1
|
Fowler JH, McQueen J, Holland PR, Manso Y, Marangoni M, Scott F, Chisholm E, Scannevin RH, Hardingham GE, Horsburgh K. Dimethyl fumarate improves white matter function following severe hypoperfusion: Involvement of microglia/macrophages and inflammatory mediators. J Cereb Blood Flow Metab 2018; 38:1354-1370. [PMID: 28606007 PMCID: PMC6077928 DOI: 10.1177/0271678x17713105] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The brain's white matter is highly vulnerable to reductions in cerebral blood flow via mechanisms that may involve elevated microgliosis and pro-inflammatory pathways. In the present study, the effects of severe cerebral hypoperfusion were investigated on white matter function and inflammation. Male C57Bl/6J mice underwent bilateral common carotid artery stenosis and white matter function was assessed at seven days with electrophysiology in response to evoked compound action potentials (CAPs) in the corpus callosum. The peak latency of CAPs and axonal refractoriness was increased following hypoperfusion, indicating a marked functional impairment in white matter, which was paralleled by axonal and myelin pathology and increased density and numbers of microglia/macrophages. The functional impairment in peak latency was significantly correlated with increased microglia/macrophages. Dimethyl fumarate (DMF; 100 mg/kg), a drug with anti-inflammatory properties, was found to reduce peak latency but not axonal refractoriness. DMF had no effect on hypoperfusion-induced axonal and myelin pathology. The density of microglia/macrophages was significantly increased in vehicle-treated hypoperfused mice, whereas DMF-treated hypoperfused mice had similar levels to that of sham-treated mice. The study suggests that increased microglia/macrophages following cerebral hypoperfusion contributes to the functional impairment in white matter that may be amenable to modulation by DMF.
Collapse
Affiliation(s)
- Jill H Fowler
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Jamie McQueen
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK.,2 Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Philip R Holland
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK.,3 Current Address: Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Yasmina Manso
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK.,4 Current Address: Developmental Neurobiology and Regeneration Lab, Parc Científic de Barcelona, Spain
| | - Martina Marangoni
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK.,5 Current Address: Department of Health Sciences, University of Florence, Florence, Italy
| | - Fiona Scott
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Emma Chisholm
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | | | - Giles E Hardingham
- 2 Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.,7 The UK Dementia Research Institute at The University of Edinburgh
| | - Karen Horsburgh
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK.,8 Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
2
|
Martin JE, McKeegan DEF, Sparrey J, Sandilands V. Evaluation of the potential killing performance of novel percussive and cervical dislocation tools in chicken cadavers. Br Poult Sci 2017; 58:216-223. [PMID: 28084791 DOI: 10.1080/00071668.2017.1280724] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
1. Four mechanical poultry killing devices; modified Armadillo (MARM), modified Rabbit Zinger (MZIN), modified pliers (MPLI) and a novel mechanical cervical dislocation (NMCD) gloved device, were assessed for their killing potential in the cadavers of euthanised birds. 2. A 4 × 4 × 4 factorial design (batch × device × bird type + age) was employed. Ten bird cadavers per bird type and age were tested with each of the 4 devices (N = 160 birds). All cadavers were examined post-mortem to establish the anatomical damage caused. 3. NMCD, MARM and MZIN demonstrated killing potential, as well as consistency in their anatomical effects. NMCD had the highest killing potential, with 100% of birds sustaining the required physical trauma to have caused rapid death. 4. The MPLI was inconsistent, and only performed optimally for 27.5% of birds. Severe crushing injury was seen in >50% of MPLI birds, suggesting that birds would die of asphyxia rather than cerebral ischaemia, a major welfare concern. As a result, the MPLI are not recommended as a humane on-farm killing device for chickens. 5. This experiment provides important data on the killing potential of untried novel percussive and mechanical cervical dislocation methods, informing future studies.
Collapse
Affiliation(s)
- J E Martin
- a Animal Behaviour and Welfare , SRUC, Roslin Institute Building , Easter Bush, Edinburgh , UK.,b Royal (Dick) School of Veterinary Studies and Roslin Institute , University of Edinburgh , Easter Bush, Edinburgh , UK.,c Institute of Biodiversity , University of Glasgow , Glasgow , UK
| | - D E F McKeegan
- c Institute of Biodiversity , University of Glasgow , Glasgow , UK
| | - J Sparrey
- d Livetec Systems Ltd , Silsoe , Bedford , UK
| | - V Sandilands
- a Animal Behaviour and Welfare , SRUC, Roslin Institute Building , Easter Bush, Edinburgh , UK
| |
Collapse
|
3
|
A Novel Approach for Studying the Physiology and Pathophysiology of Myelinated and Non-Myelinated Axons in the CNS White Matter. PLoS One 2016; 11:e0165637. [PMID: 27829055 PMCID: PMC5102346 DOI: 10.1371/journal.pone.0165637] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 10/14/2016] [Indexed: 11/19/2022] Open
Abstract
Advances in brain connectomics set the need for detailed knowledge of functional properties of myelinated and non-myelinated (if present) axons in specific white matter pathways. The corpus callosum (CC), a major white matter structure interconnecting brain hemispheres, is extensively used for studying CNS axonal function. Unlike another widely used CNS white matter preparation, the optic nerve where all axons are myelinated, the CC contains also a large population of non-myelinated axons, making it particularly useful for studying both types of axons. Electrophysiological studies of optic nerve use suction electrodes on nerve ends to stimulate and record compound action potentials (CAPs) that adequately represent its axonal population, whereas CC studies use microelectrodes (MEs), recording from a limited area within the CC. Here we introduce a novel robust isolated "whole" CC preparation comparable to optic nerve. Unlike ME recordings where the CC CAP peaks representing myelinated and non-myelinated axons vary broadly in size, "whole" CC CAPs show stable reproducible ratios of these two main peaks, and also reveal a third peak, suggesting a distinct group of smaller caliber non-myelinated axons. We provide detailed characterization of "whole" CC CAPs and conduction velocities of myelinated and non-myelinated axons along the rostro-caudal axis of CC body and show advantages of this preparation for comparing axonal function in wild type and dysmyelinated shiverer mice, studying the effects of temperature dependence, bath-applied drugs and ischemia modeled by oxygen-glucose deprivation. Due to the isolation from gray matter, our approach allows for studying CC axonal function without possible "contamination" by reverberating signals from gray matter. Our analysis of "whole" CC CAPs revealed higher complexity of myelinated and non-myelinated axonal populations, not noticed earlier. This preparation may have a broad range of applications as a robust model for studying myelinated and non-myelinated axons of the CNS in various experimental models.
Collapse
|
4
|
Rad I, Kouhzaei S, Mobasheri H, Saberi H. Novel aspects of spinal cord evoked potentials (SCEPs) in the evaluation of dorso-ventral and lateral mechanical impacts on the spinal cord. J Neural Eng 2014; 12:016004. [PMID: 25461245 DOI: 10.1088/1741-2560/12/1/016004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES The aim of the current study was to mimic mechanical impacts on the spinal cord by manifesting the effects of dorsoventral (DVMP) and lateral (LMP) mechanical pressure on neural activity to address points to be considered during surgery for different purposes, including spinal cord decompression. APPROACHES Spinal cords of anesthetized rats were compressed at T13. Different characteristics of axons, including vulnerability, excitability, and conduction velocity (CV), in response to promptness, severity, and duration of pressure were assessed by spinal cord evoked potentials (SCEPs). Real-time SCEPs recorded at L4-5 revealed N1, N2, and N3 peaks that were used to represent the activity of injured sensory afferents, interneurons, and MN fibers. The averaged SCEP recordings were fitted by trust-region algorithm to find the equivalent Gaussian and polynomial equations. MAIN RESULTS The pyramidal and extrapyramidal pathways possessed CVs of 3-11 and 16-80 m s(-1), respectively. DVMP decreased the excitability of myelinated neural fibers in antidromic and orthodromic pathways. The excitability of fibers in extrapyramidal and pyramidal pathways of lateral corticospinal (LCS) and anterior corticospinal (ACS) tracts decreased following LMP. A significant drop in the amplitude of N3 and its conduction velocity (CV) revealed higher susceptibility of less-myelinated fibers to both DVMP and LMP. The best parametric fitting model for triplet healthy spinal cord CAP was a six-term Gaussian equation (G6) that fell into a five-term equation (G5) at the complete compression stage. SIGNIFICANCE The spinal cord is more susceptible to dorsoventral than lateral mechanical pressures, and this should be considered in spinal cord operations. SCEPs have shown promising capabilities for evaluating the severity of SCI and thus can be applied for diagnostic or prognostic intraoperative monitoring (IOM).
Collapse
Affiliation(s)
- Iman Rad
- Laboratory of Membrane Biophysics and Macromolecules, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | | | | | | |
Collapse
|
5
|
Rad I, Mobasheri H, Najafi F, Rezaei M. Efficient repairing effect of PEG based tri-block copolymer on mechanically damaged PC12 cells and isolated spinal cord. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2014; 25:1539-1551. [PMID: 24519755 DOI: 10.1007/s10856-014-5168-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 01/27/2014] [Indexed: 06/03/2023]
Abstract
Membrane sealing effects of polymersomes made of tri-block copolymer, PEG-co-FA/SC-co-PEG, (PFSP) were studied on isolated spinal cord strips, PC12 cell lines and artificial bilayer following mechanical impact implemented by aneurism clip, sonication and electric shock, respectively. The homogeneity and size of PFSP, membrane permeability and cell viability were assessed by dynamic light scattering, LDH release and MTT assays. According to the results, the biocompatible, physico-chemical, size, surface charge and amphipathic nature of PFSP polymersome makes it an ideal macromolecule to rapidly reseal damaged membranes of cells in injured spinal cord as well as in culture medium. Compound action potentials recorded from intentionally damaged spinal cord strips incubated with PFSP showed restoration of neural excitability by 82.24 % and conduction velocity by 96.72 % after 5 min that monitored in real time. Thus, they triggered efficient instant and sustained sealing of membrane and reactivation of temporarily inactivated axons. Treatment of ultrasonically damaged PC12 cells by PFSP caused efficient cell membrane repair and led to their increased viability. The optimum effects of PFSP on stabilization and impermeabilizing of the lipid bilayer occurred at the same concentrations applied to the damaged cells and spinal cord fibers and was approved by restoration of membrane conductance and calcein release manifested by NanoDrop technique. The unique physico-chemical characteristics of novel polymersomes introduced here, make them capable to reorganize membrane lipid molecules, reseal the breaches and restore the hydrophobic insulation in spinal cord damaged cells. Thus, they might be considered in the clinical treatment of SCI at early stages.
Collapse
Affiliation(s)
- Iman Rad
- Laboratory of Membrane Biophysics and Macromolecules, Institute of Biochemistry & Biophysics, University of Tehran, PO Box 13145-1384, Tehran, Iran,
| | | | | | | |
Collapse
|
6
|
The Neuroprotective Ability of Polyethylene Glycol is Affected by Temperature in Ex Vivo Spinal Cord Injury Model. J Membr Biol 2013; 246:613-9. [DOI: 10.1007/s00232-013-9574-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 06/04/2013] [Indexed: 11/26/2022]
|
7
|
Borgens RB, Liu-Snyder P. Understanding secondary injury. QUARTERLY REVIEW OF BIOLOGY 2012; 87:89-127. [PMID: 22696939 DOI: 10.1086/665457] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Secondary injury is a term applied to the destructive and self-propagating biological changes in cells and tissues that lead to their dysfunction or death over hours to weeks after the initial insult (the "primary injury"). In most contexts, the initial injury is usually mechanical. The more destructive phase of secondary injury is, however, more responsible for cell death and functional deficits. This subject is described and reviewed differently in the literature. To biomedical researchers, systemic and tissue-level changes such as hemorrhage, edema, and ischemia usually define this subject. To cell and molecular biologists, "secondary injury" refers to a series of predominately molecular events and an increasingly restricted set of aberrant biochemical pathways and products. These biochemical and ionic changes are seen to lead to death of the initially compromised cells and "healthy" cells nearby through necrosis or apoptosis. This latter process is called "bystander damage." These viewpoints have largely dominated the recent literature, especially in studies of the central nervous system (CNS), often without attempts to place the molecular events in the context of progressive systemic and tissue-level changes. Here we provide a more comprehensive and inclusive discussion of this topic.
Collapse
Affiliation(s)
- Richard Ben Borgens
- Center for Paralysis Research, School of Veterinary Medicine, Department of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
| | | |
Collapse
|
8
|
Velumian AA, Wan Y, Samoilova M, Fehlings MG. Contribution of fast and slow conducting myelinated axons to single-peak compound action potentials in rat spinal cord white matter preparations. J Neurophysiol 2010; 105:929-41. [PMID: 21148097 DOI: 10.1152/jn.00435.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Unlike recordings derived from optic nerve or corpus callosum, compound action potentials (CAPs) recorded from rodent spinal cord white matter (WM) have a characteristic single-peak shape despite the heterogeneity of axonal populations. Using a double sucrose gap technique, we analyzed the CAPs recorded from dorsal, lateral, and ventral WM from mature rat spinal cord. The CAP decay was significantly prolonged with increasing stimulus intensities suggesting a recruitment of higher threshold, slower conducting axons. At 3.5 mm conduction distance, a hidden higher threshold, slower conducting component responsible for prolongation of CAP decay was uncovered in 22 of 25 of dorsal WM strips by analyzing the stimulus-response relationships and a normalization-subtraction procedure. This component had a peak conduction velocity (CV) of 5.0 ± 0.2 (SE) m/s as compared with 9.3 ± 0.5 m/s for the lower threshold peak (P < 0.0001). Oxygen-glucose deprivation (OGD), along with its known effects on CAP amplitude, significantly (P < 0.015) shortened the CAP decay. The hidden higher threshold, slower conducting component showed greater sensitivity to OGD compared with the lower threshold, faster conducting component, suggesting a differential sensitivity of axonal populations of spinal cord WM. At longer conduction distances and lower temperatures (9.8 mm, 22-24°C), the slower peak could be directly visualized in CAPs at higher stimulation intensities. A detailed analysis of single-peak CAPs to identify their fast and slow conducting components may be of particular importance for studies of axonal physiology and pathophysiology in small animals where the conduction distance is not sufficiently long to separate the CAP peaks.
Collapse
Affiliation(s)
- Alexander A Velumian
- Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, ON M5T 2S8, Canada
| | | | | | | |
Collapse
|
9
|
Colley BS, Phillips LL, Reeves TM. The effects of cyclosporin-A on axonal conduction deficits following traumatic brain injury in adult rats. Exp Neurol 2010; 224:241-51. [PMID: 20362574 DOI: 10.1016/j.expneurol.2010.03.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 02/23/2010] [Accepted: 03/24/2010] [Indexed: 11/20/2022]
Abstract
Immunophilin ligands, including cyclosporin-A (CsA), have been shown to be neuroprotective in experimental models of traumatic brain injury (TBI) and to attenuate the severity of traumatic axonal injury. Prior studies have documented CsA treatment to reduce essential components of posttraumatic axonal pathology, including impaired axoplasmic transport, spectrin proteolysis, and axonal swelling. However, the effects of CsA administration on axonal function, following TBI, have not been evaluated. The present study assessed the effects of CsA treatment on compound action potentials (CAPs) evoked in corpus callosum of adult rats following midline fluid percussion injury. Rats received a 20 mg/kg bolus of CsA, or cremaphor vehicle, at either 15 min or 1 h postinjury, and at 24 h postinjury CAP recording was conducted in coronal brain slices. To elucidate how injury and CsA treatments affect specific populations of axons, CAP waveforms generated largely by myelinated axons (N1) were analyzed separately from the CAP signal, which predominantly reflects activity in unmyelinated axons (N2). CsA administration at 15 min postinjury resulted in significant protection of CAP area, and this effect was more pronounced in N1, than in the N2, CAP component. This treatment also significantly protected against TBI-induced reductions in high-frequency responding of the N1 CAP signal. In contrast, CsA treatment at 1 h did not significantly protect CAPs but was associated with atypical waveforms in N1 CAPs, including decreased CAP duration and reduced refractoriness. The present findings also support growing evidence that myelinated and unmyelinated axons respond differentially to injury and neuroprotective compounds.
Collapse
Affiliation(s)
- Beverly S Colley
- Department of Anatomy and Neurobiology, School of Medicine, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
| | | | | |
Collapse
|
10
|
Rickett T, Li J, Patel M, Sun W, Leung G, Shi R. Ethyl-cyanoacrylate is acutely nontoxic and provides sufficient bond strength for anastomosis of peripheral nerves. J Biomed Mater Res A 2009; 90:750-4. [PMID: 18570316 DOI: 10.1002/jbm.a.32137] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Anastomosis is a common technique for the union of severed nerve trunks. This is commonly performed with sutures, a process that can be both time consuming and injurious to tissue. One promising alternative to suturing is the use of adhesives to join the severed segments. Cyanoacrylate-based glues have been used clinically as a surgical adhesive for soft tissues. However, the acute effects of these glues on nerve electrophysiology and the tensile strength of the rejoined tissues have not been evaluated. Using a guinea pig model, we analyzed the mechanical properties of transected sciatic nerves repaired with epineural application of ethyl-cyanoacrylate and the short term consequences of cyanoacrylate application on impulse conduction. Results showed that nerves coapted with ethyl-cyanoacrylate were capable of bearing in vivo forces. Additionally, no acute effects on conduction were observed in uninjured sciatic nerves exposed to ethyl-cyanoacrylate. In conjunction with long term in vivo reports from literature, the current results support the use of cyanoacrylates in nerve repair.
Collapse
Affiliation(s)
- Todd Rickett
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | | | | | | | | | | |
Collapse
|
11
|
Pellatt GC. Nontraumatic spinal cord injury part 5: Vascular causes and syringomyelia. ACTA ACUST UNITED AC 2009. [DOI: 10.12968/bjnn.2009.5.1.37805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Glynis Collis Pellatt
- Faculty of Health and Social Science, University of Bedfordshire, Aylesbury Vale Education Centre, Stoke Mandeville Hospital, Aylesbury Bucks HP21 8AL
| |
Collapse
|