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Reale LA, Dyer MS, Perry SE, Young KM, Dickson TC, Woodhouse A, Blizzard CA. Pathologically mislocalised TDP-43 in upper motor neurons causes a die-forward spread of ALS-like pathogenic changes throughout the mouse corticomotor system. Prog Neurobiol 2023; 226:102449. [PMID: 37011806 DOI: 10.1016/j.pneurobio.2023.102449] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 02/02/2023] [Accepted: 03/24/2023] [Indexed: 04/03/2023]
Abstract
Alterations in upper motor neuron excitability are one of the earliest phenomena clinically detected in ALS, and in 97% of cases, the RNA/DNA binding protein, TDP-43, is mislocalised in upper and lower motor neurons. While these are two major pathological hallmarks in disease, our understanding of where disease pathology begins, and how it spreads through the corticomotor system, is incomplete. This project used a model where mislocalised TDP-43 was expressed in the motor cortex, to determine if localised cortical pathology could result in widespread corticomotor system degeneration. Mislocalised TDP-43 caused layer V excitatory neurons in the motor cortex to become hyperexcitable after 20 days of expression. Following cortical hyperexcitability, a spread of pathogenic changes through the corticomotor system was observed. By 30 days expression, there was a significant decrease in lower motor neuron number in the lumbar spinal cord. However, cell loss occurred selectively, with a significant loss in lumbar regions 1-3, and not lumbar regions 4-6. This regional vulnerability was associated with alterations in pre-synaptic excitatory and inhibitory proteins. Excitatory inputs (VGluT2) were increased in all lumbar regions, while inhibitory inputs (GAD65/67) were increased in lumbar regions 4-6 only. This data indicates that mislocalised TDP-43 in upper motor neurons can cause lower motor neuron degeneration. Furthermore, cortical pathology increased excitatory inputs to the spinal cord, to which local circuitry compensated with an upregulation of inhibition. These findings reveal how TDP-43 mediated pathology may spread through corticofugal tracts in ALS and identify a potential pathway for therapeutic intervention.
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Le TT, Oudin MJ. Understanding and modeling nerve-cancer interactions. Dis Model Mech 2023; 16:dmm049729. [PMID: 36621886 PMCID: PMC9844229 DOI: 10.1242/dmm.049729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The peripheral nervous system plays an important role in cancer progression. Studies in multiple cancer types have shown that higher intratumoral nerve density is associated with poor outcomes. Peripheral nerves have been shown to directly regulate tumor cell properties, such as growth and metastasis, as well as affect the local environment by modulating angiogenesis and the immune system. In this Review, we discuss the identity of nerves in organs in the periphery where solid tumors grow, the known mechanisms by which nerve density increases in tumors, and the effects these nerves have on cancer progression. We also discuss the strengths and weaknesses of current in vitro and in vivo models used to study nerve-cancer interactions. Increased understanding of the mechanisms by which nerves impact tumor progression and the development of new approaches to study nerve-cancer interactions will facilitate the discovery of novel treatment strategies to treat cancer by targeting nerves.
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Affiliation(s)
- Thanh T. Le
- Department of Biomedical Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Madeleine J. Oudin
- Department of Biomedical Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
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Soni KK, Jeong HS, Jang S. Neurons for Ejaculation and Factors Affecting Ejaculation. BIOLOGY 2022; 11:biology11050686. [PMID: 35625414 PMCID: PMC9138817 DOI: 10.3390/biology11050686] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 12/31/2022]
Abstract
Simple Summary Sexual dysfunctions are rarely discussed in our current society. Males experience different sexual dysfunctions, including erectile, infertility, and ejaculatory dysfunctions. In this review only the ejaculatory dysfunction will be discussed. Ejaculation is defined as the ejection of contents collectively from the vas deferens, seminal vesicle, prostate and Cowper’s glands. It is completely controlled by a population of neurons present in the lumbar spinal cord. The presence of lesion in these neurons ceases the ejaculatory behavior in males. This population of neurons was first identified in rats; however, recently it was confirmed that these neurons are present in human males as well. The issues are known as ejaculatory dysfunction. The following are the different types of ejaculatory dysfunctions: early ejaculation, ejaculation into the urinary bladder, late ejaculation and no ejaculation. Abstract Ejaculation is a reflex and the last stage of intercourse in male mammals. It consists of two coordinated phases, emission and expulsion. The emission phase consists of secretions from the vas deferens, seminal vesicle, prostate, and Cowper’s gland. Once these contents reach the posterior urethra, movement of the contents becomes inevitable, followed by the expulsion phase. The urogenital organs are synchronized during this complete event. The L3–L4 (lumbar) segment, the spinal cord region responsible for ejaculation, nerve cell bodies, also called lumbar spinothalamic (LSt) cells, which are denoted as spinal ejaculation generators or lumbar spinothalamic cells [Lst]. Lst cells activation causes ejaculation. These Lst cells coordinate with [autonomic] parasympathetic and sympathetic assistance in ejaculation. The presence of a spinal ejaculatory generator has recently been confirmed in humans. Different types of ejaculatory dysfunction in humans include premature ejaculation (PE), retrograde ejaculation (RE), delayed ejaculation (DE), and anejaculation (AE). The most common form of ejaculatory dysfunction studied is premature ejaculation. The least common forms of ejaculation studied are delayed ejaculation and anejaculation. Despite the confirmation of Lst in humans, there is insufficient research on animals mimicking human ejaculatory dysfunction.
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The Oligodendrocyte Transcription Factor 2 OLIG2 regulates transcriptional repression during myelinogenesis in rodents. Nat Commun 2022; 13:1423. [PMID: 35301318 PMCID: PMC8931116 DOI: 10.1038/s41467-022-29068-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 02/25/2022] [Indexed: 12/13/2022] Open
Abstract
OLIG2 is a transcription factor that activates the expression of myelin-associated genes in the oligodendrocyte-lineage cells. However, the mechanisms of myelin gene inactivation are unclear. Here, we uncover a non-canonical function of OLIG2 in transcriptional repression to modulate myelinogenesis by functionally interacting with tri-methyltransferase SETDB1. Immunoprecipitation and chromatin-immunoprecipitation assays show that OLIG2 recruits SETDB1 for H3K9me3 modification on the Sox11 gene, which leads to the inhibition of Sox11 expression during the differentiation of oligodendrocytes progenitor cells (OPCs) into immature oligodendrocytes (iOLs). Tissue-specific depletion of Setdb1 in mice results in the hypomyelination during development and remyelination defects in the injured rodents. Knockdown of Sox11 by siRNA in rat primary OPCs or depletion of Sox11 in the oligodendrocyte lineage in mice could rescue the hypomyelination phenotype caused by the loss of OLIG2. In summary, our work demonstrates that the OLIG2-SETDB1 complex can mediate transcriptional repression in OPCs, affecting myelination. Transcription factors regulate gene programs during myelination. Here, the authors show that the Oligodendrocyte Transcription Factor 2 (OLIG2) regulates the differentiation of oligodendrocyte progenitor cells into immature oligodendrocytes via SETDB1 during myelination and remyelination in rodents.
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Cai TX, Williamson NH, Ravin R, Basser PJ. Disentangling the effects of restriction and exchange with diffusion exchange spectroscopy. FRONTIERS IN PHYSICS 2022; 10:805793. [PMID: 37063496 PMCID: PMC10104504 DOI: 10.3389/fphy.2022.805793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Diffusion exchange spectroscopy (DEXSY) is a multidimensional NMR technique that can reveal how water molecules exchange between compartments within heterogeneous media, such as biological tissue. Data from DEXSY experiments is typically processed using numerical inverse Laplace transforms (ILTs) to produce a diffusion-diffusion spectrum. A tacit assumption of this ILT approach is that the signal behavior is Gaussian - i.e., the spin echo intensity decays exponentially with the degree of diffusion weighting. The assumptions that underlie Gaussian signal behavior may be violated, however, depending on the gradient strength applied and the sample under study. We argue that non-Gaussian signal behavior due to restrictions is to be expected in the study of biological tissue using diffusion NMR. Further, we argue that this signal behavior can produce confounding features in the diffusion-diffusion spectra obtained from numerical ILTs of DEXSY data - entangling the effects of restriction and exchange. Specifically, restricted signal behavior can result in broadening of peaks and in the appearance of illusory exchanging compartments with distributed diffusivities, which pearl into multiple peaks if not highly regularized. We demonstrate these effects on simulated data. That said, we suggest the use of features in the signal acquisition domain that can be used to rapidly probe exchange without employing an ILT. We also propose a means to characterize the non-Gaussian signal behavior due to restrictions within a sample using DEXSY measurements with a near zero mixing time or storage interval. We propose a combined acquisition scheme to independently characterize restriction and exchange with various DEXSY measurements, which we term Restriction and Exchange from Equally-weighted Double and Single Diffusion Encodings (REEDS-DE). We test this method on ex vivo neonatal mouse spinal cord - a sample consisting primarily of gray matter - using a low-field, static gradient NMR system. In sum, we highlight critical shortcomings of prevailing DEXSY analysis methods that conflate the effects of restriction and exchange, and suggest a viable experimental approach to disentangle them.
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Affiliation(s)
- Teddy X. Cai
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Nathan H. Williamson
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
- National Institute of General Medical Sciences, National Institutes of Health, Bethesda, Maryland, USA
| | - Rea Ravin
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
- Celoptics, Rockville, Maryland, USA
| | - Peter J. Basser
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
- Correspondence: Peter J. Basser, Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 13, Room 3W16, 13 South Drive, Bethesda, Maryland 20892-5772, USA,
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Fiederling F, Hammond LA, Ng D, Mason C, Dodd J. Tools for efficient analysis of neurons in a 3D reference atlas of whole mouse spinal cord. CELL REPORTS METHODS 2021; 1:100074. [PMID: 34661190 PMCID: PMC8516137 DOI: 10.1016/j.crmeth.2021.100074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/23/2021] [Accepted: 08/16/2021] [Indexed: 12/20/2022]
Abstract
To fill the prevailing gap in methodology for whole spinal cord (SC) analysis, we have (1) designed scaffolds (SpineRacks) that facilitate efficient and ordered cryo-sectioning of the entire SC in a single block, (2) constructed a 3D reference atlas of adult mouse SC, and (3) developed software (SpinalJ) to register images of sections and for standardized analysis of cells and projections in atlas space. We have verified mapping accuracies for known neurons and demonstrated the usefulness of this platform to reveal unknown neuronal distributions. Together, these tools provide high-throughput analyses of whole mouse SC and enable direct comparison of 3D spatial information between animals and studies.
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Affiliation(s)
- Felix Fiederling
- Departments of Physiology & Cellular Biophysics, and Neuroscience, Zuckerman Institute, Columbia University, New York, NY 10027, USA
| | - Luke A. Hammond
- Zuckerman Institute, Columbia University, New York, NY 10027, USA
| | - David Ng
- Zuckerman Institute, Columbia University, New York, NY 10027, USA
| | - Carol Mason
- Department of Pathology and Cell Biology, Neuroscience, and Ophthalmology, Zuckerman Institute, Columbia University, New York, NY 10027, USA
| | - Jane Dodd
- Departments of Physiology & Cellular Biophysics, and Neuroscience, Zuckerman Institute, Columbia University, New York, NY 10027, USA
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Bourojeni FB, Zeilhofer HU, Kania A. Netrin-1 receptor DCC is required for the contralateral topography of lamina I anterolateral system neurons. Pain 2021; 162:161-175. [PMID: 32701653 PMCID: PMC7737868 DOI: 10.1097/j.pain.0000000000002012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 12/30/2022]
Abstract
Anterolateral system (AS) neurons relay nociceptive information from the spinal cord to the brain, protecting the body from harm by evoking a variety of behaviours and autonomic responses. The developmental programs that guide the connectivity of AS neurons remain poorly understood. Spinofugal axons cross the spinal midline in response to Netrin-1 signalling through its receptor deleted in colorectal carcinoma (DCC); however, the relevance of this canonical pathway to AS neuron development has only been demonstrated recently. Here, we disrupted Netrin-1:DCC signalling developmentally in AS neurons and assessed the consequences on the path finding of the different classes of spinofugal neurons. Many lamina I AS neurons normally innervate the lateral parabrachial nucleus and periaqueductal gray on the contralateral side. The loss of DCC in the developing spinal cord resulted in increased frequency of ipsilateral projection of spinoparabrachial and spinoperiaqueductal gray neurons. Given that contralateral spinofugal projections are largely associated with somatotopic representation of the body, changes in the laterality of AS spinofugal projections may contribute to reduced precision in pain localization observed in mice and humans carrying Dcc mutations.
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Affiliation(s)
- Farin B. Bourojeni
- Research Unit in Neural Circuit Development, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Switzerland
| | - Artur Kania
- Research Unit in Neural Circuit Development, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada
- Division of Experimental Medicine, Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada
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Williamson NH, Ravin R, Cai TX, Benjamini D, Falgairolle M, O'Donovan MJ, Basser PJ. Real-time measurement of diffusion exchange rate in biological tissue. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 317:106782. [PMID: 32679514 PMCID: PMC7427561 DOI: 10.1016/j.jmr.2020.106782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/22/2020] [Accepted: 06/26/2020] [Indexed: 05/05/2023]
Abstract
Diffusion exchange spectroscopy (DEXSY) provides a means to isolate the signal attenuation associated with exchange from other sources of signal loss. With the total diffusion weighting b1+b2=bs held constant, DEXSY signals acquired with b1=0 or b2=0 have no exchange weighting, while a DEXSY signal acquired with b1=b2 has maximal exchange weighting. The exchange rate can be estimated by fitting a diffusion exchange model to signals acquired with variable mixing times. Conventionally, acquired signals are normalized by a signal with b1=0 and b2=0 to remove the decay due to spin-lattice relaxation. Instead, division by a signal with equal bs but b1=0 or b2=0 reduces spin-lattice relaxation weighting of the apparent exchange rate (AXR). Furthermore, apparent diffusion-weighted R1 relaxation rates can be estimated from non-exchange-weighted DEXSY signals. Estimated R1 values are utilized to remove signal decay due to spin-lattice relaxation from exchange-weighted signals, permitting a more precise estimate of AXR with less data. Data reduction methods are proposed and tested with regards to statistical accuracy and precision of AXR estimates on simulated and experimental data. Simulations show that the methods are capable of accurately measuring the ground-truth exchange rate. The methods remain accurate even when the assumption that DEXSY signals attenuate with b is violated, as occurs for restricted diffusion. Experimental data was collected from fixed neonatal mouse spinal cord samples at 25 and 7°C using the strong static magnetic field gradient produced by a single-sided permanent magnet (i.e., an NMR MOUSE). The most rapid method for exchange measurements requires only five data points (an 80 s experiment as implemented) and achieves a similar level of accuracy and precision to the baseline method using 44 data points. This represents a significant improvement in acquisition speed, overcoming a barrier which has limited the use of DEXSY on living specimen.
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Affiliation(s)
- Nathan H Williamson
- National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD, USA; Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Rea Ravin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA; Celoptics, Rockville, MD, USA
| | - Teddy X Cai
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Dan Benjamini
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA; The Center for Neuroscience and Regenerative Medicine, Uniformed Service University of the Health Sciences, Bethesda, MD 20814, USA
| | - Melanie Falgairolle
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Michael J O'Donovan
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Peter J Basser
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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Williamson NH, Ravin R, Benjamini D, Merkle H, Falgairolle M, O'Donovan MJ, Blivis D, Ide D, Cai TX, Ghorashi NS, Bai R, Basser PJ. Magnetic resonance measurements of cellular and sub-cellular membrane structures in live and fixed neural tissue. eLife 2019; 8:51101. [PMID: 31829935 PMCID: PMC6977971 DOI: 10.7554/elife.51101] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/11/2019] [Indexed: 12/21/2022] Open
Abstract
We develop magnetic resonance (MR) methods for real-time measurement of tissue microstructure and membrane permeability of live and fixed excised neonatal mouse spinal cords. Diffusion and exchange MR measurements are performed using the strong static gradient produced by a single-sided permanent magnet. Using tissue delipidation methods, we show that water diffusion is restricted solely by lipid membranes. Most of the diffusion signal can be assigned to water in tissue which is far from membranes. The remaining 25% can be assigned to water restricted on length scales of roughly a micron or less, near or within membrane structures at the cellular, organelle, and vesicle levels. Diffusion exchange spectroscopy measures water exchanging between membrane structures and free environments at 100 s-1.
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Affiliation(s)
- Nathan H Williamson
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Rea Ravin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States.,Celoptics, Rockville, United States
| | - Dan Benjamini
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States.,Center for Neuroscience and Regenerative Medicine, Henry Jackson Foundation, Bethesda, United States
| | - Hellmut Merkle
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Melanie Falgairolle
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Michael James O'Donovan
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Dvir Blivis
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Dave Ide
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States.,National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Teddy X Cai
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Nima S Ghorashi
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Ruiliang Bai
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States.,Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Peter J Basser
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
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Park J, Decker JT, Smith DR, Cummings BJ, Anderson AJ, Shea LD. Reducing inflammation through delivery of lentivirus encoding for anti-inflammatory cytokines attenuates neuropathic pain after spinal cord injury. J Control Release 2018; 290:88-101. [PMID: 30296461 DOI: 10.1016/j.jconrel.2018.10.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 09/26/2018] [Accepted: 10/03/2018] [Indexed: 01/21/2023]
Abstract
Recently, many clinical trials have challenged the efficacy of current therapeutics for neuropathic pain after spinal cord injury (SCI) due to their life-threatening side-effects including addictions. Growing evidence suggests that persistent inflammatory responses after primary SCI lead to an imbalance between anti-inflammation and pro-inflammation, resulting in pathogenesis and maintenance of neuropathic pain. Conversely, a variety of data suggest that inflammation contributes to regeneration. Herein, we investigated long-term local immunomodulation using anti-inflammatory cytokine IL-10 or IL-4-encoding lentivirus delivered from multichannel bridges. Multichannel bridges provide guidance for axonal outgrowth and act as delivery vehicles. Anti-inflammatory cytokines were hypothesized to modulate the pro-nociceptive inflammatory niche and promote axonal regeneration, leading to neuropathic pain attenuation. Gene expression analyses demonstrated that IL-10 and IL-4 decreased pro-nociceptive genes expression versus control. Moreover, these factors resulted in an increased number of pro-regenerative macrophages and restoration of normal nociceptors expression pattern. Furthermore, the combination of bridges with anti-inflammatory cytokines significantly alleviated both mechanical and thermal hypersensitivity relative to control and promoted axonal regeneration. Collectively, these studies highlight that immunomodulatory strategies target multiple barriers to decrease secondary inflammation and attenuate neuropathic pain after SCI.
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Affiliation(s)
- Jonghyuck Park
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Joseph T Decker
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Dominique R Smith
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Brian J Cummings
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA; Department of Physical Medicine and Rehabilitation, University of California, Irvine, CA, USA
| | - Aileen J Anderson
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA; Department of Physical Medicine and Rehabilitation, University of California, Irvine, CA, USA
| | - Lonnie D Shea
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, USA.
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Lossi L, Merighi A. The Use of ex Vivo Rodent Platforms in Neuroscience Translational Research With Attention to the 3Rs Philosophy. Front Vet Sci 2018; 5:164. [PMID: 30073174 PMCID: PMC6060265 DOI: 10.3389/fvets.2018.00164] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/29/2018] [Indexed: 01/08/2023] Open
Abstract
The principles of the 3Rs—Replacement, Reduction, and Refinement—are at the basis of most advanced national and supranational (EU) regulations on animal experimentation and welfare. In the perspective to reduce and refine the use of these animals in translational research, we here discuss the use of rodent acute and organotypically cultured central nervous system slices. We describe novel applications of these ex vivo platforms in medium-throughput screening of neuroactive molecules of potential pharmacological interest, with particular attention to more recent developments that permit to fully exploit the potential of direct genetic engineering of organotypic cultures using transfection techniques. We then describe the perspectives for expanding the use ex vivo platforms in neuroscience studies under the 3Rs philosophy using the following approaches: (1) Use of co-cultures of two brain regions physiologically connected to each other (source-target) to analyze axon regeneration and reconstruction of circuitries; (2) Microinjection or co-cultures of primary cells and/or cell lines releasing one or more neuroactive molecules to screen their physiological and/or pharmacological effects onto neuronal survival and slice circuitry. Microinjected or co-cultured cells are ideally made fluorescent after transfection with a plasmid construct encoding green or red fluorescent protein under the control of a general promoter such as hCMV; (3) Use of “sniffer” cells sensing the release of biologically active molecules from organotypic cultures by means of fluorescent probes. These cells can be prepared with activatable green fluorescent protein, a unique chromophore that remains in a “dark” state because its maturation is inhibited, and can be made fluorescent (de-quenched) if specific cellular enzymes, such as proteases or kinases, are activated.
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Affiliation(s)
- Laura Lossi
- Laboratory of Neurobiology, Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Adalberto Merighi
- Laboratory of Neurobiology, Department of Veterinary Sciences, University of Turin, Turin, Italy
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12
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Merighi A. The histology, physiology, neurochemistry and circuitry of the substantia gelatinosa Rolandi (lamina II) in mammalian spinal cord. Prog Neurobiol 2018; 169:91-134. [PMID: 29981393 DOI: 10.1016/j.pneurobio.2018.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023]
Abstract
The substantia gelatinosa Rolandi (SGR) was first described about two centuries ago. In the following decades an enormous amount of information has permitted us to understand - at least in part - its role in the initial processing of pain and itch. Here, I will first provide a comprehensive picture of the histology, physiology, and neurochemistry of the normal SGR. Then, I will analytically discuss the SGR circuits that have been directly demonstrated or deductively envisaged in the course of the intensive research on this area of the spinal cord, with particular emphasis on the pathways connecting the primary afferent fibers and the intrinsic neurons. The perspective existence of neurochemically-defined sets of primary afferent neurons giving rise to these circuits will be also discussed, with the proposition that a cross-talk between different subsets of peptidergic fibers may be the structural and functional substrate of additional gating mechanisms in SGR. Finally, I highlight the role played by slow acting high molecular weight modulators in these gating mechanisms.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy.
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13
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Powis RA, Gillingwater TH. Selective loss of alpha motor neurons with sparing of gamma motor neurons and spinal cord cholinergic neurons in a mouse model of spinal muscular atrophy. J Anat 2015; 228:443-51. [PMID: 26576026 DOI: 10.1111/joa.12419] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2015] [Indexed: 02/04/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disease characterised primarily by loss of lower motor neurons from the ventral grey horn of the spinal cord and proximal muscle atrophy. Recent experiments utilising mouse models of SMA have demonstrated that not all motor neurons are equally susceptible to the disease, revealing that other populations of neurons can also be affected. Here, we have extended investigations of selective vulnerability of neuronal populations in the spinal cord of SMA mice to include comparative assessments of alpha motor neuron (α-MN) and gamma motor neuron (γ-MN) pools, as well as other populations of cholinergic neurons. Immunohistochemical analyses of late-symptomatic SMA mouse spinal cord revealed that numbers of α-MNs were significantly reduced at all levels of the spinal cord compared with controls, whereas numbers of γ-MNs remained stable. Likewise, the average size of α-MN cell somata was decreased in SMA mice with no change occurring in γ-MNs. Evaluation of other pools of spinal cord cholinergic neurons revealed that pre-ganglionic sympathetic neurons, central canal cluster interneurons, partition interneurons and preganglionic autonomic dorsal commissural nucleus neuron numbers all remained unaffected in SMA mice. Taken together, these findings indicate that α-MNs are uniquely vulnerable among cholinergic neuron populations in the SMA mouse spinal cord, with γ-MNs and other cholinergic neuronal populations being largely spared.
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Affiliation(s)
- Rachael A Powis
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
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14
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Sivertsen MS, Perreault MC, Glover JC. Pontine reticulospinal projections in the neonatal mouse: Internal organization and axon trajectories. J Comp Neurol 2015; 524:1270-91. [PMID: 26400815 DOI: 10.1002/cne.23904] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 09/11/2015] [Accepted: 09/15/2015] [Indexed: 01/02/2023]
Abstract
We recently characterized physiologically a pontine reticulospinal (pRS) projection in the neonatal mouse that mediates synaptic effects on spinal motoneurons via parallel uncrossed and crossed pathways (Sivertsen et al. [2014] J Neurophysiol 112:1628-1643). Here we characterize the origins, anatomical organization, and supraspinal axon trajectories of these pathways via retrograde tracing from the high cervical spinal cord. The two pathways derive from segregated populations of ipsilaterally and contralaterally projecting pRS neurons with characteristic locations within the pontine reticular formation (PRF). We obtained estimates of relative neuron numbers by counting from sections, digitally generated neuron position maps, and 3D reconstructions. Ipsilateral pRS neurons outnumber contralateral pRS neurons by threefold and are distributed about equally in rostral and caudal regions of the PRF, whereas contralateral pRS neurons are concentrated in the rostral PRF. Ipsilateral pRS neuron somata are on average larger than contralateral. No pRS neurons are positive in transgenic mice that report the expression of GAD, suggesting that they are predominantly excitatory. Putative GABAergic interneurons are interspersed among the pRS neurons, however. Ipsilateral and contralateral pRS axons have distinctly different trajectories within the brainstem. Their initial spinal funicular trajectories also differ, with ipsilateral and contralateral pRS axons more highly concentrated medially and laterally, respectively. The larger size and greater number of ipsilateral vs. contralateral pRS neurons is compatible with our previous finding that the uncrossed projection transmits more reliably to spinal motoneurons. The information about supraspinal and initial spinal pRS axon trajectories should facilitate future physiological assessment of synaptic connections between pRS neurons and spinal neurons.
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Affiliation(s)
- Magne S Sivertsen
- Laboratory of Neural Development and Optical Recording (NDEVOR), Department of Physiology, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0316, Oslo, Norway
| | | | - Joel C Glover
- Laboratory of Neural Development and Optical Recording (NDEVOR), Department of Physiology, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0316, Oslo, Norway.,Norwegian Center for Stem Cell Research, Oslo University Hospital, 0317, Oslo, Norway
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15
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Levine AJ, Hinckley CA, Hilde KL, Driscoll SP, Poon TH, Montgomery JM, Pfaff SL. Identification of a cellular node for motor control pathways. Nat Neurosci 2014; 17:586-93. [PMID: 24609464 DOI: 10.1038/nn.3675] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 02/13/2014] [Indexed: 12/28/2022]
Abstract
The rich behavioral repertoire of animals is encoded in the CNS as a set of motorneuron activation patterns, also called 'motor synergies'. However, the neurons that orchestrate these motor programs as well as their cellular properties and connectivity are poorly understood. Here we identify a population of molecularly defined motor synergy encoder (MSE) neurons in the mouse spinal cord that may represent a central node in neural pathways for voluntary and reflexive movement. This population receives direct inputs from the motor cortex and sensory pathways and, in turn, has monosynaptic outputs to spinal motorneurons. Optical stimulation of MSE neurons drove reliable patterns of activity in multiple motor groups, and we found that the evoked motor patterns varied on the basis of the rostrocaudal location of the stimulated MSE. We speculate that these neurons comprise a cellular network for encoding coordinated motor output programs.
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Affiliation(s)
- Ariel J Levine
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA. [3]
| | - Christopher A Hinckley
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA. [3]
| | - Kathryn L Hilde
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Shawn P Driscoll
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Tiffany H Poon
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Jessica M Montgomery
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Samuel L Pfaff
- 1] Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California, USA
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16
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SMN-dependent intrinsic defects in Schwann cells in mouse models of spinal muscular atrophy. Hum Mol Genet 2013; 23:2235-50. [DOI: 10.1093/hmg/ddt612] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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17
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Henry AM, Hohmann JG. High-resolution gene expression atlases for adult and developing mouse brain and spinal cord. Mamm Genome 2012; 23:539-49. [DOI: 10.1007/s00335-012-9406-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/21/2012] [Indexed: 01/29/2023]
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