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Kipp M. Astrocytes: Lessons Learned from the Cuprizone Model. Int J Mol Sci 2023; 24:16420. [PMID: 38003609 PMCID: PMC10671869 DOI: 10.3390/ijms242216420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
A diverse array of neurological and psychiatric disorders, including multiple sclerosis, Alzheimer's disease, and schizophrenia, exhibit distinct myelin abnormalities at both the molecular and histological levels. These aberrations are closely linked to dysfunction of oligodendrocytes and alterations in myelin structure, which may be pivotal factors contributing to the disconnection of brain regions and the resulting characteristic clinical impairments observed in these conditions. Astrocytes, which significantly outnumber neurons in the central nervous system by a five-to-one ratio, play indispensable roles in the development, maintenance, and overall well-being of neurons and oligodendrocytes. Consequently, they emerge as potential key players in the onset and progression of a myriad of neurological and psychiatric disorders. Furthermore, targeting astrocytes represents a promising avenue for therapeutic intervention in such disorders. To gain deeper insights into the functions of astrocytes in the context of myelin-related disorders, it is imperative to employ appropriate in vivo models that faithfully recapitulate specific aspects of complex human diseases in a reliable and reproducible manner. One such model is the cuprizone model, wherein metabolic dysfunction in oligodendrocytes initiates an early response involving microglia and astrocyte activation, culminating in multifocal demyelination. Remarkably, following the cessation of cuprizone intoxication, a spontaneous process of endogenous remyelination occurs. In this review article, we provide a historical overview of studies investigating the responses and putative functions of astrocytes in the cuprizone model. Following that, we list previously published works that illuminate various aspects of the biology and function of astrocytes in this multiple sclerosis model. Some of the studies are discussed in more detail in the context of astrocyte biology and pathology. Our objective is twofold: to provide an invaluable overview of this burgeoning field, and, more importantly, to inspire fellow researchers to embark on experimental investigations to elucidate the multifaceted functions of this pivotal glial cell subpopulation.
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Affiliation(s)
- Markus Kipp
- Institute of Anatomy, Rostock University Medical Center, 18057 Rostock, Germany
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2
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Shan L, Zhang T, Fan K, Cai W, Liu H. Astrocyte-Neuron Signaling in Synaptogenesis. Front Cell Dev Biol 2021; 9:680301. [PMID: 34277621 PMCID: PMC8284252 DOI: 10.3389/fcell.2021.680301] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 06/14/2021] [Indexed: 01/10/2023] Open
Abstract
Astrocytes are the key component of the central nervous system (CNS), serving as pivotal regulators of neuronal synapse formation and maturation through their ability to dynamically and bidirectionally communicate with synapses throughout life. In the past 20 years, numerous astrocyte-derived molecules promoting synaptogenesis have been discovered. However, our understanding of the cell biological basis underlying intra-neuron processes and astrocyte-mediated synaptogenesis is still in its infancy. Here, we provide a comprehensive overview of the various ways astrocytes talk to neurons, and highlight astrocytes’ heterogeneity that allow them to displays regional-specific capabilities in boosting synaptogenesis. Finally, we conclude with promises and future directions on how organoids generated from human induced pluripotent stem cells (hiPSCs) effectively address the signaling pathways astrocytes employ in synaptic development.
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Affiliation(s)
- Lili Shan
- Guangzhou Laboratory, Guangzhou, China.,Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Tongran Zhang
- Guangzhou Laboratory, Guangzhou, China.,Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Kevin Fan
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States.,Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Weibo Cai
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States.,Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Huisheng Liu
- Guangzhou Laboratory, Guangzhou, China.,Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
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3
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Canty AJ, Jackson JS, Huang L, Trabalza A, Bass C, Little G, Tortora M, Khan S, De Paola V. In vivo imaging of injured cortical axons reveals a rapid onset form of Wallerian degeneration. BMC Biol 2020; 18:170. [PMID: 33208154 PMCID: PMC7677840 DOI: 10.1186/s12915-020-00869-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 09/16/2020] [Indexed: 12/22/2022] Open
Abstract
Background Despite the widespread occurrence of axon and synaptic loss in the injured and diseased nervous system, the cellular and molecular mechanisms of these key degenerative processes remain incompletely understood. Wallerian degeneration (WD) is a tightly regulated form of axon loss after injury, which has been intensively studied in large myelinated fibre tracts of the spinal cord, optic nerve and peripheral nervous system (PNS). Fewer studies, however, have focused on WD in the complex neuronal circuits of the mammalian brain, and these were mainly based on conventional endpoint histological methods. Post-mortem analysis, however, cannot capture the exact sequence of events nor can it evaluate the influence of elaborated arborisation and synaptic architecture on the degeneration process, due to the non-synchronous and variable nature of WD across individual axons. Results To gain a comprehensive picture of the spatiotemporal dynamics and synaptic mechanisms of WD in the nervous system, we identify the factors that regulate WD within the mouse cerebral cortex. We combined single-axon-resolution multiphoton imaging with laser microsurgery through a cranial window and a fluorescent membrane reporter. Longitudinal imaging of > 150 individually injured excitatory cortical axons revealed a threshold length below which injured axons consistently underwent a rapid-onset form of WD (roWD). roWD started on average 20 times earlier and was executed 3 times slower than WD described in other regions of the nervous system. Cortical axon WD and roWD were dependent on synaptic density, but independent of axon complexity. Finally, pharmacological and genetic manipulations showed that a nicotinamide adenine dinucleotide (NAD+)-dependent pathway could delay cortical roWD independent of transcription in the damaged neurons, demonstrating further conservation of the molecular mechanisms controlling WD in different areas of the mammalian nervous system. Conclusions Our data illustrate how in vivo time-lapse imaging can provide new insights into the spatiotemporal dynamics and synaptic mechanisms of axon loss and assess therapeutic interventions in the injured mammalian brain.
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Affiliation(s)
- Alison Jane Canty
- Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, Australia.
| | - Johanna Sara Jackson
- Dementia Research Institute at Imperial College, Department of Brain Sciences, Imperial College London, London, W12 0NN, UK
| | - Lieven Huang
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Antonio Trabalza
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Cher Bass
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Graham Little
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Maria Tortora
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Shabana Khan
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Vincenzo De Paola
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK. .,Medical Research Council London Institute of Medical Sciences, London, W12 0NN, UK.
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4
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Jacobs B, Molenaar J, Deinum EE. Small GTPase patterning: How to stabilise cluster coexistence. PLoS One 2019; 14:e0213188. [PMID: 30845201 PMCID: PMC6405054 DOI: 10.1371/journal.pone.0213188] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/16/2019] [Indexed: 12/28/2022] Open
Abstract
Many biological processes have to occur at specific locations on the cell membrane. These locations are often specified by the localised activity of small GTPase proteins. Some processes require the formation of a single cluster of active GTPase, also called unipolar polarisation (here “polarisation”), whereas others need multiple coexisting clusters. Moreover, sometimes the pattern of GTPase clusters is dynamically regulated after its formation. This raises the question how the same interacting protein components can produce such a rich variety of naturally occurring patterns. Most currently used models for GTPase-based patterning inherently yield polarisation. Such models may at best yield transient coexistence of at most a few clusters, and hence fail to explain several important biological phenomena. These existing models are all based on mass conservation of total GTPase and some form of direct or indirect positive feedback. Here, we show that either of two biologically plausible modifications can yield stable coexistence: including explicit GTPase turnover, i.e., breaking mass conservation, or negative feedback by activation of an inhibitor like a GAP. Since we start from two different polarising models our findings seem independent of the precise self-activation mechanism. By studying the net GTPase flows among clusters, we provide insight into how these mechanisms operate. Our coexistence models also allow for dynamical regulation of the final pattern, which we illustrate with examples of pollen tube growth and the branching of fungal hyphae. Together, these results provide a better understanding of how cells can tune a single system to generate a wide variety of biologically relevant patterns.
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Affiliation(s)
- Bas Jacobs
- Biometris, Department for Mathematical and Statistical Methods, Wageningen University, Wageningen, The Netherlands
| | - Jaap Molenaar
- Biometris, Department for Mathematical and Statistical Methods, Wageningen University, Wageningen, The Netherlands
| | - Eva E Deinum
- Biometris, Department for Mathematical and Statistical Methods, Wageningen University, Wageningen, The Netherlands
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5
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Mansour Y, Mangold S, Chosky D, Kulesza RJ. Auditory Midbrain Hypoplasia and Dysmorphology after Prenatal Valproic Acid Exposure. Neuroscience 2019; 396:79-93. [DOI: 10.1016/j.neuroscience.2018.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 11/11/2018] [Accepted: 11/12/2018] [Indexed: 12/01/2022]
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6
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Foran L, Blackburn K, Kulesza RJ. Auditory hindbrain atrophy and anomalous calcium binding protein expression after neonatal exposure to monosodium glutamate. Neuroscience 2017; 344:406-417. [DOI: 10.1016/j.neuroscience.2017.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 12/31/2016] [Accepted: 01/03/2017] [Indexed: 01/29/2023]
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7
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von Bartheld CS, Bahney J, Herculano-Houzel S. The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting. J Comp Neurol 2016; 524:3865-3895. [PMID: 27187682 PMCID: PMC5063692 DOI: 10.1002/cne.24040] [Citation(s) in RCA: 551] [Impact Index Per Article: 68.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 05/13/2016] [Accepted: 05/16/2016] [Indexed: 12/13/2022]
Abstract
For half a century, the human brain was believed to contain about 100 billion neurons and one trillion glial cells, with a glia:neuron ratio of 10:1. A new counting method, the isotropic fractionator, has challenged the notion that glia outnumber neurons and revived a question that was widely thought to have been resolved. The recently validated isotropic fractionator demonstrates a glia:neuron ratio of less than 1:1 and a total number of less than 100 billion glial cells in the human brain. A survey of original evidence shows that histological data always supported a 1:1 ratio of glia to neurons in the entire human brain, and a range of 40-130 billion glial cells. We review how the claim of one trillion glial cells originated, was perpetuated, and eventually refuted. We compile how numbers of neurons and glial cells in the adult human brain were reported and we examine the reasons for an erroneous consensus about the relative abundance of glial cells in human brains that persisted for half a century. Our review includes a brief history of cell counting in human brains, types of counting methods that were and are employed, ranges of previous estimates, and the current status of knowledge about the number of cells. We also discuss implications and consequences of the new insights into true numbers of glial cells in the human brain, and the promise and potential impact of the newly validated isotropic fractionator for reliable quantification of glia and neurons in neurological and psychiatric diseases. J. Comp. Neurol. 524:3865-3895, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Jami Bahney
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Suzana Herculano-Houzel
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, and Instituto Nacional de Neurociência Translacional, CNPq/MCT, Brasil
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8
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von Bartheld CS, Bahney J, Herculano-Houzel S. The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting. J Comp Neurol 2016; 524:3865-3895. [PMID: 27187682 DOI: 10.1002/cne.2404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 05/13/2016] [Accepted: 05/16/2016] [Indexed: 05/25/2023]
Abstract
For half a century, the human brain was believed to contain about 100 billion neurons and one trillion glial cells, with a glia:neuron ratio of 10:1. A new counting method, the isotropic fractionator, has challenged the notion that glia outnumber neurons and revived a question that was widely thought to have been resolved. The recently validated isotropic fractionator demonstrates a glia:neuron ratio of less than 1:1 and a total number of less than 100 billion glial cells in the human brain. A survey of original evidence shows that histological data always supported a 1:1 ratio of glia to neurons in the entire human brain, and a range of 40-130 billion glial cells. We review how the claim of one trillion glial cells originated, was perpetuated, and eventually refuted. We compile how numbers of neurons and glial cells in the adult human brain were reported and we examine the reasons for an erroneous consensus about the relative abundance of glial cells in human brains that persisted for half a century. Our review includes a brief history of cell counting in human brains, types of counting methods that were and are employed, ranges of previous estimates, and the current status of knowledge about the number of cells. We also discuss implications and consequences of the new insights into true numbers of glial cells in the human brain, and the promise and potential impact of the newly validated isotropic fractionator for reliable quantification of glia and neurons in neurological and psychiatric diseases. J. Comp. Neurol. 524:3865-3895, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Jami Bahney
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Suzana Herculano-Houzel
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, and Instituto Nacional de Neurociência Translacional, CNPq/MCT, Brasil
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9
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Abstract
Jan. Evangelista Purkyně, the most famous among Czech physiologists, was the first who identified and described the largest nerve cells in the cerebellum. The most distinguished researchers of the nervous system then recommended naming these neurons Purkinje cells in his honor. Through experiments by Purkinje and his followers, the function of the cerebellum was properly attributed to the precision of motor movements and skills. This traditional concept was valid until early 1990s, when it was readjusted and replenished with new and important findings. It was discovered that the cerebellar cortex contains more neurons than the cerebral cortex and shortly thereafter was gradually revealed that such enormous numbers of neural cells are not without impact on brain functions. It was shown that the cerebellum, in addition to its traditional role, also participates in higher nervous activity. These new findings were obtained thanks to the introduction of modern methods of examination into the clinical praxis, and experimental procedures using animal models of cerebellar disorders described in this work.
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Affiliation(s)
- František Vožeh
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, 323 00, Pilsen, Czech Republic. .,Laboratory of Neurodegenerative Disorders, Biomedical Centre, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic.
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10
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Öztoprak B, Öztoprak İ, Bozkurt H, Çiğdem B, Yıldız ÖK. A DWI study of the contralateral hemisphere in cerebral hemiatrophy. J Neurol Sci 2016; 363:253-7. [PMID: 27000260 DOI: 10.1016/j.jns.2016.02.055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/04/2016] [Accepted: 02/23/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND AND AIM Cerebral hemiatrophy (CHA) is a congenital or acquired loss of volume in one hemisphere of the brain. The MR findings of the affected hemisphere have been a subject of many studies, however, the contralateral hemisphere has not been investigated. There is, in fact, an integrity between two hemispheres of the brain through transverse connection fibers. The aim of this study is to investigate the changes in the contralateral hemisphere in CHA. MATERIALS AND METHODS Apparent diffusion coefficient (ADC) values were measured in deep gray and white matter areas in the normal-appearing contralateral hemisphere in 23 patients with CHA, in order to get in vivo information about a possible Wallerian degeneration or microstructural changes. Results were compared with the control group. RESULTS Normal ADC values were encountered in the contralateral hemisphere in all (100%) CHA patients. The difference between the ADC values of gray and white matter in CHA patients and the control group was not statistically significant. CONCLUSION Normal ADC values in the contralateral hemisphere in CHA patients suggests a compensatory mechanism restricting Wallerian degeneration or diffusion alteration.
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Affiliation(s)
- Bilge Öztoprak
- Department of Radiology, Cumhuriyet University, School of Medicine, Sivas, Turkey.
| | - İbrahim Öztoprak
- Department of Radiology, Cumhuriyet University, School of Medicine, Sivas, Turkey
| | - Hüseyin Bozkurt
- Department of Neurosurgery, Cumhuriyet University, School of Medicine, Sivas, Turkey
| | - Burhanettin Çiğdem
- Department of Neurology, Cumhuriyet University, School of Medicine, Sivas, Turkey
| | - Özlem Kayım Yıldız
- Department of Neurology, Cumhuriyet University, School of Medicine, Sivas, Turkey
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11
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Abstract
The name of Jan Evangelista Purkyně and the cerebellum belong inseparably together. He was the first who saw and described the largest nerve cells in the brain, de facto in the cerebellum. The most distinguished researchers of the nervous system then showed him the highest recognition by naming these neurons as Purkinje cells. Through experiments by J. E. Purkyně and his followers properly functionally was attributed to the cerebellum share in precision of motor skills. Despite ongoing and fruitful research, after a relatively long time, especially in the last two decades, scientists had to constantly replenish and re-evaluate the traditional conception of the cerebellum and formulate a new one. It started in the early 1990s, when it was found that cerebellar cortex contains more neurons than the cerebral cortex. Shortly thereafter it was gradually revealed that such enormous numbers of neural cells are not without an impact on brain functions and that the cerebellum, except its traditional role in the motor skills, also participates in higher nervous activity. These new findings were obtained thanks to the introduction of modern methods of examination into the clinical praxis, and experimental procedures using animal models of cerebellar disorders described below.
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Affiliation(s)
- F Vožeh
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic.
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12
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Abstract
Astrocytes regulate multiple aspects of neuronal and synaptic function from development through to adulthood. Instead of addressing each function independently, this review provides a comprehensive overview of the different ways astrocytes modulate neuronal synaptic function throughout life, with a particular focus on recent findings in each area. It includes the emerging functions of astrocytes, such as a role in synapse formation, as well as more established roles, including the uptake and recycling of neurotransmitters. This broad approach covers the many ways astrocytes and neurons constantly interact to maintain the correct functioning of the brain. It is important to consider all of these diverse functions of astrocytes when investigating how astrocyte-neuron interactions regulate synaptic behavior to appreciate the complexity of these ongoing interactions.
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Affiliation(s)
- Nicola J Allen
- Salk Institute for Biological Studies, La Jolla, California 92037;
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13
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Beebe K, Wang Y, Kulesza R. Distribution of fragile X mental retardation protein in the human auditory brainstem. Neuroscience 2014; 273:79-91. [PMID: 24838064 DOI: 10.1016/j.neuroscience.2014.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/29/2014] [Accepted: 05/02/2014] [Indexed: 01/20/2023]
Abstract
Fragile X mental retardation protein (FMRP) binds select mRNAs, functions in intracellular transport of these mRNAs and represses their translation. FMRP is highly expressed in neurons and lack of FMRP has been shown to result in dendritic dysmorphology and altered synaptic function. FMRP is known to interact with mRNAs for the Kv3.1b potassium channel which is required for neurons to fire action potentials at high rates with remarkable temporal precision. Auditory brainstem neurons are known for remarkably high spike rates and expression of Kv3.1b potassium channels. Fragile X syndrome (FXS) is a genetic disorder caused by a mutation in the fragile X mental retardation 1 gene (Fmr1) resulting in decreased expression of FMRP and subsequent intellectual disability, seizures, attention deficit and hypersensitivity to auditory and other sensory stimuli. We therefore hypothesize that the auditory difficulties in FXS result, at least in part, from dysfunction of auditory brainstem neurons. To examine this hypothesis, we have studied normal human brainstem tissue with immunohistochemical techniques and confocal microscopy. Our results demonstrate that FMRP is widely expressed in cell bodies and dendritic arbors of neurons in the human cochlear nucleus and superior olivary complex and also that coincidence detector neurons of the medial superior olive colocalization of FMRP and Kv3.1b. We interpret these observations to suggest that the lower auditory brainstem is a potential site of dysfunction in FXS.
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Affiliation(s)
- K Beebe
- Lake Erie College of Osteopathic Medicine, Auditory Research Center, Erie, PA, USA
| | - Y Wang
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Seattle, WA, USA
| | - R Kulesza
- Lake Erie College of Osteopathic Medicine, Auditory Research Center, Erie, PA, USA.
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14
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Beirowski B. Concepts for regulation of axon integrity by enwrapping glia. Front Cell Neurosci 2013; 7:256. [PMID: 24391540 PMCID: PMC3867696 DOI: 10.3389/fncel.2013.00256] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/25/2013] [Indexed: 12/16/2022] Open
Abstract
Long axons and their enwrapping glia (EG; Schwann cells (SCs) and oligodendrocytes (OLGs)) form a unique compound structure that serves as conduit for transport of electric and chemical information in the nervous system. The peculiar cytoarchitecture over an enormous length as well as its substantial energetic requirements make this conduit particularly susceptible to detrimental alterations. Degeneration of long axons independent of neuronal cell bodies is observed comparatively early in a range of neurodegenerative conditions as a consequence of abnormalities in SCs and OLGs . This leads to the most relevant disease symptoms and highlights the critical role that these glia have for axon integrity, but the underlying mechanisms remain elusive. The quest to understand why and how axons degenerate is now a crucial frontier in disease-oriented research. This challenge is most likely to lead to significant progress if the inextricable link between axons and their flanking glia in pathological situations is recognized. In this review I compile recent advances in our understanding of the molecular programs governing axon degeneration, and mechanisms of EG’s non-cell autonomous impact on axon-integrity. A particular focus is placed on emerging evidence suggesting that EG nurture long axons by virtue of their intimate association, release of trophic substances, and neurometabolic coupling. The correction of defects in these functions has the potential to stabilize axons in a variety of neuronal diseases in the peripheral nervous system and central nervous system (PNS and CNS).
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Affiliation(s)
- Bogdan Beirowski
- Department of Genetics, Washington University School of Medicine Saint Louis, MO, USA
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15
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Charvet CJ, Cahalane DJ, Finlay BL. Systematic, cross-cortex variation in neuron numbers in rodents and primates. Cereb Cortex 2013; 25:147-60. [PMID: 23960207 DOI: 10.1093/cercor/bht214] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Uniformity, local variability, and systematic variation in neuron numbers per unit of cortical surface area across species and cortical areas have been claimed to characterize the isocortex. Resolving these claims has been difficult, because species, techniques, and cortical areas vary across studies. We present a stereological assessment of neuron numbers in layers II-IV and V-VI per unit of cortical surface area across the isocortex in rodents (hamster, Mesocricetus auratus; agouti, Dasyprocta azarae; paca, Cuniculus paca) and primates (owl monkey, Aotus trivigratus; tamarin, Saguinus midas; capuchin, Cebus apella); these chosen to vary systematically in cortical size. The contributions of species, cortical areas, and techniques (stereology, "isotropic fractionator") to neuron estimates were assessed. Neurons per unit of cortical surface area increase across the rostro-caudal (RC) axis in primates (varying by a factor of 1.64-2.13 across the rostral and caudal poles) but less in rodents (varying by a factor of 1.15-1.54). Layer II-IV neurons account for most of this variation. When integrated into the context of species variation, and this RC gradient in neuron numbers, conflicts between studies can be accounted for. The RC variation in isocortical neurons in adulthood mirrors the gradients in neurogenesis duration in development.
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Affiliation(s)
- Christine J Charvet
- Behavioral and Evolutionary Neuroscience Group, Department of Psychology and
| | | | - Barbara L Finlay
- Behavioral and Evolutionary Neuroscience Group, Department of Psychology and
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16
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Retinal ganglion cells: Energetics, compartmentation, axonal transport, cytoskeletons and vulnerability. Prog Retin Eye Res 2013; 36:217-46. [PMID: 23891817 DOI: 10.1016/j.preteyeres.2013.07.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/02/2013] [Accepted: 07/02/2013] [Indexed: 11/20/2022]
Abstract
Retinal ganglion cells (RGCs) are specialized projection neurons that relay an immense amount of visual information from the retina to the brain. RGC signal inputs are collected by dendrites and output is distributed from the cell body via very thin (0.5-1 μm) and long (∼50 mm) axons. The RGC cell body is larger than other retinal neurons, but is still only a very small fraction (one ten thousandths) of the length and total surface area of the axon. The total distance traversed by RGCs extends from the retina, starting from synapses with bipolar and amacrine cells, to the brain, to synapses with neurons in the lateral geniculate nucleus. This review will focus on the energy demands of RGCs and the relevant tissues that surround them. RGC survival and function unexceptionally depends upon free energy, predominantly adenosine triphosphate (ATP). RGC energy metabolism is vastly different when compared to that of the photoreceptors. Each subcellular component of the RGC is remarkably different in terms of structure, function and extracellular environment. The energy demands and distribution of each component are also distinct as evidenced by the uneven distribution of mitochondria and ATP within the RGC - signifying the presence of intracellular energy gradients. In this review we will describe RGCs as having four subcellular components, (1) Dendrites, (2) Cell body, (3) Non-myelinated axon, including intraocular and optic nerve head portions, and (4) Myelinated axon, including the intra-orbital and intracranial portions. We will also describe how RGCs integrate information from each subcellular component in order achieve intracellular homeostatic stability as well as respond to perturbations in the extracellular environment. The possible cellular mechanisms such as axonal transport and axonal cytoskeleton proteins that are involved in maintaining RGC energy homeostasis during normal and disease conditions will also be discussed in depth. The emphasis of this review will be on energetic mechanisms within RGC components that have the most relevance to clinical ophthalmology.
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17
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Hou YJ, Banerjee R, Thomas B, Nathan C, García-Sastre A, Ding A, Uccellini MB. SARM is required for neuronal injury and cytokine production in response to central nervous system viral infection. THE JOURNAL OF IMMUNOLOGY 2013; 191:875-83. [PMID: 23749635 DOI: 10.4049/jimmunol.1300374] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Four of the five members of the Toll/IL-1R domain-containing adaptor family are required for signaling downstream of TLRs, promoting innate immune responses against different pathogens. However, the role of the fifth member of this family, sterile α and Toll/IL-1R domain-containing 1 (SARM), is unclear. SARM is expressed primarily in the CNS where it is required for axonal death. Studies in Caenorhabditis elegans have also shown a role for SARM in innate immunity. To clarify the role of mammalian SARM in innate immunity, we infected SARM(-/-) mice with a number of bacterial and viral pathogens. SARM(-/-) mice show normal responses to Listeria monocytogenes, Mycobacterium tuberculosis, and influenza virus, but show dramatic protection from death after CNS infection with vesicular stomatitis virus. Protection correlates with reduced CNS injury and cytokine production by nonhematopoietic cells, suggesting that SARM is a positive regulator of cytokine production. Neurons and microglia are the predominant source of cytokines in vivo, supporting a role for SARM as a link between neuronal injury and innate immunity.
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Affiliation(s)
- Ying-Ju Hou
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
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18
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Chinea A, Korutcheva E. Intelligence and embodiment: A statistical mechanics approach. Neural Netw 2013; 40:52-72. [DOI: 10.1016/j.neunet.2013.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 01/11/2013] [Accepted: 01/11/2013] [Indexed: 10/27/2022]
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Wang JT, Medress ZA, Barres BA. Axon degeneration: molecular mechanisms of a self-destruction pathway. ACTA ACUST UNITED AC 2012; 196:7-18. [PMID: 22232700 PMCID: PMC3255986 DOI: 10.1083/jcb.201108111] [Citation(s) in RCA: 308] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Axon degeneration is a characteristic event in many neurodegenerative conditions including stroke, glaucoma, and motor neuropathies. However, the molecular pathways that regulate this process remain unclear. Axon loss in chronic neurodegenerative diseases share many morphological features with those in acute injuries, and expression of the Wallerian degeneration slow (WldS) transgene delays nerve degeneration in both events, indicating a common mechanism of axonal self-destruction in traumatic injuries and degenerative diseases. A proposed model of axon degeneration is that nerve insults lead to impaired delivery or expression of a local axonal survival factor, which results in increased intra-axonal calcium levels and calcium-dependent cytoskeletal breakdown.
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Affiliation(s)
- Jack T Wang
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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20
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Díaz E, Bravo D, Rojas X, Concha ML. Morphologic and immunohistochemical organization of the human habenular complex. J Comp Neurol 2012; 519:3727-47. [PMID: 21674490 DOI: 10.1002/cne.22687] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The habenular complex (HbCpx) is a phylogenetically conserved brain structure located in the epithalamus of vertebrates. Despite its fundamental role in decision-making processes and the proposed link between habenular dysfunction and neuropsychiatric conditions, little is known about the structural and functional organization of the HbCpx in humans. The goal of this study was thus to provide a first systematic morphologic and immunohistochemical analysis of the human HbCpx to begin dissecting its nuclear and subnuclear organization. Our results confirmed that the human HbCpx is subdivided into medial (MHb) and lateral (LHb) nuclei, each showing a large degree of intranuclear morphologic heterogeneity. Analysis of serially stained sections using a combination of morphologic and immunohistochemical criteria allowed the distinction of five subnuclei in both the MHb and LHb. Overall, the observed subnuclear organization of the MHb in humans resembles the organization of subnuclei in the MHb of rats. The shape, relative size, and intranuclear organization of the LHb, however, show significant differences. The contribution of the LHb to the entire HbCpx is about five times larger in humans than in rats. Noteworthy, a dorsal domain of the LHb that contains afferent myelinated fibers from the stria medullaris and shows GABA-(B) -R(1) immunoreactive cells, appears substantially enlarged in humans when compared to rats. This feature seems to account for a large part of the relative growth in size of the LHb in humans and opens the intriguing possibility of an increased influence of limbic and striatal afferents into the LHb of humans.
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Affiliation(s)
- Eugenia Díaz
- Laboratory of Experimental Ontogeny (LEO), Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
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Phylogenomic analyses reveal convergent patterns of adaptive evolution in elephant and human ancestries. Proc Natl Acad Sci U S A 2009; 106:20824-9. [PMID: 19926857 DOI: 10.1073/pnas.0911239106] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Specific sets of brain-expressed genes, such as aerobic energy metabolism genes, evolved adaptively in the ancestry of humans and may have evolved adaptively in the ancestry of other large-brained mammals. The recent addition of genomes from two afrotherians (elephant and tenrec) to the expanding set of publically available sequenced mammalian genomes provided an opportunity to test this hypothesis. Elephants resemble humans by having large brains and long life spans; tenrecs, in contrast, have small brains and short life spans. Thus, we investigated whether the phylogenomic patterns of adaptive evolution are more similar between elephant and human than between either elephant and tenrec lineages or human and mouse lineages, and whether aerobic energy metabolism genes are especially well represented in the elephant and human patterns. Our analyses encompassed approximately 6,000 genes in each of these lineages with each gene yielding extensive coding sequence matches in interordinal comparisons. Each gene's nonsynonymous and synonymous nucleotide substitution rates and dN/dS ratios were determined. Then, from gene ontology information on genes with the higher dN/dS ratios, we identified the more prevalent sets of genes that belong to specific functional categories and that evolved adaptively. Elephant and human lineages showed much slower nucleotide substitution rates than tenrec and mouse lineages but more adaptively evolved genes. In correlation with absolute brain size and brain oxygen consumption being largest in elephants and next largest in humans, adaptively evolved aerobic energy metabolism genes were most evident in the elephant lineage and next most evident in the human lineage.
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Baltes C, Radzwill N, Bosshard S, Marek D, Rudin M. Micro MRI of the mouse brain using a novel 400 MHz cryogenic quadrature RF probe. NMR IN BIOMEDICINE 2009; 22:834-42. [PMID: 19536757 DOI: 10.1002/nbm.1396] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The increasing number of mouse models of human disease used in biomedical research applications has led to an enhanced interest in non-invasive imaging of mice, e.g. using MRI for phenotyping. However, MRI of small rodents puts high demands on the sensitivity of data acquisition. This requirement can be addressed by using cryogenic radio-frequency (RF) detection devices. The aim of this work was to investigate the in vivo performance of a 400 MHz cryogenic transmit/receive RF probe (CryoProbe) designed for MRI of the mouse brain. To characterize this novel probe, MR data sets were acquired with both the CryoProbe and a matched conventional receive-only surface coil operating at room temperature (RT) using conventional acquisition protocols (gradient and spin echo) with identical parameter settings. Quantitative comparisons in phantom and in vivo experiments revealed gains in the signal-to-noise ratio (SNR) of 2.4 and 2.5, respectively. The increased sensitivity of the CryoProbe was invested to enhance the image quality of high resolution structural images acquired in scan times compatible with routine operation (< 45 min). In high resolution (30 x 30 x 300 microm(3)) structural images of the mouse cerebellum, anatomical details such as Purkinje cell and molecular layers could be identified. Similarly, isotropic (60 x 60 x 60 microm(3)) imaging of mouse cortical and subcortical areas revealed anatomical structures smaller than 100 microm. Finally, 3D MR angiography (52 x 80 x 80 microm(3)) of the brain vasculature enabled the detailed reconstruction of intracranial vessels (anterior and middle cerebral artery). In conclusion, this low temperature detection device represents an attractive option to increase the performance of small animal MR systems operating at 9.4 Tesla.
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Affiliation(s)
- Christof Baltes
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland.
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Jehee JFM, Murre JMJ. The scalable mammalian brain: emergent distributions of glia and neurons. BIOLOGICAL CYBERNETICS 2008; 98:439-445. [PMID: 18414892 PMCID: PMC2798959 DOI: 10.1007/s00422-008-0228-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 03/17/2008] [Indexed: 05/26/2023]
Abstract
In this paper, we demonstrate that two characteristic properties of mammalian brains emerge when scaling-up modular, cortical structures. Firstly, the glia-to-neuron ratio is not constant across brains of different sizes: large mammalian brains have more glia per neuron than smaller brains. Our analyses suggest that if one assumes that glia number is proportional to wiring, a particular quantitative relationship emerges between brain size and glia-to-neuron ratio that fits the empirical data. Secondly, many authors have reported that the number of neurons underlying one mm(2) of mammalian cortex is remarkably constant, across both areas and species. Here, we will show that such a constancy emerges when enlarging modular, cortical brain structures. Our analyses thus corroborate recent studies on the mammalian brain as a scalable architecture, providing a possible mechanism to explain some of the principles, constancies and rules that hold across brains of different size.
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Affiliation(s)
- Janneke F. M. Jehee
- University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands
- Department of Psychology, Vanderbilt University, 301 Wilson Hall, 111 21st Ave, Nashville, TN 37203 USA
| | - Jaap M. J. Murre
- University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands
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Savage VM, Allen AP, Brown JH, Gillooly JF, Herman AB, Woodruff WH, West GB. Scaling of number, size, and metabolic rate of cells with body size in mammals. Proc Natl Acad Sci U S A 2007; 104:4718-23. [PMID: 17360590 PMCID: PMC1838666 DOI: 10.1073/pnas.0611235104] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The size and metabolic rate of cells affect processes from the molecular to the organismal level. We present a quantitative, theoretical framework for studying relationships among cell volume, cellular metabolic rate, body size, and whole-organism metabolic rate that helps reveal the feedback between these levels of organization. We use this framework to show that average cell volume and average cellular metabolic rate cannot both remain constant with changes in body size because of the well known body-size dependence of whole-organism metabolic rate. Based on empirical data compiled for 18 cell types in mammals, we find that many cell types, including erythrocytes, hepatocytes, fibroblasts, and epithelial cells, follow a strategy in which cellular metabolic rate is body size dependent and cell volume is body size invariant. We suggest that this scaling holds for all quickly dividing cells, and conversely, that slowly dividing cells are expected to follow a strategy in which cell volume is body size dependent and cellular metabolic rate is roughly invariant with body size. Data for slowly dividing neurons and adipocytes show that cell volume does indeed scale with body size. From these results, we argue that the particular strategy followed depends on the structural and functional properties of the cell type. We also discuss consequences of these two strategies for cell number and capillary densities. Our results and conceptual framework emphasize fundamental constraints that link the structure and function of cells to that of whole organisms.
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Affiliation(s)
- Van M. Savage
- *Department of Systems Biology, Harvard Medical School, Boston, MA 02115
- Bauer Laboratory, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501
- Los Alamos National Laboratory, Los Alamos, NM 87545
- To whom correspondence may be addressed. E-mail: or
| | - Andrew P. Allen
- National Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101
| | - James H. Brown
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501
- **Department of Biology, University of New Mexico, Albuquerque, NM 87131; and
- To whom correspondence may be addressed. E-mail: or
| | | | - Alexander B. Herman
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - William H. Woodruff
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Geoffrey B. West
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501
- Los Alamos National Laboratory, Los Alamos, NM 87545
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Savage VM, West GB. A quantitative, theoretical framework for understanding mammalian sleep. Proc Natl Acad Sci U S A 2007; 104:1051-6. [PMID: 17215372 PMCID: PMC1783362 DOI: 10.1073/pnas.0610080104] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sleep is one of the most noticeable and widespread phenomena occurring in multicellular animals. Nevertheless, no consensus for a theory of its origins has emerged. In particular, no explicit, quantitative theory exists that elucidates or distinguishes between the myriad hypotheses proposed for sleep. Here, we develop a general, quantitative theory for mammalian sleep that relates many of its fundamental parameters to metabolic rate and body size. Several mechanisms suggested for the function of sleep can be placed in this framework, e.g., cellular repair of damage caused by metabolic processes as well as cortical reorganization to process sensory input. Our theory leads to predictions for sleep time, sleep cycle time, and rapid eye movement time as functions of body and brain mass, and it explains, for example, why mice sleep approximately 14 hours per day relative to the 3.5 hours per day that elephants sleep. Data for 96 species of mammals, spanning six orders of magnitude in body size, are consistent with these predictions and provide strong evidence that time scales for sleep are set by the brain's, not the whole-body, metabolic rate.
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Affiliation(s)
- Van M Savage
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA.
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Ho KC, Gwozdz JT, Hause LL, Antuono PG. Correlation of neuronal cell body size in motor cortex and hippocampus with body height, body weight, and axonal length. Int J Neurosci 1992; 65:147-53. [PMID: 1341676 DOI: 10.3109/00207459209003286] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This study examined the comparative effects of body height and body weight on the neuronal cell size in humans and investigated their possible mechanisms. A total of 21 cases between the ages of 20 and 40 years were studied. Data on body height, body weight, and neuropathology were obtained from autopsy records. Mean cross sectional areas of cell bodies for 30 normal neurons were determined for the motor cortex projecting to lumbar spinal cord segments (L) 1-4 (Betz cells) as well as various regions of the hippocampus. Approximate axonal length of the motor neuron studied was measured from motor cortex to L2. We found that only motor cortex neuronal cell body size was significantly proportional to body height and the respective axonal length (p < .05). The findings indicate that: 1) body height has a greater effect than body weight on the motor neuron cell size, probably because of its association with axonal length; 2) the effect is regional (motor cortex) rather than general.
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Affiliation(s)
- K C Ho
- Department of Pathology and Neurology, Medical College of Wisconsin, Milwaukee 53226
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Pentreath VW, Radojcic T, Seal LH, Winstanley EK. The glial cells and glia-neuron relations in the buccal ganglia of Planorbis corneus (L.): cytological, qualitative and quantitative changes during growth and ageing. Philos Trans R Soc Lond B Biol Sci 1985; 307:399-455. [PMID: 2857493 DOI: 10.1098/rstb.1985.0002] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The glial tissue in
Planorbis
ganglia surrounds and ensheaths the neurons. The majority of the glial processes are interwoven around the neuronal perikarya and their major axon branches. Glial cell processes form a layer between the blood and nerve perikarya, but this does not significantly interfere with the movements of many small molecules in and out of the tissue. Such movements can occur paracellularly, through the extracellular spaces, since there are no occluding junctions between the cells.
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O'Kusky J, Colonnier M. A laminar analysis of the number of neurons, glia, and synapses in the adult cortex (area 17) of adult macaque monkeys. J Comp Neurol 1982; 210:278-90. [PMID: 7142443 DOI: 10.1002/cne.902100307] [Citation(s) in RCA: 227] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The number of neurons, glia, and synapses in the visual cortex of adult macaque monkeys has been estimated by stereological methods. The data is presented separately for 13 sublaminae. For the total cortical thickness, the average numerical density of neurons is approximately 120,000 per mm3 of tissue. This density increases and decreases in the different sublaminae in the direction that one would expect from the classical descriptions of Nissl-stained material (e.g., 137,000/mm3 in IVC alpha; 211,000/mm3 in IVC beta). There are about 200,000 neurons under 1 mm2 or cortical surface: 28% are in layers I-III, 45% are in layer IV, and 27% are in layers V and VI. The total number in area 17 of one hemisphere is close to 160,000,000. For the total cortical thickness the numerical density of synapses is 276,000,000 per mm3 of tissue. Laminae with higher neuronal densities tend to have higher synaptic densities but the correlation is not perfectly concordant. Moreover, the changes in synaptic densities are not as great as those in neuronal densities so that laminae with higher neuronal densities have a lower synapse to neuron ratio and laminae with lower neuronal densities have a higher synapse to neuron ratio. For the total cortical thickness this ratio is 2,300 synapses per neuron (1,400 in layer IVC beta and 2,800 in layers II and III). There are 478 million synapses under 1 mm2 cortical surface: 40% are in layers I-III, 35% are in layer IV, and 25% are in layers V and VI. The numerical densities of astrocytes, oligodendrocytes, and microcytes are 38,000, 17,000, and 4,000 per mm3, respectively. The overall glia/neuron ratio is 0.49.
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Ghandour MS, Vincendon G, Gombos G. Astrocyte and oligodendrocyte distribution in adult rat cerebellum: an immunohistological study. JOURNAL OF NEUROCYTOLOGY 1980; 9:637-46. [PMID: 6777466 DOI: 10.1007/bf01205030] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The distribution of the different types of glial cell in adult rat cerebellar cortex and in the underlying white matter was studied by immunohistology with a specific immune serum raised against form II of carbonic anhydrase, a specific marker for oligodendrocytes in rat cerebellum and an immune serum raised against glial fibrillary acidic protein, a specific astrocyte marker. The cellular specificity of each marker was confirmed by experiments in which the two antigens were revealed in the same cerebellar section. The unequivocal identification, with the optical microscope, of the different glial cell types allowed also a tentative estimation of the number of oligodendrocytes and astrocytes, in relation to Purkinje cells.
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Wallace LJ, Partlow LM, Ferrendelli JA. Comparison of levels of adenosine 3',5'-monophosphate in highly purified and mixed primary cultures of neurons and non-neuronal cells from embryonic chick sympathetic ganglia. J Neurochem 1978; 31:801-7. [PMID: 212532 DOI: 10.1111/j.1471-4159.1978.tb00114.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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32
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Heinsen H. Postnatal quantitative changes in the cerebellar uvula of albino rats. ANATOMY AND EMBRYOLOGY 1978; 154:285-304. [PMID: 707819 DOI: 10.1007/bf00345658] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The postnatal quantitative changes in cell diameter, cell density and total number of granule cells in the sublobule IXa of female rats from 6 to 760 days old were examined. There occurs and initial rapid increase in cell density from 1232.00 +/- 91.92 granule cells per 10(-3) mm 3 to 2995.50 +/- 322.07 granule cells per 10(-3) mm 3 and from 3 135 316 +/- 233 937 to more than 24 millions of granule cells between the 6th and 25th postnatal day. After the middle of the 3rd postnatal week, cell density and total number of granule cells decrease. The diameter of the granule cells reaches a maximum at the 6th day post partum and decreases continuously with progressing age. The possible mechanisms of these quantitative changes are discussed.
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Abstract
The Mauthner cells (M-cells) are a pair of neurons found in the medulla oblongata of most fish and amphibians. This neuron is not the same size in all teleosts. Based on the hypothesis that differences in M-cell size might be related to fish family and possibly fish habitat, M-cell and nuclear size were compared between fish families. In order to minimize effects of fish length on cell or nuclear size, statistical treatment of the data was made for four separate length classes. The results indicate at least three groupings by cell or nuclear size. The cell is large in fish from the Salmonidae, Catostomidae and Cyprinidae, small in the Stichaeidae, Cottidae and Pleuronectidae and absent in Batrachoididae, Lophiidae, Ogcocephalidae and Cylopteridae. In general a correlation exists between fish that lack or have small M-cells and a demersal habitat. Since these fish may rely on camouflage for protection against predation, the M-cells may have altered excitability or function as compared to more active fish in which the M-cell is known to function in initiating the startle response (larval zebrafish and goldfish). Differences in input to M-cells of different sizes in conjunction with known electrophysiological properties of the goldfish M-cell are discussed in relation to the function of this neuron.
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Abstract
The morphological basis of intermittent conduction failure in the excitor axon innervating the crayfish opener and stretcher muscles was investigated using the electron microscope. The connective tissue component of the sheath surrounding the axon was found consistently to be thinner in the region at which blocking occurs than in control regions located one cm either proximally or distally, at which blocking does not occur. Otherwise in these regions differences in the width of the periaxonal spaces, the length or width of the mesaxons, the density of mitochondria, the width of the adaxonal glial cell layer, or the structure of lamination of the sheath are not observed. Because of the thinner connective tissue component of the sheath in the joint region, neighboring axons are distributed more densely around the excitor, and the volume of the extracellular space is reduced. The possibility that the reduced extracellular space might allow excessive accumulation of potassium during repetitive discharge, causing conduction block, is discussed. Alternative mechanisms consistent with this morphology are also considered.
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Lange W. Cell number and cell density in the cerebellar cortex of man and some other mammals. Cell Tissue Res 1975; 157:115-24. [PMID: 804353 DOI: 10.1007/bf00223234] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The number of cells per unit volume was determined in the cerebellar cortex of man and 19 other mammals. The cell density (i.e. the number of cells per unit volume) decreases from mammals with a low brain weight to those with a higher brain weight. This decrease in the number of cells is found to be proportional for all three layers of the cerebellar cortex. In addition, the ratio of Purkinje cells to granule cells was determined. In contrast to the decrease of all cell types with increasing brain weight, this ratio varies remarkably among the mammals and is not correlated with brain weight. In man, this ratio is 1:2991, while it is lower in all other mammals investigated. These differences in the ratio of Purkinje cells to granule cells and the decrease in cell density with increasing brain weight are discussed in relation to brain evolution.
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Collins GH, Converse WK. Cerebellar degeneration in thiamine-deficient rats. THE AMERICAN JOURNAL OF PATHOLOGY 1970; 58:219-33. [PMID: 4908519 PMCID: PMC2032823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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King JS. A comparative investigation of neuroglia in representative vertebrates: a silver carbonate study. J Morphol 1966; 119:435-65. [PMID: 4165380 DOI: 10.1002/jmor.1051190405] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Blinkov SM, Ponomarev VS. Quantitative determinations of neurons and glial cells in the nuclei of the facial and vestibular nerves in man, monkey and dog. J Comp Neurol 1965; 125:295-301. [PMID: 15101316 DOI: 10.1002/cne.901250302] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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DUPONT JR, JERVIS H, SPRINZ H. A kinetic study of the myenteric neurones. Size variations in the neurovegetative periphery with body weight and organ size. ACTA ACUST UNITED AC 1965; 116:335-9. [PMID: 14283290 DOI: 10.1002/aja.1001160118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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