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Dos Santos BL, Dos Santos CC, da Silva KC, Nonaka CKV, Souza BSDF, David JM, de Oliveira JVR, Costa MDFD, Butt AM, da Silva VDA, Costa SL. The Phytochemical Agathisflavone Modulates miR146a and miR155 in Activated Microglia Involving STAT3 Signaling. Int J Mol Sci 2024; 25:2547. [PMID: 38473794 DOI: 10.3390/ijms25052547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 01/23/2024] [Accepted: 02/06/2024] [Indexed: 03/14/2024] Open
Abstract
MicroRNAs (miRs) act as important post-transcriptional regulators of gene expression in glial cells and have been shown to be involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we investigated the effects of agathisflavone, a biflavonoid purified from the leaves of Cenostigma pyramidale (Tul.), on modulating the expression of miRs and inflammatory mediators in activated microglia. C20 human microglia were exposed to oligomers of the β-amyloid peptide (Aβ, 500 nM) for 4 h or to lipopolysaccharide (LPS, 1 µg/mL) for 24 h and then treated or not with agathisflavone (1 µM) for 24 h. We observed that β-amyloid and LPS activated microglia to an inflammatory state, with increased expression of miR-146a, miR-155, IL1-β, IL-6, and NOS2. Treatment with agathisflavone resulted in a significant reduction in miR146a and miR-155 induced by LPS or Aβ, as well as inflammatory cytokines IL1-β, IL-6, and NOS2. In cells stimulated with Aβ, there was an increase in p-STAT3 expression that was reduced by agathisflavone treatment. These data identify a role for miRs in the anti-inflammatory effect of agathisflavone on microglia in models of neuroinflammation and AD.
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Affiliation(s)
- Balbino Lino Dos Santos
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
- College of Nursing, Federal University of Vale do São Francisco, Av. José de Sá Maniçoba, S/N, Petrolina 56304-917, PE, Brazil
| | - Cleonice Creusa Dos Santos
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
| | - Karina Costa da Silva
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
| | - Carolina Kymie Vasques Nonaka
- Center of Biotechnology and Cell Therapy, São Rafael Hospital, D'Or Institute for Research and Teaching (IDOR), Salvador 41253-190, BA, Brazil
| | - Bruno Solano de Freitas Souza
- Center of Biotechnology and Cell Therapy, São Rafael Hospital, D'Or Institute for Research and Teaching (IDOR), Salvador 41253-190, BA, Brazil
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador 40296-710, BA, Brazil
| | - Jorge Mauricio David
- Department of General and Inorganic Chemistry, Institute of Chemistry, Federal University of Bahia, Salvador 40231-300, BA, Brazil
| | - Juciele Valéria Ribeiro de Oliveira
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
| | - Maria de Fátima Dias Costa
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
- National Institute of Translational Neuroscience (INNT), Rio de Janeiro 21941-971, RJ, Brazil
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
| | - Victor Diogenes Amaral da Silva
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
| | - Silvia Lima Costa
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil
- National Institute of Translational Neuroscience (INNT), Rio de Janeiro 21941-971, RJ, Brazil
- Instituto de Ciências da Saúde, Av. Reitor Miguel Calmon S/N Vale do Canela, Salvador 40110-902, BA, Brazil
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Ferreira RS, Ribeiro PR, Silva JHCE, Hoppe JB, de Almeida MMA, de Lima Ferreira BC, Andrade GB, de Souza SB, Ferdandez LG, de Fátima Dias Costa M, Salbego CG, Rivera AD, Longoni A, de Assis AM, Pieropan F, Moreira JCF, Costa SL, Butt AM, da Silva VDA. Amburana cearensis seed extract stimulates astrocyte glutamate homeostatic mechanisms in hippocampal brain slices and protects oligodendrocytes against ischemia. BMC Complement Med Ther 2023; 23:154. [PMID: 37170258 PMCID: PMC10173544 DOI: 10.1186/s12906-023-03959-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 04/13/2023] [Indexed: 05/13/2023] Open
Abstract
BACKGROUND Stroke is a leading cause of death and disability worldwide. A major factor in brain damage following ischemia is excitotoxicity caused by elevated levels of the neurotransmitter glutamate. In the brain, glutamate homeostasis is a primary function of astrocytes. Amburana cearensis has long been used in folk medicine and seed extract obtained with dichloromethane (EDAC) have previously been shown to exhibit cytoprotective activity in vitro. The aim of the present study was to analyse the activity of EDAC in hippocampal brain slices. METHODS We prepared a dichloromethane extract (EDAC) from A. cearensis seeds and characterized the chemical constituents by 1H and 13C-NMR. Hippocampal slices from P6-8 or P90 Wistar rats were used for cell viability assay or glutamate uptake test. Hippocampal slices from P10-12 transgenic mice SOX10-EGFP and GFAP-EGFP and immunofluorescence for GS, GLAST and GLT1 were used to study oligodendrocytes and astrocytes. RESULTS Astrocytes play a critical role in glutamate homeostasis and we provide immunohistochemical evidence that in excitotoxicity EDAC increased expression of glutamate transporters and glutamine synthetase, which is essential for detoxifying glutamate. Next, we directly examined astrocytes using transgenic mice in which glial fibrillary acidic protein (GFAP) drives expression of enhanced green fluorescence protein (EGFP) and show that glutamate excitotoxicity caused a decrease in GFAP-EGFP and that EDAC protected against this loss. This was examined further in the oxygen-glucose deprivation (OGD) model of ischemia, where EDAC caused an increase in astrocytic process branching, resulting in an increase in GFAP-EGFP. Using SOX10-EGFP reporter mice, we show that the acute response of oligodendrocytes to OGD in hippocampal slices is a marked loss of their processes and EDAC protected oligodendrocytes against this damage. CONCLUSION This study provides evidence that EDAC is cytoprotective against ischemia and glutamate excitotoxicity by modulating astrocyte responses and stimulating their glutamate homeostatic mechanisms.
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Affiliation(s)
- Rafael Short Ferreira
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - Paulo Roberto Ribeiro
- Metabolomics Research Group, Department of Organic Chemistry, Chemistry Institute, Federal University of Bahia, Salvador, Bahia, Brazil
| | - Juliana Helena Castro E Silva
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - Juliana Bender Hoppe
- Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande Do Sul, Porto Alegre, Brazil
| | - Monique Marylin Alves de Almeida
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - Beatriz Correia de Lima Ferreira
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
| | - Gustavo Borges Andrade
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
| | - Suzana Braga de Souza
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
| | - Luzimar Gonzaga Ferdandez
- Biochemistry, Biotechnology and Bioproducts Laboratory, Institute of Health Sciences, Federal University of Bahia, Salvador, Bahia, Brazil
| | - Maria de Fátima Dias Costa
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil
| | - Christianne Gazzana Salbego
- Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande Do Sul, Porto Alegre, Brazil
| | - Andrea Domenico Rivera
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - Aline Longoni
- Health Sciences Centre, Post-Graduate Program in Health and Behaviour, Catholic University of Pelotas, Pelotas, Brazil
| | - Adriano Martimbianco de Assis
- Health Sciences Centre, Post-Graduate Program in Health and Behaviour, Catholic University of Pelotas, Pelotas, Brazil
| | - Francesca Pieropan
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - José Cláudio Fonseca Moreira
- Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande Do Sul, Porto Alegre, Brazil
| | - Silvia Lima Costa
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil.
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK.
| | - Victor Diogenes Amaral da Silva
- Laboratory of Neurochemistry and Cell Biology, Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia - UFBA, Salvador, Bahia, 40110-902, Brazil.
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK.
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Dos Santos BL, Dos Santos CC, Soares JRP, da Silva KC, de Oliveira JVR, Pereira GS, de Araújo FM, Costa MDFD, David JM, da Silva VDA, Butt AM, Costa SL. The Flavonoid Agathisflavone Directs Brain Microglia/Macrophages to a Neuroprotective Anti-Inflammatory and Antioxidant State via Regulation of NLRP3 Inflammasome. Pharmaceutics 2023; 15:pharmaceutics15051410. [PMID: 37242652 DOI: 10.3390/pharmaceutics15051410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 04/16/2023] [Accepted: 04/19/2023] [Indexed: 05/28/2023] Open
Abstract
Agathisflavone, purified from Cenostigma pyramidale (Tul.) has been shown to be neuroprotective in in vitro models of glutamate-induced excitotoxicity and inflammatory damage. However, the potential role of microglial regulation by agathisflavone in these neuroprotective effects is unclear. Here we investigated the effects of agathisflavone in microglia submitted to inflammatory stimulus in view of elucidating mechanisms of neuroprotection. Microglia isolated from cortices of newborn Wistar rats were exposed to Escherichia coli lipopolysaccharide (LPS, 1 µg/mL) and treated or not with agathisflavone (1 µM). Neuronal PC12 cells were exposed to a conditioned medium from microglia (MCM) treated or not with agathisflavone. We observed that LPS induced microglia to assume an activated inflammatory state (increased CD68, more rounded/amoeboid phenotype). However, most microglia exposed to LPS and agathisflavone, presented an anti-inflammatory profile (increased CD206 and branched-phenotype), associated with the reduction in NO, GSH mRNA for NRLP3 inflammasome, IL1-β, IL-6, IL-18, TNF, CCL5, and CCL2. Molecular docking also showed that agathisflavone bound at the NLRP3 NACTH inhibitory domain. Moreover, in PC12 cell cultures exposed to the MCM previously treated with the flavonoid most cells preserved neurites and increased expression of β-tubulin III. Thus, these data reinforce the anti-inflammatory activity and the neuroprotective effect of agathisflavone, effects associated with the control of NLRP3 inflammasome, standing out it as a promising molecule for the treatment or prevention of neurodegenerative diseases.
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Affiliation(s)
- Balbino Lino Dos Santos
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
- College of Nursing, Federal University of Vale do São Francisco, Petrolina 56304-917, Pernambuco, Brazil
| | - Cleonice Creusa Dos Santos
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
| | - Janaina R P Soares
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
| | - Karina C da Silva
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
| | - Juciele Valeria R de Oliveira
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
| | - Gabriele S Pereira
- Group of Studies and Research for Health Development, University Salvador, Salvador 40140-110, Bahia, Brazil
| | - Fillipe M de Araújo
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
- Group of Studies and Research for Health Development, University Salvador, Salvador 40140-110, Bahia, Brazil
| | - Maria de Fátima D Costa
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
| | - Jorge Mauricio David
- Department of General and Inorganic Chemistry, Institute of Chemistry, University Federal da Bahia, Salvador 40170-110, Bahia, Brazil
| | - Victor Diogenes A da Silva
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2UP, UK
| | - Silvia Lima Costa
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, Bahia, Brazil
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Rivera AD, Butt AM, Azim K. Resolving the age-related decline in central nervous system myelin turnover and drug discovery for oligodendroglial rejuvenation. Neural Regen Res 2022; 17:2677-2678. [PMID: 35662206 PMCID: PMC9165362 DOI: 10.4103/1673-5374.338995] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 11/12/2021] [Accepted: 12/09/2021] [Indexed: 11/23/2022] Open
Affiliation(s)
- Andrea Domenico Rivera
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK
- Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Arthur Morgan Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK
| | - Kasum Azim
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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de Almeida MMA, Pieropan F, Footz T, David JM, David JP, da Silva VDA, Dos Santos Souza C, Voronova A, Butt AM, Costa SL. Agathisflavone Modifies Microglial Activation State and Myelination in Organotypic Cerebellar Slices Culture. J Neuroimmune Pharmacol 2022; 17:206-217. [PMID: 33881709 DOI: 10.1007/s11481-021-09991-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 03/10/2021] [Indexed: 12/29/2022]
Abstract
Oligodendrocytes produce the myelin that is critical for rapid neuronal transmission in the central nervous system (CNS). Disruption of myelin has devastating effects on CNS function, as in the demyelinating disease multiple sclerosis (MS). Microglia are the endogenous immune cells of the CNS and play a central role in demyelination and repair. There is a need for new potential therapies that regulate myelination and microglia to promote repair. Agathisflavone (FAB) is a non-toxic flavonoid that is known for its anti-inflammatory and neuroprotective properties. Here, we examined the effects of FAB (5-50 μM) on myelination and microglia in organotypic cerebellar slices prepared from P10-P12 Sox10-EGFP and Plp1-DsRed transgenic mice. Immunofluorescence labeling for myelin basic protein (MBP) and neurofilament (NF) demonstrates that FAB significantly increased the proportion of MBP + /NF + axons but did not affect the overall number of oligodendroglia or axons, or the expression of oligodendroglial proteins CNPase and MBP. FAB is known to be a phytoestrogen, but blockade of α- or β- estrogen receptors (ER) indicated the myelination promoting effects of FAB were not mediated by ER. Examination of microglial responses by Iba1 immunohistochemistry demonstrated that FAB markedly altered microglial morphology, characterized by smaller somata and reduced branching of their processes, consistent with a decreased state of activation, and increased Iba1 protein expression. The results provide evidence that FAB increases the extent of axonal coverage by MBP immunopositive oligodendroglial processes and has a modulatory effect upon microglial cells, which are important therapeutic strategies in multiple neuropathologies.
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Affiliation(s)
- Monique Marylin Alves de Almeida
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Bahia, Brazil
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Francesca Pieropan
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK
| | - Tim Footz
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Jorge Mauricio David
- Department of General and Inorganic Chemistry, Institute of Chemistry, Federal University of Bahia, Bahia, Brazil
| | - Juceni Pereira David
- Department of Medication, Faculty of Pharmacy, Federal University of Bahia, Bahia, Brazil
| | | | - Cleide Dos Santos Souza
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Bahia, Brazil
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Anastassia Voronova
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK.
| | - Silvia Lima Costa
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Bahia, Brazil.
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Rivera AD, Pieropan F, Williams G, Calzolari F, Butt AM, Azim K. Drug connectivity mapping and functional analysis reveal therapeutic small molecules that differentially modulate myelination. Biomed Pharmacother 2022; 145:112436. [PMID: 34813998 PMCID: PMC8664715 DOI: 10.1016/j.biopha.2021.112436] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/29/2021] [Accepted: 11/12/2021] [Indexed: 12/30/2022] Open
Abstract
Disruption or loss of oligodendrocytes (OLs) and myelin has devastating effects on CNS function and integrity, which occur in diverse neurological disorders, including Multiple Sclerosis (MS), Alzheimer's disease and neuropsychiatric disorders. Hence, there is a need to develop new therapies that promote oligodendrocyte regeneration and myelin repair. A promising approach is drug repurposing, but most agents have potentially contrasting biological actions depending on the cellular context and their dose-dependent effects on intracellular pathways. Here, we have used a combined systems biology and neurobiological approach to identify compounds that exert positive and negative effects on oligodendroglia, depending on concentration. Notably, next generation pharmacogenomic analysis identified the PI3K/Akt modulator LY294002 as the most highly ranked small molecule with both pro- and anti-oligodendroglial concentration-dependent effects. We validated these in silico findings using multidisciplinary approaches to reveal a profoundly bipartite effect of LY294002 on the generation of OPCs and their differentiation into myelinating oligodendrocytes in both postnatal and adult contexts. Finally, we employed transcriptional profiling and signalling pathway activity assays to determine cell-specific mechanisms of action of LY294002 on oligodendrocytes and resolve optimal in vivo conditions required to promote myelin repair. These results demonstrate the power of multidisciplinary strategies in determining the therapeutic potential of small molecules in neurodegenerative disorders.
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Affiliation(s)
- A D Rivera
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, PO1 2DT Portsmouth, UK; Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy.
| | - F Pieropan
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, PO1 2DT Portsmouth, UK
| | - G Williams
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London, UK
| | - F Calzolari
- Research Group Adult Neurogenesis & Cellular Reprogramming Institute of Physiological Chemistry, University Medical Center, Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 19, 55128 Mainz, Germany
| | - A M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, PO1 2DT Portsmouth, UK
| | - K Azim
- Department of Neurology, Neuroregeneration, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
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de Almeida MMA, Pieropan F, de Mattos Oliveira L, Dos Santos Junior MC, David JM, David JP, da Silva VDA, Dos Santos Souza C, Costa SL, Butt AM. The flavonoid agathisflavone modulates the microglial neuroinflammatory response and enhances remyelination. Pharmacol Res 2020; 159:104997. [PMID: 32534098 PMCID: PMC7482432 DOI: 10.1016/j.phrs.2020.104997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 05/27/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022]
Abstract
Myelin loss is the hallmark of the demyelinating disease multiple sclerosis (MS) and plays a significant role in multiple neurodegenerative diseases. A common factor in all neuropathologies is the central role of microglia, the intrinsic immune cells of the central nervous system (CNS). Microglia are activated in pathology and can have both pro- and anti-inflammatory functions. Here, we examined the effects of the flavonoid agathisflavone on microglia and remyelination in the cerebellar slice model following lysolecithin induced demyelination. Notably, agathisflavone enhances remyelination and alters microglial activation state, as determined by their morphology and cytokine profile. Furthermore, these effects of agathisflavone on remyelination and microglial activation were inhibited by blockade of estrogen receptor α. Thus, our results identify agathisflavone as a novel compound that may act via ER to regulate microglial activation and enhance remyelination and repair.
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Affiliation(s)
- Monique Marylin Alves de Almeida
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Brazil; School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
| | - Francesca Pieropan
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
| | | | | | - Jorge Mauricio David
- Department of General and Inorganic Chemistry, Institute of Chemistry, Federal University of Bahia, Brazil
| | - Juceni Pereira David
- Department of Medication, Faculty of Pharmacy, Federal University of Bahia, Brazil
| | - Victor Diógenes A da Silva
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Brazil
| | - Cleide Dos Santos Souza
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Brazil; Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Silvia Lima Costa
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Brazil.
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom.
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de Amorim VCM, Júnior MSO, da Silva AB, David JM, David JPL, de Fátima Dias Costa M, Butt AM, da Silva VDA, Costa SL. Agathisflavone modulates astrocytic responses and increases the population of neurons in an in vitro model of traumatic brain injury. Naunyn Schmiedebergs Arch Pharmacol 2020; 393:1921-1930. [PMID: 32444988 DOI: 10.1007/s00210-020-01905-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 05/10/2020] [Indexed: 12/20/2022]
Abstract
Traumatic brain injury (TBI) is a critical health problem worldwide, with a high incidence rate and potentially severe long-term consequences. Depending on the level of mechanical stress, astrocytes react with complex morphological and functional changes known as reactive astrogliosis. In cases of severe tissue injury, astrocytes proliferate in the area immediately adjacent to the lesion to form the glial scar, which is a major barrier to neuronal regeneration in the central nervous system. The flavonoid agathisflavone has been shown to have neuroprotective, neurogenic, and immunomodulatory effects and could have beneficial effects in situations of TBI. In this study, we investigated the effects of agathisflavone on modulating the responses of astrocytes and neurons to injury, using the in vitro scratch wound model of TBI in primary cultures of rat cerebral cortex. In control conditions, the scratch wound induced an astroglial injury response, characterized by upregulation of glial fibrillary acidic protein (GFAP) and hypertrophy, together with the reduction in proportion of neurons within the lesion site. Treatment with agathisflavone (1 μM) decreased astroglial GFAP expression and hypertrophy and induced an increase in the number of neurons and neurite outgrowth into the lesion site. Agathisflavone also induced increased expression of the neurotrophic factors NGF and GDNF, which are associated with the neuroprotective profile of glial cells. These results demonstrate that in an in vitro model of TBI, the flavonoid agathisflavone modulates the astrocytic injury response and glial scar formation, stimulating neural recomposition.
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Affiliation(s)
- Vanessa Cristina Meira de Amorim
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon, Salvador, BA, 40100-902, Brazil
| | - Markley Silva Oliveira Júnior
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon, Salvador, BA, 40100-902, Brazil
| | - Alessandra Bispo da Silva
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon, Salvador, BA, 40100-902, Brazil
| | - Jorge M David
- Department of General and Inorganic Chemistry, Institute of Chemistry, Federal University of Bahia, R. Barão de Jeremoabo, Salvador, BA, 40170-115, Brazil
| | - Juceni Pereira Lima David
- Department of Medication, Faculty of Pharmacy, Federal University of Bahia, R. Barão de Jeremoabo, Salvador, BA, 40170-115, Brazil
| | - Maria de Fátima Dias Costa
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon, Salvador, BA, 40100-902, Brazil
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Science, University of Portsmouth, Winston Churchill Avenue, Portsmouth, PO1 2UP, UK
| | - Victor Diogenes Amaral da Silva
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon, Salvador, BA, 40100-902, Brazil
| | - Silvia Lima Costa
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon, Salvador, BA, 40100-902, Brazil.
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Dourado NS, Souza CDS, de Almeida MMA, Bispo da Silva A, Dos Santos BL, Silva VDA, De Assis AM, da Silva JS, Souza DO, Costa MDFD, Butt AM, Costa SL. Neuroimmunomodulatory and Neuroprotective Effects of the Flavonoid Apigenin in in vitro Models of Neuroinflammation Associated With Alzheimer's Disease. Front Aging Neurosci 2020; 12:119. [PMID: 32499693 PMCID: PMC7243840 DOI: 10.3389/fnagi.2020.00119] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 04/08/2020] [Indexed: 12/20/2022] Open
Abstract
Neurodegenerative disorders (ND) are characterized by the progressive and irreversible loss of neurons. Alzheimer’s Disease (AD) is the most incident age-related ND, in which the presence of a chronic inflammatory compound seems to be related to its pathogenesis. Different stimuli in the central nervous system (CNS) can induce activation, proliferation, and changes in phenotype and glial function, which can be modulated by anti-inflammatory agents. Apigenin (4,5,7–trihydroxyflavone) is a flavonoid found in abundance in many fruits and vegetables, that has shown important effects upon controlling the inflammatory response. This study evaluated the neuroprotective and neuroimmunomodulatory potential of apigenin using in vitro models of neuroinflammation associated with AD. Co-cultures of neurons and glial cells were obtained from the cortex of newborn and embryonic Wistar rats. After 26 days in vitro, cultures were exposed to lipopolysaccharide (LPS; 1 μg/ml), or IL-1β (10 ng/ml) for 24 h, or to Aβ oligomers (500 nM) for 4 h, and then treated with apigenin (1 μM) for further 24 h. It was observed that the treatment with apigenin preserved neurons and astrocytes integrity, determined by Rosenfeld’s staining and immunocytochemistry for β-tubulin III and GFAP, respectively. Moreover, it was observed by Fluoro-Jade-B and caspase-3 immunostaining that apigenin was not neurotoxic and has a neuroprotective effect against inflammatory damage. Additionally, apigenin reduced microglial activation, characterized by inhibition of proliferation (BrdU+ cells) and modulation of microglia morphology (Iba-1 + cells), and decreased the expression of the M1 inflammatory marker CD68. Moreover, as determined by RT-qPCR, inflammatory stimuli induced by IL-1β increased the mRNA expression of IL-6, IL-1β, and CCL5, and decreased the mRNA expression of IL-10. Contrary, after treatment with apigenin in inflammatory stimuli (IL-1β or LPS) there was a modulation of the mRNA expression of inflammatory cytokines, and reduced expression of OX42, IL-6 and gp130. Moreover, apigenin alone and after an inflammatory stimulus with IL-1β also induced the increase in the expression of brain-derived neurotrophic factor (BDNF), an effect that may be associated with anti-inflammatory and neuroprotective effects. Together these data demonstrate that apigenin presents neuroprotective and anti-inflammatory effects in vitro and might represent an important neuroimmunomodulatory agent for the treatment of neurodegenerative conditions.
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Affiliation(s)
- Naiara Silva Dourado
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil
| | - Cleide Dos Santos Souza
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil.,Sheffield Institute of Translational Neuroscience (SITraN), The University of Sheffield, Sheffield, United Kingdom
| | - Monique Marylin Alves de Almeida
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil
| | - Alessandra Bispo da Silva
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil
| | - Balbino Lino Dos Santos
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil.,College of Nursing, Federal University of Vale do São Francisco (UNIVASF), Petrolina, Brazil
| | - Victor Diogenes Amaral Silva
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil.,INCT for Excitotoxicity and Neuroprotection (INCT-EN, BR), Porto Alegre, Brazil
| | - Adriano Martimbianco De Assis
- INCT for Excitotoxicity and Neuroprotection (INCT-EN, BR), Porto Alegre, Brazil.,Postgraduate in Health and Behavior, Catholic University of Pelotas (UCPEL), Pelotas, Brazil.,Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Jussemara Souza da Silva
- Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Diogo Onofre Souza
- INCT for Excitotoxicity and Neuroprotection (INCT-EN, BR), Porto Alegre, Brazil.,Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Maria de Fatima Dias Costa
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil.,Instituto Nacional de Ciência e Tecnologia em Excitotoxicidade e Neuroproteção (INCT)-Translational Neuroscience (INCT-TN, BR), Porto Alegre, Brazil
| | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Silvia Lima Costa
- Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Av. Reitor Miguel Calmon S/N, Federal University of Bahia (UFBA), Salvador, Brazil.,INCT for Excitotoxicity and Neuroprotection (INCT-EN, BR), Porto Alegre, Brazil.,Instituto Nacional de Ciência e Tecnologia em Excitotoxicidade e Neuroproteção (INCT)-Translational Neuroscience (INCT-TN, BR), Porto Alegre, Brazil
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10
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Dos Santos Souza C, Grangeiro MS, Lima Pereira EP, Dos Santos CC, da Silva AB, Sampaio GP, Ribeiro Figueiredo DD, David JM, David JP, da Silva VDA, Butt AM, Lima Costa S. Agathisflavone, a flavonoid derived from Poincianella pyramidalis (Tul.), enhances neuronal population and protects against glutamate excitotoxicity. Neurotoxicology 2018; 65:85-97. [PMID: 29425760 DOI: 10.1016/j.neuro.2018.02.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 01/16/2018] [Accepted: 02/02/2018] [Indexed: 01/01/2023]
Abstract
Flavonoids are bioactive compounds that are known to be neuroprotective against glutamate-mediated excitotoxicity, one of the major causes of neurodegeneration. The mechanisms underlying these effects are unresolved, but recent evidence indicates flavonoids may modulate estrogen signaling, which can delay the onset and ameliorate the severity of neurodegenerative disorders. Furthermore, the roles played by glial cells in the neuroprotective effects of flavonoids are poorly understood. The aim of this study was to investigate the effects of the flavonoid agathisflavone (FAB) in primary neuron-glial co-cultures from postnatal rat cerebral cortex. Compared to controls, treatment with FAB significantly increased the number of neuronal progenitors and mature neurons, without increasing astrocytes or microglia. These pro-neuronal effects of FAB were suppressed by antagonists of estrogen receptors (ERα and ERβ). In addition, treatment with FAB significantly reduced cell death induced by glutamate and this was associated with reduced expression levels of pro-inflammatory (M1) microglial cytokines, including TNFα, IL1β and IL6, which are associated with neurotoxicity, and increased expression of IL10 and Arginase 1, which are associated with anti-inflammatory (M2) neuroprotective microglia. We also observed that FAB increased neuroprotective trophic factors, such as BDNF, NGF, NT4 and GDNF. The neuroprotective effects of FAB were also associated with increased expression of glutamate regulatory proteins in astrocytes, namely glutamine synthetase (GS) and Excitatory Amino Acid Transporter 1 (EAAT1). These findings indicate that FAB acting via estrogen signaling stimulates production of neurons in vitro and enhances the neuroprotective properties of microglia and astrocytes to significantly ameliorate glutamate-mediated neurotoxicity.
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Affiliation(s)
- Cleide Dos Santos Souza
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil
| | - Maria Socorro Grangeiro
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil
| | - Erica Patricia Lima Pereira
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil
| | - Cleonice Creusa Dos Santos
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil
| | - Alessandra Bispo da Silva
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil
| | - Geraldo Pedral Sampaio
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil
| | | | - Jorge Mauricio David
- Department of General and Inorganic Chemistry, Institute of Chemistry, Universidade Federal da Bahia, Brazil
| | - Juceni Pereira David
- Departament of Medication, Faculty of Pharmacy, Universidade Federal da Bahia, Brazil
| | | | - Arthur Morgan Butt
- School of Pharmacy and Biomedical Science, University of Portsmouth, United Kingdom
| | - Silvia Lima Costa
- Department of Biochemistry and Biophysics, Institute of Health Sciences, Universidade Federal da Bahia, Brazil.
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11
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Papanikolaou M, Lewis A, Butt AM. Store-operated calcium entry is essential for glial calcium signalling in CNS white matter. Brain Struct Funct 2017; 222:2993-3005. [PMID: 28247021 PMCID: PMC5585307 DOI: 10.1007/s00429-017-1380-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/27/2017] [Indexed: 11/06/2022]
Abstract
‘Calcium signalling’ is the ubiquitous response of glial cells to multiple extracellular stimuli. The primary mechanism of glial calcium signalling is by release of calcium from intracellular stores of the endoplasmic reticulum (ER). Replenishment of ER Ca2+ stores relies on store-operated calcium entry (SOCE). However, despite the importance of calcium signalling in glial cells, little is known about their mechanisms of SOCE. Here, we investigated SOCE in glia of the mouse optic nerve, a typical CNS white matter tract that comprises bundles of myelinated axons and the oligodendrocytes and astrocytes that support them. Using quantitative RT-PCR, we identified Orai1 channels, both Stim1 and Stim2, and the transient receptor potential M3 channel (TRPM3) as the primary channels for SOCE in the optic nerve, and their expression in both astrocytes and oligodendrocytes was demonstrated by immunolabelling of optic nerve sections and cultures. The functional importance of SOCE was demonstrated by fluo-4 calcium imaging on isolated intact optic nerves and optic nerve cultures. Removal of extracellular calcium ([Ca2+]o) resulted in a marked depletion of glial cytosolic calcium ([Ca2+]i), which recovered rapidly on restoration of [Ca2+]o via SOCE. 2-aminoethoxydiphenylborane (2APB) significantly decreased SOCE and severely attenuated ATP-mediated calcium signalling. The results provide evidence that Orai/Stim and TRPM3 are important components of the ‘calcium toolkit’ that underpins SOCE and the sustainability of calcium signalling in white matter glia.
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Affiliation(s)
- M Papanikolaou
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - A Lewis
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - A M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK.
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12
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Brasko C, Hawkins V, De La Rocha IC, Butt AM. Expression of Kir4.1 and Kir5.1 inwardly rectifying potassium channels in oligodendrocytes, the myelinating cells of the CNS. Brain Struct Funct 2017; 222:41-59. [PMID: 26879293 PMCID: PMC5225165 DOI: 10.1007/s00429-016-1199-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 02/01/2016] [Indexed: 12/21/2022]
Abstract
The inwardly rectifying K+ channel subtype Kir5.1 is only functional as a heteromeric channel with Kir4.1. In the CNS, Kir4.1 is localised to astrocytes and is the molecular basis of their strongly negative membrane potential. Oligodendrocytes are the specialised myelinating glia of the CNS and their resting membrane potential provides the driving force for ion and water transport that is essential for myelination. However, little is known about the ion channel profile of mature myelinating oligodendrocytes. Here, we identify for the first time colocalization of Kir5.1 with Kir4.1 in oligodendrocytes in white matter. Immunolocalization with membrane-bound Na+/K+-ATPase and western blot of the plasma membrane fraction of the optic nerve, a typical CNS white matter tract containing axons and the oligodendrocytes that myelinate them, demonstrates that Kir4.1 and Kir5.1 are colocalized on oligodendrocyte cell membranes. Co-immunoprecipitation provides evidence that oligodendrocytes and astrocytes express a combination of homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels. Genetic knock-out and shRNA to ablate Kir4.1 indicates plasmalemmal expression of Kir5.1 in glia is largely dependent on Kir4.1 and the plasmalemmal anchoring protein PSD-95. The results demonstrate that, in addition to astrocytes, oligodendrocytes express both homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels. In astrocytes, these channels are essential to their key functions of K+ uptake and CO2/H+ chemosensation. We propose Kir4.1/Kir5.1 channels have equivalent functions in oligodendrocytes, maintaining myelin integrity in the face of large ionic shifts associated with action potential propagation along myelinated axons.
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Affiliation(s)
- C Brasko
- Institute of Biology and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - V Hawkins
- Institute of Biology and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - I Chacon De La Rocha
- Institute of Biology and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK
| | - A M Butt
- Institute of Biology and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK.
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13
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Bukhari SNA, Butt AM, Amjad MWB, Ahmad W, Shah VH, Trivedi AR. Synthesis and evaluation of chalcone analogues based pyrimidines as angiotensin converting enzyme inhibitors. Pak J Biol Sci 2013; 16:1368-1372. [PMID: 24511749 DOI: 10.3923/pjbs.2013.1368.1372] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Hypertension is a widespread and frequently progressive ailment that imparts a foremost threat for cardiovascular and renal disorders. Mammoth efforts are needed for the synthesis of innovative antihypertensive agents to combat this lethal disease. Chalcones have shown antihypertensive activity through inhibition of Angiotensin Converting Enzyme (ACE). Hence, a series of chalcone analogues is synthesized and used as precursor for the synthesis of novel series of pyrimidines. Precursor chalcones were prepared by reacting aldehydes and ketones in presence of sodium hydroxide followed by synthesis of corresponding pyrimidines by reaction with urea in presence of potassium hydroxide. Both groups were then evaluated for their effects on ACE. The results depicted that pyrimidines were more active than chalcones with methoxy (C5 and P5) substitution showing best results to inhibit ACE. Given that chalcone analogues and pyrimidines show a potential as the angiotensin converting enzyme inhibitors.
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Affiliation(s)
| | - A M Butt
- Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur,50300, Malaysia
| | - M W B Amjad
- Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur,50300, Malaysia
| | - W Ahmad
- Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur,50300, Malaysia
| | - V H Shah
- Department of Chemistry, Saurashtra University, Rajkot- 360 005, Gujarat, India
| | - A R Trivedi
- Department of Chemistry, Saurashtra University, Rajkot- 360 005, Gujarat, India
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14
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Rehman S, Ullah R, Butt AM, Gohar ND. Strategies of making TiO2 and ZnO visible light active. J Hazard Mater 2009; 170:560-9. [PMID: 19540666 DOI: 10.1016/j.jhazmat.2009.05.064] [Citation(s) in RCA: 305] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 05/13/2009] [Accepted: 05/14/2009] [Indexed: 05/08/2023]
Abstract
In modern purification techniques employing semiconductor mediated photooxidation of toxic substances, zinc oxide (ZnO) and titanium dioxide (TiO2) are the most widely used metal oxides due to their unique blend of properties. However, the band edges of these semiconductors lie in the UV region which makes them inactive under visible light irradiation. Researchers have been interested in the modification of electronic and optical properties of these metal oxides for their efficient use in water and air purification under visible light irradiation. Visible light activity has been induced in TiO2 and ZnO by surface modification via organic materials/semiconductor coupling and band gap modification by doping with metals and nonmetals, co-doping with nonmetals, creation of oxygen vacancies and oxygen sub-stoichiometry. This paper encompasses the progress and developments made so far through these techniques in the visible light photocatalysis with TiO2 and ZnO. Recently, nitrogen doping in titania has been extensively carried out and therefore somewhat detailed discussion in this respect has been presented. Visible light activation of titania clusters encapsulated in zeolite-Y by nitrogen doping and incorporation of dye or organic sensitizers inside the zeolite framework, has also been highlighted in this review.
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Affiliation(s)
- Shama Rehman
- Nanotechnology Research Group, School of Electrical Engineering and Computer Science (SEECS), National University of Sciences and Technology (NUST), Sector H-12, Islamabad, Punjab 44000, Pakistan.
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15
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Butt AM, Dinsdale J. Opposing actions of fibroblast growth factor-2 on early and late oligodendrocyte lineage cells in vivo. J Neuroimmunol 2005; 166:75-87. [PMID: 16005082 DOI: 10.1016/j.jneuroim.2005.05.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
In vitro studies indicate that fibroblast growth factor 2 (FGF2) has diverse effects on cells of the early and late oligodendrocyte lineage. Here, we have examined this in vivo by comparing the actions of FGF2 on the developing and developed anterior medullary velum (AMV) of postnatal rats. FGF2, or saline vehicle in controls, was administered into the cerebrospinal fluid of anaesthetised rats between postnatal day (P)6 and P9 either for 1 day (1d), 2d, or 3d, and AMV were analysed at P8 or P9. Immunolabelling for NG2 was used to identify oligodendrocyte progenitor cells (OPCs) and Rip for premyelinating and myelin-forming oligodendrocytes. At P6-9, the AMV was clearly demarcated into myelinated caudal and premyelinated rostral areas. The caudal AMV was populated by differentiated myelin-forming oligodendrocytes and 'adult' OPCs, whilst the rostral AMV contained mixed populations of 'perinatal' OPCs, and both premyelinating and myelin-forming oligodendrocytes. Administration of FGF2 resulted in the accumulation of OPCs in both the developing and developed AMV. Notably, FGF2 had a bipartite action on premyelinating oligodendrocytes, at first dramatically expanding their population throughout the premyelinated and myelinated AMV, but subsequently causing the loss of these previously generated cells. In addition, FGF2 induced the loss of existing myelin-forming oligodendrocytes in the developed AMV, and arrested the generation of new myelin-forming cells in the developing AMV. This study provides evidence that FGF2 has opposing positive and negative actions on early and late oligodendrocyte lineage cells in vivo.
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Affiliation(s)
- A M Butt
- Wolfson Centre for Age Related Diseases, GKT Guy's Campus, King's College, London, UK.
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16
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Abstract
An early concept of glial function envisaged them as passive and unexcitable structural elements, much like the connective tissues of organs in the periphery. It is now known that glia have a widespread range of physiological roles and react to all forms of pathological insult. This paper reviews the major functions of oligodendrocytes and astrocytes, the main types of glia in the optic nerve, and examines novel NG2-glia, otherwise known as oligodendrocyte progenitor cells (OPCs). The major function of oligodendrocytes is to produce the myelin sheaths that insulate CNS axons, but they also have important roles in the establishment of nodes of Ranvier, the sites of action potential propagation, and axonal integrity. Astrocytes have multiple physiological and pathological functions, including potassium homeostasis and metabolism, and reactive astrogliosis in response to CNS insults. The bulk of NG2-glia are postmitotic complex cells, distinct from OPCs, and respond to any insult to the CNS by a rapid and stereotypic injury response. This may be their primary unction, but NG2-glia, or a subpopulation of NG2-expressing adult OPCs, also provide remyelinating oligodendrocytes following demyelination. Oligodendrocytes, astrocytes, and NG2-glia all contact axons at nodes of Ranvier and respond to glutamate, ATP, and potassium released during axonal electrical activity. Glutamate and ATP evoke calcium signalling in optic nerve glia and have dual roles in physiology and pathology, coupling glial functions to axonal activity during normal activity, but enhanced activation induces an injury response, as seen following injury, demyelination, and ischaemia.
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Affiliation(s)
- A M Butt
- Centre for Neuroscience Research, GKT School of Biomedical Sciences, King's College, London, UK.
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17
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Abstract
We present evidence that NG2+ glia are an integral part of an oligodendrocyte/synantocyte (OS) lineage stream the progenitors of which begin to produce both glial phenotypes at about birth. The NG2 CSPG is differentially distributed within the OS lineage, being expressed in progenitors and synantocytes but not in oligodendrocytes. All cells in the OS lineage, except the primordial stem cells, express O4. The oligodendrocyte line reacts with CD9, but synantocytes are CD9-. Nonetheless, synantocytes are morphologically complex and specialised glia which contact axolemma in myelinated fibres at nodes of Ranvier and synaptic terminals, and form >99% of all NG2+ glia in the adult CNS. Thus, the other NG2+ phenotype, the adult oligodendrocyte progenitor cell (AOPC), constitutes a small population of <1% of all NG2+ glia in the mature CNS. AOPC are a heterogeneous set of cells probably originating from multiple sources which, by definition, produce oligodendrocytes in the adult to replace loss after trauma, demyelination and normal 'wear and tear'. The definitive functions of synantocytes remain undefined.
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Affiliation(s)
- M Berry
- Neural Damage and Repair, Centre for Neuroscience Research, Hodgkin Building, GKT School of Biomedical Sciences, Guy's Campus, London Bridge, London SE1 1UL, UK.
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18
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Chekenya M, Enger PØ, Thorsen F, Tysnes BB, Al-Sarraj S, Read TA, Furmanek T, Mahesparan R, Levine JM, Butt AM, Pilkington GJ, Bjerkvig R. The glial precursor proteoglycan, NG2, is expressed on tumour neovasculature by vascular pericytes in human malignant brain tumours. Neuropathol Appl Neurobiol 2002; 28:367-80. [PMID: 12366818 DOI: 10.1046/j.1365-2990.2002.00412.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glial precursor cells express NG2 and GD3 in the developing brain. These antigens are both over-expressed during neoplasia, which suggests they may have specific functions in the malignant progression of human brain tumours. This study describes the expression of NG2 and GD3 in 28 paediatric and adult brain tumours. Glioblastoma biopsy spheroids were also implanted into nude rats to assess the regional distribution of the molecules within the tumour. These xenografts showed extensive infiltration and growth that mimicked the growth patterns of human gliomas in situ. NG2 was identified in 20 out of 28 brain tumours, where the expression was confined to the main mass of the tumour, and was reduced towards the tumour periphery. NG2 was mainly associated with blood vessels on both the pericyte and basement membrane components of the tumour vasculature. Ki67 (MIB-1) labelling indicated that NG2 expression was associated with areas of high cellular proliferation. Conversely, all the tumours expressed GD3, which was present both in the tumour main mass and throughout the periphery. Thus, the expression of NG2 may be indicative of tumour progression and might be an amenable target for future therapeutic interventions.
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Affiliation(s)
- M Chekenya
- Department of Anatomy and Cell Biology, University of Bergen, Bergen, Norway.
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Butt AM, Murch SH, Ng CL, Kitching P, Montgomery SM, Phillips AD, Walker-Smith JA, Thomson MA. Upregulated eotaxin expression and T cell infiltration in the basal and papillary epithelium in cows' milk associated reflux oesophagitis. Arch Dis Child 2002; 87:124-30. [PMID: 12138061 PMCID: PMC1719188 DOI: 10.1136/adc.87.2.124] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Cows' milk sensitive reflux oesophagitis is an emerging clinical entity in children, normally indistinguishable from primary gastro-oesophageal reflux (GOR) apart from the response to dietary antigen exclusion. It is conjectural whether a tendency towards mucosal eosinophilia distinguishes this group from primary GOR. AIMS To determine whether there may be differences in the mucosal lesion within the oesophagus in those children with reflux in association with cows' milk induced small bowel pathology, particularly in relation to the eosinophil chemokine eotaxin. METHODS A total of 29 children underwent endoscopic assessment, including nine with cows' milk sensitive enteropathy (CMSE) and associated GOR, seven histologically normal controls, six with primary GOR, and seven disease controls. Oesophageal biopsy specimens were examined immunohistochemically for the chemokines eotaxin and MCP-2, and T cell lineage and activation markers. RESULTS Strong upregulation of eotaxin expression, limited to basal and papillary epithelium, occurred in all CMSE patients. By contrast, weak expression was seen in a minority of controls and in 50% of primary GOR patients. Infiltration of CD3, CD4, and CD8 lymphocytes occurred in similar distribution in CMSE patients, significantly increased above controls. Significant upregulation of activation markers (CD25, HLA-DR) was also seen in the CMSE group within basal and papillary epithelium compared to controls and primary GOR. CONCLUSION Basal and papillary epithelial eotaxin expression, with focal lymphocyte activation, was seen in infants with CMSE associated GOR. This preliminary study provides early evidence to suggest a pathogenesis distinct from primary GOR, in which specific recruitment of T cells and eosinophils may contribute to oesophageal dysmotility.
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Affiliation(s)
- A M Butt
- Centre for Paediatric Gastroenterology, Royal Free and University College School of Medicine, London, UK
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20
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Abstract
Fibroblast growth factor-2 (FGF-2) controls in part the timely differentiation of oligodendrocytes into the myelin-producing cells of the CNS. However, although differentiated oligodendrocytes express FGF receptors (R), the effect of FGF-2 on myelin-producing oligodendrocytes in vivo was unknown. In the present study, we show that delivery of FGF-2 into the cerebrospinal fluid of anaesthetized rat pups, aged postnatal day (P) 6 to 9, induced a severe loss of myelin in the caudal anterior medullary velum (AMV). Furthermore, we show that the caudal AMV was myelinated at the time of treatment, so the effects of FGF-2 represent a loss of myelin and not delayed differentiation. This was confirmed by injection of platelet-derived growth factor-AA (PDGF-AA), a factor known to affect the differentiation of PDGF-alphaR expressing oligodendrocyte progenitors, but which did not induce myelin loss in the caudal AMV and did not affect differentiated oligodendrocytes, which do not express PDGF-alphaR. Compared to controls treated with saline or PDGF-AA, FGF-2 induced an accumulation of PLP protein and MBP mRNA within the somata of myelin-producing oligodendrocytes. The results indicate that FGF receptor signalling disrupts myelin production in differentiated oligodendrocytes in vivo and interrupted the transport of myelin-related gene products from the oligodendrocyte cell body to their myelin sheaths.
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Affiliation(s)
- D R Goddard
- Centre for Neuroscience, GKT School of Biomedical Sciences, King's College London, United Kingdom
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21
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Abstract
Purinoceptors have been shown to be important in mediating Ca(2+) signalling in glial cells and it has been proposed that they may have a role in their response to injury. To investigate this, the glial response to adenosine 5'triphosphate (ATP) was measured in situ, in optic nerves from juvenile rats that were enucleated at postnatal day (P) 1; age-matched normal nerves were used as controls. The optic nerve is a typical central nervous system (CNS) white matter tract containing axons and glial cells, but not neurones or synapses. Following neonatal enucleation, axons degenerate and oligodendrocytes do not develop, so that the optic nerve is populated predominantly by reactive astrocytes, with a minor population of activated microglia. Application of 1 mM ATP evoked a large and rapid increase in glial [Ca(2+)](i) in fura-2 ratiometric whole nerve recordings from normal and gliotic axon-free nerves. Significantly, the response to ATP had a prolonged duration in gliotic axon-free nerves and there was as shift in the agonist rank order of potency from ATP = ADP > UTP >> alpha,beta-metATP to ATP > ADP = UTP = alpha,beta-metATP. The results indicate an in situ role for ATP signalling in reactive astrocytes, via metabotropic P2Y(1) and P2Y(2/4) purinoceptors and ionotropic P2X purinoreceptors. The change in the purinoceptor profile following axon degeneration suggests a special role for P2X purinoceptors in mediating the glial reaction to CNS injury.
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Affiliation(s)
- G James
- Neural Damage & Repair Research Group, Centre for Neuroscience Research, Guy's Campus, Hodgkin Building, King's College London, London SE1 1UL, UK
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22
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Abstract
It is known that ATP acts as an extracellular messenger mediating Ca2+ signalling in glial cells. Here, the mechanisms involved in the ATP-evoked increase in glial [Ca2+]i were studied in situ, in the acutely isolated rat optic nerve. ATP and agonists for P2X (a,b-metATP) and P2Y (2MeSATP) purinoreceptors triggered raised glial [Ca2+]i, and there was no significant difference between cells identified morphologically as astrocytes and oligodendrocytes. Dose-response curves indicated that P2Y receptors were activated at nanomolar concentrations, whereas P2X purinoreceptors were only activated above 10 microM. The rank order of potency for several agonists indicated optic nerve glia expressed heterogeneous purinoreceptors, with P2Y1< or = P2Y2/4< or = P2X. The ATP evoked increase in [Ca2+]i was reversibly blocked by the P2X/Y purinoreceptor antagonist suramin (100 microM) and markedly reduced by thapsigargin (10 microM), which blocks IP3-dependent release of Ca2+ from intracellular stores. Removal of extracellular Ca2+ reduced the ATP evoked increase in [Ca2+]i and completely blocked its recovery, indicating that refilling of intracellular stores was ultimately dependent on Ca2+ influx from the extracellular milieu. The results implicate ATP as an important signal in CNS white matter astrocytes and oligodendrocytes in situ, and indicate that metabotropic P2Y purinoreceptors mobilize intracellular Ca2+ at physiological concentrations of ATP, whereas ionotropic P2X purinoreceptors induce Ca2+ influx across the plasmalemma only at high concentrations of ATP, such as occur following CNS injury.
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Affiliation(s)
- G James
- Neural Damage & Repair Research Group, Centre for Neuroscience Research, King's College London, London, London, UK
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23
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Butt AM, Johnman C, Nandwani R. Sexually transmitted infections in people with HIV infection. BMJ 2001; 322:796. [PMID: 11282881 PMCID: PMC1119967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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25
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Song J, Goetz BD, Kirvell SL, Butt AM, Duncan ID. Selective myelin defects in the anterior medullary velum of the taiep mutant rat. Glia 2001; 33:1-11. [PMID: 11169787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The taiep rat is a myelin mutant in which initial hypomyelination is followed by progressive demyelination of the CNS. An in vitro study suggests that accumulation of microtubules within oligodendrocytes is the cause of the taiep myelin defects (Song et al., 1999). In this article, we analyze microtubule accumulation in relation to taiep myelin defects in vivo in the anterior medullary velum (AMV), a CNS tissue that enables entire oligodendrocyte units to be resolved. Immunohistochemical analysis demonstrated notably high levels of beta-tubulin and the microtubule associated protein tau in the somata and processes of taiep oligodendrocytes. This was correlated with markedly reduced expression of the myelin proteins, proteolipid protein (PLP), myelin basic protein (MBP), 2',3 -cyclic nucleotide 3'-phosphodiesterase, and both large (L) and small (S) isoforms of myelin-associated glycoprotein (MAG). Moreover, PLP and L-MAG, which are dependent on the microtubule system for intracellular transport, accumulated in the perinuclear cytoplasm of the taiep oligodendrocyte. The myelin deficit was most marked in the area of the AMV populated by the small somata oligodendrocytes that have fine long processes that support numerous myelin sheaths of small diameter axons. Type III/IV oligodendrocytes, which have large somata and short processes that support a small number of myelin sheaths of large diameter axons, were also affected to a certain degree in compact myelin sheath formation. These results support the hypothesis that myelin loss and oligodendrocyte disruption in the taiep mutant result from a defect in the microtubule system that transports myelin components from the somata to the myelin sheath.
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Affiliation(s)
- J Song
- Department of Medical Science, Shool of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin 53706, USA.
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26
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Abstract
The rat anterior medullary velum (AMV) is representative of the brain and spinal cord, overall, and provides an almost two-dimensional preparation for investigating axon-glial interactions in vivo. Here, we review some of our findings on axon-oligodendrocyte unit relations in our adult, development, and injury paradigms: (1) adult oligodendrocytes are phenotypically heterogeneous, conforming to Del Rio Hortega's types I-IV, whereby differences in oligodendrocyte morphology, metabolism, myelin sheath radial and longitudinal dimensions, and biochemistry correlate with the diameters of axons in the unit; (2) oligodendrocytes derive from a common premyelinating oligodendrocyte phenotype, and divergence of types I-IV is related to the age they emerge and the presumptive diameter of axons in the unit; (3) during myelination, axon-oligodendrocyte units progress through a sequence of maturation phases, related to axon contact, ensheathment, establishment of internodal myelin sheaths, and finally the radial growth and compaction of the myelin sheath; (4) we provide direct in vivo evidence that platelet-derived growth factor-AA (PDGF-AA), fibroblast growth factor (FGF-2), and insulin-like growth factor-I (IGF-I) differentially regulate these events, by injecting the growth factors into the cerebrospinal fluid of neonatal rat pups; (5) in lesioned adult AMV, transected central nervous system (CNS) axons regenerate through the putatively inhibitory environment of the glial scar, but remyelination by oligodendrocytes is incomplete, indicating that axon-oligodendrocyte interactions are defective; and (6) in the adult AMV, cells expressing the NG2 chondroitin sulphate have a presumptive adult oligodendrocyte progenitor antigenic phenotype, but are highly complex cells and send processes to contact axolemma at nodes of Ranvier, suggesting they subserve a specific perinodal function. Thus, axons and oligodendrocyte lineage cells form interdependent functional units, but oligodendrocyte numbers, differentiation, phenotype divergence, and myelinogenesis are governed by axons in the units, mediated by growth factors and contact-dependent signals.
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Affiliation(s)
- A M Butt
- Neural Damage and Repair Group, Centre for Neuroscience, Guy's Campus, GKT School of Biomedical Sciences, King's College London, London, United Kingdom.
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27
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Chekenya M, Rooprai HK, Davies D, Levine JM, Butt AM, Pilkington GJ. The NG2 chondroitin sulfate proteoglycan: role in malignant progression of human brain tumours. Int J Dev Neurosci 1999; 17:421-35. [PMID: 10571405 DOI: 10.1016/s0736-5748(99)00019-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The expression and function of NG2, a transmembrane chondroitin sulfate proteoglycan was studied in human gliomas of various histological types in culture using immunocytochemistry and flow cytometry. NG2 was differentially expressed in the neoplasms, with higher expression in high compared to low-grade gliomas. In acutely isolated cells from human biopsies, NG2 +ve and NG2 -ve populations were morphologically distinct from each other, and NG2 +ve cells were more proliferative than NG2 -ve cells. The mitogens platelet derived growth factor (PDGF-AA) and basic fibroblast growth factor (bFGF) added in combination to serum-free medium (SFM) upregulated NG2 expression on glioblastoma multiforme cells in culture but had little effect on NG2 expression on the anaplastic astrocytoma cells. Furthermore, NG2 was colocalised with the platelet derived growth factor alpha receptor (PDGFalphaR) and antibody blockade of the PDGF-alphaR ablated NG2 expression on the glioblastoma multiforme cells, suggesting that increased NG2 expression in the presence of PDGF-AA is mediated via the PDGF-alphaR. Assays of migration and invasion indicate that NG2 +ve glioma cells migrated more efficiently on collagen IV and that NG2 -ve cells were more invasive than their NG2 +ve counterparts. The results indicate that NG2 may be, respectively, positively and negatively related to the proliferative and invasive capacity of glioma cells. Thus, expression of the NG2 proteoglycan may have major implications for malignant progression in glial neoplasms and may prove a useful target for future therapeutic regimens.
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Affiliation(s)
- M Chekenya
- Experimental Neuro-oncology Group, Department of Neuropathology, Institute of Psychiatry, King's College, London, UK
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28
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Abstract
The in vivo effects of fibroblast growth factor-2 (FGF-2) and insulin-like growth factor-I (IGF-I) on oligodendrocytes and CNS myelination were determined in the postnatal rat anterior medullary velum (AMV) following injection of both cytokines into the cerebrospinal fluid. Either FGF-2, IGF-I, or saline were administered via the lateral ventricle, twice daily commencing at postnatal day (P) 6. At P9, AMV were immunohistochemically labeled with the Rip antibody, to enable analysis of the numbers of myelin sheaths and of promyelinating and myelinating oligodendrocytes; promyelinating oligodendrocytes are a recognisable immature phenotype which express myelin-related proteins prior to forming myelin sheaths. In parallel experiments, AMV were treated for Western blot analysis to determine relative changes in expression of the myelin proteins 2', 3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and myelin oligodendrocyte glycoprotein (MOG), which, respectively, characterise early and late stages of myelin maturation. In FGF-2-treated AMV, the number of promyelinating oligodendrocytes increased by 87% compared to saline-injected controls. The numbers of myelinating oligodendrocytes and myelin sheaths were not decreased, but conspicuous unmyelinated gaps within fibre tracts were indications of retarded myelination following FGF-2 treatment. Western blot analysis demonstrated decreased expression of CNP and a near-total loss of MOG, confirming that FGF-2 decreased myelin maturation. In contrast, IGF-I had no effect on the number of promyelinating oligodendrocytes, but increased the numbers of myelinating oligodendrocytes and myelin sheaths by 100% and 93%, respectively. Western blot analysis showed that the amount of CNP was increased following IGF-I treatment, correlating with the greater number of oligodendrocytes, but that MOG expression was lower than in controls, suggesting that the increased number of myelin sheaths in IGF-I was not matched by increased myelin maturation. The results provide in vivo evidence that FGF-2 and IGF-I control the numbers of oligodendrocytes in the brain and, respectively, retard and promote myelination.
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Affiliation(s)
- D R Goddard
- Division of Physiology, Guy's King's and St. Thomas' School of Biomedical Sciences, King's College, London, England
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29
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James G, Butt AM. Adenosine 5' triphosphate evoked mobilization of intracellular calcium in central nervous system white matter of adult mouse optic nerve. Neurosci Lett 1999; 268:53-6. [PMID: 10400076 DOI: 10.1016/s0304-3940(99)00370-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although it has been established that immature glial cells express functional purinergic receptors, the responsiveness of mature glial cells in vivo had not been elucidated. This question was addressed using fura-2 ratiometric measurements of [Ca2+]i in the adult mouse optic nerve, a central nervous system (CNS) white matter tract, taking advantage of the facts that (i), the optic nerve contains glial cells but not neurons and (ii), that fura-2 loads primarily astrocytes in isolated intact optic nerves. We show that adenosine 5' triphosphate (ATP) evoked an increase in [Ca2+]i in a concentration-dependent manner with a half-maximal effect at 3 microm ATP, and with a rank order of agonist potency of ATP > ADP > alpha,beta-methyline-ATP > UDP > adenosine. The results indicate mainly P2Y and P2X components, consistent with the in vitro astroglial purinergic receptor profile. The in vivo response of mature glia to ATP may be important in their response to CNS damage.
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Affiliation(s)
- G James
- Division of Physiology, GKT School of Biomedical Sciences, Kings College London, St. Thomas' Hospital, UK
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30
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Butt AM, Duncan A, Hornby MF, Kirvell SL, Hunter A, Levine JM, Berry M. Cells expressing the NG2 antigen contact nodes of Ranvier in adult CNS white matter. Glia 1999; 26:84-91. [PMID: 10088675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The NG2 antibody, which recognises an integral membrane chondroitin sulphate, labels a significant population of cells in adult CNS white matter tracts of the rat optic nerve and anterior medullary velum (AMV). Adult NG2+ cells are highly complex with multiple branching processes and we show by EM immunocytochemistry that they extend perinodal processes, which contact nodes of Ranvier. NG2+ cells do not react to conventional immunohistochemical markers for adult glia and so we reservedly term them NG2P cells. In vitro, NG2 labels oligodendrocyte-type-2 astrocyte (O-2A) progenitors that can give rise to oligodendrocytes or type-2 astrocytes, depending on the culture medium. Thus, it is possible that NG2P cells may be derived from the same stem cells as oligodendrocytes. Interestingly, NG2+ cells identified previously in adult CNS displayed phenotypic characteristics of O-2Aadult progenitors and it is possible that, like them, NG2P cells might retain the capacity of generating oligodendrocytes in the adult CNS. This may be an important role of NG2P cells in demyelinating diseases such as multiple sclerosis. It is significant therefore that the perinodal processes of NG2P cells contact the only sites of exposed axolemma in myelinated axons, so that NG2P cells are ideally situated to detect and respond to changes in axonal function during demyelination. A further implication of our finding is that NG2P cells may perform functions at nodes of Ranvier previously attributed to perinodal astrocytes, including the clustering and maintenance of sodium channels in the axon membrane at nodes, during development and following demyelination.
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Affiliation(s)
- A M Butt
- Division of Physiology, Guy's, King's and St. Thomas' School of Biomedical Sciences, King's College London, United Kingdom.
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31
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Berry M, Hunter AS, Duncan A, Lordan J, Kirvell S, Tsang WL, Butt AM. Axon-glial relations during regeneration of axons in the adult rat anterior medullary velum. J Neurocytol 1998; 27:915-37. [PMID: 10659683 DOI: 10.1023/a:1006953107636] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The anterior medullary velum (AMV) of adult Wistar rats was lesioned in the midsagittal plane, transecting all decussating axons including those of the central projection of the IVth nerve. At selected times up to 200 days after transection, the degenerative and regenerative responses of axons and glia were analyzed using transmission and scanning electron microscopy and immunohistochemistry. In particular, both the capacity of oligodendrocytes to remyelinate regenerated fibers and the stability of the CNS/PNS junctional zone of the IVth nerve rootlet were documented. Transected central AMV axons exhibited four patterns of fiber regeneration in which fibers grew: rostrocaudally in the reactive paralesion neuropil (Group 1); randomly within the AMV (Group 2); into the ipsilateral IVth nerve rootlet, after turning at the lesion edge and growing recurrently through the old degenerated contralateral central trochlear nerve trajectory (Group 3); and ectopically through paralesion tears in the ependyma onto the surface of the IVth ventricle (Group 4). Group 1-3 axons regenerated unperturbed through degenerating central myelin, reactive astrocytes, oligodendrocytes, microglia, and large accumulations of hematogenous macrophages. Only Group 3 axons survived long term in significant numbers, and all became myelinated by oligodendrocytes, ultimately establishing thin sheaths with relatively normal nodal gaps and intersegmental myelin sheath lengths. Schwann cells at the CNS/PNS junction of the IVth nerve rootlet did not invade the CNS, but astrocyte processes grew across the junction into the PNS portion of the IVth nerve. The basal lamina of the junctional glia limitans remained stable throughout the experimental period.
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Affiliation(s)
- M Berry
- Division of Anatomy, Cell and Human Biology, GKT, London, UK
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Butt AM, Ibrahim M, Gregson N, Berry M. Differential expression of the L- and S-isoforms of myelin associated glycoprotein (MAG) in oligodendrocyte unit phenotypes in the adult rat anterior medullary velum. J Neurocytol 1998; 27:271-80. [PMID: 10640185 DOI: 10.1023/a:1006996713413] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have previously demonstrated differences in the expression of carbonic anhydrase II (CAII) in oligodendrocyte units myelinating small and large diameter fibres in the anterior medullary velum (AMV) of the adult rat (each unit comprises the cell body, processes and myelin sheaths). Others have indicated that myelin composition may also vary with respect to myelin basic protein (MBP) and proteolipid protein (PLP), and the small (S)- and large (L)-isoforms of myelin associated glycoprotein (MAG). In this study, we have determined the expression of myelin proteins in oligodendrocyte unit phenotypes I-IV, which myelinate fibres ranging in diameter from 0.3-12 microns diameter in the AMV, by using double immunolabelling for Rip, which labels entire units, and MBP, PLP, myelin oligodendrocyte glycoprotein (MOG), L-MAG and S-MAG. We show differences in the expression of L- and S-MAG in units which myelinate different diameter fibres: (1) type I/II units myelinating small diameter fibres had a L-MAG+/S-MAG-/CAII+ phenotype; (2) type II/III units myelinating different diameter fibres had a L-MAG+/S-MAG+/CAII+ phenotype; (3) type III/IV units myelinated large diameter fibres had a L-MAG+/S-MAG+/CAII- phenotype. All units, irrespective of fibre diameter, expressed Rip, MBP, PLP and MOG. The results indicate that type I-IV units may be variants of a single oligodendrocyte population and that phenotypic differences are determined by the diameter of fibres within the unit. The possible significance of metabolic and biochemical differences between oligodendrocytes myelinating small and large diameter axons are discussed with reference to the pathology of demyelination.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, Guy's Hospital, London, U.K
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33
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Butt AM, Ibrahim M, Berry M. Axon-myelin sheath relations of oligodendrocyte unit phenotypes in the adult rat anterior medullary velum. J Neurocytol 1998; 27:259-69. [PMID: 10640184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Axon-oligodendrocyte relations of Rip-immunolabelled and dye-injected oligodendrocyte units are characterised in the adult rat anterior medullary velum (AMV). Each oligodendrocyte unit comprised the oligodendrocyte cell body, processes and the internodal myelin segments they support. Oligodendrocyte units corresponded to classically described type I/II or type III/IV unit phenotypes which respectively myelinated discrete populations of small and large diameter axons, delineated by a myelinated fire diameter of 2-4 microns (diameter of the axon plus its myelin sheath). Within units, mean fibre diameter was directly related to mean internodal length and inversely related to the number of myelin sheaths in the unit. The relationship between fibre diameter and internodal length was retained in units which myelinated axons of different diameters, indicating that axon diameter was an important determinant of the longitudinal dimensions of myelin sheaths. We also show that type III/IV units maintained a far greater volume of myelin than type I/II units. It was concluded that type I/II and III/IV oligodendrocytes represent two functionally and morphologically distinct phenotypes whose distribution densities were determined by the diameter and spatial dispersion of axons.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, Guy's Hospital, London, U.K
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O'Neill JK, Baker D, Morris MM, Gschmeissner SE, Jenkins HG, Butt AM, Kirvell SL, Amor S. Optic neuritis in chronic relapsing experimental allergic encephalomyelitis in Biozzi ABH mice: demyelination and fast axonal transport changes in disease. J Neuroimmunol 1998; 82:210-8. [PMID: 9585818 DOI: 10.1016/s0165-5728(97)00203-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The encephalitogenicity of optic nerve tissue was demonstrated in Biozzi ABH (H-2(dq1)) mice. Acute experimental allergic encephalomyelitis (EAE) occurred in 11/14 animals and 4/5 exhibited relapse. The involvement of the optic nerve in spinal cord homogenate induced chronic relapsing EAE (CREAE) was demonstrated by mononuclear cell infiltration and myelin degradation in the optic nerve prior to and during clinical disease. During the relapse phase gross pathological assessment revealed swollen and translucent plaques on the optic nerves. Advanced lesions showed widespread demyelination, astrocytic gliosis and fibrotic changes of the blood vessels. Physiologically, the fast axonal transport of proteins from the retina to the optic nerve and superior colliculus was significantly decreased during relapse. The association of inflammation and demyelination with physiological deficit in the optic nerve highlights the usefulness of this model in the study of multiple sclerosis in which acute monosymptomatic unilateral optic neuritis is a common manifestation. Furthermore, the novel induction of CREAE with optic nerve homogenate suggests that optic neuritis is a common significant role in the pathophysiology and progression of neurological disease in CREAE which may be relevant to studies of optic neuritis in multiple sclerosis.
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Affiliation(s)
- J K O'Neill
- Department of Clinical Ophthalmology, University College London, UK
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35
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Abstract
There is electrophysiological evidence of a functional role for gamma-aminobutyric acid (GABA) and GABA transporters (GATs) in the neonatal rat optic nerve, and that they are down-regulated during development. The results of the present study demonstrate directly by reverse transcription-polymerase chain reaction (RT-PCR) that the mRNAs encoding for GAT-1, -2 and -3 are expressed in the optic nerves of both neonatal (5 day old) and adult rats. The results support a role for GABA in the developing rat optic nerve, a typical white matter tract which contains axons and glia, but neither neuronal cell bodies nor synapses. Significantly, the persistence of GAT mRNAs suggests an enduring function for both GABA and glial uptake mechanisms in the adult optic nerve.
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Affiliation(s)
- A G Howd
- Division of Physiology, UMDS, Guys' and St. Thomas' Hospital, London, UK
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Butt AM, Hornby MF, Kirvell S, Berry M. Platelet-derived growth factor delays oligodendrocyte differentiation and axonal myelination in vivo in the anterior medullary velum of the developing rat. J Neurosci Res 1997; 48:588-96. [PMID: 9210529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The AA dimeric form of platelet-derived growth factor (PDGF-AA) is implicated in the differentiation of cells of the oligodendrocyte lineage, which express PDGF receptors of the alpha subunit type (PDGF-alphaR). In the present study, we show that a single injection of PDGF-AA into the cerebrospinal fluid of neonatal rats delays oligodendrocyte differentiation and interrupts the progress of myelination in the anterior medullary velum (AMV), a white matter tract roofing the IVth ventricle of the brain. PDGF-AA or saline was injected intrathecally in postnatal day (P) 7 rats, and the AMV was subsequently removed and immunolabelled with the oligodendrocyte-specific antibody Rip, at P9, P12, and P21, corresponding to postinjection days (PID) 2, 5, and 14. At P9 (PID2), myelination was retarded in PDGF-AA-treated rats as opposed to saline-treated controls but progressed rapidly after P12 (PID5). Quantification supported the qualitative observations that PDGF-AA mediated an acute decrease in the number of Rip+ oligodendrocytes at P9-12, which largely recovered by P21, suggesting that PDGF-AA may have delayed recruitment of myelinating oligodendrocytes. However, the definitive number of Rip+ oligodendrocytes in the AMV was not increased, suggesting that its action as a promoter of early oligodendrocyte survival may not ultimately affect the definitive number of myelinating oliogdendrocytes in vivo. We discuss the possibilities that excess PDGF-AA may have acted on early oligodendrocytes (precursors or preoligodendrocytes) to either (1) delay their differentiation by maintaining them in the cell cycle or (2) accelerate their differentiation, which may result in premature cell death in the absence of synchronised survival signals. This study supports a role for PDGF-AA in the timing of oligodendrocyte differentiation in vivo, as has been shown in vitro.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, Guy's and St. Thomas' Hospitals, London, United Kingdom.
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37
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Butt AM, Ibrahim M, Berry M. The relationship between developing oligodendrocyte units and maturing axons during myelinogenesis in the anterior medullary velum of neonatal rats. J Neurocytol 1997; 26:327-38. [PMID: 9192296 DOI: 10.1023/a:1018556702353] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Myelinogenesis was investigated in whole-mounted anterior medullary vela from rats aged postnatal day (P) 10-12, using double immunofluorescence labelling with Rip and anti-neurofilament 200 (NF200) antibodies, to identify oligodendrocytes and axons, respectively. A number of discrete phases of maturation of oligodendrocyte units were recognised. (1) Promyelinating oligodendrocytes co-expressed Rip and Myelin basic Protein and formed axonal associations, prior to ensheathment. (2) Transitional oligodendrocytes contained both ensheathing and non-ensheating processes. (3) Myelinating oligodendrocytes were established after a period of remodelling (in which non-ensheathing processes were lost), appearing as oligodendrocyte unit morphological phenotypes with a definitive number of incipient myelin sheaths. (4) Maturation of myelinating oligodendrocytes was defined as the establishment of internodal sheath lengths and the redistrubution of myelin basic protein from the cell somata and radial processes into the myelin sheaths only. Myelination was probably related to the maturational state of the axons, since it was initiated when the latter had attained a critical diameter of between approximately 0.2 and 0.4 micron, coincident with the expression of NF200. Oligodendrocyte differentiation and myelination of the AMV were asynchronous and multifocal, and at P10: (1) axons which were destined to be of the largest calibre in the adult AMV were already myelinated by early developing oligodendrocytes, whilst those which were destined to be the smallest calibre in the adult were unmyelinated, but ultimately became ensheathed by late developing oligoendrocytes; (2) axons were sequentially ensheathed by early developing myelinating oligodendrocytes and late developing promyelinating oligodendrocytes; (3) all axons were small calibre; (4) oligodendrocyte units exhibited polymorphism. Thus, the development of oligodendrocyte morphological phenotypes was not related solely to either the physical dimension of axon calibre at the time of ensheathment, nor oligodendrocyte birth dates.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, Guy's Hospital, London, UK
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Butt AM, Hornby MF, Ibrahim M, Kirvell S, Graham A, Berry M. PDGF-alpha receptor and myelin basic protein mRNAs are not coexpressed by oligodendrocytes in vivo: a double in situ hybridization study in the anterior medullary velum of the neonatal rat. Mol Cell Neurosci 1997; 8:311-22. [PMID: 9073394 DOI: 10.1006/mcne.1996.0590] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Platelet-derived growth factor (PDGF) is a growth-regulatory dimer with A and B subunits. PDGF-AA, acting via PDGF receptors of the alpha-unit subtype (PDGF-alphaR), is implicated in the differentiation of oligodendrocyte precursors and in the survival of newly formed oligodendrocytes, which gradually lose expression of PDGF-alphaR. However, it is unclear whether terminally differentiated oligodendrocytes express PDGF-alphaR in vivo. To address this question, and to help clarify the role of PDGF-AA in late oligodendrocyte differentiation, we have used double in situ hybridization with digoxigenin- and fluorescein-labeled riboprobes to relate PDGF-alphaR mRNA and myelin basic protein (MBP) mRNA expression in the isolated intact anterior medullary velum (AMV) of rats ages Postnatal Day (P) 10-12 and P30-32. In parallel experiments, AMV were immunolabeled with the oligodendrocyte-specific monoclonal antibody Rip to provide information on oligodendrocyte development and the extent of myelination. At P10, the AMV contained tracts in which axons ranged from unmyelinated to fully myelinated, whereas myelination was complete in P30-32 AMV. The first oligodendrocytes to express MBP mRNA or Rip were promyelinating oligodendrocytes, which had a "star-burst" morphology and had not yet begun to form myelin sheaths. As myelination proceeded, MBP mRNA became dispersed throughout oligodendrocyte units, comprising cell somata, processes, and internodal myelin sheaths. By P30-32, MBP mRNA had been redistributed to the myelin sheaths only, reflecting a change in the site of protein synthesis in mature myelinated axon tracts. At no stage of oligodendrocyte differentiation did we observe cellular coexpression of mRNA for PDGFalphaR and MBP. Our results indicated that oligodendrocytes lost the expression of PDGFalphaR prior to gaining that of myelin gene products, and preclude an action of PDGF-AA on Rip+/MBP+ star-burst promyelinating oligodendrocytes. The spatial and temporal expression of PDGF-alphaR mRNA in the AMV was inversely related to the pattern of maturation of both myelin and oligodendrocytes, and is consistent with PDGF-alphaR being expressed by pro-oligodendrocytes. A notable finding was the high level of expression of PDGF-alphaR mRNA in the AMV of juvenile rats, localized to cell bodies within the myelinated axon tracts, strongly suggesting that oligodendrocyte precursors persisted in the mature velum.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, London SE1 7EH, United Kingdom
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Butt AM, Tutton MG, Kirvell SL, Amor S, Jenkins HG. Morphology of oligodendrocytes during demyelination in optic nerves of mice infected with Semliki Forest virus. Neuropathol Appl Neurobiol 1996; 22:540-7. [PMID: 9004245 DOI: 10.1111/j.1365-2990.1996.tb01133.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Multiple sclerosis (MS) is a demyelinating disease which affects oligodendrocytes, the myelinating cells of the CNS. Demyelination is known to occur in the optic nerves of Balb/c mice infected with the avirulent A7(74) strain of Semliki Forest virus (SFV), and many of the changes are similar to those of patients with MS. The aim of the present study was to determine how demyelination proceeds in individual oligodendrocytes in SFV infection, to help in understanding the pathology of demyelination and remyelination in MS. The whole-cell morphology of individual oligodendrocyte units (defined as the oligodendrocyte, its processes and the internodal myelin segments of the axons it ensheaths) was characterized using intracellular dye injection in isolated intact optic nerves. In untreated control mice, oligodendrocytes had a relatively uniform morphology and each cell on average provided 20 or so nearby axons with single myelin sheaths with internodal lengths of approximately equal to 150 microns. In SFV infected mice, during the peak of demyelination at post-inoculation days 14-21, 55% of oligodendrocytes displayed a range of morphological abnormalities, which most likely represented sequential changes in oligodendrocytes during demyelination. Thus, at the earliest stage of demyelination oligodendrocytes developed swellings or vacuolations along their internodal myelin sheaths, which became gradually attenuated and were completely lost in extreme cases. The results show that whole oligodendrocyte units were affected during SFV-induced demyelination and this is the basis of the focal nature of lesions in this viral model of MS. Individual oligodendrocyte units which had lost their full complement of myelin sheaths had the appearance of immature oligodendrocytes, suggesting they had undergone dedifferentiation. We concluded that these cells may not be destroyed during demyelination and it is possible they are capable of remyelination which is a feature of SFV infection in mice and MS in humans.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS. St Thomas' Hospital, London, UK
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Abstract
In this paper we make the surprising observation that intracellular injection of horseradish peroxidase (HRP) into a single myelinating oligodendrocyte also resulted in localised HRP labelling at the nodes of Ranvier of some axons of the unit. It appeared that HRP had been transferred to the nodal axoplasm from the paranodal loops of the HRP-filled oligodendrocyte. Three HRP-filled oligodendrocytes from isolated optic nerves of 14-day-old rats were analysed by serial section electron microscopy, and HRP was observed in the axonal cytoplasm at three of the nodes of Ranvier delineated by one of the cells. At labelled nodes, HRP was of a uniform intensity throughout the nodal axoplasm. Axonal labelling gradually diminished along the paranodal regions and was not evident in the contiguous internodal axoplasm beyond 20 microns from the node. The myelin sheaths, paranodal loops, and axons appeared normal at labelled nodes, and the paranodal loops and astrocyte perinodal processes adjacent to those of the HRP-filled oligodendrocyte unit did not contain HRP. There was no evidence of extracellular HRP or tissue damage in the surrounding neuropil, and axons neighbouring those enwrapped by the HRP-filled oligodendrocyte did not contain HRP. The possibility that axonal labelling was an artefact of either iontophoretic injection or tissue preparation is discussed. This provocative finding is not definite proof of exchange, but the balance of evidence supports the possibility that there was transcellular exchange of HRP at paranodes between the labelled oligodendrocyte and some of the axons in the unit. The rarity of HRP transfer to axons suggests that it may be a transient or labile event. It is not clear whether oligodendrocyte to axon macromolecular exchange has real physiological and/or pathological significance.
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Affiliation(s)
- A Duncan
- Division of Physiology, U.M.D.S., Guy's Hospital, London, United Kingdom
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Abstract
The glia response to Wallerian degeneration was studied in optic nerves 21 days after unilateral enucleation (PED21) of immature rats, 21 days old (P21), using immunohistochemical labelling. Nerves from normal P21 and P42 nerves were also studied for comparison. At PED21, there was a virtual loss of axons apart from a few solitary fibres of unknown origin. The nerve comprised a homogeneous glial scar tissue formed by dense astrocyte processes, oriented parallel to the long axis of the nerve along the tracks of degenerated axons. Astrocytes were almost perfectly co-labelled by antibodies to glial fibrillary acid protein and vimentin in both normal and transected nerves. However, there was a small population of VIM+GFAP- cells in normal P21 and P42 nerves, and we discuss the possibility that they correspond to O-2A progenitor cells described in vitro. Significantly, double immunofluorescence labelling in transected nerves revealed a distinct population of hypertrophic astrocytes which were GFAP+VIM-. These cells represented a novel morphological and antigenic subtype of reactive astrocyte. It was also noted that the number of oligodendrocytes in transected nerves did not appear to be less than in normal nerves, on the basis of double immunofluorescence staining for carbonic anhydrase II, myelin oligodendrocyte glycoprotein, myelin basic protein, glial fibrillary acid protein and ED-1 (for macrophages), although it was not excluded that a small proportion may have been microglia. A further prominent feature of transected nerves was that they contained a substantial amount of myelin debris, notwithstanding that OX-42 and ED1 immunostaining showed that there were abundant microglia and macrophages, sufficient for the rapid and almost complete removal of axonal debris. In conclusion, glial cells in the immature P21 rat optic nerve reacted to Wallerian degeneration in a way equivalent to the adult CNS, i.e. astrocytes underwent pronounced reactive changes and formed a dense glial scar, oligodendrocytes persisted and were not dependent on axons for their continued survival, and there was ineffective phagocytosis of myelin possibly due to incomplete activation of microglia/macrophages.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, St. Thomas' Hospital, London, UK
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Butt AM, Colquhoun K. Glial cells in transected optic nerves of immature rats. I. An analysis of individual cells by intracellular dye-injection. J Neurocytol 1996; 25:365-80. [PMID: 8835785 DOI: 10.1007/bf02284808] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The glial response to Wallerian degeneration was studied in optic nerves following unilateral enucleation in immature rats, aged 21 days old (P21). The three-dimensional morphology of dye-filled glia was determined in intact nerves, at post-enucleation day 21 in normal nerves from untreated P21 rats, by correlating laser scanning confocal microscopy and camera lucida drawings of single cells. In normal and transected nerves, the majority of dye-filled cells comprized astrocytes (54% and 65%, respectively). In normal P21 nerves, the predominant astrocyte form had a complex stellate morphology and had a centrally-located cell body from which branching processes extended randomly. Two other distinct forms were transverse and longitudinal astrocytes, which had a polarized process extension in a plane perpendicular or parallel to the long axis of the nerve, respectively. These forms were recognized in transected nerves also, but astrocytes in transected nerves had a simple morphology on the whole, and extended few, dense processes which branched infrequently. Quantitative analysis of astrocyte morphology confirmed that individual astrocytes underwent considerable remodelling in response to Wallerian degeneration. A prominent reaction was that astrocytes had withdrawn radial processes and extended a greater proportion of processes longitudinally, parallel to the long axis of the nerve and along the course of degenerated axons. A further, notable feature of transected nerves was the development of novel longitudinal forms and of hypertrophic astroglia. These results indicated that all astrocytes became reactive following enucleation and that glial scar formation was not the function of a single astrocyte subtype. Oligodendrocytes in transected nerves had lost their myelin sheaths and appeared as small cells with numerous bifurcating processes which extended radially, but a small number of oligodendrocytes were recognized which apparently supported myelin sheaths (9%, compared to 40% in normal nerves). In addition, there was a significant population of indeterminate cells in transected nerves (26%, compared to 6% in normal nerves) and, although some of these were identified as microglia/macrophages, it was concluded that many were likely to be dedifferentiated oligodendrocytes.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, St. Thomas' Hospital, London, UK
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Berry M, Ibrahim M, Carlile J, Ruge F, Duncan A, Butt AM. Axon-glial relationships in the anterior medullary velum of the adult rat. J Neurocytol 1995; 24:965-83. [PMID: 8719823 DOI: 10.1007/bf01215646] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The anterior medullary velum is a thin sheet of CNS tissue which roofs the rostral part of the IVth ventricle and contains fascicles of myelinated fibres which, in part, arise from the nucleus of the IVth cranial nerve. This study used histochemical, immunohistochemical, and intracellular dye-injection techniques to describe cellular interrelationships in the velum in whole-mounts and in sections. Rip antibody-stained whole mounts provided a unique description of both oligodendrocyte units (defined as an oligodendrocyte and the complement of myelinated internodal segments it forms), and consecutive myelin sheaths along the same axon. A broad range of unit morphologies was categorised into four arbitrary groups, according to classical criteria, which comprised small cells supporting the short, thin myelin sheaths of 15-30 small diameter axons (Type I), through intermediate types (II & III), to the largest cells forming the long, thick myelin sheaths of 1-3 large diameter axons. Rip antibody and ferric ion-ferrocyanide staining, together with intracellular dye injection, revealed oligodendrocyte process branching patterns and their mode of engagement of myelin sheaths, nodes of Ranvier, and the spatial disposition of the outer cytoplasmic rims of myelin sheaths. The latter formed a conspicuous spiral ridge on the exterior surface of myelin sheaths which connected with the paranodal loops at each heminode. Large bundles of axons decussated through the velum, the bulk of which were IVth nerve fibres which constituted the IVth nerve rootlet. The PNS/CNS transitional zone of the IVth nerve was located 0.25-0.50 mm along the root, where astrocytic end-feet defined an abrupt margin, convex towards the periphery, where the heminodes of central and peripheral myelin were apposed, and where the basal lamina tubes of the Schwann cell units were discontinued. The basal processes of ependymal cells lining the ventricular wall of the velum, passed between axon bundles before abutting on the basal lamina of the pia. Many of these processes branched and ran along the axonal bundles. A monolayer of microglia occupied a subependymal stratum in which the non-overlapping dendritic territories of each cell formed a regular mosaic throughout the velum without any obvious interaction with either axons or other glial cells. Astrocytes were also uniformly distributed; their fine processes made up a dense lattice amongst axons, often running parallel and within the fibre bundles; stouter ones had terminal end-feet which undercoated the basal lamina of both the glia limitans externa and the blood vessels in the velum.
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Affiliation(s)
- M Berry
- Division of Anatomy and Cell Biology, UMDS, Guy's and St. Thomas's Hospitals, London, UK
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Ibrahim M, Butt AM, Berry M. Relationship between myelin sheath diameter and internodal length in axons of the anterior medullary velum of the adult rat. J Neurol Sci 1995; 133:119-27. [PMID: 8583214 DOI: 10.1016/0022-510x(95)00174-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Relations between myelin sheath diameters and internodal lengths were measured in whole mounts of osmium stained intact anterior medullary velum (AMV) from glutaraldehyde perfused adult rats. The AMV is a sheet of CNS tissue which roofs the IVth ventricle and contains fascicles of myelinated fibres which arise mainly from the nucleus of the IVth cranial nerve. These fibers displayed a broad range of myelin sheath external diameters and internodal lengths, from < 1-12 microns and 50-750 microns, respectively. Myelin sheath external diameter was a measurement of the axonal diameter plus the thickness of its myelin sheath, while internodal length was measured as the distance between consecutive nodes. There was a broadly linear relationship between myelin sheath diameters and internodal lengths, with the smaller diameter sheaths tending to have shorter internodes than the larger. However, the correlation was weak and for any given diameter myelin sheaths displayed considerable variation in their internodal lengths. The smallest diameter myelin sheaths, < 4 microns, consistently had shorter internodes than predicted by a linear regression and, in an analysis of consecutive internodes in single fibres, the slope was flattened in fibres with a diameter > 4 microns. Our results indicated that small and large calibre fibres may have different myelin sheath diameter-internodal length interrelations.
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Affiliation(s)
- M Ibrahim
- Division of Physiology, U.M.D.S., Guy's Hospital, London, UK
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Abstract
The effect of histamine, bradykinin and serotonin on blood-brain barrier permeability was investigated using in situ measurement of transendothelial electrical resistance in pial microvessels of anaesthetized rats. Mean resistance of vessels superfused with artificial cerebrospinal fluid was 1800 omega cm2, indicating a tight barrier with extremely low ion permeability. In paired experiments from continuous measurements in single vessels, addition of 10(-3) M serotonin to the solution bathing the brain had no marked effect on resistance; whereas both histamine and bradykinin, applied at a concentration of 10(-4) M, caused a rapid and reversible decrease in resistance. Mean resistance was 408 and 505 omega cm2 in 10(-4) M histamine and bradykinin, respectively, and approximately 50% of vessels had a resistance less than 250 omega cm2, compared to 12% in controls, indicating a leaky blood-brain barrier that is not capable of normal brain ion homeostasis. Histamine and bradykinin had similar dose-response relations, and a maximal effect was observed between 20 and 50 microM. Thus, histamine and bradykinin act at the abluminal (brain-facing) membranes of the cerebral endothelium to mediate blood-brain barrier opening. These results support a role for histamine and bradykinin in brain oedema formation.
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Affiliation(s)
- A M Butt
- Division of Physiology, U.M.D.S., St. Thomas' Hospital, London, UK
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Butt AM, Ibrahim M, Ruge FM, Berry M. Biochemical subtypes of oligodendrocyte in the anterior medullary velum of the rat as revealed by the monoclonal antibody Rip. Glia 1995; 14:185-97. [PMID: 7591030 DOI: 10.1002/glia.440140304] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Oligodendrocytes were studied in the anterior medullary velum (AMV) of the rat using the monoclonal antibody Rip, an oligodendrocyte marker of unknown function. Confocal microscopic imaging of double immunofluorescent labelling with antibodies to Rip and carbonic anhydrase II (CAII) revealed two biochemically and morphologically distinct populations of oligodendrocyte which were either Rip+CAII+ or Rip+CAII-. Double immunofluorescent labelling with Rip and myelin basic protein (MBP) or glial fibrillary acidic protein (GFAP) provided direct evidence that Rip-labelled cells were phenotypically oligodendrocytes and confirmed that Rip did not recognise astrocytes. Oligodendrocytes which were Rip+CAII+ supported numerous myelin sheaths for small diameter axons, whilst Rip+CAII- oligodendrocytes supported fewer myelin sheaths for large diameter axons. Morphologically, Rip+CAII+ oligodendrocytes corresponded to types I or II of classical nomenclature, whilst Rip+CAII- oligodendrocytes corresponded to types III and IV. The results demonstrated a biochemical difference between oligodendrocytes which myelinated small and large diameter fibres.
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Affiliation(s)
- A M Butt
- Division of Physiology, U.M.D.S., Guy's Hospital, London, United Kingdom
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Abstract
There is increasing evidence that glial cells respond to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), and astrocytes have been shown to possess GABAA receptors both in vivo and in vitro. A recent study by Sakatani et al. (Proc. R. Soc. Lond. B247, 155 (1992)) demonstrated the transient expression of functional GABAA receptors in the developing rat optic nerve, but axonal and glial components of the response were not distinguished. To help address this problem, we have determined the electrophysiological response to GABA in astrocytes of the isolated intact optic nerves from neonatal rats, identified morphologically following intracellular injection of horseradish peroxidase. Astrocytes responded to GABA by a GABAA receptor-mediated depolarization which attenuated gradually during post-natal development; astrocytes in 21-day-old nerves were not observed to respond to GABA. The results indicate the transient presence of functional GABAA receptors in developing rat optic nerve astrocytes in situ, and we speculate upon a role for GABA in glial signalling and the organization of axonglial interrelations during development.
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Affiliation(s)
- A M Butt
- Division of Physiology, UMDS, St Thomas's Hospital, London, U.K
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Butt AM, Duncan A, Berry M. Astrocyte associations with nodes of Ranvier: ultrastructural analysis of HRP-filled astrocytes in the mouse optic nerve. J Neurocytol 1994; 23:486-99. [PMID: 7983475 DOI: 10.1007/bf01184072] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Astrocytes are implicated in the function of nodes of Ranvier because their perinodal processes form contacts with the axonal membrane at nodes. We have filled astrocytes iontophoretically with horseradish peroxidase in the intact mouse optic nerve to resolve the precise relationship between perinodal processes and astrocyte three dimensional structure. We confirm that nodal contacts were formed either by single processes which almost completely enveloped nodes, or by delicate, finger-like projections from larger processes which made discrete nodal contacts. A single perinodal process can form multiple contacts with a node and nodes were contacted by processes from more than one astrocyte. Perinodal processes emanated from larger processes, which terminated as end-feet on blood vessels and at the pia, as well as collateral branches which subsequently ended at nodes; these latter may specifically subserve nodes. Perinodal contacts were also formed directly by the soma and cytoplasmic expansions of the cell body. Both primary processes and collateral branches formed multiple associations with nodes which often appeared in clusters. Thus, all astrocytes formed multiple contacts with nodes, blood vessels and the subpial glia limitans. We conclude that perinodal processes are not formed by a specialized astrocyte in the mouse optic nerve.
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Affiliation(s)
- A M Butt
- Sherrington School of Physiology, UMDS, Guy's Hospital, London, UK
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Butt AM, Colquhoun K, Tutton M, Berry M. Three-dimensional morphology of astrocytes and oligodendrocytes in the intact mouse optic nerve. J Neurocytol 1994; 23:469-85. [PMID: 7527074 DOI: 10.1007/bf01184071] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The three-dimensional morphology of astrocytes and oligodendrocytes was analysed in the isolated intact mature mouse optic nerve, by correlating laser scanning confocal microscopy and camera lucida drawings of single cells, dye-filled with lysinated rhodamine dextran or horseradish peroxidase, respectively. These techniques enabled the entire process field of single dye-filled cells to be visualized in all planes and resolved the fine details of glial morphology. Morphometric analysis showed that the processes of all astrocytes had branches ending at the pial surface, on blood vessels, and freely in the nerve; branches ending in the nerve were described to end at nodes of Ranvier in the accompanying paper. Astrocytes were classified into a single morphological population in which each cell subserved multiple functions. The results of this study do not support the contention that astrocytes can be subdivided into two morphological and functional subtypes, namely type-1 and type-2, which have process ending either at the glia limitans or at nodes, respectively. Three-dimensional analysis of oligodendrocyte units, defined as the oligodendrocyte, its processes and the axons it ensheaths, showed the provision of single myelin segments for an average of 19 nearby axons (range 12-35) with a mean internodal length of 138 microns (range 50-350 microns). Mouse optic nerve oligodendrocytes were a homogeneous population and were markedly similar to those in the rat optic nerve. The results of our analysis of oligodendrocyte morphology are consistent with the view that the number and internodal length of myelin sheaths supported by a single oligodendrocyte are related to the diameter of the ensheathed axons.
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Affiliation(s)
- A M Butt
- Sherrington School of Physiology, UMDS, Guy's Hospital, London, UK
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Abstract
Astrocytes and oligodendrocytes in the isolated intact mature rat optic nerve have been computer imaged in three dimensions by laser scanning confocal microscopy of single cells, dye-filled with lysinated rhodamine dextran (LRD). Our results illustrate the first application of these techniques to an intact CNS white matter tract and provide comparative data for previous studies on neonatal rat optic nerve (Butt and Ransom: Glia 2:470-475, 1989; Butt and Ransom: J Comp Neurol 338:141-158, 1993). The combined use of intracellular injection of LRD and confocal imaging significantly improves the resolution of glial cell structure, particularly that of mature astrocytes, for a number of reasons. 1) Single mature dye-filled glia can be imaged, because LRD does not pass through gap junctions. 2) The entire process field of astrocytes can be visualized in a single two-dimensional image. 3) Cell images can be rotated through 360 degrees in all planes to provide a new perspective of glial cell structure in the intact tissue. 4) Reconstruction of optical sections, within a narrow focal plane, provides a high definition and resolution of the finer details of glial morphology. Using these techniques, three astrocyte subclasses were distinguished on morphological criteria. It is the conclusion of this study that the majority of these forms represent a single population of fibrous astrocytes which are well-suited to perform the multiple functions attributed to astrocytes in the CNS. The morphology of mature myelin-forming oligodendrocytes was also described.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A M Butt
- Sherrington School of Physiology, U.M.D.S., Guy's Hospital, London
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