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Zhang L, Huang J, Dai L, Zhu G, Yang XL, He Z, Li YH, Yang H, Zhang CQ, Shen KF, Liang P. Expression profiles of α-synuclein in cortical lesions of patients with FCD IIb and TSC, and FCD rats. Front Neurol 2023; 14:1255097. [PMID: 38020594 PMCID: PMC10662349 DOI: 10.3389/fneur.2023.1255097] [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: 07/08/2023] [Accepted: 10/06/2023] [Indexed: 12/01/2023] Open
Abstract
Background Focal cortical dysplasia (FCD) IIb and tuberous sclerosis complex (TSC) are common causes of drug-resistant epilepsy in children. However, the etiologies related to the development of FCD IIb and TSC are not fully understood. α-synuclein (α-syn) is a member of synucleins family that plays crucial roles in modulating synaptic transmission in central nervous system. Here, we explored the expression profiles and potential pathogenic functions of α-syn in cortical lesions of epileptic patients with FCD IIb and TSC. Methods Surgical specimens from epileptic patients with FCD IIb and TSC, as well as FCD rats generated by in utero X-ray-radiation were adopted in this study and studied with immunohistochemistry, immunofluorescence, western blotting, and co-immunoprecipitation etc. molecular biological techniques. Result Our results showed that α-syn expression was reduced in FCD IIb and TSC lesions. Specifically, α-syn protein was intensely expressed in dysplastic neurons (DNs) and balloon cells (BCs) in FCD IIb lesions, whereas was barely detected in DNs and giant cells (GCs) of TSC lesions. Additionally, p-α-syn, the aggregated form of α-syn, was detected in DNs, BCs, GCs, and glia-like cells of FCD IIb and TSC lesions. We previous showed that the function of N-methyl-D-aspartate receptor (NMDAR) was enhanced in FCD rats generated by X-ray-radiation. Here, we found the interaction between α-syn and NMDAR subunits NMDAR2A, NMDAR2B were augmented in cortical lesions of FCD patients and FCD rats. Conclusion These results suggested a potential role of α-syn in the pathogenesis of FCD IIb and TSC by interfering with NMDAR.
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Affiliation(s)
- Li Zhang
- Department of Neurosurgery, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing, China
| | - Jun Huang
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Lu Dai
- Chongqing Institute for Brain and Intelligence, Guang Yang Bay Laboratory, Chongqing, China
| | - Gang Zhu
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Xiao-Lin Yang
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Zeng He
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Yu-Hong Li
- Department of Cell Biology, Basic Medical College, Army Medical University, Chongqing, China
| | - Hui Yang
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
- Chongqing Institute for Brain and Intelligence, Guang Yang Bay Laboratory, Chongqing, China
| | - Chun-Qing Zhang
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Kai-Feng Shen
- Department of Neurosurgery, Epilepsy Research Center of PLA, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Ping Liang
- Department of Neurosurgery, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing, China
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Aquiles A, Fiordelisio T, Luna-Munguia H, Concha L. Altered functional connectivity and network excitability in a model of cortical dysplasia. Sci Rep 2023; 13:12335. [PMID: 37518675 PMCID: PMC10387479 DOI: 10.1038/s41598-023-38717-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/13/2023] [Indexed: 08/01/2023] Open
Abstract
Focal cortical dysplasias (FCDs) are malformations of cortical development that often result in medically refractory epilepsy, with a greater incidence in the pediatric population. The relationship between the disturbed cortical morphology and epileptogenic activity of FCDs remains unclear. We used the BCNU (carmustine 1-3-bis-chloroethyl-nitrosourea) animal model of cortical dysplasia to evaluate neuronal and laminar alterations and how these result in altered activity of intracortical networks in early life. We corroborated the previously reported morphological anomalies characteristic of the BCNU model, comprising slightly larger and rounder neurons and abnormal cortical lamination. Next, the neuronal activity of live cortical slices was evaluated through large field-of-view calcium imaging as well as the neuronal response to a stimulus that leads to cortical hyperexcitability (pilocarpine). Examination of the joint activity of neuronal calcium time series allowed us to identify intracortical communication patterns and their response to pilocarpine. The baseline power density distribution of neurons in the cortex of BCNU-treated animals was different from that of control animals, with the former showing no modulation after stimulus. Moreover, the intracortical communication pattern differed between the two groups, with cortexes from BCNU-treated animals displaying decreased inter-layer connectivity as compared to control animals. Our results indicate that the altered anatomical organization of the cortex of BCNU-treated rats translates into altered functional networks that respond abnormally to a hyperexcitable stimulus and highlight the role of network dysfunction in the pathophysiology of cortical dysplasia.
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Affiliation(s)
- A Aquiles
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Querétaro, Mexico
| | - T Fiordelisio
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia LaNSBioDyT, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - H Luna-Munguia
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Querétaro, Mexico
| | - L Concha
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Querétaro, Mexico.
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Villaseñor PJ, Cortés-Servín D, Pérez-Moriel A, Aquiles A, Luna-Munguía H, Ramirez-Manzanares A, Coronado-Leija R, Larriva-Sahd J, Concha L. Multi-tensor diffusion abnormalities of gray matter in an animal model of cortical dysplasia. Front Neurol 2023; 14:1124282. [PMID: 37342776 PMCID: PMC10278582 DOI: 10.3389/fneur.2023.1124282] [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: 12/15/2022] [Accepted: 04/18/2023] [Indexed: 06/23/2023] Open
Abstract
Focal cortical dysplasias are a type of malformations of cortical development that are a common cause of drug-resistant focal epilepsy. Surgical treatment is a viable option for some of these patients, with their outcome being highly related to complete surgical resection of lesions visible in magnetic resonance imaging (MRI). However, subtle lesions often go undetected on conventional imaging. Several methods to analyze MRI have been proposed, with the common goal of rendering subtle cortical lesions visible. However, most image-processing methods are targeted to detect the macroscopic characteristics of cortical dysplasias, which do not always correspond to the microstructural disarrangement of these cortical malformations. Quantitative analysis of diffusion-weighted MRI (dMRI) enables the inference of tissue characteristics, and novel methods provide valuable microstructural features of complex tissue, including gray matter. We investigated the ability of advanced dMRI descriptors to detect diffusion abnormalities in an animal model of cortical dysplasia. For this purpose, we induced cortical dysplasia in 18 animals that were scanned at 30 postnatal days (along with 19 control animals). We obtained multi-shell dMRI, to which we fitted single and multi-tensor representations. Quantitative dMRI parameters derived from these methods were queried using a curvilinear coordinate system to sample the cortical mantle, providing inter-subject anatomical correspondence. We found region- and layer-specific diffusion abnormalities in experimental animals. Moreover, we were able to distinguish diffusion abnormalities related to altered intra-cortical tangential fibers from those associated with radial cortical fibers. Histological examinations revealed myelo-architectural abnormalities that explain the alterations observed through dMRI. The methods for dMRI acquisition and analysis used here are available in clinical settings and our work shows their clinical relevance to detect subtle cortical dysplasias through analysis of their microstructural properties.
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Affiliation(s)
- Paulina J. Villaseñor
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | - David Cortés-Servín
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | | | - Ana Aquiles
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | - Hiram Luna-Munguía
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | | | - Ricardo Coronado-Leija
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States
| | - Jorge Larriva-Sahd
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | - Luis Concha
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
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Luhmann HJ. Malformations-related neocortical circuits in focal seizures. Neurobiol Dis 2023; 178:106018. [PMID: 36706927 DOI: 10.1016/j.nbd.2023.106018] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 01/18/2023] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
This review article gives an overview on the molecular, cellular and network mechanisms underlying focal seizures in neocortical networks with developmental malformations. Neocortical malformations comprise a large variety of structural abnormalities associated with epilepsy and other neurological and psychiatric disorders. Genetic or acquired disorders of neocortical cell proliferation, neuronal migration and/or programmed cell death may cause pathologies ranging from the expression of dysmorphic neurons and heterotopic cell clusters to abnormal layering and cortical misfolding. After providing a brief overview on the pathogenesis and structure of neocortical malformations in humans, animal models are discussed and how they contributed to our understanding on the mechanisms of neocortical hyperexcitability associated with developmental disorders. State-of-the-art molecular biological and electrophysiological techniques have been also used in humans and on resectioned neocortical tissue of epileptic patients and provide deep insights into the subcellular, cellular and network mechanisms contributing to focal seizures. Finally, a brief outlook is given how novel models and methods can shape translational research in the near future.
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Affiliation(s)
- Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz, Germany.
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Rodríguez-Arzate CA, Martínez-Mendoza ML, Rocha-Mendoza I, Luna-Palacios Y, Licea-Rodríguez J, Martínez-Torres A. Morphological and Calcium Signaling Alterations of Neuroglial Cells in Cerebellar Cortical Dysplasia Induced by Carmustine. Cells 2021; 10:cells10071581. [PMID: 34201497 PMCID: PMC8304447 DOI: 10.3390/cells10071581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 02/07/2023] Open
Abstract
Cortical dysplasias are alterations in the organization of the layers of the brain cortex due to problems in neuronal migration during development. The neuronal component has been widely studied in experimental models of cortical dysplasias. In contrast, little is known about how glia are affected. In the cerebellum, Bergmann glia (BG) are essential for neuronal migration during development, and in adult they mediate the control of fine movements through glutamatergic transmission. The aim of this study was to characterize the morphology and intracellular calcium dynamics of BG and astrocytes from mouse cerebellum and their modifications in a model of cortical dysplasia induced by carmustine (BCNU). Carmustine-treated mice were affected in their motor coordination and balance. Cerebellar dysplasias and heterotopias were more frequently found in lobule X. Morphology of BG cells and astrocytes was affected, as were their spontaneous [Ca2+]i transients in slice preparation and in vitro.
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Affiliation(s)
- Cynthia Alejandra Rodríguez-Arzate
- Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro 76230, QT, Mexico; (C.A.R.-A.); (M.L.M.-M.)
| | - Marianne Lizeth Martínez-Mendoza
- Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro 76230, QT, Mexico; (C.A.R.-A.); (M.L.M.-M.)
| | - Israel Rocha-Mendoza
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana, No. 3918, Zona Playitas, Ensenada 22860, BC, Mexico; (I.R.-M.); (Y.L.-P.); (J.L.-R.)
| | - Yryx Luna-Palacios
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana, No. 3918, Zona Playitas, Ensenada 22860, BC, Mexico; (I.R.-M.); (Y.L.-P.); (J.L.-R.)
| | - Jacob Licea-Rodríguez
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana, No. 3918, Zona Playitas, Ensenada 22860, BC, Mexico; (I.R.-M.); (Y.L.-P.); (J.L.-R.)
- Cátedras CONACYT, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada 22860, BC, Mexico
| | - Ataúlfo Martínez-Torres
- Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro 76230, QT, Mexico; (C.A.R.-A.); (M.L.M.-M.)
- Correspondence:
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Chemotherapy-induced cognitive impairments: A systematic review of the animal literature. Neurosci Biobehav Rev 2019; 102:382-399. [DOI: 10.1016/j.neubiorev.2019.05.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/02/2019] [Accepted: 05/01/2019] [Indexed: 12/14/2022]
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Neural plasticity and network remodeling: From concepts to pathology. Neuroscience 2017; 344:326-345. [PMID: 28069532 DOI: 10.1016/j.neuroscience.2016.12.048] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/24/2016] [Accepted: 12/27/2016] [Indexed: 11/22/2022]
Abstract
Neuroplasticity has been subject to a great deal of research in the last century. Recently, significant emphasis has been placed on the global effect of localized plastic changes throughout the central nervous system, and on how these changes integrate in a pathological context. Specifically, alterations of network functionality have been described in various pathological contexts to which corresponding structural alterations have been proposed. However, considering the amount of literature and the different pathological contexts, an integration of this information is still lacking. In this paper we will review the concepts of neural plasticity as well as their repercussions on network remodeling and provide a possible explanation to how these two concepts relate to each other. We will further examine how alterations in different pathological contexts may relate to each other and will discuss the concept of plasticity diseases, its models and implications.
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Pennacchio P, Noé F, Gnatkovsky V, Moroni RF, Zucca I, Regondi MC, Inverardi F, de Curtis M, Frassoni C. Increased pCREB expression and the spontaneous epileptiform activity in a BCNU-treated rat model of cortical dysplasia. Epilepsia 2015; 56:1343-54. [DOI: 10.1111/epi.13070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Paolo Pennacchio
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Francesco Noé
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Vadym Gnatkovsky
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Ramona Frida Moroni
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Ileana Zucca
- Scientific Department; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Maria Cristina Regondi
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Francesca Inverardi
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Marco de Curtis
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
| | - Carolina Frassoni
- Clinical Epileptology and Experimental Neurophysiology Unit; IRCCS Foundation Neurological Institute “C. Besta”; Milano Italy
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Models of cortical malformation--Chemical and physical. J Neurosci Methods 2015; 260:62-72. [PMID: 25850077 DOI: 10.1016/j.jneumeth.2015.03.034] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 03/27/2015] [Accepted: 03/30/2015] [Indexed: 11/21/2022]
Abstract
Pharmaco-resistant epilepsies, and also some neuropsychiatric disorders, are often associated with malformations in hippocampal and neocortical structures. The mechanisms leading to these cortical malformations causing an imbalance between the excitatory and inhibitory system are largely unknown. Animal models using chemical or physical manipulations reproduce different human pathologies by interfering with cell generation and neuronal migration. The model of in utero injection of methylazoxymethanol (MAM) acetate mimics periventricular nodular heterotopia. The freeze lesion model reproduces (poly)microgyria, focal heterotopia and schizencephaly. The in utero irradiation model causes microgyria and heterotopia. Intraperitoneal injections of carmustine 1-3-bis-chloroethyl-nitrosurea (BCNU) to pregnant rats produces laminar disorganization, heterotopias and cytomegalic neurons. The ibotenic acid model induces focal cortical malformations, which resemble human microgyria and ulegyria. Cortical dysplasia can be also observed following prenatal exposure to ethanol, cocaine or antiepileptic drugs. All these models of cortical malformations are characterized by a pronounced hyperexcitability, few of them also produce spontaneous epileptic seizures. This dysfunction results from an impairment in GABAergic inhibition and/or an increase in glutamatergic synaptic transmission. The cortical region initiating or contributing to this hyperexcitability may not necessarily correspond to the site of the focal malformation. In some models wide-spread molecular and functional changes can be observed in remote regions of the brain, where they cause pathophysiological activities. This paper gives an overview on different animal models of cortical malformations, which are mostly used in rodents and which mimic the pathology and to some extent the pathophysiology of neuronal migration disorders associated with epilepsy in humans.
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González-González MA, Ostos-Valverde A, Becerra-Hernández A, Sánchez-Castillo H, Martínez-Torres A. The effect of carmustine on Bergmann cells of the cerebellum. Neurosci Lett 2015; 595:18-24. [PMID: 25841791 DOI: 10.1016/j.neulet.2015.03.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/21/2015] [Accepted: 03/31/2015] [Indexed: 11/15/2022]
Abstract
Administration of the alkylating agent carmustine to pregnant mice induces hyperlocomotion in the offspring. Motor performance was evaluated by the rotarod task, which revealed that these animals have diminished Grab Frequency and a higher Performance Index, whereas Error of Latency and Latency to Fall were unaffected. Considering the recently revealed role of Bergmann cells of cerebellum in the control of motor activity, we used the transgenic mice GFAP-GFP to explore the impact of carmustine on the organization of these glial cells. Multiple examples of cell layer disorganization were detected; many soma of Bergmann cells were displaced to the external cell layer, and their processes were not well defined until young adulthood. In addition, the roof of the fourth ventricle was convoluted. These observations suggest that the exacerbated locomotion induced by carmustine may be due, in part, to the altered organization of the cell layers of cerebellum.
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Affiliation(s)
- María Alejandra González-González
- Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, 76230 Querétaro, Qro, Mexico
| | - Aline Ostos-Valverde
- Laboratory of Neuropsychopharmacology and Timing, School of Psychology, UNAM, Building B, B001, Mexico City 04510, Mexico
| | - Armando Becerra-Hernández
- Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, 76230 Querétaro, Qro, Mexico
| | - Hugo Sánchez-Castillo
- Laboratory of Neuropsychopharmacology and Timing, School of Psychology, UNAM, Building B, B001, Mexico City 04510, Mexico
| | - Ataúlfo Martínez-Torres
- Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, 76230 Querétaro, Qro, Mexico.
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Moroni RF, Inverardi F, Regondi MC, Pennacchio P, Spreafico R, Frassoni C. Genesis of heterotopia in BCNU model of cortical dysplasia, detected by means of in utero electroporation. Dev Neurosci 2013; 35:516-26. [PMID: 24246662 DOI: 10.1159/000355392] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/30/2013] [Indexed: 11/19/2022] Open
Abstract
Derangements of cortical development can cause a wide spectrum of malformations, generally termed 'cortical dysplasia' (CD), which are frequently associated with drug-resistant epilepsy and other neurological and mental disorders. 1,3-Bis-chloroethyl-nitrosurea (BCNU)-treated rats represent a model of CD due to the presence of histological alterations similar to those observed in human CD. BCNU is an alkylating agent that, administered at embryonic day 15 (E15), causes the loss of many cells destined to cortical layers; this results in cortical thinning but also in histological alterations imputable to migration defects, such as laminar disorganization and cortical and periventricular heterotopia. In the present study we investigated the genesis of heterotopia in BCNU-treated rats by labeling cortical ventricular zone (VZ) cells with a green fluorescent protein (GFP) expression vector by means of in utero electroporation. Here, we compared the migratory pattern and subsequent distribution of the GFP-labeled cells in the developing somatosensory cortex of control and BCNU-treated animals. To this aim, we investigated the expression of a panel of developmental marker genes which identified radial glia cells (Pax6), intermediate precursors cells (Tbr2), and postmitotic neurons destined to infragranular (Tbr1) or supragranular layers (Satb2). The VZ of BCNU-treated rats appeared disorganized since E18 and at E21 the embryos showed an altered migratory pattern: migration of superficial layers appeared delayed, with a number of migrating cells in the intermediate zone and some neurons destined to superficial layers arrested in the VZ, thus forming periventricular heterotopia. Moreover, neurons that reached their correct position did not extend their axons through the corpus callosum in the contralateral hemisphere as in the control, but toward the ipsilateral cingulated cortex. Our analysis sheds light on how a malformed cortex develops after a temporally discrete environmental insult.
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Affiliation(s)
- Ramona Frida Moroni
- Unit of Clinical Epileptology and Experimental Neurophysiology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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