/cne.25202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 01/06/2023]
Abstract
We examined the number, distribution, and immunoreactivity of the infracortical white matter neuronal population, also termed white matter interstitial cells (WMICs), throughout the telencephalic white matter of an adult female chimpanzee. Staining for neuronal nuclear marker (NeuN) revealed WMICs throughout the infracortical white matter, these cells being most numerous and dense close to the inner border of cortical layer VI, decreasing significantly in density with depth in the white matter. Stereological analysis of NeuN-immunopositive cells revealed an estimate of approximately 137.2 million WMICs within the infracortical white matter of the chimpanzee brain studied. Immunostaining revealed subpopulations of WMICs containing neuronal nitric oxide synthase (nNOS, approximately 14.4 million in number), calretinin (CR, approximately 16.7 million), very few WMICs containing parvalbumin (PV), and no calbindin-immunopositive neurons. The nNOS, CR, and PV immunopositive WMICs, possibly all inhibitory neurons, represent approximately 22.6% of the total WMIC population. As the white matter is affected in many cognitive conditions, such as schizophrenia, autism, epilepsy, and also in neurodegenerative diseases, understanding these neurons across species is important for the translation of findings of neural dysfunction in animal models to humans. Furthermore, studies of WMICs in species such as apes provide a crucial phylogenetic context for understanding the evolution of these cell types in the human brain.
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Affiliation(s)
- Jordan Swiegers
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Victoria M Williams
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Busisiwe C Maseko
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA
| | | | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University, School of Medicine, Boston, Massachusetts, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
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9
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Kullander K, Topolnik L. Cortical disinhibitory circuits: cell types, connectivity and function. Trends Neurosci 2021; 44:643-657. [PMID: 34006387 DOI: 10.1016/j.tins.2021.04.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 04/16/2021] [Accepted: 04/22/2021] [Indexed: 12/16/2022]
Abstract
The concept of a dynamic excitation/inhibition balance tuned by circuit disinhibition, which can shape information flow during complex behavioral tasks, has arisen as an important and conserved information-processing motif. In cortical circuits, different subtypes of GABAergic inhibitory interneurons are connected to each other, offering an anatomical foundation for disinhibitory processes. Moreover, a subpopulation of GABAergic cells that express vasoactive intestinal polypeptide (VIP) preferentially innervates inhibitory interneurons, highlighting their central role in disinhibitory modulation. We discuss inhibitory neuron subtypes involved in disinhibition, with a focus on local circuits and long-range synaptic connections that drive disinhibitory function. We highlight multiple layers of disinhibition across cortical circuits that regulate behavior and serve to maintain an excitation/inhibition balance.
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Affiliation(s)
- Klas Kullander
- Department of Neuroscience, Uppsala University, Uppsala, Sweden.
| | - Lisa Topolnik
- Department of Biochemistry, Microbiology, and Bioinformatics, Laval University, Québec, QC, Canada; Neuroscience Axis, Centre de Recherche du Centre Hospitalier Universitaire de Québec (CRCHUQ), Laval University, Québec, QC, Canada.
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10
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White Matter Interstitial Neurons in the Adult Human Brain: 3% of Cortical Neurons in Quest for Recognition. Cells 2021; 10:cells10010190. [PMID: 33477896 PMCID: PMC7833373 DOI: 10.3390/cells10010190] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 02/03/2023] Open
Abstract
White matter interstitial neurons (WMIN) are a subset of cortical neurons located in the subcortical white matter. Although they were fist described over 150 years ago, they are still largely unexplored and often considered a small, functionally insignificant neuronal population. WMIN are adult remnants of neurons located in the transient fetal subplate zone (SP). Following development, some of the SP neurons undergo apoptosis, and the remaining neurons are incorporated in the adult white matter as WMIN. In the adult human brain, WMIN are quite a large population of neurons comprising at least 3% of all cortical neurons (between 600 and 1100 million neurons). They include many of the morphological neuronal types that can be found in the overlying cerebral cortex. Furthermore, the phenotypic and molecular diversity of WMIN is similar to that of the overlying cortical neurons, expressing many glutamatergic and GABAergic biomarkers. WMIN are often considered a functionally unimportant subset of neurons. However, upon closer inspection of the scientific literature, it has been shown that WMIN are integrated in the cortical circuitry and that they exhibit diverse electrophysiological properties, send and receive axons from the cortex, and have active synaptic contacts. Based on these data, we are able to enumerate some of the potential WMIN roles, such as the control of the cerebral blood flow, sleep regulation, and the control of information flow through the cerebral cortex. Also, there is a number of studies indicating the involvement of WMIN in the pathophysiology of many brain disorders such as epilepsy, schizophrenia, Alzheimer’s disease, etc. All of these data indicate that WMIN are a large population with an important function in the adult brain. Further investigation of WMIN could provide us with novel data crucial for an improved elucidation of the pathophysiology of many brain disorders. In this review, we provide an overview of the current WMIN literature, with an emphasis on studies conducted on the human brain.
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11
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Ding C, Emmenegger V, Schaffrath K, Feldmeyer D. Layer-Specific Inhibitory Microcircuits of Layer 6 Interneurons in Rat Prefrontal Cortex. Cereb Cortex 2021; 31:32-47. [PMID: 32829414 PMCID: PMC7727376 DOI: 10.1093/cercor/bhaa201] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 06/06/2020] [Accepted: 07/02/2020] [Indexed: 12/15/2022] Open
Abstract
GABAergic interneurons in different cortical areas play important roles in diverse higher-order cognitive functions. The heterogeneity of interneurons is well characterized in different sensory cortices, in particular in primary somatosensory and visual cortex. However, the structural and functional properties of the medial prefrontal cortex (mPFC) interneurons have received less attention. In this study, a cluster analysis based on axonal projection patterns revealed four distinct clusters of L6 interneurons in rat mPFC: Cluster 1 interneurons showed axonal projections similar to Martinotti-like cells extending to layer 1, cluster 2 displayed translaminar projections mostly to layer 5, and cluster 3 interneuron axons were confined to the layer 6, whereas those of cluster 4 interneurons extend also into the white matter. Correlations were found between neuron location and axonal distribution in all clusters. Moreover, all cluster 1 L6 interneurons showed a monotonically adapting firing pattern with an initial high-frequency burst. All cluster 2 interneurons were fast-spiking, while neurons in cluster 3 and 4 showed heterogeneous firing patterns. Our data suggest that L6 interneurons that have distinct morphological and physiological characteristics are likely to innervate different targets in mPFC and thus play differential roles in the L6 microcircuitry and in mPFC-associated functions.
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Affiliation(s)
- Chao Ding
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
| | - Vishalini Emmenegger
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Kim Schaffrath
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
- Department of Ophthalmology, RWTH Aachen University Hospital, Medical School, 52074 Aachen, Germany
| | - Dirk Feldmeyer
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University Hospital, 52074 Aachen, Germany
- JARA-Translational Brain Medicine, 52074 Aachen, Germany
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12
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Bhagwandin A, Debipersadh U, Kaswera-Kyamakya C, Gilissen E, Rockland KS, Molnár Z, Manger PR. Distribution, number, and certain neurochemical identities of infracortical white matter neurons in the brains of three megachiropteran bat species. J Comp Neurol 2020; 528:3023-3038. [PMID: 32103488 DOI: 10.1002/cne.24894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/06/2020] [Accepted: 02/24/2020] [Indexed: 12/13/2022]
Abstract
A large population of infracortical white matter neurons, or white matter interstitial cells (WMICs), are found within the subcortical white matter of the mammalian telencephalon. We examined WMICs in three species of megachiropterans, Megaloglossus woermanni, Casinycteris argynnis, and Rousettus aegyptiacus, using immunohistochemical and stereological techniques. Immunostaining for neuronal nuclear marker (NeuN) revealed substantial numbers of WMICs in each species-M. woermanni 124,496 WMICs, C. argynnis 138,458 WMICs, and the larger brained R. aegyptiacus having an estimated WMIC population of 360,503. To examine the range of inhibitory neurochemical types we used antibodies against parvalbumin, calbindin, calretinin, and neural nitric oxide synthase (nNOS). The calbindin and nNOS immunostained neurons were the most commonly observed, while those immunoreactive for calretinin and parvalbumin were sparse. The proportion of WMICs exhibiting inhibitory neurochemical profiles was ~26%, similar to that observed in previously studied primates. While for the most part the WMIC population in the megachiropterans studied was similar to that observed in other mammals, the one feature that differed was the high proportion of WMICs immunoreactive to calbindin, whereas in primates (macaque monkey, lar gibbon and human) the highest proportion of inhibitory WMICs contain calretinin. Interestingly, there appears to be an allometric scaling of WMIC numbers with brain mass. Further quantitative comparative work across more mammalian species will reveal the developmental and evolutionary trends associated with this infrequently studied neuronal population.
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Affiliation(s)
- Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, South Africa
- Division of Clinical Anatomy and Biological Anthropology, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - Ulsana Debipersadh
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, South Africa
| | | | - Emmanuel Gilissen
- Department of African Zoology, Royal Museum for Central Africa, Tervuren, Belgium
- Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, Brussels, Belgium
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University, School of Medicine, Boston, Massachusetts, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, South Africa
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13
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Borra E, Luppino G, Gerbella M, Rozzi S, Rockland KS. Projections to the putamen from neurons located in the white matter and the claustrum in the macaque. J Comp Neurol 2019; 528:453-467. [PMID: 31483857 DOI: 10.1002/cne.24768] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 08/24/2019] [Accepted: 08/26/2019] [Indexed: 12/21/2022]
Abstract
Continuing investigations of corticostriatal connections in rodents emphasize an intricate architecture where striatal projections originate from different combinations of cortical layers, include an inhibitory component, and form terminal arborizations which are cell-type dependent, extensive, or compact. Here, we report that in macaque monkeys, deep and superficial cortical white matter neurons (WMNs), peri-claustral WMNs, and the claustrum proper project to the putamen. WMNs retrogradely labeled by injections in the putamen (four injections in three macaques) were widely distributed, up to 10 mm antero-posterior from the injection site, mainly dorsal to the putamen in the external capsule, and below the premotor cortex. Striatally projecting labeled WMNs (WMNsST) were heterogeneous in size and shape, including a small GABAergic component. We compared the number of WMNsST with labeled claustral and cortical neurons and also estimated their proportion in relation to total WMNs. Since some WMNsST were located adjoining the claustrum, we wanted to compare results for density and distribution of striatally projecting claustral neurons (ClaST). ClaST neurons were morphologically heterogeneous and mainly located in the dorsal and anterior claustrum, in regions known to project to frontal, motor, and cingulate cortical areas. The ratio of ClaST to WMNsST was about 4:1 averaged across the four injections. These results provide new specifics on the connectional networks of WMNs in nonhuman primates, and delineate additional loops in the corticostriatal architecture, consisting of interconnections across cortex, claustralstriatal and striatally projecting WMNs.
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Affiliation(s)
- Elena Borra
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Parma, Italy
| | - Giuseppe Luppino
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Parma, Italy
| | - Marzio Gerbella
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Parma, Italy
| | - Stefano Rozzi
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Parma, Italy
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA
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14
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Duchatel RJ, Shannon Weickert C, Tooney PA. White matter neuron biology and neuropathology in schizophrenia. NPJ SCHIZOPHRENIA 2019; 5:10. [PMID: 31285426 PMCID: PMC6614474 DOI: 10.1038/s41537-019-0078-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/06/2019] [Indexed: 12/17/2022]
Abstract
Schizophrenia is considered a neurodevelopmental disorder as it often manifests before full brain maturation and is also a cerebral cortical disorder where deficits in GABAergic interneurons are prominent. Whilst most neurons are located in cortical and subcortical grey matter regions, a smaller population of neurons reside in white matter tracts of the primate and to a lesser extent, the rodent brain, subjacent to the cortex. These interstitial white matter neurons (IWMNs) have been identified with general markers for neurons [e.g., neuronal nuclear antigen (NeuN)] and with specific markers for neuronal subtypes such as GABAergic neurons. Studies of IWMNs in schizophrenia have primarily focused on their density underneath cortical areas known to be affected in schizophrenia such as the dorsolateral prefrontal cortex. Most of these studies of postmortem brains have identified increased NeuN+ and GABAergic IWMN density in people with schizophrenia compared to healthy controls. Whether IWMNs are involved in the pathogenesis of schizophrenia or if they are increased because of the cortical pathology in schizophrenia is unknown. We also do not understand how increased IWMN might contribute to brain dysfunction in the disorder. Here we review the literature on IWMN pathology in schizophrenia. We provide insight into the postulated functional significance of these neurons including how they may contribute to the pathophysiology of schizophrenia.
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Affiliation(s)
- Ryan J Duchatel
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, 2308, Australia.,Priority Centre for Brain and Mental Health Research and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Cynthia Shannon Weickert
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, NSW, 2031, Australia.,School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, NSW, 2052, Australia.,Department of Neuroscience & Physiology, Upstate Medical University, Syracuse, New York, 13210, USA
| | - Paul A Tooney
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, 2308, Australia. .,Priority Centre for Brain and Mental Health Research and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW, 2308, Australia.
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15
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Sedmak G, Judaš M. The total number of white matter interstitial neurons in the human brain. J Anat 2019; 235:626-636. [PMID: 31173356 DOI: 10.1111/joa.13018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2019] [Indexed: 02/06/2023] Open
Abstract
In the adult human brain, the interstitial neurons (WMIN) of the subcortical white matter are the surviving remnants of the fetal subplate zone. It has been suggested that they perform certain important functions and may be involved in the pathogenesis of several neurological and psychiatric disorders. However, many important features of this class of human cortical neurons remain insufficiently explored. In this study, we analyzed the total number, and regional and topological distribution of WMIN in the adult human subcortical white matter, using a combined immunocytochemical (NeuN) and stereological approaches. We found that the average number of WMIN in 1 mm3 of the subcortical white matter is 1.230 ± 549, which translates to the average total number of 593 811 183.6 ± 264 849 443.35 of WMIN in the entire subcortical telencephalic white matter. While there were no significant differences in their regional distribution, the lowest number of WMIN has been consistently observed in the limbic cortex, and the highest number in the frontal cortex. With respect to their topological distribution, the WMIN were consistently more numerous within gyral crowns, less numerous along gyral walls and least numerous at the bottom of cortical sulci (where they occupy a narrow and compact zone below the cortical-white matter border). The topological location of WMIN is also significantly correlated with their morphology: pyramidal and multipolar forms are the most numerous within gyral crowns, whereas bipolar forms predominate at the bottom of cortical sulci. Our results indicate that WMIN represent substantial neuronal population in the adult human cerebral cortex (e.g. more numerous than thalamic or basal ganglia neurons) and thus deserve more detailed morphological and functional investigations in the future.
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Affiliation(s)
- Goran Sedmak
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.,Center for Excellence in Basic, Clinical and Translational Neuroscience, Zagreb, Croatia
| | - Miloš Judaš
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.,Center for Excellence in Basic, Clinical and Translational Neuroscience, Zagreb, Croatia
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16
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Ellis JK, Sorrells SF, Mikhailova S, Chavali M, Chang S, Sabeur K, Mcquillen P, Rowitch DH. Ferret brain possesses young interneuron collections equivalent to human postnatal migratory streams. J Comp Neurol 2019; 527:2843-2859. [PMID: 31050805 PMCID: PMC6773523 DOI: 10.1002/cne.24711] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 03/27/2019] [Accepted: 04/29/2019] [Indexed: 12/16/2022]
Abstract
The human early postnatal brain contains late migratory streams of immature interneurons that are directed to cortex and other focal brain regions. However, such migration is not observed in rodent brain, and whether other small animal models capture this aspect of human brain development is unclear. Here, we investigated whether the gyrencephalic ferret cortex possesses human‐equivalent postnatal streams of doublecortin positive (DCX+) young neurons. We mapped DCX+ cells in the brains of ferrets at P20 (analogous to human term gestation), P40, P65, and P90. In addition to the rostral migratory stream, we identified three populations of young neurons with migratory morphology at P20 oriented toward: (a) prefrontal cortex, (b) dorsal posterior sigmoid gyrus, and (c) occipital lobe. These three neuronal collections were all present at P20 and became extinguished by P90 (equivalent to human postnatal age 2 years). DCX+ cells in such collections all expressed GAD67, identifying them as interneurons, and they variously expressed the subtype markers SP8 and secretagogin (SCGN). SCGN+ interneurons appeared in thick sections to be oriented from white matter toward multiple cortical regions, and persistent SCGN‐expressing cells were observed in cortex. These findings indicate that ferret is a suitable animal model to study the human‐relevant process of late postnatal cortical interneuron integration into multiple regions of cortex.
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Affiliation(s)
- Justin K Ellis
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Shawn F Sorrells
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Sasha Mikhailova
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Manideep Chavali
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Sandra Chang
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Khalida Sabeur
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Patrick Mcquillen
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - David H Rowitch
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California.,Department of Paediatrics and Wellcome Trust-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
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17
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Swiegers J, Bhagwandin A, Sherwood CC, Bertelsen MF, Maseko BC, Hemingway J, Rockland KS, Molnár Z, Manger PR. The distribution, number, and certain neurochemical identities of infracortical white matter neurons in a lar gibbon (Hylobates lar) brain. J Comp Neurol 2018; 527:1633-1653. [PMID: 30378128 DOI: 10.1002/cne.24545] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/04/2018] [Accepted: 09/21/2018] [Indexed: 01/08/2023]
Abstract
We examined the number, distribution, and immunoreactivity of the infracortical white matter neuronal population, also termed white matter interstitial cells (WMICs), in the brain of a lesser ape, the lar gibbon. Staining for neuronal nuclear marker (NeuN) revealed WMICs throughout the infracortical white matter, these cells being most numerous and dense close to cortical layer VI, decreasing significantly in density with depth in the white matter. Stereological analysis of NeuN-immunopositive cells revealed a global estimate of ~67.5 million WMICs within the infracortical white matter of the gibbon brain, indicating that the WMICs are a numerically significant population, ~2.5% of the total cortical gray matter neurons that would be estimated for a primate brain the mass of that of the lar gibbon. Immunostaining revealed subpopulations of WMICs containing neuronal nitric oxide synthase (nNOS, ~7 million in number, with both small and large soma volumes), calretinin (~8.6 million in number, all of similar soma volume), very few WMICs containing parvalbumin, and no calbindin-immunopositive neurons. These nNOS, calretinin, and parvalbumin immunopositive WMICs, presumably all inhibitory neurons, represent ~23.1% of the total WMIC population. As the white matter is affected in many cognitive conditions, such as schizophrenia, autism and also in neurodegenerative diseases, understanding these neurons across species is important for the translation of findings of neural dysfunction in animal models to humans. Furthermore, studies of WMICs in species such as apes provide a crucial phylogenetic context for understanding the evolution of these cell types in the human brain.
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Affiliation(s)
- Jordan Swiegers
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Adhil Bhagwandin
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia
| | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Busisiwe C Maseko
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Jason Hemingway
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, School of Medicine, Boston University, Boston, Massachusetts
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England
| | - Paul R Manger
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
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18
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Lim L, Mi D, Llorca A, Marín O. Development and Functional Diversification of Cortical Interneurons. Neuron 2018; 100:294-313. [PMID: 30359598 PMCID: PMC6290988 DOI: 10.1016/j.neuron.2018.10.009] [Citation(s) in RCA: 364] [Impact Index Per Article: 60.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 12/18/2022]
Abstract
In the cerebral cortex, GABAergic interneurons have evolved as a highly heterogeneous collection of cell types that are characterized by their unique spatial and temporal capabilities to influence neuronal circuits. Current estimates suggest that up to 50 different types of GABAergic neurons may populate the cerebral cortex, all derived from progenitor cells in the subpallium, the ventral aspect of the embryonic telencephalon. In this review, we provide an overview of the mechanisms underlying the generation of the distinct types of interneurons and their integration in cortical circuits. Interneuron diversity seems to emerge through the implementation of cell-intrinsic genetic programs in progenitor cells, which unfold over a protracted period of time until interneurons acquire mature characteristics. The developmental trajectory of interneurons is also modulated by activity-dependent, non-cell-autonomous mechanisms that influence their ability to integrate in nascent circuits and sculpt their final distribution in the adult cerebral cortex.
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Affiliation(s)
- Lynette Lim
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Da Mi
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Alfredo Llorca
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Oscar Marín
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK.
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19
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Mortazavi F, Romano SE, Rosene DL, Rockland KS. A Survey of White Matter Neurons at the Gyral Crowns and Sulcal Depths in the Rhesus Monkey. Front Neuroanat 2017; 11:69. [PMID: 28860975 PMCID: PMC5559435 DOI: 10.3389/fnana.2017.00069] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 07/31/2017] [Indexed: 12/14/2022] Open
Abstract
Gyrencephalic brains exhibit deformations of the six neocortical laminae at gyral crowns and sulcal depths, where the deeper layers are, respectively, expanded and compressed. The present study addresses: (1) the degree to which the underlying white matter neurons (WMNs) observe the same changes at gyral crowns and sulcal depths; and (2) whether these changes are consistent or variable across different cortical regions. WMNs were visualized by immunohistochemistry using the pan-neuronal label NeuN, and their density was quantified in eight rhesus monkey brains for four regions; namely, frontal (FR), superior frontal gyrus (SFG), parietal (Par) and temporal (TE). In all four regions, there were about 50% fewer WMNs in the sulcal depth, but there was also distinct variability from region to region. For the gyral crown, we observed an average density per 0.21 mm2 of 82 WMNs for the FR, 51 WMNs for SFG, 80 WMNs for Par and 93 WMNs for TE regions. By contrast, for the sulcal depth, the average number of WMNs per 0.21 mm2 was 41 for FR, 31 for cingulate sulcus (underlying the SFG), 54 for Par and 63 for TE cortical regions. Since at least some WMNs participate in cortical circuitry, these results raise the possibility of their differential influence on cortical circuitry in the overlying gyral and sulcal locations. The results also point to a possible role of WMNs in the differential vulnerability of gyral vs. sulcal regions in disease processes, and reinforce the increasing awareness of the WMNs as part of a complex, heterogeneous and structured microenvironment.
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Affiliation(s)
- Farzad Mortazavi
- Department of Anatomy and Neurobiology, Boston University School of MedicineBoston, MA, United States
| | - Samantha E. Romano
- Department of Anatomy and Neurobiology, Boston University School of MedicineBoston, MA, United States
| | - Douglas L. Rosene
- Department of Anatomy and Neurobiology, Boston University School of MedicineBoston, MA, United States
| | - Kathleen S. Rockland
- Department of Anatomy and Neurobiology, Boston University School of MedicineBoston, MA, United States
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20
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Frazer S, Prados J, Niquille M, Cadilhac C, Markopoulos F, Gomez L, Tomasello U, Telley L, Holtmaat A, Jabaudon D, Dayer A. Transcriptomic and anatomic parcellation of 5-HT 3AR expressing cortical interneuron subtypes revealed by single-cell RNA sequencing. Nat Commun 2017; 8:14219. [PMID: 28134272 PMCID: PMC5290279 DOI: 10.1038/ncomms14219] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 12/08/2016] [Indexed: 11/09/2022] Open
Abstract
Cortical GABAergic interneurons constitute a highly diverse population of inhibitory neurons that are key regulators of cortical microcircuit function. An important and heterogeneous group of cortical interneurons specifically expresses the serotonin receptor 3A (5-HT3AR) but how this diversity emerges during development is poorly understood. Here we use single-cell transcriptomics to identify gene expression patterns operating in Htr3a-GFP+ interneurons during early steps of cortical circuit assembly. We identify three main molecular types of Htr3a-GFP+ interneurons, each displaying distinct developmental dynamics of gene expression. The transcription factor Meis2 is specifically enriched in a type of Htr3a-GFP+ interneurons largely confined to the cortical white matter. These MEIS2-expressing interneurons appear to originate from a restricted region located at the embryonic pallial–subpallial boundary. Overall, this study identifies MEIS2 as a subclass-specific marker for 5-HT3AR-containing interstitial interneurons and demonstrates that the transcriptional and anatomical parcellation of cortical interneurons is developmentally coupled. Cortical GABAergic interneurons are highly diverse in their gene expression, electrophysiological properties, and connectivity. Here the authors reveal three distinct subtypes of Htr3a-GFP+ interneurons using the single-cell RNA-seq approach, and identify MEIS2 as a marker for one such subtype.
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Affiliation(s)
- Sarah Frazer
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Julien Prados
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Mathieu Niquille
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Christelle Cadilhac
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Foivos Markopoulos
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Lucia Gomez
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Ugo Tomasello
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Ludovic Telley
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Anthony Holtmaat
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Denis Jabaudon
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Alexandre Dayer
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
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21
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Involvement of 5-HT 3 receptors in the action of vortioxetine in rat brain: Focus on glutamatergic and GABAergic neurotransmission. Neuropharmacology 2016; 108:73-81. [DOI: 10.1016/j.neuropharm.2016.04.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/18/2016] [Accepted: 04/18/2016] [Indexed: 01/03/2023]
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22
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Kondo M. Molecular mechanisms of experience-dependent structural and functional plasticity in the brain. Anat Sci Int 2016; 92:1-17. [DOI: 10.1007/s12565-016-0358-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/16/2016] [Indexed: 11/24/2022]
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23
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Mortazavi F, Wang X, Rosene DL, Rockland KS. White Matter Neurons in Young Adult and Aged Rhesus Monkey. Front Neuroanat 2016; 10:15. [PMID: 26941613 PMCID: PMC4761867 DOI: 10.3389/fnana.2016.00015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/05/2016] [Indexed: 01/21/2023] Open
Abstract
In humans and non-human primates (NHP), white matter neurons (WMNs) persist beyond early development. Their functional importance is largely unknown, but they have both corticothalamic and corticocortical connectivity and at least one subpopulation has been implicated in vascular regulation and sleep. Several other studies have reported that the density of WMNs in humans is altered in neuropathological or psychiatric conditions. The present investigation evaluates and compares the density of superficial and deep WMNs in frontal (FR), temporal (TE), and parietal (Par) association regions of four young adult and four aged male rhesus monkeys. A major aim was to determine whether there was age-related neuronal loss, as might be expected given the substantial age-related changes known to occur in the surrounding white matter environment. Neurons were visualized by immunocytochemistry for Neu-N in coronal tissue sections (30 μm thickness), and neuronal density was assessed by systematic random sampling. Per 0.16 mm2 sampling box, this yielded about 40 neurons in the superficial WM and 10 in the deep WM. Consistent with multiple studies of cell density in the cortical gray matter of normal brains, neither the superficial nor deep WM populations showed statistically significant age-related neuronal loss, although we observed a moderate decrease with age for the deep WMNs in the frontal region. Morphometric analyses, in contrast, showed significant age effects in soma size and circularity. In specific, superficial WMNs were larger in FR and Par WM regions of the young monkeys; but in the TE, these were larger in the older monkeys. An age effect was also observed for soma circularity: superficial WMNs were more circular in FR and Par of the older monkeys. This second, morphometric result raises the question of whether other age-related morphological, connectivity, or molecular changes occur in the WMNs. These could have multiple impacts, given the wide range of putative WMN functions and their involvement in both corticothalamic and corticocortical circuitry.
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Affiliation(s)
- Farzad Mortazavi
- Department of Anatomy and Neurobiology, Boston University School of Medicine Boston, MA, USA
| | - Xiyue Wang
- Department of Anatomy and Neurobiology, Boston University School of Medicine Boston, MA, USA
| | - Douglas L Rosene
- Department of Anatomy and Neurobiology, Boston University School of Medicine Boston, MA, USA
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University School of Medicine Boston, MA, USA
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Ortiz FC, Balia M, Orduz D. A commentary on: "Anti-muscarinic adjunct therapy accelerates functional human oligodendrocyte repair". Front Cell Neurosci 2015; 9:274. [PMID: 26257606 PMCID: PMC4508516 DOI: 10.3389/fncel.2015.00274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/03/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Fernando C Ortiz
- Neurophysiology and New Microscopies Laboratory, INSERM U1128, Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - Maddalena Balia
- Neurophysiology and New Microscopies Laboratory, INSERM U1128, Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - David Orduz
- Neurophysiology and New Microscopies Laboratory, INSERM U1128, Université Paris Descartes, Sorbonne Paris Cité Paris, France
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25
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von Engelhardt J, Bocklisch C, Tönges L, Herb A, Mishina M, Monyer H. GluN2D-containing NMDA receptors-mediate synaptic currents in hippocampal interneurons and pyramidal cells in juvenile mice. Front Cell Neurosci 2015; 9:95. [PMID: 25859181 PMCID: PMC4373385 DOI: 10.3389/fncel.2015.00095] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/02/2015] [Indexed: 01/15/2023] Open
Abstract
The differential regulation of the two major N-methyl-D-aspartate receptor (NMDAR) subunits GluN2A and GluN2B during development in forebrain pyramidal cells has been thoroughly investigated. In contrast, much less is known about the role of GluN2D, which is expressed at low levels and is downregulated following the second postnatal week. However, it appears that few cells, presumably interneurons, continue to express GluN2D also in juvenile mice. To investigate which hippocampal cell types express this subunit, we generated transgenic mice with EGFP-tagged GluN2D receptors. The expression of the transgene was confined to hippocampal interneurons, most of which were parvalbumin- and/or somatostatin-positive. Electrophysiological and morphological analyses showed that GluN2D was present mainly in fast spiking basket and axo-axonic cells. Based on pharmacological evidence and electrophysiological analysis of GluN2D knockout mice, we conclude that GluN2D-containing NMDARs mediate synaptic currents in hippocampal interneurons of young and juvenile mice and in CA1 pyramidal neurons of newborn mice.
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Affiliation(s)
- Jakob von Engelhardt
- Synaptic Signalling and Neurodegeneration, German Cancer Research Center (DKFZ) Heidelberg, Germany ; Synaptic Signalling and Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE) Bonn, Germany
| | - Christina Bocklisch
- Department of Clinical Neurobiology, Medical Faculty of Heidelberg University and DKFZ Heidelberg, Germany
| | - Lars Tönges
- Department of Clinical Neurobiology, Medical Faculty of Heidelberg University and DKFZ Heidelberg, Germany
| | - Anne Herb
- Department of Clinical Neurobiology, Medical Faculty of Heidelberg University and DKFZ Heidelberg, Germany
| | - Masayoshi Mishina
- Brain Science Laboratory, The Research Organization of Science and Technology, Ritsumeikan University Kusatsu, Shiga, Japan
| | - Hannah Monyer
- Department of Clinical Neurobiology, Medical Faculty of Heidelberg University and DKFZ Heidelberg, Germany
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26
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Transient Sp8+ handlebar-like interneuron structure traversing the corpus callosum during the second postnatal week. Neuroreport 2015; 26:216-22. [DOI: 10.1097/wnr.0000000000000331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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27
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Butt AM, Fern RF, Matute C. Neurotransmitter signaling in white matter. Glia 2014; 62:1762-79. [PMID: 24753049 DOI: 10.1002/glia.22674] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 03/04/2014] [Accepted: 03/31/2014] [Indexed: 12/16/2022]
Abstract
White matter (WM) tracts are bundles of myelinated axons that provide for rapid communication throughout the CNS and integration in grey matter (GM). The main cells in myelinated tracts are oligodendrocytes and astrocytes, with small populations of microglia and oligodendrocyte precursor cells. The prominence of neurotransmitter signaling in WM, which largely exclude neuronal cell bodies, indicates it must have physiological functions other than neuron-to-neuron communication. A surprising aspect is the diversity of neurotransmitter signaling in WM, with evidence for glutamatergic, purinergic (ATP and adenosine), GABAergic, glycinergic, adrenergic, cholinergic, dopaminergic and serotonergic signaling, acting via a wide range of ionotropic and metabotropic receptors. Both axons and glia are potential sources of neurotransmitters and may express the respective receptors. The physiological functions of neurotransmitter signaling in WM are subject to debate, but glutamate and ATP-mediated signaling have been shown to evoke Ca(2+) signals in glia and modulate axonal conduction. Experimental findings support a model of neurotransmitters being released from axons during action potential propagation acting on glial receptors to regulate the homeostatic functions of astrocytes and myelination by oligodendrocytes. Astrocytes also release neurotransmitters, which act on axonal receptors to strengthen action potential propagation, maintaining signaling along potentially long axon tracts. The co-existence of multiple neurotransmitters in WM tracts suggests they may have diverse functions that are important for information processing. Furthermore, the neurotransmitter signaling phenomena described in WM most likely apply to myelinated axons of the cerebral cortex and GM areas, where they are doubtless important for higher cognitive function.
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Affiliation(s)
- Arthur M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
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28
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Kondo M, Nakamura Y, Ishida Y, Yamada T, Shimada S. The 5-HT3A receptor is essential for fear extinction. Learn Mem 2013; 21:1-4. [PMID: 24344177 PMCID: PMC3867712 DOI: 10.1101/lm.032193.113] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The 5-HT3 receptor, the only ionotropic 5-HT receptor, is expressed in limbic regions, including the hippocampus, amygdala, and cortex. However, it is not known whether it has a role in fear memory processes. Analysis of 5-HT3A receptor knockout mice in fear conditioning paradigms revealed that the 5-HT3A receptor is not required for the acquisition or retention of fear memory but is essential for the extinction of contextual and tone-cued fear. Our data suggest that the 5-HT3A receptor could be a key molecule regulating fear memory processes and a potential therapeutic target for fear disorders.
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Affiliation(s)
- Makoto Kondo
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
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29
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Engel M, Smidt MP, van Hooft JA. The serotonin 5-HT3 receptor: a novel neurodevelopmental target. Front Cell Neurosci 2013; 7:76. [PMID: 23761731 PMCID: PMC3669892 DOI: 10.3389/fncel.2013.00076] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 05/06/2013] [Indexed: 01/28/2023] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT), next to being an important neurotransmitter, recently gained attention as a key-regulator of pre- and postnatal development in the mammalian central nervous system (CNS). Several receptors for 5-HT are expressed in the developing brain including a ligand-gated ion channel, the 5-HT3 receptor. Over the past years, evidence has been accumulating that 5-HT3 receptors are involved in the regulation of neurodevelopment by serotonin. Here, we review the spatial and temporal expression patterns of 5-HT3 receptors in the pre- and early postnatal rodent brain and its functional implications. First, 5-HT3 receptors are expressed on GABAergic interneurons in neocortex and limbic structures derived from the caudal ganglionic eminence. Mature inhibitory GABAergic interneurons fine-tune neuronal excitability and thus are crucial for the physiological function of the brain. Second, 5-HT3 receptors are expressed on specific glutamatergic neurons, Cajal-Retzius cells in the cortex and granule cells in the cerebellum, where they regulate morphology, positioning, and connectivity of the local microcircuitry. Taken together, the 5-HT3 receptor emerges as a potential key-regulator of network formation and function in the CNS, which could have a major impact on our understanding of neurodevelopmental disorders in which 5-HT plays a role.
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Affiliation(s)
- Mareen Engel
- Center for NeuroScience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
- Max Planck Institute of PsychiatryMunich, Germany
| | - Marten P. Smidt
- Center for NeuroScience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
| | - Johannes A. van Hooft
- Center for NeuroScience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
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Characterization of immature and mature 5-hydroxytryptamine 3A receptor-expressing cells within the adult SVZ–RMS–OB system. Neuroscience 2012; 227:180-90. [DOI: 10.1016/j.neuroscience.2012.09.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 09/23/2012] [Accepted: 09/24/2012] [Indexed: 12/19/2022]
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31
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Rockland KS, Nayyar N. Association of type I neurons positive for NADPH-diaphorase with blood vessels in the adult monkey corpus callosum. Front Neural Circuits 2012; 6:4. [PMID: 22363265 PMCID: PMC3282256 DOI: 10.3389/fncir.2012.00004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/01/2012] [Indexed: 12/11/2022] Open
Abstract
Sagittal sections through the corpus callosum of adult macaque monkeys (n = 7) reveal a subpopulation of neurons positive for NADPH-diaphorase (NADPHd). These are sparsely distributed, with 2–12 neurons scored over the anterior two-thirds of the callosum (about 14 mm). Neurons are densely labeled, type 1; but on the basis of soma and dendritic morphology, these neurons exhibit distinct heterogeneity. In one subpopulation, the cell body is narrowly attenuated (7–10 μm in width). These have bipolar dendrites, extending 300–800 μm from the cell body. One or both of the dendrites is often closely associated with blood vessels and tends to be aligned dorso-ventral, perpendicular to the body of the callosum. Another subpopulation of neurons has a larger soma (typically, 15 μm × 20 μm) and more multipolar dendrites, which are not as obviously associated with blood vessels. White matter neurons positive for NADPHd have previously been observed as a transient population, most numerous during development, in the human corpus callosum, as well as in that of other species. Their persistence in the corpus callosum of adult macaques and their close association with blood vessels has not previously been reported and is suggestive of roles other than axon guidance.
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Affiliation(s)
- Kathleen S Rockland
- Laboratory for Cortical Organization and Systematics, RIKEN Brain Science Institute Wako-shi, Saitama, Japan
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