1
|
Lopez-Virgen V, Olivares-Moreno R, de Lafuente V, Concha L, Rojas-Piloni G. Different subtypes of motor cortex pyramidal tract neurons projects to red and pontine nuclei. Front Cell Neurosci 2022; 16:1073731. [PMID: 36605617 PMCID: PMC9807917 DOI: 10.3389/fncel.2022.1073731] [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: 10/18/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Introduction Pyramidal tract neurons (PTNs) are fundamental elements for motor control. However, it is largely unknown if PTNs are segregated into different subtypes with distinct characteristics. Methods Using anatomical and electrophysiological tools, we analyzed in mice motor cortex PTNs projecting to red and pontine midbrain nuclei, which are important hubs connecting cerebral cortex and cerebellum playing a critical role in the regulation of movement. Results We reveal that the vast majority of M1 neurons projecting to the red and pontine nuclei constitutes different populations. Corticopontine neurons have higher conduction velocities and morphologically, a most homogeneous dendritic and spine distributions along cortical layers. Discussion The results indicate that cortical neurons projecting to the red and pontine nuclei constitute distinct anatomical and functional pathways which may contribute differently to sensorimotor integration.
Collapse
|
2
|
Kathe C, Skinnider MA, Hutson TH, Regazzi N, Gautier M, Demesmaeker R, Komi S, Ceto S, James ND, Cho N, Baud L, Galan K, Matson KJE, Rowald A, Kim K, Wang R, Minassian K, Prior JO, Asboth L, Barraud Q, Lacour SP, Levine AJ, Wagner F, Bloch J, Squair JW, Courtine G. The neurons that restore walking after paralysis. Nature 2022; 611:540-547. [DOI: 10.1038/s41586-022-05385-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 09/23/2022] [Indexed: 11/10/2022]
Abstract
AbstractA spinal cord injury interrupts pathways from the brain and brainstem that project to the lumbar spinal cord, leading to paralysis. Here we show that spatiotemporal epidural electrical stimulation (EES) of the lumbar spinal cord1–3 applied during neurorehabilitation4,5 (EESREHAB) restored walking in nine individuals with chronic spinal cord injury. This recovery involved a reduction in neuronal activity in the lumbar spinal cord of humans during walking. We hypothesized that this unexpected reduction reflects activity-dependent selection of specific neuronal subpopulations that become essential for a patient to walk after spinal cord injury. To identify these putative neurons, we modelled the technological and therapeutic features underlying EESREHAB in mice. We applied single-nucleus RNA sequencing6–9 and spatial transcriptomics10,11 to the spinal cords of these mice to chart a spatially resolved molecular atlas of recovery from paralysis. We then employed cell type12,13 and spatial prioritization to identify the neurons involved in the recovery of walking. A single population of excitatory interneurons nested within intermediate laminae emerged. Although these neurons are not required for walking before spinal cord injury, we demonstrate that they are essential for the recovery of walking with EES following spinal cord injury. Augmenting the activity of these neurons phenocopied the recovery of walking enabled by EESREHAB, whereas ablating them prevented the recovery of walking that occurs spontaneously after moderate spinal cord injury. We thus identified a recovery-organizing neuronal subpopulation that is necessary and sufficient to regain walking after paralysis. Moreover, our methodology establishes a framework for using molecular cartography to identify the neurons that produce complex behaviours.
Collapse
|
3
|
Kawamura A, Katayama Y, Nishiyama M, Shoji H, Tokuoka K, Ueta Y, Miyata M, Isa T, Miyakawa T, Hayashi-Takagi A, Nakayama KI. Oligodendrocyte dysfunction due to Chd8 mutation gives rise to behavioral deficits in mice. Hum Mol Genet 2021; 29:1274-1291. [PMID: 32142125 DOI: 10.1093/hmg/ddaa036] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/23/2020] [Accepted: 02/27/2020] [Indexed: 01/01/2023] Open
Abstract
Mutations in the gene encoding the chromatin remodeler CHD8 are strongly associated with autism spectrum disorder (ASD). CHD8 haploinsufficiency also results in autistic phenotypes in humans and mice. Although myelination defects have been observed in individuals with ASD, whether oligodendrocyte dysfunction is responsible for autistic phenotypes has remained unknown. Here we show that reduced expression of CHD8 in oligodendrocytes gives rise to abnormal behavioral phenotypes in mice. CHD8 was found to regulate the expression of many myelination-related genes and to be required for oligodendrocyte maturation and myelination. Ablation of Chd8 specifically in oligodendrocytes of mice impaired myelination, slowed action potential propagation and resulted in behavioral deficits including increased social interaction and anxiety-like behavior, with similar effects being apparent in Chd8 heterozygous mutant mice. Our results thus indicate that CHD8 is essential for myelination and that dysfunction of oligodendrocytes as a result of CHD8 haploinsufficiency gives rise to several neuropsychiatric phenotypes.
Collapse
Affiliation(s)
- Atsuki Kawamura
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Yuta Katayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Masaaki Nishiyama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Hirotaka Shoji
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Kota Tokuoka
- Department of Neuroscience, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Yoshifumi Ueta
- Department of Physiology I (Neurophysiology), Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Mariko Miyata
- Department of Physiology I (Neurophysiology), Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Tadashi Isa
- Department of Neuroscience, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Tsuyoshi Miyakawa
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Akiko Hayashi-Takagi
- Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan.,PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Keiichi I Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| |
Collapse
|
4
|
Llorens-Bobadilla E, Chell JM, Le Merre P, Wu Y, Zamboni M, Bergenstråhle J, Stenudd M, Sopova E, Lundeberg J, Shupliakov O, Carlén M, Frisén J. A latent lineage potential in resident neural stem cells enables spinal cord repair. Science 2020; 370:370/6512/eabb8795. [PMID: 33004487 DOI: 10.1126/science.abb8795] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/04/2020] [Indexed: 12/20/2022]
Abstract
Injuries to the central nervous system (CNS) are inefficiently repaired. Resident neural stem cells manifest a limited contribution to cell replacement. We have uncovered a latent potential in neural stem cells to replace large numbers of lost oligodendrocytes in the injured mouse spinal cord. Integrating multimodal single-cell analysis, we found that neural stem cells are in a permissive chromatin state that enables the unfolding of a normally latent gene expression program for oligodendrogenesis after injury. Ectopic expression of the transcription factor OLIG2 unveiled abundant stem cell-derived oligodendrogenesis, which followed the natural progression of oligodendrocyte differentiation, contributed to axon remyelination, and stimulated functional recovery of axon conduction. Recruitment of resident stem cells may thus serve as an alternative to cell transplantation after CNS injury.
Collapse
Affiliation(s)
- Enric Llorens-Bobadilla
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - James M Chell
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Pierre Le Merre
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Yicheng Wu
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Margherita Zamboni
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Joseph Bergenstråhle
- Science for Life Laboratory, Karolinska Institutet Science Park, SE-171 21 Solna, Sweden
| | - Moa Stenudd
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Elena Sopova
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Joakim Lundeberg
- Science for Life Laboratory, Karolinska Institutet Science Park, SE-171 21 Solna, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Institute of Translational Biomedicine, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Marie Carlén
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - Jonas Frisén
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
| |
Collapse
|
5
|
Hutson TH, Kathe C, Palmisano I, Bartholdi K, Hervera A, De Virgiliis F, McLachlan E, Zhou L, Kong G, Barraud Q, Danzi MC, Medrano-Fernandez A, Lopez-Atalaya JP, Boutillier AL, Sinha SH, Singh AK, Chaturbedy P, Moon LDF, Kundu TK, Bixby JL, Lemmon VP, Barco A, Courtine G, Di Giovanni S. Cbp-dependent histone acetylation mediates axon regeneration induced by environmental enrichment in rodent spinal cord injury models. Sci Transl Med 2020; 11:11/487/eaaw2064. [PMID: 30971452 DOI: 10.1126/scitranslmed.aaw2064] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/21/2019] [Indexed: 12/24/2022]
Abstract
After a spinal cord injury, axons fail to regenerate in the adult mammalian central nervous system, leading to permanent deficits in sensory and motor functions. Increasing neuronal activity after an injury using electrical stimulation or rehabilitation can enhance neuronal plasticity and result in some degree of recovery; however, the underlying mechanisms remain poorly understood. We found that placing mice in an enriched environment before an injury enhanced the activity of proprioceptive dorsal root ganglion neurons, leading to a lasting increase in their regenerative potential. This effect was dependent on Creb-binding protein (Cbp)-mediated histone acetylation, which increased the expression of genes associated with the regenerative program. Intraperitoneal delivery of a small-molecule activator of Cbp at clinically relevant times promoted regeneration and sprouting of sensory and motor axons, as well as recovery of sensory and motor functions in both the mouse and rat model of spinal cord injury. Our findings showed that the increased regenerative capacity induced by enhancing neuronal activity is mediated by epigenetic reprogramming in rodent models of spinal cord injury. Understanding the mechanisms underlying activity-dependent neuronal plasticity led to the identification of potential molecular targets for improving recovery after spinal cord injury.
Collapse
Affiliation(s)
- Thomas H Hutson
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Claudia Kathe
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, UK.,Brain Mind Institute and Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland
| | - Ilaria Palmisano
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Kay Bartholdi
- Brain Mind Institute and Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland
| | - Arnau Hervera
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Francesco De Virgiliis
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Eilidh McLachlan
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Luming Zhou
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK.,Hertie Institute for Clinical Brain Research, University of Tubingen, Tubingen, Germany
| | - Guiping Kong
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK.,Hertie Institute for Clinical Brain Research, University of Tubingen, Tubingen, Germany
| | - Quentin Barraud
- Brain Mind Institute and Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland
| | - Matt C Danzi
- Miami Project to Cure Paralysis, University of Miami, Miami, FL 33136, USA
| | - Alejandro Medrano-Fernandez
- Instituto de Neurociencias, Universidad Miguel Hernandez Consejo Superior de Investigaciones Científicas, 03550 Alicante, Spain
| | - Jose P Lopez-Atalaya
- Instituto de Neurociencias, Universidad Miguel Hernandez Consejo Superior de Investigaciones Científicas, 03550 Alicante, Spain
| | - Anne L Boutillier
- Université de Strasbourg, CNRS, UMR 7364, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), F-67000 Strasbourg, France
| | - Sarmistha H Sinha
- Transcription and Disease Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Akash K Singh
- Transcription and Disease Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Piyush Chaturbedy
- Nanomaterials and Catalysis Laboratory, Chemistry and Physics of Materials Unit, JNCASR, Bangalore 560064, India
| | - Lawrence D F Moon
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, UK
| | - Tapas K Kundu
- Transcription and Disease Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - John L Bixby
- Miami Project to Cure Paralysis, University of Miami, Miami, FL 33136, USA
| | - Vance P Lemmon
- Miami Project to Cure Paralysis, University of Miami, Miami, FL 33136, USA
| | - Angel Barco
- Instituto de Neurociencias, Universidad Miguel Hernandez Consejo Superior de Investigaciones Científicas, 03550 Alicante, Spain
| | - Gregoire Courtine
- Brain Mind Institute and Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland
| | - Simone Di Giovanni
- Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK. .,Hertie Institute for Clinical Brain Research, University of Tubingen, Tubingen, Germany
| |
Collapse
|
6
|
Abstract
BACKGROUND Genetic techniques rendering murine models a popular choice for neuroscience research has led to important insights on neural networks controlling locomotor function. Using genetically altered mouse models for in vivo, electrophysiological studies in the adult state could validate key principles of locomotor network organization that have been described in neonatal, in vitro preparations. NEW METHOD The experimental model presented here describes a decerebrate, in vivo adult mouse preparation in which focal, electrical midbrain stimulation was combined with monitoring lumbar neural activity and motor output after pre-collicular decerebration and neuromuscular blockade. RESULTS Lumbar cord dorsum potentials (in 9/10 animals) and motoneuron output (in 3/5 animals) including fictive locomotion, was achieved by focal midbrain stimulation. The stimulation electrode locations could be reconstructed (in 6/7 animals) thereby allowing anatomical identification of the stimulated supraspinal regions. COMPARISON WITH EXISTING METHODS This preparation allows for concomitant recording or stimulation in the spinal cord and in the mid/hindbrain of adult mice. It differs from other methods used in the past with adult mice as it does not require pharmacological manipulation of neural excitability in order to generate motor output. CONCLUSIONS Midbrain stimulation can consistently be used for inducing lumbar neural activity in adult mice under neuromuscular blockade. This model is suited for examination of brain-spinal connectivity and it may benefit a wide range of fields depending on the features of the genetically modified mouse models used in combination with the presented methods.
Collapse
Affiliation(s)
- Katinka Stecina
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Ave., BMSB-436, Winnipeg, MB, R3E0J9, Canada.
| |
Collapse
|
7
|
Kondo T, Yoshihara Y, Yoshino-Saito K, Sekiguchi T, Kosugi A, Miyazaki Y, Nishimura Y, Okano HJ, Nakamura M, Okano H, Isa T, Ushiba J. Histological and electrophysiological analysis of the corticospinal pathway to forelimb motoneurons in common marmosets. Neurosci Res 2015; 98:35-44. [DOI: 10.1016/j.neures.2015.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 05/07/2015] [Accepted: 05/08/2015] [Indexed: 01/18/2023]
|
8
|
Chan KM, Gordon T, Zochodne DW, Power HA. Improving peripheral nerve regeneration: from molecular mechanisms to potential therapeutic targets. Exp Neurol 2014; 261:826-35. [PMID: 25220611 DOI: 10.1016/j.expneurol.2014.09.006] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/29/2014] [Accepted: 09/05/2014] [Indexed: 11/19/2022]
Abstract
Peripheral nerve injury is common especially among young individuals. Although injured neurons have the ability to regenerate, the rate is slow and functional outcomes are often poor. Several potential therapeutic agents have shown considerable promise for improving the survival and regenerative capacity of injured neurons. These agents are reviewed within the context of their molecular mechanisms. The PI3K/Akt and Ras/ERK signaling cascades play a key role in neuronal survival. A number of agents that target these pathways, including erythropoietin, tacrolimus, acetyl-l-carnitine, n-acetylcysteine and geldanamycin have been shown to be effective. Trk receptor signaling events that up-regulate cAMP play an important role in enhancing the rate of axonal outgrowth. Agents that target this pathway including rolipram, testosterone, fasudil, ibuprofen and chondroitinase ABC hold considerable promise for human application. A tantalizing prospect is to combine different molecular targeting strategies in complementary pathways to optimize their therapeutic effects. Although further study is needed prior to human trials, these modalities could open a new horizon in the clinical arena that has so far been elusive.
Collapse
Affiliation(s)
- K Ming Chan
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, Alberta, Canada; Centre for Neuroscience, University of Alberta, Canada.
| | - Tessa Gordon
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, Alberta, Canada; Centre for Neuroscience, University of Alberta, Canada; Division of Plastic Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Douglas W Zochodne
- Department of Clinical Neuroscience, University of Calgary, Calgary, Alberta, Canada
| | - Hollie A Power
- Division of Plastic Surgery, University of Alberta, Canada
| |
Collapse
|
9
|
Suter BA, Migliore M, Shepherd GMG. Intrinsic electrophysiology of mouse corticospinal neurons: a class-specific triad of spike-related properties. Cereb Cortex 2012; 23:1965-77. [PMID: 22761308 DOI: 10.1093/cercor/bhs184] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Corticospinal pyramidal neurons mediate diverse aspects of motor behavior. We measured spike-related electrophysiological properties of identified corticospinal neurons in primary motor cortex slices from young adult mice. Several consistent features were observed in the suprathreshold responses to current steps: 1) Corticospinal neurons fired relatively fast action potentials (APs; width at half-maximum 0.65 ± 0.13 ms, mean ± standard deviation [SD]) compared with neighboring callosally projecting corticostriatal neurons. Corticospinal AP width was intermediate between 2 classes of inhibitory interneuron in layer 5B. Spike-to-spike variability in AP width and other spike waveform parameters was low, even during repetitive firing up to 20 Hz, that is, the relative narrowness of corticospinal APs was essentially frequency independent. 2) Frequency-current (f-I) relationships were nearly linear. 3) Trains of APs displayed regular firing, with rates typically staying constant or accelerating over time. Corticospinal neurons recorded from older mice (up to 4 months) or from a separate lateral cortical area (Region B; corresponding to secondary somatosensory cortex) showed generally similar intrinsic properties. Our findings have implications for interpreting spike waveforms of in vivo recorded neurons in the motor cortex. This analysis provides a framework for further biophysical and computational investigations of corticospinal neurons and their roles in motor cortical function.
Collapse
Affiliation(s)
- Benjamin A Suter
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | | | | |
Collapse
|
10
|
Bando Y, Takakusaki K, Ito S, Terayama R, Kashiwayanagi M, Yoshida S. Differential changes in axonal conduction following CNS demyelination in two mouse models. Eur J Neurosci 2009; 28:1731-42. [PMID: 18973589 DOI: 10.1111/j.1460-9568.2008.06474.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transgenic and disease model mice have been used to investigate the molecular mechanisms of demyelinating diseases. However, less attention has been given to elucidating changes in nerve conduction in these mice. We established an experimental system to measure the response latency of cortical neurons and examined changes in nerve conduction in cuprizone-induced demyelinating mice and in myelin basic protein-deficient shiverer mice. Stimulating and recording electrodes were placed in the right and left sensori-motor cortices, respectively. Electrical stimulation of the right cortex evoked antidromic responses in left cortical neurons with a latency of 9.38 +/- 0.31 ms (n = 107; mean +/- SEM). While response latency was longer in mice at 7 days and 4 weeks of cuprizone treatment (12.35 +/- 0.35 ms, n = 102; 11.72 +/- 0.29 ms, n = 103, respectively), response latency at 7 days and 4 weeks after removal of cuprizone was partially restored (10.72 +/- 0.45 ms, n = 106; 10.27 +/- 0.34 ms, n = 107, respectively). Likewise, electron microscopy showed cuprizone-induced demyelination in the corpus callosum and nearly complete remyelination after cuprizone removal. We also examined whether the myelin abnormalities in shiverer mice affected their response latencies. But there were no significant differences in response latencies in shiverer (9.83 +/- 0.24 ms, n = 103) and wild-type (9.33 +/- 0.22 ms, n = 112) mice. The results of these electrophysiological assessments imply that different demyelinating mechanisms, differentially affecting axon conduction, are present in the cuprizone-treated and shiverer mice, and may provide new insights to understanding the pathophysiology of demyelination in animal models in the CNS.
Collapse
Affiliation(s)
- Yoshio Bando
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical College, Asahikawa, Hokkaido 078-8510, Japan.
| | | | | | | | | | | |
Collapse
|
11
|
Tanaka H, Ikenaka K, Isa T. Electrophysiological abnormalities precede apparent histological demyelination in the central nervous system of mice overexpressing proteolipid protein. J Neurosci Res 2007; 84:1206-16. [PMID: 16917838 DOI: 10.1002/jnr.21018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Myelin proteolipid protein (plp), a major myelin protein in the CNS, has been proposed to function in myelin assembly. Transgenic mice overexpressing the plp gene by introduction of two extra wild-type (Wt) mouse plp genes (plp(tg/-)) exhibit normal myelination and ion channel clustering at the age of 2 months. However, at the age of 5 months, demyelination becomes observable, accompanied by a reduction in the number of K+ channel clusters at Ranvier's node and a progressive increase in motor deficit. To clarify how these age-dependent changes are related to nerve conduction in the CNS, we analyzed the conduction velocity (CV) and relative refractory period (RRP) of identified spinal ascending or descending tracts, such as the dorsal column pathway, the vestibulospinal and reticulospinal tracts, and the pyramidal tract, in plp(tg/-) mice 2, 5, and 8 months of age. We found that CVs decreased as age increased. Importantly, CVs were significantly reduced and prolonged RRPs were observed in 2-month-old (2M) plp(tg/-) mice that had no apparent demyelination. Immunohistological examination revealed that densities of Na+ and K+ channel clusters decreased as plp(tg/-) and Wt mice aged. However, a clear correlation was not observed between CVs and mean channel cluster densities or between mean channel cluster densities and progress of demyelination. Performance in the rotarod test was normal in 2M plp(tg/-) mice but deteriorated in mice older than age 5 months. These results suggest that electrophysiological analysis can detect the abnormalities of the plp(tg/-) mice earlier than histological or behavioral measures.
Collapse
Affiliation(s)
- Hisataka Tanaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Myodaiji, Okazaki, Japan
| | | | | |
Collapse
|
12
|
Abstract
This review focuses on investigations by Sir John Eccles and co-workers in Canberra, AUS in the 1950s, in which they used intracellular recordings to unravel the organization of neuronal networks in the cat spinal cord. Five classical spinal reflexes are emphasized: recurrent inhibition of motoneurons via motor axon collaterals and Renshaw cells, pathways from muscle spindles and Golgi tendon organs, presynaptic inhibition, and the flexor reflex. To set the scene for these major achievements I first provide a brief account of the understanding of the spinal cord in "reflex" and "voluntary" motor activities from the beginning of the 20th century. Next, subsequent work is reviewed on the convergence on spinal interneurons from segmental sensory afferents and descending motor pathways, much of which was performed and inspired by Anders Lundberg's group in Gothenburg, SWE. This work was the keystone for new hypotheses on the role of spinal circuits in normal motor control. Such hypotheses were later tested under more natural conditions; either by recording directly from interneurons in reduced animal preparations or by use of indirect non-invasive techniques in humans performing normal movements. Some of this latter work is also reviewed. These developments would not have been possible without the preceding work on spinal reflexes by Eccles and Lundberg. Finally, there is discussion of how Eccles' work on spinal reflexes remains central (1) as new techniques are introduced on direct recording from interneurons in behaving animals; (2) in experiments on plastic neuronal changes in relation to motor learning and neurorehabilitation; (3) in experiments on transgenic animals uncovering aspects of human pathophysiology; and (4) in evaluating the function of genetically identified classes of neurons in studies on the development of the spinal cord.
Collapse
Affiliation(s)
- Hans Hultborn
- Department of Medical Physiology, University of Copenhagen, Denmark.
| |
Collapse
|
13
|
Alstermark B, Ogawa J. In vivo recordings of bulbospinal excitation in adult mouse forelimb motoneurons. J Neurophysiol 2004; 92:1958-62. [PMID: 15084639 DOI: 10.1152/jn.00092.2004] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Here we report on pyramidal and reticulospinal excitation in forelimb motoneurons in the adult mouse using intracellular recordings in vivo. The results have been obtained in BALB/C mice, which were anesthetized with midazolam fentanyl/fluanison. In contrast to the rat, only weak and infrequent pyramidal excitation could be evoked with a minimal trisynaptic linkage. Disynaptic reticulospinal excitation could always be evoked, as well as monosynaptic excitation from the medial longitudinal fasciculus. The results suggest that the reticulospinal pathway in the mouse is important in voluntary motor control of the forelimbs and that the role of the corticospinal tract might be different in mouse compared with rat. Our study provides an opening for studying the effect of genetic manipulation on specified descending systems in the mouse in vivo.
Collapse
Affiliation(s)
- Bror Alstermark
- Department of Integrative Medical Biology, Section of Physiology, Umeå University, S-901 87 Umeå, Sweden.
| | | |
Collapse
|