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Hu B, Zhang H, Xu M, Li L, Wu M, Zhang S, Liu X, Xia W, Xu K, Xiao J, Zhang H, Ni L. Delivery of Basic Fibroblast Growth Factor Through an In Situ Forming Smart Hydrogel Activates Autophagy in Schwann Cells and Improves Facial Nerves Generation via the PAK-1 Signaling Pathway. Front Pharmacol 2022; 13:778680. [PMID: 35431972 PMCID: PMC9011134 DOI: 10.3389/fphar.2022.778680] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/14/2022] [Indexed: 11/25/2022] Open
Abstract
Although studies have shown that basic fibroblast growth factor (bFGF) can activate autophagy and promote peripheral nerve repair, the role and the molecular mechanism of action of bFGF in the facial nerve are not clear. In this study, a thermosensitive in situ forming poloxamer hydrogel was used as a vehicle to deliver bFGF for treating facial nerve injury (FNI) in the rat model. Using H&E and Masson’s staining, we found that bFGF hydrogel can promote the functional recovery and regeneration of the facial nerve. Furthermore, studies on the mechanism showed that bFGF can promote FNI recovery by promoting autophagy and inhibiting apoptosis. Additionally, this study demonstrated that the role of hydrogel binding bFGF in nerve repair was mediated through the activation of the PAK1 signaling pathway in Schwann cells (SCs). These results indicated that poloxamer thermosensitive hydrogel loaded with bFGF can significantly restore the morphology and function of the injured facial nerve by promoting autophagy and inhibiting apoptosis by activating the PAK1 pathway, which can provide a promising strategy for FNI recovery.
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Affiliation(s)
- Binbin Hu
- Department of Otorhinolaryngology, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Hanbo Zhang
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Menglu Xu
- Department of Otorhinolaryngology, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Lei Li
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Man Wu
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Susu Zhang
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Xuejun Liu
- Department of Otorhinolaryngology, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
| | - Weidong Xia
- Department of Burn, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Ke Xu
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
| | - Jian Xiao
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
- *Correspondence: Jian Xiao, ; Hongyu Zhang, ; Liyan Ni,
| | - Hongyu Zhang
- Key Laboratory of Biotechnology and Pharmaceutical Engineering, School of Pharmaceutical Sciences, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, China
- *Correspondence: Jian Xiao, ; Hongyu Zhang, ; Liyan Ni,
| | - Liyan Ni
- Department of Otorhinolaryngology, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- *Correspondence: Jian Xiao, ; Hongyu Zhang, ; Liyan Ni,
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Yu G, Zhang Y, Ning B. Reactive Astrocytes in Central Nervous System Injury: Subgroup and Potential Therapy. Front Cell Neurosci 2022; 15:792764. [PMID: 35002629 PMCID: PMC8733560 DOI: 10.3389/fncel.2021.792764] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/07/2021] [Indexed: 12/13/2022] Open
Abstract
Traumatic central nervous system (CNS) injury, which includes both traumatic brain injury (TBI) and spinal cord injury (SCI), is associated with irreversible loss of neurological function and high medical care costs. Currently, no effective treatment exists to improve the prognosis of patients. Astrocytes comprise the largest population of glial cells in the CNS and, with the advancements in the field of neurology, are increasingly recognized as having key functions in both the brain and the spinal cord. When stimulated by disease or injury, astrocytes become activated and undergo a series of changes, including alterations in gene expression, hypertrophy, the loss of inherent functions, and the acquisition of new ones. Studies have shown that astrocytes are highly heterogeneous with respect to their gene expression profiles, and this heterogeneity accounts for their observed context-dependent phenotypic diversity. In the inured CNS, activated astrocytes play a dual role both as regulators of neuroinflammation and in scar formation. Identifying the subpopulations of reactive astrocytes that exert beneficial or harmful effects will aid in deciphering the pathological mechanisms underlying CNS injuries and ultimately provide a theoretical basis for the development of effective strategies for the treatment of associated conditions. Following CNS injury, as the disease progresses, astrocyte phenotypes undergo continuous changes. Although current research methods do not allow a comprehensive and accurate classification of astrocyte subpopulations in complex pathological contexts, they can nonetheless aid in understanding the roles of astrocytes in disease. In this review, after a brief introduction to the pathology of CNS injury, we summarize current knowledge regarding astrocyte activation following CNS injury, including: (a) the regulatory factors involved in this process; (b) the functions of different astrocyte subgroups based on the existing classification of astrocytes; and (c) attempts at astrocyte-targeted therapy.
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Affiliation(s)
- GuiLian Yu
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Ying Zhang
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Bin Ning
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
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Jiang Y, Liang J, Li R, Peng Y, Huang J, Huang L. Basic fibroblast growth factor accelerates myelin debris clearance through activating autophagy to facilitate early peripheral nerve regeneration. J Cell Mol Med 2021; 25:2596-2608. [PMID: 33512767 PMCID: PMC7933946 DOI: 10.1111/jcmm.16274] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/01/2020] [Accepted: 12/31/2020] [Indexed: 01/17/2023] Open
Abstract
The successful removal of damaged myelin sheaths during Wallerian degeneration (WD) is essential for ensuring structural remodelling and functional recovery following traumatic peripheral nerve injury (PNI). Recent studies have established that autophagy involves myelin phagocytosis and cellular homoeostasis, and its disorder impairs myelin clearance. Based on the role of basic fibroblast growth factor (bFGF) on exerting neuroprotection and angiogenesis during nerve tissue regeneration, we now explicitly focus on the issue about whether the therapeutic effect of bFGF on supporting nerve regeneration is closely related to accelerate the autophagic clearance of myelin debris during WD. Using sciatic nerve crushed model, we found that bFGF remarkedly improved axonal outgrowth and nerve reconstruction at the early phase of PNI (14 days after PNI). More importantly, we further observed that bFGF could enhance phagocytic capacity of Schwann cells (SCs) to engulf myelin debris. Additionally, this enhancing effect is accomplished by autophagy activation and the increase of autophagy flux by immunoblotting and immune‐histochemical analyses. Taken together, our data suggest that the action of bFGF on modulating early peripheral nerve regeneration is closely associated with myelin debris removal by SCs, which might result in SC‐mediated autophagy activation, highlighting its insight molecular mechanism as a neuroprotective agent for repairing PNI.
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Affiliation(s)
- Yongsheng Jiang
- The Affiliated Xiangshan Hospital of Wenzhou Medial University Zhejiang China
| | - Jiahong Liang
- The Affiliated Xiangshan Hospital of Wenzhou Medial University Zhejiang China
- HangZhou Zhuyangxin Pharmaceutical Co.,LTD Hangzhou Zhejiang China
| | - Rui Li
- The Affiliated Xiangshan Hospital of Wenzhou Medial University Zhejiang China
- PCFM Lab, GD HPPC Lab School of Chemistry Sun Yat‐sen University Guangzhou China
| | - Yan Peng
- The Affiliated Xiangshan Hospital of Wenzhou Medial University Zhejiang China
- Hangzhou Institute for Food and Drug control Hangzhou Zhejiang China
| | - JiangLi Huang
- The Affiliated Xiangshan Hospital of Wenzhou Medial University Zhejiang China
| | - Lijiang Huang
- The Affiliated Xiangshan Hospital of Wenzhou Medial University Zhejiang China
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Successful optic nerve regeneration in the senescent zebrafish despite age-related decline of cell intrinsic and extrinsic response processes. Neurobiol Aging 2017; 60:1-10. [DOI: 10.1016/j.neurobiolaging.2017.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/18/2017] [Accepted: 08/13/2017] [Indexed: 12/12/2022]
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In vivo imaging of Mauthner axon regeneration, remyelination and synapses re-establishment after laser axotomy in zebrafish larvae. Exp Neurol 2017; 300:67-73. [PMID: 29092800 DOI: 10.1016/j.expneurol.2017.10.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/24/2017] [Accepted: 10/27/2017] [Indexed: 12/31/2022]
Abstract
Zebrafish is an excellent model to study central nervous system (CNS) axonal degeneration and regeneration since we can observe these processes in vivo and in real time in transparent larvae. Previous studies have shown that Mauthner cell (M-cell) axon regenerates poorly after mechanical spinal cord injury. Inconsistent with this result, however, we have found that M-cell possesses a great capacity for axon regeneration after two-photon laser ablation. By using ZEISS LSM 710 two-photon microscope, we performed specific unilateral axotomy of GFP labeled M-cells in the Tol-056 enhancer trap line larvae. Our results showed that distal axons almost degenerated completely at 24h after laser axotomy. After that, the proximal axons initiated a robust regeneration and many of the M-cell axons almost regenerated fully at 4days post axotomy. Furthermore, we also visualized that regenerated axons were remyelinated when we severed fluorescent dye labeled M-cells in the Tg (mbp:EGFP-CAAX) line larvae. Moreover, by single M-cell co-electroporation with Syp:EGFP and DsRed2 plasmids we observed synapses re-establishment in vivo during laser injury-induced axon re-extension which suggested re-innervation of denervated pathways. In addition, we further demonstrated that nocodazole administration could completely abolish this regeneration capacity. These results together suggested that in vivo time-lapse imaging of M-cell axon laser injury may provide a powerful analytical model for understanding the underlying cellular and molecular mechanisms of the CNS axon regeneration.
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Ponath G, Ramanan S, Mubarak M, Housley W, Lee S, Sahinkaya FR, Vortmeyer A, Raine CS, Pitt D. Myelin phagocytosis by astrocytes after myelin damage promotes lesion pathology. Brain 2016; 140:399-413. [PMID: 28007993 DOI: 10.1093/brain/aww298] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 10/14/2016] [Accepted: 10/17/2016] [Indexed: 12/20/2022] Open
Abstract
Astrocytes are key players in the pathology of multiple sclerosis and can assume beneficial and detrimental roles during lesion development. The triggers and timing of the different astroglial responses in acute lesions remain unclear. Astrocytes in acute multiple sclerosis lesions have been shown previously to contain myelin debris, although its significance has not been examined. We hypothesized that myelin phagocytosis by astrocytes is an early event during lesion formation and leads to astroglial immune responses. We examined multiple sclerosis lesions and other central nervous system pathologies with prominent myelin injury, namely, progressive multifocal leukoencephalopathy, metachromatic leukodystrophy and subacute infarct. In all conditions, we found that myelin debris was present in most astrocytes at sites of acute myelin breakdown, indicating that astroglial myelin phagocytosis is an early and prominent feature. Functionally, myelin debris was taken up by astrocytes through receptor-mediated endocytosis and resulted in astroglial NF-κB activation and secretion of chemokines. These in vitro results in rats were validated in human disease where myelin-positive hypertrophic astrocytes showed increased nuclear localization of NF-κB and elevated chemokine expression compared to myelin-negative, reactive astrocytes. Thus, our data suggest that myelin uptake is an early response of astrocytes in diseases with prominent myelin injury that results in recruitment of immune cells. This first line response of astrocytes to myelin injury may exert beneficial or detrimental effects on the lesion pathology, depending on the inflammatory context. Modulating this response might be of therapeutic relevance in multiple sclerosis and other demyelinating conditions.
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Affiliation(s)
- Gerald Ponath
- Yale University, School of Medicine, Department of Neurology, 300 George St, New Haven, CT 06511, USA
| | - Sriram Ramanan
- Yale University, School of Medicine, Department of Neurology, 300 George St, New Haven, CT 06511, USA
| | - Mayyan Mubarak
- Yale University, School of Medicine, Department of Neurology, 300 George St, New Haven, CT 06511, USA
| | - William Housley
- Yale University, School of Medicine, Department of Neurology, 300 George St, New Haven, CT 06511, USA
| | - Seunghoon Lee
- Yale University, School of Medicine, Department of Ophthalmology and Visual Science, 300 George St, New Haven, CT 06511, USA
| | - F Rezan Sahinkaya
- The Ohio State University College of Medicine, Department of Neuroscience, 670 Biomedical Research Tower, Columbus, OH, 43210, USA
| | - Alexander Vortmeyer
- Yale University, School of Medicine, Department of Pathology, 310 Cedar Street New Haven, CT 06520-8023, USA
| | - Cedric S Raine
- Albert Einstein College of Medicine, Department of Pathology (Neuropathology), 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - David Pitt
- Yale University, School of Medicine, Department of Neurology, 300 George St, New Haven, CT 06511, USA
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Mills EA, Davis CHO, Bushong EA, Boassa D, Kim KY, Ellisman MH, Marsh-Armstrong N. Astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of Xenopus laevis at metamorphosis. Proc Natl Acad Sci U S A 2015; 112:10509-14. [PMID: 26240339 PMCID: PMC4547286 DOI: 10.1073/pnas.1506486112] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Oligodendrocytes can adapt to increases in axon diameter through the addition of membrane wraps to myelin segments. Here, we report that myelin segments can also decrease their length in response to optic nerve (ON) shortening during Xenopus laevis metamorphic remodeling. EM-based analyses revealed that myelin segment shortening is accomplished by focal myelin-axon detachments and protrusions from otherwise intact myelin segments. Astrocyte processes remove these focal myelin dystrophies using known phagocytic machinery, including the opsonin milk fat globule-EGF factor 8 (Mfge8) and the downstream effector ras-related C3 botulinum toxin substrate 1 (Rac1). By the end of metamorphic nerve shortening, one-quarter of all myelin in the ON is enwrapped or internalized by astrocytes. As opposed to the removal of degenerating myelin by macrophages, which is usually associated with axonal pathologies, astrocytes selectively remove large amounts of myelin without damaging axons during this developmental remodeling event.
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Affiliation(s)
- Elizabeth A Mills
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Chung-ha O Davis
- Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205
| | - Eric A Bushong
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California at San Diego, La Jolla, CA 92093
| | - Daniela Boassa
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California at San Diego, La Jolla, CA 92093
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California at San Diego, La Jolla, CA 92093
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California at San Diego, La Jolla, CA 92093; Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093
| | - Nicholas Marsh-Armstrong
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205;
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Nguyen LH, Diao HJ, Chew SY. MicroRNAs and their potential therapeutic applications in neural tissue engineering. Adv Drug Deliv Rev 2015; 88:53-66. [PMID: 25980934 DOI: 10.1016/j.addr.2015.05.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 05/08/2015] [Accepted: 05/10/2015] [Indexed: 01/01/2023]
Abstract
The inherent poor regeneration capacity of nerve tissues, especially in the central nervous system, poses a grand challenge for neural tissue engineering. After injuries, the local microenvironment often contains potent inhibitory molecules and glial scars, which do not actively support axonal regrowth. MicroRNAs can direct fate of neural cells and are tightly controlled during nerve development. Thus, RNA interference using microRNAs is a promising method to enhance nerve regeneration. Although the physiological roles of microRNA expression levels in various cellular activities or disease conditions have been extensively investigated, the translational use of these understanding for neural tissue engineering remains limited. This review aims to highlight essential microRNAs that participate in cellular behaviors within the adult nervous system and their potential therapeutic applications. In addition, possible delivery methods are also suggested for effective gene silencing in neural tissue engineering.
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Affiliation(s)
- Lan Huong Nguyen
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Hua Jia Diao
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Sing Yian Chew
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 308232, Singapore.
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Li HJ, Zhang X, Zhang F, Wen XH, Lu LJ, Shen J. Enhanced repair effect of toll-like receptor 4 activation on neurotmesis: assessment using MR neurography. AJNR Am J Neuroradiol 2014; 35:1608-14. [PMID: 24874529 DOI: 10.3174/ajnr.a3977] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND PURPOSE Alternative use of molecular approaches is promising for improving nerve regeneration in surgical repair of neurotmesis. The purpose of this study was to determine the role of MR imaging in assessment of the enhanced nerve regeneration with toll-like receptor 4 signaling activation in surgical repair of neurotmesis. MATERIALS AND METHODS Forty-eight healthy rats in which the sciatic nerve was surgically transected followed by immediate surgical coaptation received intraperitoneal injection of toll-like receptor 4 agonist lipopolysaccharide (n = 24, study group) or phosphate buffered saline (n = 24, control group) until postoperative day 7. Sequential T2 measurements and gadofluorine M-enhanced MR imaging and sciatic functional index were obtained over an 8-week follow-up period, with histologic assessments performed at regular intervals. T2 relaxation times and gadofluorine enhancement of the distal nerve stumps were measured and compared between nerves treated with lipopolysaccharide and those treated with phosphate buffered saline. RESULTS Nerves treated with lipopolysaccharide injection achieved better functional recovery and showed more prominent gadofluorine enhancement and prolonged T2 values during the degenerative phase compared with nerves treated with phosphate buffered saline. T2 values in nerves treated with lipopolysaccharide showed a more rapid return to baseline level than did gadofluorine enhancement. Histology exhibited more macrophage recruitment, faster myelin debris clearance, and more pronounced nerve regeneration in nerves treated with toll-like receptor 4 activation. CONCLUSIONS The enhanced nerve repair with toll-like receptor 4 activation in surgical repair of neurotmesis can be monitored by using gadofluorine M-enhanced MR imaging and T2 relaxation time measurements. T2 relaxation time seems more sensitive than gadofluorine M-enhanced MR imaging for detecting such improved nerve regeneration.
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Affiliation(s)
- H J Li
- From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China
| | - X Zhang
- From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China
| | - F Zhang
- From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China
| | - X H Wen
- From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China
| | - L J Lu
- From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China
| | - J Shen
- From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China.
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Romero-Alemán MDM, Monzón-Mayor M, Santos E, Yanes CM. Regrowth of transected retinal ganglion cell axons despite persistent astrogliosis in the lizard (Gallotia galloti). J Anat 2013; 223:22-37. [PMID: 23656528 DOI: 10.1111/joa.12053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2013] [Indexed: 12/14/2022] Open
Abstract
We analysed the astroglia response that is concurrent with spontaneous axonal regrowth after optic nerve (ON) transection in the lizard Gallotia galloti. At different post-lesional time points (0.5, 1, 3, 6, 9 and 12 months) we used conventional electron microscopy and specific markers for astrocytes [glial fibrillary acidic protein (GFAP), vimentin (Vim), sex-determining region Y-box-9 (Sox9), paired box-2 (Pax2)¸ cluster differentiation-44 (CD44)] and for proliferating cells (PCNA). The experimental retina showed a limited glial response since the increase of gliofilaments was not significant when compared with controls, and proliferating cells were undetectable. Conversely, PCNA(+) cells populated the regenerating ON, optic tract (OTr) and ventricular wall of both the hypothalamus and optic tectum (OT). Subpopulations of these PCNA(+) cells were identified as GFAP(+) and Vim(+) reactive astrocytes and radial glia. Reactive astrocytes up-regulated Vim at 1 month post-lesion, and both Vim and GFAP at 12 months post-lesion in the ON-OTr, indicating long-term astrogliosis. They also expressed Pax2, Sox9 and CD44 in the ON, and Sox9 in the OTr. Concomitantly, persistent tissue cavities and disorganised regrowing fibre bundles reaching the OT were observed. Our ultrastructural data confirm abundant gliofilaments in reactive astrocytes joined by desmosomes. Remarkably, they also accumulated myelin debris and lipid droplets until late stages, indicating their participation in myelin removal. These data suggest that persistent mammalian-like astrogliosis in the adult lizard ON contributes to a permissive structural scaffold for long-term axonal regeneration and provides a useful model to study the molecular mechanisms involved in these beneficial neuron-glia interactions.
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Affiliation(s)
- María del Mar Romero-Alemán
- Departamento de Morfología (Biología Celular), Universidad de Las Palmas de Gran Canaria, Canary Islands, Spain.
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Parrilla M, Lillo C, Herrero-Turrión M, Arévalo R, Aijón J, Lara J, Velasco A. Pax2+ astrocytes in the fish optic nerve head after optic nerve crush. Brain Res 2013; 1492:18-32. [DOI: 10.1016/j.brainres.2012.11.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/31/2012] [Accepted: 11/10/2012] [Indexed: 12/21/2022]
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12
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Veth KN, Willer JR, Collery RF, Gray MP, Willer GB, Wagner DS, Mullins MC, Udvadia AJ, Smith RS, John SWM, Gregg RG, Link BA. Mutations in zebrafish lrp2 result in adult-onset ocular pathogenesis that models myopia and other risk factors for glaucoma. PLoS Genet 2011; 7:e1001310. [PMID: 21379331 PMCID: PMC3040661 DOI: 10.1371/journal.pgen.1001310] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 01/13/2011] [Indexed: 11/18/2022] Open
Abstract
The glaucomas comprise a genetically complex group of retinal neuropathies that typically occur late in life and are characterized by progressive pathology of the optic nerve head and degeneration of retinal ganglion cells. In addition to age and family history, other significant risk factors for glaucoma include elevated intraocular pressure (IOP) and myopia. The complexity of glaucoma has made it difficult to model in animals, but also challenging to identify responsible genes. We have used zebrafish to identify a genetically complex, recessive mutant that shows risk factors for glaucoma including adult onset severe myopia, elevated IOP, and progressive retinal ganglion cell pathology. Positional cloning and analysis of a non-complementing allele indicated that non-sense mutations in low density lipoprotein receptor-related protein 2 (lrp2) underlie the mutant phenotype. Lrp2, previously named Megalin, functions as an endocytic receptor for a wide-variety of bioactive molecules including Sonic hedgehog, Bone morphogenic protein 4, retinol-binding protein, vitamin D-binding protein, and apolipoprotein E, among others. Detailed phenotype analyses indicated that as lrp2 mutant fish age, many individuals—but not all—develop high IOP and severe myopia with obviously enlarged eye globes. This results in retinal stretch and prolonged stress to retinal ganglion cells, which ultimately show signs of pathogenesis. Our studies implicate altered Lrp2-mediated homeostasis as important for myopia and other risk factors for glaucoma in humans and establish a new genetic model for further study of phenotypes associated with this disease. Complex genetic inheritance, including variable penetrance and severity, underlies many common eye diseases. In this study, we present analysis of a zebrafish mutant, bugeye, which shows complex inheritance of multiple ocular phenotypes that are known risk factors for glaucoma, including high myopia, elevated intraocular pressure, and up-regulation of stress-response genes in retinal ganglion cells. Molecular genetic analysis revealed that mutations in low density lipoprotein receptor-related protein 2 (lrp2) underlie the mutant phenotypes. Lrp2 is a large transmembrane protein expressed in epithelia of the eye. It facilitates transport and clearance of multiple secreted bioactive factors through receptor-mediated endocytosis. Glaucoma, a progressive blinding disorder, usually presents in adulthood and is characterized by optic nerve damage followed by ganglion cell death. In bugeye/lrp2 mutants, ganglion cell death was significantly elevated, but surprisingly moderate, and therefore they do not model this endpoint of glaucoma. As such, bugeye/lrp2 mutants should be considered valuable as a genetic model (A) for buphthalmia, myopia, and regulated eye growth; (B) for identifying genes and pathways that modify the observed ocular phenotypes; and (C) for studying the initiation of retinal ganglion cell pathology in the context of high myopia and elevated intraocular pressure.
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Affiliation(s)
- Kerry N. Veth
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Jason R. Willer
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Ross F. Collery
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Matthew P. Gray
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Gregory B. Willer
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Daniel S. Wagner
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Mary C. Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania Medical School, Philadelphia, Pennsylvania, United States of America
| | - Ava J. Udvadia
- Department of Biological Sciences, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin, United States of America
| | - Richard S. Smith
- Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Simon W. M. John
- Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Ronald G. Gregg
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Brian A. Link
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail:
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Myelination transition zone astrocytes are constitutively phagocytic and have synuclein dependent reactivity in glaucoma. Proc Natl Acad Sci U S A 2011; 108:1176-81. [PMID: 21199938 DOI: 10.1073/pnas.1013965108] [Citation(s) in RCA: 165] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Optic nerve head (ONH) astrocytes have been proposed to play both protective and deleterious roles in glaucoma. We now show that, within the postlaminar ONH myelination transition zone (MTZ), there are astrocytes that normally express Mac-2 (also known as Lgals3 or galectin-3), a gene typically expressed only in phagocytic cells. Surprisingly, even in healthy mice, MTZ and other ONH astrocytes constitutive internalize large axonal evulsions that contain whole organelles. In mouse glaucoma models, MTZ astrocytes further up-regulate Mac-2 expression. During glaucomatous degeneration, there are dystrophic processes in the retina and optic nerve, including the MTZ, which contain protease resistant γ-synuclein. The increased Mac-2 expression by MTZ astrocytes during glaucoma likely depends on this γ-synuclein, as mice lacking γ-synuclein fail to up-regulate Mac-2 at the MTZ after elevation of intraocular pressure. These results suggest the possibility that a newly discovered normal degradative pathway for axons might contribute to glaucomatous neurodegeneration.
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Valentine HL, Viquez OM, Valentine WM. Peripheral nerve and brain differ in their capacity to resolve N,N-diethyldithiocarbamate-mediated elevations in copper and oxidative injury. Toxicology 2010; 274:10-7. [PMID: 20452388 DOI: 10.1016/j.tox.2010.04.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/28/2010] [Accepted: 04/30/2010] [Indexed: 11/24/2022]
Abstract
Previous studies have demonstrated that N,N-diethyldithiocarbamate (DEDC) elevates copper and promotes oxidative stress within the nervous system. However, whether these effects resolve following cessation of exposure or have the potential to persist and result in cumulative injury has not been determined. In this study, an established model for DEDC myelin injury in the rat was used to determine whether copper levels, oxidative stress, and neuromuscular deficits resolve following the cessation of DEDC exposure. Rats were exposed to DEDC for 8 weeks and then either euthanized or maintained for 2, 6 or 12 weeks after cessation of exposure. At each time point copper levels were measured by inductively coupled mass spectrometry to assess the ability of sciatic nerve, brain, spinal cord and liver to eliminate excess copper post-exposure. The protein expression levels of glutathione transferase alpha, heme oxygenase 1 and superoxide dismutase 1 in peripheral nerve and brain were also determined by western blot to assess levels of oxidative stress as a function of post-exposure duration. As an initial assessment of the bioavailability of the excess copper in brain the protein expression levels of copper chaperone for superoxide dismutase 1, and prion protein were determined by western blot as a function of exposure and post-exposure duration. Neuromuscular function in peripheral nerve was evaluated using grip strengths, nerve conduction velocities, and morphologic changes at the light microscope level. The data demonstrated that in peripheral nerve, copper levels and oxidative stress return to control levels within several weeks after cessation of exposure. Neuromuscular function also showed a trend towards pre-exposure values, although the resolution of myelin lesions was more delayed. In contrast, total copper and antioxidant enzyme levels remained significantly elevated in brain for longer post-exposure periods. The persistence of effects observed in brain suggests that the central nervous system is more susceptible to long-term cumulative adverse effects from dithiocarbamates. Additionally, significant changes in expression levels of chaperone for superoxide dismutase 1, and prion protein were observed consistent with at least a portion of the excess copper being bioactive.
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Affiliation(s)
- Holly L Valentine
- Department of Pathology, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232-2561, USA
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Zou T, Ling C, Xiao Y, Tao X, Ma D, Chen ZL, Strickland S, Song H. Exogenous tissue plasminogen activator enhances peripheral nerve regeneration and functional recovery after injury in mice. J Neuropathol Exp Neurol 2006; 65:78-86. [PMID: 16410751 DOI: 10.1097/01.jnen.0000195942.25163.f5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Tissue plasminogen activator (tPA) is an essential component of the proteolytic cascade that lyses blood clots. Various studies also suggest that tPA plays important roles in the nervous system. We show that exogenous tPA or tPA/plasminogen (plg) promotes axonal regeneration, remyelination, and functional recovery after sciatic nerve injury in the mouse. Local application of tPA or tPA/plg 7 days after sciatic nerve crush significantly increased the total number of axons and myelinated axons, which is accompanied by enhanced expression of neurofilament. Treatment with tPA or tPA/plg reduced the deposition of fibrin(ogen) after nerve injury. Moreover, tPA or tPA/plg increased the number of macrophages and induced MMP-9 expression at the injury site, coincident with reduced collagen scar formation and accelerated clearance of myelin and lipid debris after treatment. Consequently, tPA or tPA/plg treatment protected muscles from atrophy after nerve injury, indicating better functional recovery. These results suggest that administration of exogenous tPA or tPA/plg promotes axonal regeneration and remyelination through removal of fibrin deposition and activation of MMP-9-positive macrophages, which may be responsible for myelin debris clearance and preventing collagen scar formation. Therefore, tPA may be useful for treatment of peripheral nerve injury.
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Affiliation(s)
- Tie Zou
- Department of Molecular Genetics & the Key Laboratory of Molecular Medicine Ministry of Education, Fudan University, Shanghai, P.R. China
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Becker CG, Schweitzer J, Feldner J, Schachner M, Becker T. Tenascin-R as a repellent guidance molecule for newly growing and regenerating optic axons in adult zebrafish. Mol Cell Neurosci 2004; 26:376-89. [PMID: 15234343 DOI: 10.1016/j.mcn.2004.03.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 02/23/2004] [Accepted: 03/03/2004] [Indexed: 10/26/2022] Open
Abstract
In adult fish, in contrast to mammals, new optic axons are continuously added to the optic projection, and optic axons regrow after injury. Thus, pathfinding of optic axons during development, adult growth, and adult regeneration may rely on the same guidance cues. We have shown that tenascin-R, a component of the extracellular matrix, borders the optic pathway in developing zebrafish and acts as a repellent guidance molecule for optic axons. Here we analyze tenascin-R expression patterns along the unlesioned and lesioned optic pathway of adult zebrafish and test the influence of tenascin-R on growing optic axons of adult fish in vitro. Within intraretinal fascicles of optic axons and in the optic nerve, newly added optic axons grow in a tenascin-R immunonegative pathway, which is bordered by tenascin-R immunoreactivity. In the brain, tenascin-R expression domains in the ventral diencephalon, in non-retinorecipient pretectal nuclei and in some tectal layers closely border the optic pathway in unlesioned animals and during axon regrowth. We mimicked these boundary situations with a sharp substrate border of tenascin-R in vitro. Optic axons emanating from adult retinal explants were repelled by tenascin-R substrate borders. This is consistent with a function of tenascin-R as a repellent guidance molecule in boundaries for adult optic axons. Thus, tenascin-R may guide newly added and regenerating optic axons by a contact-repellent mechanism in the optic pathway of adult fish.
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Affiliation(s)
- Catherina G Becker
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, D-20246 Hamburg, Germany.
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17
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Houalla T, Levine RL. The isolation and culture of microglia-like cells from the goldfish brain. J Neurosci Methods 2003; 131:121-31. [PMID: 14659832 DOI: 10.1016/j.jneumeth.2003.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have developed a method for isolating goldfish microglia. Cells were identified as microglia immunohistochemically with NN-2, a monoclonal antibody (MAb) raised against teleost retinal microglial cells, and by their phagocytic abilities. Morphological characterization of the cells identified round, phase-bright cells as well as flattened macrophage-like cells. Ramified cells were also seen but they were rare. Fusion of macrophage-like cells occurred in high density cultures and resulted in the formation of giant cells that disintegrated a few days later. Immunohistochemical studies demonstrated that virtually all of the cells in our cultures were NN-2+ and did not label with either antiGFAP (an astrocyte marker) or MAb 6D2 (an oligodendrocyte marker). Cells identified as microglia were intensely phagocytic and ingested latex microspheres, DiIAcLDL and goldfish myelin in vitro. In addition, we labelled microglial cells in vivo with intracranial injections of fluorescent dextran and found that microglia isolated from these animals contained the dextran and phagocytosed microspheres. We also studied the effect of myelin on microsphere uptake and compared the effect of myelin and opsonized myelin on the phagocytic activity of the cells. Our results showed a clear increase in the phagocytic activity of microglia when incubated with myelin, with an enhanced effect of opsonized myelin.
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Affiliation(s)
- T Houalla
- Department of Biology, McGill University, Montréal, Qué, Canada H3A 1B1
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Su YK, Elam JS. Differential growth of goldfish retinal explants on regenerating and non-regenerating optic tract membranes. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 139:319-23. [PMID: 12480148 DOI: 10.1016/s0165-3806(02)00552-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Regenerating goldfish retinal explants were cultured on poly-L-lysine (control) or poly-L-lysine overlaid with membranes isolated from non-regenerating optic tract (OTr) and 10- or 21-day regenerating OTr. Non-regenerating OTr substrate inhibited all neurite growth while 10- and 21-day regenerating OTr substrates significantly increased the average neurite number per explant and average neurite length compared to controls. These results indicate an upregulation of neurite growth permissive properties of regenerating OTr membranes.
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Affiliation(s)
- Yung Kang Su
- Neuroscience Program, Department of Biological Science, Florida State University, Biology Unit I, Rm 212, Tallahassee, FL 32306, USA
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Clemente D, Porteros A, Alonso JR, Weruaga E, Aijón J, Arévalo R. Effects of axotomy on the expression of NADPH-diaphorase in the visual pathway of the tench. Brain Res 2002; 925:183-94. [PMID: 11792367 DOI: 10.1016/s0006-8993(01)03279-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The distribution of NADPH-diaphorase (ND) positive elements was analyzed throughout the visual pathway of the tench in normal conditions and after optic nerve transection. In the control retina, ND-labeled elements were observed in the photoreceptor, inner nuclear, outer nuclear and ganglion cell layers. In the optic nerve of control animals, small and numerous ND-positive glial cells that were identified as presumably astrocyte-like cells were observed. In the optic tracts and optic tectum, a different type of ND-positive glial cell was detected. Axotomy induced severe changes in the ND staining pattern in the visual pathway. A decrease in the number of ND-stained cells was detected in the retina. In the optic nerve of lesioned animals, the number of small cells gradually decreased, whereas the number of large cells did not change. Two new ND-positive cell populations were observed after the lesion: microglial-like cells appeared close to the lesioned area from 24 h to 7 days after transection, and astrocyte-like cells were found throughout the optic nerve from 14 days up to at least 120 days. The total number of ND-stained glial cells increased at 30 and 60 days and returned to control parameters at 120 days. In addition, the number of ND-positive cells increased at the same survival times in the optic tracts and in the retinorecipient strata of the optic tectum with respect to control animals. Thus, degenerative/regenerative processes in the fish visual pathway are accompanied by an increase in the number of ND-positive cells. Synthesis of nitric oxide is elicited in microglial-like cells as a response to axon injury, whereas the expression in astrocyte-like cells seems to be associated with both normal processes under physiological conditions and with the regenerative phase after the lesion.
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Affiliation(s)
- D Clemente
- Dpto. de Biología Celular y Patología, Facultad de Medicina, Campus Miguel de Unamuno, Universidad de Salamanca, c/Alfonso X el Sabio 1, E-37007 Salamanca, Spain
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Levine RL, Evans MDC. The source of reactive cells during central Wallerian degeneration in the goldfish: a differential irradiation protocol. Exp Neurol 2002; 173:136-44. [PMID: 11771946 DOI: 10.1006/exnr.2001.7821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have used a partial irradiation paradigm to examine the provenance of cells that participate in Wallerian cellular responses in the goldfish visual system. Animals which received 50 Gy whole-body gamma-irradiation showed virtually complete inhibition of the proliferative burst usually seen after optic nerve section. These animals did, however, show a robust hyperplastic response in the optic tract that we believe represents the migration of nearby microglial cells into the affected tract. When only the postcephalic body was irradiated, proliferating cells in the major hematopoietic organs of the fish, the kidney and pronephros, were substantially inhibited. Despite this, the Wallerian cellular response in the visual paths was essentially normal. Thus, there is no obligate requirement for peripheral proliferative cells to participate in central Wallerian degeneration in the fish. However, when only the head was irradiated, and the hematopoietic organs were spared, there was a proliferative response in the visual system. We believe this represents the invasion of the visual pathways by peripheral blood cells through the optic nerve lesion and blood vessels in the nerve itself. This invasion, however, is not sufficient to generate substantial hyperplasia. In summary, although we find evidence for a small contribution by exogenous cells, the major source of reactive cells during central Wallerian degeneration in the fish is the endogenous microglia. Our data underscore the importance of elucidating the mechanisms by which microglial cells are activated and the role that they play in regeneration.
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Affiliation(s)
- R L Levine
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada.
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Becker T, Becker CG. Regenerating descending axons preferentially reroute to the gray matter in the presence of a general macrophage/microglial reaction caudal to a spinal transection in adult zebrafish. J Comp Neurol 2001; 433:131-47. [PMID: 11283955 DOI: 10.1002/cne.1131] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We analyzed pathway choices of regenerating, mostly supraspinal, descending axons in the spinal cord of adult zebrafish and the cellular changes in the spinal cord caudal to a lesion site after complete spinal transection. Anterograde tracing (by application of the tracer rostral to the spinal lesion site) showed that significantly more descending axons (74%) regenerated in the spinal gray matter of the caudal spinal cord than would be expected from random growth. Retrograde tracing (by application of the tracer caudal to the spinal lesion site) showed that, rostral to the lesion, most of these axons (80%) extended into the major white matter tracts. Thus, ventral descending tracts often were devoid of labeled axons caudal to a spinal lesion but contained many axons rostral to the lesion in the same animals, indicating a pathway switch of descending axons from the white matter to the gray matter. Ascending axons of spinal neurons were not observed regrowing to the rostral tracer application site; therefore, they most likely did not contribute to the axonal populations analyzed. A macrophage/microglia response within 2 days of spinal cord transection, along with phagocytosis of myelin, was observed caudal to the transection by immunohistochemistry and electron microscopy. Nevertheless, caudal to the lesion, descending tracts in the white matter were filled with myelin debris during the time of axonal regrowth, at least up to 6 weeks postlesion. We suggest that the spontaneous regeneration of axons of supraspinal origin after spinal cord transection in adult zebrafish may be due in part to the axons' ability to negotiate novel pathways in the spinal cord gray matter.
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Affiliation(s)
- T Becker
- Zentrum für Molekulare Neurobiologie Hamburg, Universität Hamburg, Martinistr. 52, D-20246 Hamburg, Germany.
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