1
|
Rayner CL, Bottle SE, Martyn AP, Barnett NL. Preserving Retinal Structure and Function with the Novel Nitroxide Antioxidant, DCTEIO. Neurochem Res 2023; 48:3402-3419. [PMID: 37450210 PMCID: PMC10514139 DOI: 10.1007/s11064-023-03978-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 06/16/2023] [Accepted: 06/27/2023] [Indexed: 07/18/2023]
Abstract
Oxidative stress is a major contributor to progressive neurodegenerative disease and may be a key target for the development of novel preventative and therapeutic strategies. Nitroxides have been successfully utilised to study changes in redox status (biological probes) and modulate radical-induced oxidative stress. This study investigates the efficacy of DCTEIO (5,6-dicarboxy-1,1,3,3-tetraethyllisoindolin-2-yloxyl), a stable, kinetically-persistent, nitroxide-based antioxidant, as a retinal neuroprotectant. The preservation of retinal function following an acute ischaemic/reperfusion (I/R) insult in the presence of DCTEIO was quantified by electroretinography (ERG). Inflammatory responses in retinal glia were analysed by GFAP and IBA-1 immunohistochemistry, and retinal integrity assessed by histology. A nitroxide probe combined with flow cytometry provided a rapid technique to assess oxidative stress and the mitigation offered by antioxidant compounds in cultured 661W photoreceptor cells. DCTEIO protected the retina from I/R-induced damage, maintaining retinal function. Histological analysis showed preservation of retinal integrity with reduced disruption and disorganisation of the inner and outer nuclear layers. I/R injury upregulated GFAP expression, indicative of retinal stress, which was significantly blunted by DCTEIO. The number of 'activated' microglia, particularly in the outer retina, in response to cellular stress was also significantly reduced by DCTEIO, potentially suggesting reduced inflammasome activation and cell death. DCTEIO mitigated oxidative stress in 661W retinal cell cultures, in a dose-dependent fashion. Together these findings demonstrate the potential of DCTEIO as a neuroprotective therapeutic for degenerative diseases of the CNS that involve an ROS-mediated component, including those of the retina e.g. age-related macular degeneration and glaucoma.
Collapse
Affiliation(s)
- Cassie L Rayner
- Clem Jones Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, 14 University Drive, Robina, Gold Coast, QLD, 4226, Australia
- Queensland Eye Institute, South Brisbane, QLD, 4101, Australia
| | - Steven E Bottle
- School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - Alexander P Martyn
- School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, QLD, 4000, Australia
- Cancer and Ageing Research Program (CARP), Princess Alexandra Hospital, Brisbane, QLD, 4102, Australia
| | - Nigel L Barnett
- Clem Jones Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, 14 University Drive, Robina, Gold Coast, QLD, 4226, Australia.
- Queensland Eye Institute, South Brisbane, QLD, 4101, Australia.
| |
Collapse
|
2
|
Padovani-Claudio DA, Ramos CJ, Capozzi ME, Penn JS. Elucidating glial responses to products of diabetes-associated systemic dyshomeostasis. Prog Retin Eye Res 2023; 94:101151. [PMID: 37028118 PMCID: PMC10683564 DOI: 10.1016/j.preteyeres.2022.101151] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 04/08/2023]
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness in working age adults. DR has non-proliferative stages, characterized in part by retinal neuroinflammation and ischemia, and proliferative stages, characterized by retinal angiogenesis. Several systemic factors, including poor glycemic control, hypertension, and hyperlipidemia, increase the risk of DR progression to vision-threatening stages. Identification of cellular or molecular targets in early DR events could allow more prompt interventions pre-empting DR progression to vision-threatening stages. Glia mediate homeostasis and repair. They contribute to immune surveillance and defense, cytokine and growth factor production and secretion, ion and neurotransmitter balance, neuroprotection, and, potentially, regeneration. Therefore, it is likely that glia orchestrate events throughout the development and progression of retinopathy. Understanding glial responses to products of diabetes-associated systemic dyshomeostasis may reveal novel insights into the pathophysiology of DR and guide the development of novel therapies for this potentially blinding condition. In this article, first, we review normal glial functions and their putative roles in the development of DR. We then describe glial transcriptome alterations in response to systemic circulating factors that are upregulated in patients with diabetes and diabetes-related comorbidities; namely glucose in hyperglycemia, angiotensin II in hypertension, and the free fatty acid palmitic acid in hyperlipidemia. Finally, we discuss potential benefits and challenges associated with studying glia as targets of DR therapeutic interventions. In vitro stimulation of glia with glucose, angiotensin II and palmitic acid suggests that: 1) astrocytes may be more responsive than other glia to these products of systemic dyshomeostasis; 2) the effects of hyperglycemia on glia are likely to be largely osmotic; 3) fatty acid accumulation may compound DR pathophysiology by promoting predominantly proinflammatory and proangiogenic transcriptional alterations of macro and microglia; and 4) cell-targeted therapies may offer safer and more effective avenues for DR treatment as they may circumvent the complication of pleiotropism in retinal cell responses. Although several molecules previously implicated in DR pathophysiology are validated in this review, some less explored molecules emerge as potential therapeutic targets. Whereas much is known regarding glial cell activation, future studies characterizing the role of glia in DR and how their activation is regulated and sustained (independently or as part of retinal cell networks) may help elucidate mechanisms of DR pathogenesis and identify novel drug targets for this blinding disease.
Collapse
Affiliation(s)
- Dolly Ann Padovani-Claudio
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, B3321A Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232-0011, USA.
| | - Carla J Ramos
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, AA1324 Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232-0011, USA.
| | - Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University School of Medicine, 300 North Duke Street, Durham, NC, 27701, USA.
| | - John S Penn
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, B3307 Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232-0011, USA.
| |
Collapse
|
3
|
Chen C, Fan P, Zhang L, Xue K, Hu J, Huang J, Lu W, Xu J, Xu S, Qiu G, Ran J, Gan S. Bumetanide Rescues Aquaporin-4 Depolarization via Suppressing β-Dystroglycan Cleavage and Provides Neuroprotection in Rat Retinal Ischemia-Reperfusion Injury. Neuroscience 2023; 510:95-108. [PMID: 36493910 DOI: 10.1016/j.neuroscience.2022.11.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
Aquaporin-4 (AQP4) regulates retinal water homeostasis and participates in retinal oedema pathophysiology. β-dystroglycan (β-DG) is responsible for AQP4 polarization and can be cleaved by matrix metalloproteinase-9 (MMP9). Retinal oedema induced by ischemia-reperfusion (I/R) injury is an early complication. Bumetanide (BU) has potential efficacy against cytotoxic oedema. Our study investigated the effects of β-DG cleavage on AQP4 and the roles of BU in a rat retinal I/R injury model. The model was induced by applying 110 mm Hg intraocular pressure to the anterior eye chamber. BU and U0126 (a selective ERK inhibitor) were intraperitoneally administered 15 and 30 min, respectively, before I/R induction. Rhodamine isothiocyanate extravasation detection, quantitative real-time PCR, transmission electron microscopy, hematoxylin-eosin staining, immunofluorescence staining, western blotting, and TUNEL staining were performed. AQP4 lost its polarization in the retinal perivascular domain as a result of β-DG cleavage. BU rescued AQP4 depolarization, suppressed AQP4 protein expression, attenuated retinal cytotoxic oedema, and downregulated β-DG and AQP4 mRNA expression. BU suppressed glial responses and mitochondria-mediated apoptotic protein expression, including that of Caspase-3 and Cyto C, raised the Bcl-2/Bax ratio, and lowered the number of apoptotic cells in the retina. Both BU and U0126 downregulated p-ERK and MMP9 expression. Thus, BU treatment suppressed β-DG cleavage, recovered AQP4 polarization partially via inhibiting ERK/MMP9 signaling pathway, and possess potential neuroprotective efficacy in the rat retinal ischemia-reperfusion injury model.
Collapse
Affiliation(s)
- Chunyan Chen
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Ping Fan
- Department of Gynecology and Obstetrics of The Fifth People's Hospital of Chongqing, PR China
| | - Lirong Zhang
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Kaige Xue
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Jiaheng Hu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Juan Huang
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Weitian Lu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Jin Xu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Shiye Xu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Guoping Qiu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Jianhua Ran
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Shengwei Gan
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China.
| |
Collapse
|
4
|
Tian Y, Li M, Zhang S, Hu J, Wu H, Wan M, Xue J, Wang L, Xiao H, Zhou G, Wang K, Liu Q. Microglia activation in the hippocampus mediates retinal degeneration-induced depressive-like behaviors via the NLRP3/IL-1β pathway. Brain Res Bull 2023; 192:70-79. [PMID: 36332880 DOI: 10.1016/j.brainresbull.2022.10.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 10/24/2022] [Accepted: 10/31/2022] [Indexed: 11/13/2022]
Abstract
Epidemiological studies have shown that patients with glaucoma are more prone to depression, but the mechanism of comorbid depression in patients with glaucoma remains unknown. Excessive neuroinflammation has been shown to participate in glaucoma-induced retinal degeneration and hippocampal neural apoptosis in depression. However, little research has been conducted to determine whether neuroinflammation contributes to glaucoma-induced depression. Since the degeneration of retinal ganglion cells is a hallmark of glaucoma, we investigated the role of microglia-induced neuroinflammation in retinal degeneration-induced depression and its potential mechanism. An N-methyl-D-aspartate (NMDA)-induced retinal degeneration model was established, and behavioral tests were conducted at 3, 7, 14, and 21 days after retinal degeneration. After tissue collection, we used immunohistochemistry to assess the activation of microglia and real-time polymerase chain reaction to measure the levels of pro-inflammatory cytokines and the NOD-, LRR-, and pyrin-domain containing protein 3 (NLRP3) inflammasome. The mice exhibited depressive-like behaviors 14 and 21 days after retinal degeneration, based on the open field test, tail suspension test, and forced swimming test. Mice also displayed a lower body weight gain than the control group. In addition, microglial activation was observed in the hippocampus. Microglial proliferation was first observed in the dentate gyrus on day 3, while the number of microglia in cornu ammonis 1 grew the most. Moreover, not only was the expression of pro-inflammatory cytokines, including interleukin-1β, interleukin-18, and interleukin-6 promoted, but the messenger ribonucleic acid levels of the NLRP3 inflammasome were also increased. In conclusion, our research shows that NMDA-induced retinal degeneration can induce depressive-like behaviors, which may be attributed to hippocampal neuroinflammation.
Collapse
Affiliation(s)
- Yi Tian
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China; Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China
| | - Meihui Li
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Shanshan Zhang
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Juntao Hu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Haoran Wu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Mitchell Wan
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Jingxin Xue
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Leilei Wang
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Honglei Xiao
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Guomin Zhou
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China; Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai, China.
| | - Kaidi Wang
- Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China.
| | - Qiong Liu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China; Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai, China.
| |
Collapse
|
5
|
Rahimi M, Leahy S, Matei N, Burford J, Blair NP, Shahidi M. Impairments of retinal hemodynamics and oxygen metrics in ocular hypertension-induced ischemia-reperfusion. Exp Eye Res 2022; 225:109278. [PMID: 36252653 PMCID: PMC10985794 DOI: 10.1016/j.exer.2022.109278] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/23/2022] [Accepted: 10/10/2022] [Indexed: 12/29/2022]
Abstract
Ischemia-reperfusion (I/R) is an established model for retinal neurodegeneration. However, there is limited knowledge of retinal physiological metrics and their relationships to retinal function and morphology in the I/R model. The purpose of the study was to test the hypotheses that retinal hemodynamic and oxygen metrics are impaired and associated with visual dysfunction, retinal thinning, and retinal ganglion cell (RGC) loss due to I/R injury. Intraocular pressure (IOP) was increased in one eye of 10 rats for 90 min followed by reperfusion. Fellow eyes served as controls. After one week of reperfusion, multimodal imaging was performed to quantify total retinal blood flow (TRBF) and retinal vascular oxygen contents. Retinal oxygen delivery (DO2) and metabolism (MO2) were calculated. Pattern-evoked electroretinography (PERG) and optical coherence tomography were performed to measure RGC function and retinal thicknesses, respectively. RGCs were counted from retina whole mounts. After one week of reperfusion, TRBF was lower in study eyes than in control eyes (p < 0.0003). Similarly, DO2 and MO2 were reduced in study eyes compared to control eyes (p < 0.003). PERG amplitude, TRT, IRT, ORT, and RGCs were also lower in study eyes (p ≤ 0.01). DO2 and MO2 were correlated with PERG amplitude, TRT, IRT, and ORT (r ≥ 0.6, p ≤ 0.005). The findings improve knowledge of physiological metrics affected by I/R injury and have the potential for identifying biomarkers of injury and outcomes for evaluating experimental treatments.
Collapse
Affiliation(s)
- Mansour Rahimi
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - Sophie Leahy
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - Nathanael Matei
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - James Burford
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Mahnaz Shahidi
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA.
| |
Collapse
|
6
|
Chidlow G, Chan WO, Wood JPM, Casson RJ. Investigations into photoreceptor energy metabolism during experimental retinal detachment. Front Cell Neurosci 2022; 16:1036834. [PMID: 36467607 PMCID: PMC9716104 DOI: 10.3389/fncel.2022.1036834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 11/01/2022] [Indexed: 08/27/2023] Open
Abstract
Retinal detachment is a sight-threatening disorder, which occurs when the photoreceptors are separated from their vascular supply. The aim of the present study was to shed light on photoreceptor energy metabolism during experimental detachment in rats. Retinal detachment was induced in the eyes of rats via subretinal injection of sodium hyaluronate. Initially, we investigated whether detachment caused hypoxia within photoreceptors, as evaluated by the exogenous and endogenous biomarkers pimonidazole and HIF-1α, as well as by qPCR analysis of HIF target genes. The results showed no unequivocal staining for pimonidazole or HIF-1α within any detached retina, nor upregulation of HIF target genes, suggesting that any reduction in pO2 is of insufficient magnitude to produce hypoxia-induced covalent protein adducts or HIF-1α stabilisation. Subsequently, we analysed expression of cellular bioenergetic enzymes in photoreceptors during detachment. We documented loss of mitochondrial, and downregulation of glycolytic enzymes during detachment, indicating that photoreceptors have reduced energetic requirements and/or capacity. Given that detachment did not cause widespread hypoxia, but did result in downregulated expression of bioenergetic enzymes, we hypothesised that substrate insufficiency may be critical in terms of pathogenesis, and that boosting metabolic inputs may preserve photoreceptor bioenergetic production and, protect against their degeneration. Thus, we tested whether supplementation with the bioavailable energy substrate pyruvate mitigated rod and cone injury and degeneration. Despite protecting photoreceptors in culture from nutrient deprivation, pyruvate failed to protect against apoptotic death of rods, loss of cone opsins, and loss of inner segment mitochondria, in situ, when evaluated at 3 days after detachment. The regimen was also ineffective against cumulative photoreceptor deconstruction and degeneration when evaluated after 4 weeks. Retinal metabolism, particularly the bioenergetic profiles and pathological responses of the various cellular subtypes still presents a considerable knowledge gap that has important clinical consequences. While our data do not support the use of pyruvate supplementation as a means of protecting detached photoreceptors, they do provide a foundation and motivation for future research in this area.
Collapse
Affiliation(s)
- Glyn Chidlow
- Ophthalmic Research Laboratories, Discipline of Ophthalmology and Visual Sciences, University of Adelaide, Adelaide, SA, Australia
| | | | | | | |
Collapse
|
7
|
Hanna J, David LA, Touahri Y, Fleming T, Screaton RA, Schuurmans C. Beyond Genetics: The Role of Metabolism in Photoreceptor Survival, Development and Repair. Front Cell Dev Biol 2022; 10:887764. [PMID: 35663397 PMCID: PMC9157592 DOI: 10.3389/fcell.2022.887764] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
Vision commences in the retina with rod and cone photoreceptors that detect and convert light to electrical signals. The irreversible loss of photoreceptors due to neurodegenerative disease leads to visual impairment and blindness. Interventions now in development include transplanting photoreceptors, committed photoreceptor precursors, or retinal pigment epithelial (RPE) cells, with the latter protecting photoreceptors from dying. However, introducing exogenous human cells in a clinical setting faces both regulatory and supply chain hurdles. Recent work has shown that abnormalities in central cell metabolism pathways are an underlying feature of most neurodegenerative disorders, including those in the retina. Reversal of key metabolic alterations to drive retinal repair thus represents a novel strategy to treat vision loss based on cell regeneration. Here, we review the connection between photoreceptor degeneration and alterations in cell metabolism, along with new insights into how metabolic reprogramming drives both retinal development and repair following damage. The potential impact of metabolic reprogramming on retinal regeneration is also discussed, specifically in the context of how metabolic switches drive both retinal development and the activation of retinal glial cells known as Müller glia. Müller glia display latent regenerative properties in teleost fish, however, their capacity to regenerate new photoreceptors has been lost in mammals. Thus, re-activating the regenerative properties of Müller glia in mammals represents an exciting new area that integrates research into developmental cues, central metabolism, disease mechanisms, and glial cell biology. In addition, we discuss this work in relation to the latest insights gleaned from other tissues (brain, muscle) and regenerative species (zebrafish).
Collapse
Affiliation(s)
- Joseph Hanna
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
| | - Luke Ajay David
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
| | - Yacine Touahri
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Taylor Fleming
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
| | - Robert A. Screaton
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Carol Schuurmans
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
- *Correspondence: Carol Schuurmans,
| |
Collapse
|
8
|
Erichev VP, Khachatryan GK, Khomchik OV. [Current trends in studying pathogenesis of glaucoma]. Vestn Oftalmol 2021; 137:268-274. [PMID: 34669337 DOI: 10.17116/oftalma2021137052268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Glaucoma is a group of neurodegenerative disorders comprising one of the main causes of irreversible blindness. Glaucoma-related blindness is a globally relevant problem. By now, many aspects of glaucoma pathogenesis have been studied: impact of increased intraocular pressure (IOP) on the development of optic neuropathy, ischemia and reperfusion of the retina, most of the direct mechanisms of neuronal death (excitotoxicity, oxidative stress, etc). However, the only effective glaucoma treatment is lowering the IOP, while early glaucoma diagnosis is based on determining structural and functional retinal defects. Therefore, it is important to emphasize further research on the insufficiently studied aspects of glaucoma pathogenesis - such as neuroinflammation, translaminar pressure, genetic factors, association of glaucomatous damage with changes in the brain, mitochondrial pathologies, and others. The article reviews the most perspective directions in research of the pathogenesis of glaucomatous optic neuropathy.
Collapse
Affiliation(s)
- V P Erichev
- Research Institute of Eye Diseases, Moscow, Russia
| | | | - O V Khomchik
- Research Institute of Eye Diseases, Moscow, Russia
| |
Collapse
|
9
|
Affiliation(s)
- Zheng He
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - James A Armitage
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia E‐mail:
| | - Bang V Bui
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| |
Collapse
|
10
|
Kalloniatis M, Loh CS, Acosta ML, Tomisich G, Zhu Y, Nivison‐smith L, Fletcher EL, Chua J, Sun D, Arunthavasothy N. Retinal amino acid neurochemistry in health and disease. Clin Exp Optom 2021; 96:310-32. [DOI: 10.1111/cxo.12015] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 07/01/2012] [Accepted: 07/17/2012] [Indexed: 12/25/2022] Open
Affiliation(s)
- Michael Kalloniatis
- Centre for Eye Health, University of New South Wales, Sydney, New South Wales, Australia,
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia,
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia,
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Chee Seang Loh
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Monica L Acosta
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Guido Tomisich
- Department of Optometry and Vision Science, The University of Melbourne, Parkville, Victoria, Australia,
| | - Yuan Zhu
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia,
| | - Lisa Nivison‐smith
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia,
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia,
| | - Jacqueline Chua
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Daniel Sun
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Niru Arunthavasothy
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| |
Collapse
|
11
|
Jha KA, Gentry J, Del Mar NA, Reiner A, Sohl N, Gangaraju R. Adipose Tissue-Derived Mesenchymal Stem Cell Concentrated Conditioned Medium Alters the Expression Pattern of Glutamate Regulatory Proteins and Aquaporin-4 in the Retina after Mild Traumatic Brain Injury. J Neurotrauma 2021; 38:1702-1716. [PMID: 33183134 DOI: 10.1089/neu.2020.7309] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Concentrated conditioned media from adipose tissue-derived mesenchymal stem cells (ASC-CCM) show promise for retinal degenerative diseases. In this study, we hypothesized that ASC-CCM could rescue retinal damage and thereby improve visual function by acting through Müller glia in mild traumatic brain injury (mTBI). Adult C57Bl/6 mice were subjected to a 50-psi air pulse on the left side of the head, resulting in an mTBI. After blast injury, 1 μL (∼100 ng total protein) of human ASC-CCM was delivered intravitreally and followed up after 4 weeks for visual function assessed by electroretinogram and histopathological markers for Müller cell-related markers. Blast mice that received ASC-CCM, compared with blast mice that received saline, demonstrated a significant improvement in a- and b-wave response correlated with a 1.3-fold decrease in extracellular glutamate levels and a concomitant increase in glutamine synthetase (GS), as well as the glutamate transporter (GLAST) in Müller cells. Additionally, an increase in aquaporin-4 (AQP4) in Müller cells in blast mice received saline restored to normal levels in blast mice that received ASC-CCM. In vitro studies on rMC-1 Müller glia exposed to 100 ng/mL glutamate or RNA interference knockdown of GLAST expression mimicked the increased Müller cell glial fibrillary acidic protein (a marker of gliosis) seen with mTBI, and suggested that an increase in glutamate and/or a decrease in GLAST might contribute to the Müller cell activation in vivo. Taken together, our data suggest a novel neuroprotective role for ASC-CCM in the rescue of the visual deficits and pathologies of mTBI via restoration of Müller cell health.
Collapse
Affiliation(s)
- Kumar Abhiram Jha
- Department of Ophthalmology, Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Jordy Gentry
- Department of Ophthalmology, Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Nobel A Del Mar
- Department of Ophthalmology, Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Anton Reiner
- Department of Ophthalmology, Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Nicolas Sohl
- Cell Care Therapeutics, Inc., Monrovia, California, USA
| | - Rajashekhar Gangaraju
- Department of Ophthalmology, Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| |
Collapse
|
12
|
Tribble JR, Vasalauskaite A, Redmond T, Young RD, Hassan S, Fautsch MP, Sengpiel F, Williams PA, Morgan JE. Midget retinal ganglion cell dendritic and mitochondrial degeneration is an early feature of human glaucoma. Brain Commun 2019; 1:fcz035. [PMID: 31894207 PMCID: PMC6928391 DOI: 10.1093/braincomms/fcz035] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/29/2019] [Accepted: 11/01/2019] [Indexed: 12/31/2022] Open
Abstract
Glaucoma is characterized by the progressive dysfunction and loss of retinal ganglion cells. However, the earliest degenerative events that occur in human glaucoma are relatively unknown. Work in animal models has demonstrated that retinal ganglion cell dendrites remodel and atrophy prior to the loss of the cell soma. Whether this occurs in human glaucoma has yet to be elucidated. Serial block face scanning electron microscopy is well established as a method to determine neuronal connectivity at high resolution but so far has only been performed in normal retina from animal models. To assess the structure-function relationship of early human glaucomatous neurodegeneration, regions of inner retina assessed to have none-to-moderate loss of retinal ganglion cell number were processed using serial block face scanning electron microscopy (n = 4 normal retinas, n = 4 glaucoma retinas). This allowed detailed 3D reconstruction of retinal ganglion cells and their intracellular components at a nanometre scale. In our datasets, retinal ganglion cell dendrites degenerate early in human glaucoma, with remodelling and redistribution of the mitochondria. We assessed the relationship between visual sensitivity and retinal ganglion cell density and discovered that this only partially conformed to predicted models of structure-function relationships, which may be affected by these early neurodegenerative changes. In this study, human glaucomatous retinal ganglion cells demonstrate compartmentalized degenerative changes as observed in animal models. Importantly, in these models, many of these changes have been demonstrated to be reversible, increasing the likelihood of translation to viable therapies for human glaucoma.
Collapse
Affiliation(s)
- James R Tribble
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, CF24 4HQ Wales, UK
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 112 82 Stockholm, Sweden
| | | | - Tony Redmond
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, CF24 4HQ Wales, UK
| | - Robert D Young
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, CF24 4HQ Wales, UK
| | - Shoaib Hassan
- School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XW Wales, UK
| | | | - Frank Sengpiel
- School of Biosciences, Cardiff University, Cardiff, CF10 3AX Wales, UK
| | - Pete A Williams
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 112 82 Stockholm, Sweden
| | - James E Morgan
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, CF24 4HQ Wales, UK
- School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XW Wales, UK
| |
Collapse
|
13
|
Vroemen PAMM, Gorgels TGMF, Webers CAB, de Boer J. Modeling the Mechanical Parameters of Glaucoma. TISSUE ENGINEERING PART B-REVIEWS 2019; 25:412-428. [PMID: 31088331 DOI: 10.1089/ten.teb.2019.0044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glaucoma is a major eye disease characterized by a progressive loss of retinal ganglion cells (RGCs). Biomechanical forces as a result of hydrostatic pressure and strain play a role in this disease. Decreasing intraocular pressure is the only available therapy so far, but is not always effective and does not prevent blindness in many cases. There is a need for drugs that protect RGCs from dying in glaucoma; to develop these, we need valid glaucoma and drug screening models. Since in vivo models are unsuitable for screening purposes, we focus on in vitro and ex vivo models in this review. Many groups have studied pressure and strain model systems to mimic glaucoma, to investigate the molecular and cellular events leading to mechanically induced RGC death. Therefore, the focus of this review is on the different mechanical model systems used to mimic the biomechanical forces in glaucoma. Most models use either cell or tissue strain, or fluid- or gas-controlled hydrostatic pressure application and apply it to the relevant cell types such as trabecular meshwork cells, optic nerve head astrocytes, and RGCs, but also to entire eyes. New model systems are warranted to study concepts and test experimental compounds for the development of new drugs to protect vision in glaucoma patients. Impact Statement The outcome of currently developed models to investigate mechanically induced retinal ganglion cell death by applying different mechanical strains varies widely. This suggests that a robust glaucoma model has not been developed yet. However, a comprehensive overview of current developments is not available. In this review, we have therefore assessed what has been done before and summarized the available knowledge in the field, which can be used to develop improved models for glaucoma research.
Collapse
Affiliation(s)
- Pascal A M M Vroemen
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Centre+, Maastricht, The Netherlands.,Department of Complex Tissue Regeneration (CTR), MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, The Netherlands.,Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Theo G M F Gorgels
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Centre+, Maastricht, The Netherlands.,Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Carroll A B Webers
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Jan de Boer
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.,Institute for Complex Molecular Structures, Eindhoven University of Technology, Eindhoven, The Netherlands
| |
Collapse
|
14
|
Çomaklı S, Sevim Ç, Kontadakis G, Doğan E, Taghizadehghalehjoughi A, Özkaraca M, Aschner M, Nikolouzakis TK, Tsatsakis A. Acute glufosinate-based herbicide treatment in rats leads to increased ocular interleukin-1β and c-Fos protein levels, as well as intraocular pressure. Toxicol Rep 2019; 6:155-160. [PMID: 30723690 PMCID: PMC6351388 DOI: 10.1016/j.toxrep.2019.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 01/15/2019] [Indexed: 01/01/2023] Open
Abstract
Glufosinate is a common herbicide with neurotoxic effects, leading to seizures, convulsions and memory loss. Glufosinate indirectly induces glutamate toxicity by inhibiting glutamine synthesis in astrocytes. Here, we studied the acute toxic effects of a glufosinate-based herbicide in rat optic nerve at three doses (40, 80 or 120 μM, equal to 714 or 21 mg/kg bw/day). Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea, glucose, calcium, as well as creatinine concentrations were analyzed after 24, 48 and 72 h treatment. Intraocular pressure (IOP) (expressed as the average of both eyes) was measured with a rebound tonometer. Interleukin-1β (IL-1β) and c-Fos expression were determined by immunohistochemistry. The results established that the glufosinate-based herbicide significantly increased IL-1β and c-Fos immunopositivity in the optic nerve (p < 0.05), concomitant with increased IOP. These results suggest that commercial formulations of glufosinate acutely affect the optic nerve.
Collapse
Affiliation(s)
- Selim Çomaklı
- Department of Veterinary Pathology, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum, Turkey
- Corresponding authors.
| | - Çiğdem Sevim
- Department of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum, Turkey
- Corresponding authors.
| | - George Kontadakis
- Laboratory of Vision and Optics and Ophthalmology Department, School of Medicine, University of Crete, 71003, Heraklion, Greece
| | - Elif Doğan
- Department of Veterinary Surgery, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum, Turkey
| | - Ali Taghizadehghalehjoughi
- Department of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum, Turkey
| | - Mustafa Özkaraca
- Department of Veterinary Pathology, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum, Turkey
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, United States
| | | | - Aristides Tsatsakis
- Laboratory of Toxicology, School of Medicine, University of Crete, 71003, Heraklion, Greece
| |
Collapse
|
15
|
Kuehn S, Reinehr S, Stute G, Rodust C, Grotegut P, Hensel AT, Dick HB, Joachim SC. Interaction of complement system and microglia activation in retina and optic nerve in a NMDA damage model. Mol Cell Neurosci 2018; 89:95-106. [PMID: 29738834 DOI: 10.1016/j.mcn.2018.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 04/14/2018] [Accepted: 05/04/2018] [Indexed: 01/01/2023] Open
Abstract
It is known that intravitreally injected N-methyl-d-aspartate (NMDA) leads to fast retina and optic nerve degeneration and can directly activate microglia. Here, we analyzed the relevance for microglia related degenerating factors, the proteins of the complement system, at a late stage in the NMDA damage model. Therefore, different doses of NMDA (0 (PBS), 20, 40, 80 nmol) were intravitreally injected in rat eyes. Proliferative and activated microglia/macrophages (MG/Mϕ) were found in retina and optic nerve 2 weeks after NMDA injection. All three complement pathway proteins were activated in retinas after 40 and 80 nmol NMDA treatment. 80 nmol NMDA injection also lead to more numerous depositions of complement factors C3 and membrane attack complex (MAC) in retina and MAC in optic nerve. Additionally, more MAC+ depositions were detected in optic nerves of the 40 nmol NMDA group. In this NMDA model, the retina is first affected followed by optic nerve damage. However, we found initiating complement processes in the retina, while more deposits of the terminal complex were present 2 weeks after NMDA injection in the optic nerve. The complement system can be activated in waves and possibly a second wave is still on-going in the retina, while the first activation wave is in the final phase in the optic nerve. Only the damaged tissues showed microglia activation as well as proliferation and an increase of complement proteins. Interestingly, the microglia/macrophages (MG/Mϕ) in this model were closely connected with the inductors of the classical and lectin pathway, but not with the alternative pathway. However, all three initiating complement pathways were upregulated in the retina. The alternative pathway seems to be triggered by other mechanisms in this NMDA model. Our study showed an ongoing interaction of microglia and complement proteins in a late stage of a degenerative process.
Collapse
Affiliation(s)
- Sandra Kuehn
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - Sabrina Reinehr
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - Gesa Stute
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - Cara Rodust
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - Pia Grotegut
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - Alexander-Tobias Hensel
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - H Burkhard Dick
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany
| | - Stephanie C Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892 Bochum, Germany.
| |
Collapse
|
16
|
Evangelho K, Mogilevskaya M, Losada-Barragan M, Vargas-Sanchez JK. Pathophysiology of primary open-angle glaucoma from a neuroinflammatory and neurotoxicity perspective: a review of the literature. Int Ophthalmol 2017; 39:259-271. [PMID: 29290065 DOI: 10.1007/s10792-017-0795-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 12/11/2017] [Indexed: 11/29/2022]
Abstract
PURPOSE Glaucoma is the leading cause of blindness in humans, affecting 2% of the population. This disorder can be classified into various types including primary, secondary, glaucoma with angle closure and with open angle. The prevalence of distinct types of glaucoma differs for each particular region of the world. One of the most common types of this disease is primary open-angle glaucoma (POAG), which is a complex inherited disorder characterized by progressive retinal ganglion cell death, optic nerve head excavation and visual field loss. Nowadays, POAG is considered an optic neuropathy, while intraocular pressure is proposed to play a fundamental role in its pathophysiology and especially in optic disk damage. However, the exact mechanism of optic nerve head damage remains a topic of debate. This literature review aims to bring together the information on the pathophysiology of primary open-angle glaucoma, particularly focusing on neuroinflammatory mechanisms leading to the death of the retinal ganglion cell. METHODS A literature search was done on PubMed using key words including primary open-angle glaucoma, retinal ganglion cells, Müller cells, glutamate, glial cells, ischemia, hypoxia, exitotoxicity, neuroinflammation, axotomy and neurotrophic factors. The literature was reviewed to collect the information published about the pathophysiologic mechanisms of RGC death in the POAG, from a neuroinflammatory and neurotoxicity perspective. RESULTS Proposed mechanisms for glaucomatous damage are a result of pressure in RGC followed by ischemia, hypoxia of the ONH, and consequently death due to glutamate-induced excitotoxicity, deprivation of energy and oxygen, increase in levels of inflammatory mediators and alteration of trophic factors flow. These events lead to blockage of anterograde and retrograde axonal transport with ensuing axotomy and eventually blindness. CONCLUSIONS The damage to ganglion cells and eventually glaucomatous injury can occur via various mechanisms including baric trauma, ischemia and impact of metabolic toxins, which triggers an inflammatory process and secondary degeneration in the ONH.
Collapse
Affiliation(s)
- Karine Evangelho
- Grupo de Investigación en Ciencias Biomédicas GRINCIBIO, Facultad de medicina, Sede Bogotá, Universidad Antonio Nariño, Bogotá, Colombia
| | - Maria Mogilevskaya
- Grupo de Investigación en Ingeniería Clínica - Hospital Universitario la Samaritana GINIC-HUS, Sede Bogotá, ECCI, Bogotá, Colombia
| | - Monica Losada-Barragan
- Grupo de Biología Celular y Funcional e Ingeniería de Biomoléculas, Facultad de Ciencias, Sede Bogotá, Universidad Antonio Nariño, Bogotá, Colombia
| | - Jeinny Karina Vargas-Sanchez
- Grupo de Investigación en Ciencias Biomédicas GRINCIBIO, Facultad de medicina, Sede Bogotá, Universidad Antonio Nariño, Bogotá, Colombia.
| |
Collapse
|
17
|
Salari V, Scholkmann F, Vimal RLP, Császár N, Aslani M, Bókkon I. Phosphenes, retinal discrete dark noise, negative afterimages and retinogeniculate projections: A new explanatory framework based on endogenous ocular luminescence. Prog Retin Eye Res 2017; 60:101-119. [DOI: 10.1016/j.preteyeres.2017.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/13/2017] [Accepted: 07/15/2017] [Indexed: 02/07/2023]
|
18
|
Chidlow G, Wood JPM, Casson RJ. Investigations into Hypoxia and Oxidative Stress at the Optic Nerve Head in a Rat Model of Glaucoma. Front Neurosci 2017; 11:478. [PMID: 28883787 PMCID: PMC5573812 DOI: 10.3389/fnins.2017.00478] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 08/11/2017] [Indexed: 01/03/2023] Open
Abstract
The vascular hypothesis of glaucoma proposes that retinal ganglion cell axons traversing the optic nerve head (ONH) undergo oxygen and nutrient insufficiency as a result of compromised local blood flow, ultimately leading to their degeneration. To date, evidence for the hypothesis is largely circumstantial. Herein, we made use of an induced rat model of glaucoma that features reproducible and widespread axonal transport disruption at the ONH following chronic elevation of intraocular pressure. If vascular insufficiency plays a role in the observed axonal transport failure, there should exist a physical signature at this time point. Using a range of immunohistochemical and molecular tools, we looked for cellular events indicative of vascular insufficiency, including the presence of hypoxia, upregulation of hypoxia-inducible, or antioxidant-response genes, alterations to antioxidant enzymes, increased formation of superoxide, and the presence of oxidative stress. Our data show that ocular hypertension caused selective hypoxia within the laminar ONH in 11/13 eyes graded as either medium or high for axonal transport disruption. Hypoxia was always present in areas featuring injured axons, and, the greater the abundance of axonal transport disruption, the greater the likelihood of a larger hypoxic region. Nevertheless, hypoxic regions were typically focal and were not necessarily evident in sections taken deeper within the same ONH, while disrupted axonal transport was frequently encountered without any discernible hypoxia. Ocular hypertension caused upregulation of heme oxygenase-1—an hypoxia-inducible and redox-sensitive enzyme—in ONH astrocytes. The distribution and abundance of heme oxygenase-1 closely matched that of axonal transport disruption, and encompassed hypoxic regions and their immediate penumbra. Ocular hypertension also caused upregulations in the iron-regulating protein ceruloplasmin, the anaerobic glycolytic enzyme lactate dehydrogenase, and the transcription factors cFos and p-cJun. Moreover, ocular hypertension increased the generation of superoxide radicals in the retina and ONH, as well as upregulating the active subunit of the superoxide-generating enzyme NADPH oxidase, and invoking modest alterations to antioxidant-response enzymes. The results of this study provide further indirect support for the hypothesis that reduced blood flow to the ONH contributes to axonal injury in glaucoma.
Collapse
Affiliation(s)
- Glyn Chidlow
- Ophthalmic Research Laboratories, Discipline of Ophthalmology and Visual Sciences, University of AdelaideAdelaide, SA, Australia
| | - John P M Wood
- Ophthalmic Research Laboratories, Discipline of Ophthalmology and Visual Sciences, University of AdelaideAdelaide, SA, Australia
| | - Robert J Casson
- Ophthalmic Research Laboratories, Discipline of Ophthalmology and Visual Sciences, University of AdelaideAdelaide, SA, Australia
| |
Collapse
|
19
|
Jha KA, Nag TC, Wadhwa S, Roy TS. Immunohistochemical Localization of GFAP and Glutamate Regulatory Proteins in Chick Retina and Their Levels of Expressions in Altered Photoperiods. Cell Mol Neurobiol 2017; 37:1029-1042. [PMID: 27815657 DOI: 10.1007/s10571-016-0436-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/18/2016] [Indexed: 01/05/2023]
Abstract
Moderate to intense light is reported to damage the chick retina, which is cone dominated. Light damage alters neurotransmitter pools, such as those of glutamate. Glutamate level in the retina is regulated by glutamate-aspartate transporter (GLAST) and glutamine synthetase (GS). We examined immunolocalization patterns and the expression levels of both markers and of glial fibrillary acidic protein (GFAP, a marker of neuronal stress) in chick retina exposed to 2000 lux under 12-h light:12-h dark (12L:12D; normal photoperiod), 18L:6D (prolonged photoperiod), and 24L:0D (constant light) at post-hatch day 30. Retinal damage (increased death of photoreceptors and inner retinal neurons and Müller cell hypertrophy) and GFAP expression in Müller cells were maximal in 24L:0D condition compared to that seen in 12L:12D and 18L:6D conditions. GS was present in Müller cells and GLAST expressed in Müller cell processes and photoreceptor inner segments. GLAST expression was decreased in 24L:0D condition, and the expression levels between 12L:12D and 18L:6D, though increased marginally, were statistically insignificant. Similar was the case with GS expression that significantly decreased in 24L:0D condition. Our previous study with chicks exposed to 2000 lux reported increased retinal glutamate level in 24L:0D condition. The present results indicate that constant light induces decreased expressions of GLAST and GS, a condition that might aggravate glutamate-mediated neurotoxicity and delay neuroprotection in a cone-dominated retina.
Collapse
Affiliation(s)
- Kumar Abhiram Jha
- Department of Anatomy, All India Institute of Medical Sciences, Room No. 1029, New Delhi, 110029, India
| | - Tapas C Nag
- Department of Anatomy, All India Institute of Medical Sciences, Room No. 1029, New Delhi, 110029, India.
| | - Shashi Wadhwa
- Department of Anatomy, All India Institute of Medical Sciences, Room No. 1029, New Delhi, 110029, India
| | - Tara Sankar Roy
- Department of Anatomy, All India Institute of Medical Sciences, Room No. 1029, New Delhi, 110029, India
| |
Collapse
|
20
|
Morrison JC, Cepurna WO, Tehrani S, Choe TE, Jayaram H, Lozano DC, Fortune B, Johnson EC. A Period of Controlled Elevation of IOP (CEI) Produces the Specific Gene Expression Responses and Focal Injury Pattern of Experimental Rat Glaucoma. Invest Ophthalmol Vis Sci 2017; 57:6700-6711. [PMID: 27942722 PMCID: PMC5156512 DOI: 10.1167/iovs.16-20573] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We determine if several hours of controlled elevation of IOP (CEI) will produce the optic nerve head (ONH) gene expression changes and optic nerve (ON) damage pattern associated with early experimental glaucoma in rats. Methods The anterior chambers of anesthetized rats were cannulated and connected to a reservoir to elevate IOP. Physiologic parameters were monitored. Following CEI at various recovery times, ON cross-sections were graded for axonal injury. Anterior ONHs were collected at 0 hours to 10 days following CEI and RNA extracted for quantitative PCR measurement of selected messages. The functional impact of CEI was assessed by electroretinography (ERG). Results During CEI, mean arterial pressure (99 ± 6 mm Hg) and other physiologic parameters remained stable. An 8-hour CEI at 60 mm Hg produced significant focal axonal degeneration 10 days after exposure, with superior lesions in 83% of ON. Message analysis in CEI ONH demonstrated expression responses previously identified in minimally injured ONH following chronic IOP elevation, as well as their sequential patterns. Anesthesia with cannulation at 20 mm Hg did not alter these message levels. Electroretinographic A- and B-waves, following a significant reduction at 2 days after CEI, were fully recovered at 2 weeks, while peak scotopic threshold response (pSTR) remained mildly but significantly depressed. Conclusions A single CEI reproduces ONH message changes and patterns of ON injury previously observed with chronic IOP elevation. Controlled elevation of IOP can allow detailed determination of ONH cellular and functional responses to an injurious IOP insult and provide a platform for developing future therapeutic interventions.
Collapse
Affiliation(s)
- John C Morrison
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - William O Cepurna
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Shandiz Tehrani
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Tiffany E Choe
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Hari Jayaram
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States 2Glaucoma Service, NIHR Moorfields Biomedical Research Centre, London, United Kingdom
| | - Diana C Lozano
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Brad Fortune
- Devers Eye Institute, Portland, Oregon, United States
| | - Elaine C Johnson
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| |
Collapse
|
21
|
Real-time quantification of oxidative stress and the protective effect of nitroxide antioxidants. Neurochem Int 2016; 92:1-12. [DOI: 10.1016/j.neuint.2015.11.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/28/2015] [Accepted: 11/10/2015] [Indexed: 11/18/2022]
|
22
|
Jung KI, Kim JH, Park CK. α2-Adrenergic modulation of the glutamate receptor and transporter function in a chronic ocular hypertension model. Eur J Pharmacol 2015; 765:274-83. [PMID: 26300392 DOI: 10.1016/j.ejphar.2015.08.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 08/19/2015] [Accepted: 08/19/2015] [Indexed: 12/13/2022]
Abstract
Excitotoxicity, glutamate-induced toxic effects to retinal ganglion cells (RGCs), is one of several mechanisms of RGC loss suggested in glaucoma. In this study, we focused on the role of glutamate transporter of glial cells as well as N-methyl-d-aspartate (NMDA) receptor with regard to glutamate toxicity in glaucoma. We also investigated whether α2-adrenoceptor activation could modulate glutamate transporters and NMDA receptors in a chronic ocular hypertension model. Brimonidine 0.15% was administered topically to the eyes of experimental glaucoma and control animals twice daily. After 8 weeks of intraocular pressure (IOP) elevation, staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) revealed an increase in the ganglion cell layer, and the number of TUNEL-positive cells was reduced by brimonidine treatment (P<0.05). Animals with experimentally induced glaucoma exhibited an increase in retinal stress marker glial fibrillary acidic protein (GFAP) immunoreactivity; brimonidine treatment reduced GFAP. Excitatory amino acid transporter 1(EAAT1) expression remained stable throughout the period of chronic ocular hypertension. α2-Adrenergic treatment upregulated EAAT1 protein levels (P<0.05). NMDA receptor (GluN1) expression was stimulated by chronic elevation of IOP, and GluN1-positive cells in ganglion cell layer were co-localized with TUNEL staining. Brimonidine administration suppressed GluN1 levels (P<0.05). These results indicate that brimonidine decreased RGC apoptosis, upregulating EAAT1 and downregulating NMDA receptors. We suggest that topical brimonidine treatment may decrease the glutamate excitotoxicity through modulation of glutamate transporter and NMDA receptor in glaucoma.
Collapse
Affiliation(s)
- Kyoung In Jung
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of Korea, Seoul, Korea
| | - Jie Hyun Kim
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of Korea, Seoul, Korea
| | - Chan Kee Park
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of Korea, Seoul, Korea.
| |
Collapse
|
23
|
Yang ZJ, Zhong YS. Effect of adenosine on GLAST expression in the retina of a chronic ocular hypertension rat model. Exp Ther Med 2015; 10:991-994. [PMID: 26622427 DOI: 10.3892/etm.2015.2607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 04/02/2015] [Indexed: 11/06/2022] Open
Abstract
This study was performed to evaluate the effect of adenosine and an adenosine receptor antagonist on the expression of the L-glutamate/L-aspartate transporter (GLAST) in the retina of a chronic ocular hypertension (COH) rat model. COH models were established via the cauterization of three episcleral veins. Measurements of the intraocular pressure of the right eye (COH eye) were taken weekly by a handheld digital tonometer. A total of 10 µM adenosine or 10 µM adenosine + 100 nM SCH442416 solution (2 µl) was injected into the rat vitreous space. The reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry were used to detect GLAST expression. Compared with the COH group, GLAST mRNA expression was decreased by 33.6% in the group treated with adenosine (n=6, P=0.020) and was increased by 159.6% in the group treated with SCH442416 (n=6, P=0.001). Administration of adenosine decreased GLAST protein expression by 34.7% (n=6, P<0.001), while treatment with the adenosine A2A receptor antagonist SCH442416 increased GLAST protein expression by 48.3% compared with the control COH group (n=6, P<0.001). Immunohistochemical experiments showed that administration of adenosine decreased GLAST protein expression, as compared with expression in the control COH rat retina. Administration of SCH442416 markedly increased GLAST protein expression. The results of the present study may provide a novel method for retinal neuron protection.
Collapse
Affiliation(s)
- Zi-Jian Yang
- Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, P.R. China
| | - Yi-Sheng Zhong
- Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, P.R. China
| |
Collapse
|
24
|
|
25
|
Abbott CJ, Choe TE, Burgoyne CF, Cull G, Wang L, Fortune B. Comparison of retinal nerve fiber layer thickness in vivo and axonal transport after chronic intraocular pressure elevation in young versus older rats. PLoS One 2014; 9:e114546. [PMID: 25501362 PMCID: PMC4263742 DOI: 10.1371/journal.pone.0114546] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 11/11/2014] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. METHOD IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. RESULTS Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77-80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75-95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). CONCLUSION Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age.
Collapse
Affiliation(s)
- Carla J. Abbott
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Tiffany E. Choe
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Claude F. Burgoyne
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Grant Cull
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Lin Wang
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| |
Collapse
|
26
|
Dynamic, in vivo, real-time detection of retinal oxidative status in a model of elevated intraocular pressure using a novel, reversibly responsive, profluorescent nitroxide probe. Exp Eye Res 2014; 129:48-56. [DOI: 10.1016/j.exer.2014.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/15/2014] [Accepted: 10/16/2014] [Indexed: 12/15/2022]
|
27
|
Bennett LD, Hopiavuori BR, Brush RS, Chan M, Van Hook MJ, Thoreson WB, Anderson RE. Examination of VLC-PUFA-deficient photoreceptor terminals. Invest Ophthalmol Vis Sci 2014; 55:4063-72. [PMID: 24764063 DOI: 10.1167/iovs.14-13997] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Juvenile-onset autosomal dominant Stargardt-like macular dystrophy (STGD3) is caused by mutations in ELOVL4 (elongation of very long fatty acids-4), an elongase necessary for the biosynthesis of very long chain fatty acids (VLC-FAs ≥ C26). Photoreceptors are enriched with VLC polyunsaturated fatty acids (VLC-PUFAs), which are necessary for long-term survival of rod photoreceptors. The purpose of these studies was to determine the effect of deletion of VLC-PUFAs on rod synaptic function in retinas of mice conditionally depleted (KO) of Elovl4. METHODS Retina function was assessed in wild-type (WT) and KO by electroretinography. Outer plexiform structure was evaluated by immunofluorescence and transmission electron microscopy. Single-cell recordings measured rod ion channel operation and rod bipolar glutamate signaling. Sucrose gradient centrifugation was used to isolate synaptosomes from bovine retina. Proteins and lipids were analyzed by Western blotting and tandem mass spectroscopy, respectively. RESULTS Inner retinal responses (b-wave, oscillatory potentials, and scotopic threshold responses) of the ERG were decreased in the KO mice compared to controls. However the rod ion channel operation and bipolar glutamate responses were comparable between groups. Biochemical analysis revealed that conventional and ribbon synapses have VLC-PUFAs. Ultrastructural analysis showed that the outer plexiform layer was disorganized and the diameter of vesicles in rod terminals was smaller in the KO mice. CONCLUSIONS Very long chain PUFAs affect rod function by contributing to synaptic vesicle size, which may alter the dynamics of synaptic transmission, ultimately resulting in a loss of neuronal connectivity and death of rod photoreceptors.
Collapse
Affiliation(s)
- Lea D Bennett
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Blake R Hopiavuori
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Richard S Brush
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Michael Chan
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Matthew J Van Hook
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Robert E Anderson
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| |
Collapse
|
28
|
Abbott CJ, Choe TE, Lusardi TA, Burgoyne CF, Wang L, Fortune B. Evaluation of retinal nerve fiber layer thickness and axonal transport 1 and 2 weeks after 8 hours of acute intraocular pressure elevation in rats. Invest Ophthalmol Vis Sci 2014; 55:674-87. [PMID: 24398096 DOI: 10.1167/iovs.13-12811] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
PURPOSE To compare in vivo retinal nerve fiber layer thickness (RNFLT) and axonal transport at 1 and 2 weeks after an 8-hour acute IOP elevation in rats. METHODS Forty-seven adult male Brown Norway rats were used. Procedures were performed under anesthesia. The IOP was manometrically elevated to 50 mm Hg or held at 15 mm Hg (sham) for 8 hours unilaterally. The RNFLT was measured by spectral-domain optical coherence tomography. Anterograde and retrograde axonal transport was assessed from confocal scanning laser ophthalmoscopy imaging 24 hours after bilateral injections of 2 μL 1% cholera toxin B-subunit conjugated to AlexaFluor 488 into the vitreous or superior colliculi, respectively. Retinal ganglion cell (RGC) and microglial densities were determined using antibodies against Brn3a and Iba-1. RESULTS The RNFLT in experimental eyes increased from baseline by 11% at 1 day (P < 0.001), peaked at 19% at 1 week (P < 0.0001), remained 11% thicker at 2 weeks (P < 0.001), recovered at 3 weeks (P > 0.05), and showed no sign of thinning at 6 weeks (P > 0.05). There was no disruption of anterograde transport at 1 week (superior colliculi fluorescence intensity, 75.3 ± 7.9 arbitrary units [AU] for the experimental eyes and 77.1 ± 6.7 AU for the control eyes) (P = 0.438) or 2 weeks (P = 0.188). There was no obstruction of retrograde transport at 1 week (RCG density, 1651 ± 153 per mm(2) for the experimental eyes and 1615 ± 135 per mm(2) for the control eyes) (P = 0.63) or 2 weeks (P = 0.25). There was no loss of Brn3a-positive RGC density at 6 weeks (P = 0.74) and no increase in microglial density (P = 0.92). CONCLUSIONS Acute IOP elevation to 50 mm Hg for 8 hours does not cause a persisting axonal transport deficit at 1 or 2 weeks or a detectable RNFLT or RGC loss by 6 weeks but does lead to transient RNFL thickening that resolves by 3 weeks.
Collapse
Affiliation(s)
- Carla J Abbott
- Discoveries in Sight Research Laboratories, Legacy Good Samaritan Devers Eye Institute, and Legacy Research Institute, Legacy Health, Portland, Oregon
| | | | | | | | | | | |
Collapse
|
29
|
Bui BV, Batcha AH, Fletcher E, Wong VHY, Fortune B. Relationship between the magnitude of intraocular pressure during an episode of acute elevation and retinal damage four weeks later in rats. PLoS One 2013; 8:e70513. [PMID: 23922999 PMCID: PMC3726657 DOI: 10.1371/journal.pone.0070513] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 06/24/2013] [Indexed: 01/20/2023] Open
Abstract
Purpose To determine relationship between the magnitude of intraocular pressure (IOP) during a fixed-duration episode of acute elevation and the loss of retinal function and structure 4 weeks later in rats. Methods Unilateral elevation of IOP (105 minutes) was achieved manometrically in adult Brown Norway rats (9 groups; n = 4 to 8 each, 10–100 mm Hg and sham control). Full-field ERGs were recorded simultaneously from treated and control eyes 4 weeks after IOP elevation. Scotopic ERG stimuli were white flashes (−6.04 to 2.72 log cd.s.m−2). Photopic ERGs were recorded (1.22 to 2.72 log cd.s.m−2) after 15 min of light adaptation (150 cd/m2). Relative amplitude (treated/control, %) of ERG components versus IOP was described with a cummulative normal function. Retinal ganglion cell (RGC) layer density was determined post mortem by histology. Results All ERG components failed to recover completely normal amplitudes by 4 weeks after the insult if IOP was 70 mmHg or greater during the episode. There was no ERG recovery at all if IOP was 100 mmHg. Outer retinal (photoreceptor) function demonstrated the least sensitivity to prior acute IOP elevation. ERG components reflecting inner retinal function were correlated with post mortem RGC layer density. Conclusions Retinal function recovers after IOP normalization, such that it requires a level of acute IOP elevation approximately 10 mmHg higher to cause a pattern of permanent dysfunction similar to that observed during the acute event. There is a ‘threshold’ for permanent retinal functional loss in the rat at an IOP between 60 and 70 mmHg if sustained for 105 minutes or more.
Collapse
Affiliation(s)
- Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, Australia.
| | | | | | | | | |
Collapse
|
30
|
Dietary ω-3 deficiency and IOP insult are additive risk factors for ganglion cell dysfunction. J Glaucoma 2013; 22:269-77. [PMID: 23221900 DOI: 10.1097/ijg.0b013e318237cac7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIM Dietary deficiencies in ω-3 polyunsaturated fatty acids are known to effect retinal function including retinal ganglion cell (RGC) activity, which may have implications for glaucoma. In this study we consider retinal function after dietary manipulation and intraocular pressure (IOP) stress designed to compromise RGCs. METHODS Sprague-Dawley dams were fed either ω-3 sufficient (ω-3, n=15) or deficient (ω-3, n=16) diets 5 weeks before conception with pups subsequently weaned onto their mothers diets. At 20 weeks of age, acute IOP elevation was induced repeatedly through anterior chamber cannulation to 70 mm Hg for 1 hour on 3 separate occasions separated by 1 week. Electroretinograms were recorded 1 week after each IOP elevation to assay the photoreceptors (PIII), ON-bipolar cells (PII), and ganglion/amacrine cells (STR). RESULTS Repeat IOP insult results in a specific RGC dysfunction (pSTR -14.5%, P<0.035) as does ω-3 deficiency (-26.4%, P<0.01). However, the combination of both causes an even larger RGC functional loss (-40.1%, P<0.001) than does either diet or IOP insult in isolation (P<0.001). CONCLUSIONS Both ω-3 deficiency and repeat acute IOP insult cause RGC dysfunction and the combination of these factors results in a cumulative effect. Our data indicate that sufficient dietary ω-3 improves RGC function making it less susceptible to IOP insult.
Collapse
|
31
|
Zhou L, Huang J, Wang H, Luo J, Zeng L, Xiong K, Chen D. Expression of Glutamate and GABA during the Process of Rat Retinal Synaptic Plasticity Induced by Acute High Intraocular Pressure. Acta Histochem Cytochem 2013; 46:11-8. [PMID: 23554535 PMCID: PMC3596602 DOI: 10.1267/ahc.12029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 11/12/2012] [Indexed: 11/30/2022] Open
Abstract
Acute high intraocular pressure (HIOP) can induce plastic changes of retinal synapses during which the expression of the presynaptic marker synaptophysin (SYN) has a distinct spatiotemporal pattern from the inner plexiform layer to the outer plexiform layer. We identified the types of neurotransmitters in the retina that participated in this process and determined the response of these neurotransmitters to HIOP induction. The model of acute HIOP was established by injecting normal saline into the anterior chamber of the rat eye. We found that the number of glutamate-positive cells increased successively from the inner part to the outer part of the retina (from the ganglion cell layer to the inner nuclear layer to the outer nuclear layer) after HIOP, which was similar to the spatiotemporal pattern of SYN expression (internally to externally) following HIOP. However, the distribution and intensity of GABA immunoreactivity in the retina did not change significantly at different survival time post injury and had no direct correlation with SYN expression. Our results suggested that the excitatory neurotransmitter glutamate might participate in the plastic process of retinal synapses following acute HIOP, but no evidence was found for the role of the inhibitory neurotransmitter GABA.
Collapse
Affiliation(s)
- Lihong Zhou
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Jufang Huang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Hui Wang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Jia Luo
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Leping Zeng
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Kun Xiong
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Dan Chen
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| |
Collapse
|
32
|
Reichenbach A, Bringmann A. New functions of Müller cells. Glia 2013; 61:651-78. [PMID: 23440929 DOI: 10.1002/glia.22477] [Citation(s) in RCA: 466] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/10/2012] [Indexed: 12/12/2022]
Abstract
Müller cells, the major type of glial cells in the retina, are responsible for the homeostatic and metabolic support of retinal neurons. By mediating transcellular ion, water, and bicarbonate transport, Müller cells control the composition of the extracellular space fluid. Müller cells provide trophic and anti-oxidative support of photoreceptors and neurons and regulate the tightness of the blood-retinal barrier. By the uptake of glutamate, Müller cells are more directly involved in the regulation of the synaptic activity in the inner retina. This review gives a survey of recently discoved new functions of Müller cells. Müller cells are living optical fibers that guide light through the inner retinal tissue. Thereby they enhance the signal/noise ratio by minimizing intraretinal light scattering and conserve the spatial distribution of light patterns in the propagating image. Müller cells act as soft, compliant embedding for neurons, protecting them in case of mechanical trauma, and also as soft substrate required for neurite growth and neuronal plasticity. Müller cells release neuroactive signaling molecules which modulate neuronal activity, are implicated in the mediation of neurovascular coupling, and mediate the homeostasis of the extracellular space volume under hypoosmotic conditions which are a characteristic of intense neuronal activity. Under pathological conditions, a subset of Müller cells may differentiate to neural progenitor/stem cells which regenerate lost photoreceptors and neurons. Increasing knowledge of Müller cell function and responses in the normal and diseased retina will have great impact for the development of new therapeutic approaches for retinal diseases.
Collapse
Affiliation(s)
- Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
| | | |
Collapse
|
33
|
Bringmann A, Grosche A, Pannicke T, Reichenbach A. GABA and Glutamate Uptake and Metabolism in Retinal Glial (Müller) Cells. Front Endocrinol (Lausanne) 2013; 4:48. [PMID: 23616782 PMCID: PMC3627989 DOI: 10.3389/fendo.2013.00048] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 04/04/2013] [Indexed: 12/11/2022] Open
Abstract
Müller cells, the principal glial cells of the retina, support the synaptic activity by the uptake and metabolization of extracellular neurotransmitters. Müller cells express uptake and exchange systems for various neurotransmitters including glutamate and γ-aminobutyric acid (GABA). Müller cells remove the bulk of extracellular glutamate in the inner retina and contribute to the glutamate clearance around photoreceptor terminals. By the uptake of glutamate, Müller cells are involved in the shaping and termination of the synaptic activity, particularly in the inner retina. Reactive Müller cells are neuroprotective, e.g., by the clearance of excess extracellular glutamate, but may also contribute to neuronal degeneration by a malfunctioning or even reversal of glial glutamate transporters, or by a downregulation of the key enzyme, glutamine synthetase. This review summarizes the present knowledge about the role of Müller cells in the clearance and metabolization of extracellular glutamate and GABA. Some major pathways of GABA and glutamate metabolism in Müller cells are described; these pathways are involved in the glutamate-glutamine cycle of the retina, in the defense against oxidative stress via the production of glutathione, and in the production of substrates for the neuronal energy metabolism.
Collapse
Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of LeipzigLeipzig, Germany
| | - Antje Grosche
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of LeipzigLeipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of LeipzigLeipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of LeipzigLeipzig, Germany
- *Correspondence: Andreas Reichenbach, Paul Flechsig Institute of Brain Research, University of Leipzig, Jahnallee 59, D-04109 Leipzig, Germany. e-mail:
| |
Collapse
|
34
|
Reichenbach A, Bringmann A. Cell Biology of the Müller Cell. Retina 2013. [DOI: 10.1016/b978-1-4557-0737-9.00017-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
35
|
Chen F, Jiang L, Shen C, Wan H, Xu L, Wang N, Jonas JB. Neuroprotective effect of epigallocatechin-3-gallate against N-methyl-D-aspartate-induced excitotoxicity in the adult rat retina. Acta Ophthalmol 2012; 90:e609-15. [PMID: 22974415 DOI: 10.1111/j.1755-3768.2012.02502.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE Epigallocatechin-3-gallate (EGCG), the major polyphenol of green tea, has been suggested to reduce glutamate excitotoxicity. We therefore investigated the potentially protective effects of EGCG against N-methyl-d-aspartate (NMDA)-induced excitotoxicity in the retina. METHODS Female Wistar rats (n = 171) were divided into a normal control group (n = 9); saline control group with intravitreal saline injections (n = 54); NMDA control group with an intravitreal NMDA injection and intraperitoneal saline injections (n = 54); and NMDA study group (n = 54) receiving an intravitreal NMDA injection plus intraperitoneal EGCG (25 mg/kg) injections. Starting at 2 days prior to the intravitreal NMDA injection, the intraperitoneal injections were performed daily for the whole study period. At 12 hr, 1, 2, 3 days, 1 and 2 weeks after the intravitreal NMDA injection, the animals were killed. We counted the neurons in the retinal ganglion cell layer (GCL) on histological sections, measured the thickness of Thy-1 immunoreactivity and assessed the expression of Thy-1 mRNA by real-time polymerase chain reaction. RESULTS At all time-points, GCL cell density, thickness of Thy-1 immunoreactivity and expression of Thy-1 mRNA were significantly (all p < 0.05) lower in the NMDA control group than in the NMDA study group, in which the parameters were significantly (all p < 0.05) lower than in the saline control group and the normal control group. In both groups with an intravitreal NMDA injection, GCL cell density, thickness of Thy-1 immunoreactivity and expression of Thy-1 mRNA decreased significantly with increasing follow-up time. CONCLUSIONS Intraperitoneal application of EGCG resulted in a significantly less marked NMDA-associated loss of retinal ganglion cells.
Collapse
Affiliation(s)
- Fei Chen
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | | | | | | | | | | | | |
Collapse
|
36
|
Furuya T, Pan Z, Kashiwagi K. Role of retinal glial cell glutamate transporters in retinal ganglion cell survival following stimulation of NMDA receptor. Curr Eye Res 2012; 37:170-8. [PMID: 22335803 DOI: 10.3109/02713683.2011.645105] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate the role of glutamate transporters (GLTs)in retinal glial cells that were treated with N-methyl-D-aspartate (NMDA), in retinal ganglion cell (RGC) survival. METHODS Primary cultures of retinal glial cells or RGCs from 3-day-old Sprague-Dawley rats were employed in the present study. Retinal glial cells were treated with NMDA and changes in GLT mRNA and protein expression were analyzed. The effects of pretreating retinal glial cells with the GLAST-specific inhibitor, rottlerin (ROT), and the GLT-1-specific inhibitor, dihydrokainic acid (DHK), on RGC survival were investigated under exposure to NMDA. The amount of glutamate in the culture medium of retinal glial cells was measured by high-performance liquid chromatography. RESULTS NMDA treatment increased GLAST and GLT-1 expression. GLAST and GLT-1 mRNA expression increased by 2.94-fold and 3.36-fold at 12 h after treatment with the highest concentration of NMDA (33 mM), and by 1.41-fold and 1.39-fold at 24 h, respectively. GLT-1 and GLAST protein expression also increased. MK801, an NMDA-receptor antagonist, inhibited the NMDA-induced upregulation of GLT mRNA expression. Co-culture with retinal glial cells increased the survival rate of RGCs. ROT decreased the survival rate of RGCs, whereas DHK significantly increased the survival rate of RGCs treated with 33 mM NMDA. NMDA treatment reduced the total amount of glutamate in the culture medium, particularly when 33 mM NMDA was added to the medium. ROT pretreatment increased the amount of glutamate in the culture medium, whereas DHK pretreatment decreased it. CONCLUSION GLAST and GLT-1 may have different roles in the survival of RGCs mediated by retinal glial cells. These results suggest that the NMDA-associated induction of GLTs plays an important role in RGC survival.
Collapse
Affiliation(s)
- Toshie Furuya
- Department of Ophthalmology, Interdisciplinary School of Medicine and Engineering, University of Yamanashi, Chuo Yamanashi, Japan
| | | | | |
Collapse
|
37
|
Kong YXG, van Bergen N, Bui BV, Chrysostomou V, Vingrys AJ, Trounce IA, Crowston JG. Impact of aging and diet restriction on retinal function during and after acute intraocular pressure injury. Neurobiol Aging 2012; 33:1126.e15-25. [DOI: 10.1016/j.neurobiolaging.2011.11.026] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 11/15/2011] [Accepted: 11/20/2011] [Indexed: 11/15/2022]
|
38
|
Gan SW, Ran JH, Chen H, Ren ZQ, Sun SQ, Zhu SJ, Lu WT, Xu J, Zhang B, Huang J, Wang KJ, Chen Z. Lysosomal degradation of retinal glial AQP4 following its internalization induced by acute ocular hypertension. Neurosci Lett 2012; 516:135-40. [DOI: 10.1016/j.neulet.2012.03.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Revised: 03/13/2012] [Accepted: 03/24/2012] [Indexed: 11/26/2022]
|
39
|
Bringmann A, Wiedemann P. Müller glial cells in retinal disease. ACTA ACUST UNITED AC 2011; 227:1-19. [PMID: 21921569 DOI: 10.1159/000328979] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 04/27/2011] [Indexed: 11/19/2022]
Abstract
Virtually all pathogenic stimuli activate Müller cells. Reactive Müller cells exert protective and toxic effects on photoreceptors and neurons. They contribute to oxidative stress and glutamate toxicity due to malfunctions of glutamate uptake and glutathione synthesis. Downregulation of potassium conductance disrupts transcellular potassium and water transport, resulting in neuronal hyperexcitability and edema. Protective effects of reactive Müller cells include upregulation of adenosine 5'-triphosphate (ATP)-degrading ectoenzymes, which enhances the extracellular availability of the neuroprotectant adenosine, abrogation of the osmotic release of ATP, which might protect retinal ganglion cells from apoptosis, and the release of antioxidants and neurotrophic factors. The dedifferentiation of reactive Müller cells to progenitor-like cells might have an impact on future therapeutic approaches. A better understanding of the gliotic mechanisms will be helpful in developing efficient therapeutic strategies aiming at increased protective and regenerative properties and decreased toxicity of reactive Müller cells.
Collapse
Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | | |
Collapse
|
40
|
Gunn DJ, Gole GA, Barnett NL. Specific amacrine cell changes in an induced mouse model of glaucoma. Clin Exp Ophthalmol 2011; 39:555-63. [PMID: 21176046 DOI: 10.1111/j.1442-9071.2010.02488.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND To investigate retinal cell population changes under chronic elevated intraocular pressure in an inducible mouse model of glaucoma. METHODS Chronic unilateral ocular hypertension was induced in 40 C57BL6/J mice by ablation of the limbal episcleral veins. After 5, 20, 40 and 60 days of elevated intraocular pressure, specific retinal cell types were identified and/or quantified by immunohistochemistry for protein kinase C α, glial fibrillary acidic protein, parvalbumin and calretinin. Apoptotic cells were identified by TUNEL and cleaved caspase-3 immunohistochemistry. RESULTS Elevations in intraocular pressure in the range 22-30 mmHg were developed and sustained in mice for up to 60 days. Protein kinase C α immunoreactivity localized to bipolar cells was unchanged. We observed a rapid increase in glial fibrillary acidic protein expression in Müller cells and a progressive loss of parvalbumin-labelled ganglion cells. After 60 days of elevated intraocular pressure, calretinin-immunoreactive cell counts declined by 55.4% and 46.4% in the inner nuclear and ganglion cell layers, respectively. However, at all time points examined, the markers of cell death were only observed in the ganglion cell layer, not in the inner nuclear layer. CONCLUSIONS In addition to ganglion cell death and reactive Müller cell changes, chronic experimental elevation of intraocular pressure alters calcium-binding protein immunohistochemistry in amacrine cells. However, these changes are not indicative of amacrine cell loss but may represent early indicators of cellular distress that precede physiological dysfunction or cell death.
Collapse
Affiliation(s)
- David J Gunn
- The University of Queensland, Perinatal Research Centre, Brisbane, Queensland, Australia
| | | | | |
Collapse
|
41
|
The calcineurin inhibitor, FK506, does not alter glutamate transport in the ischaemic mouse retina. Exp Eye Res 2010; 91:315-9. [PMID: 20434440 DOI: 10.1016/j.exer.2010.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 11/20/2022]
Abstract
The protein phosphatase 2B inhibitor, FK506, is an immunomodulatory polypeptide that has neuroprotective properties, the mechanisms of which have not been elucidated. A possible mechanism may be phosphorylation-mediated regulation of glutamate transporter activity. In the present study, we investigated the effect of FK506 on glutamate transporter localization and activity in the ischaemic mouse retina. FK506 did not appear to modulate the localization or activity of glutamate transporters under simulated ischaemic conditions. Our present data suggest that the mechanism by which FK506 exerts its neuroprotective action is not attributable to alterations in retinal glutamate transport.
Collapse
|
42
|
S-adenosyl-L-methionine restores photoreceptor function following acute retinal ischemia. Vis Neurosci 2009; 26:429-41. [PMID: 19919727 DOI: 10.1017/s0952523809990241] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The survival and function of retinal neurons is dependent on mitochondrial energy generation and its intracellular distribution by creatine kinase. Post ischemic disruption of retinal creatine synthesis, creatine kinase activity, or transport of creatine into neurons may impair retinal function. S-adenosyl-L-methionine (SAMe) is required for creatine synthesis, phosphatidylcholine and glutathione synthesis, and transducin methylation. These reactions are essential for photoreceptor function but may be downregulated after ischemia due to a reduction in SAMe. Our aim was to determine whether administration of SAMe after ischemia could improve retinal function. Unilateral retinal ischemia was induced in adult rats by increasing the intraocular pressure to 110 mm Hg for 60 min. Immediately after the ischemic insult, SAMe was injected into the vitreous (100 microM), followed by oral administration (69 mg/kg/day) for 5 or 10 days. Retinal function (electroretinography), histology, and creatine transporter (CRT-1) expression were analyzed. Photoreceptoral responses (R(mP3), S), rod and cone bipolar cell responses (PII), and oscillatory potentials were reduced by the ischemia/reperfusion insult. Although SAMe treatment ameliorated the ischemia-induced histological damage by day 5, there was no improvement in retinal function and the intensity of CRT-1 labeling in ischemic retinas was markedly reduced. However, 10 days after ischemia, a recovery in CRT-1 immunolabeling was evident and SAMe supplementation significantly restored photoreceptor function and rod PII responses. In conclusion, these data suggest that creatine transport and methylation reactions, such as creatine synthesis, may be compromised by an ischemic insult contributing to retinal dysfunction and injury. Oral SAMe supplementation after retinal ischemia may provide an effective, safe, and accessible neuroprotective strategy.
Collapse
|
43
|
Role of retinal glial cells in neurotransmitter uptake and metabolism. Neurochem Int 2009; 54:143-60. [DOI: 10.1016/j.neuint.2008.10.014] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 10/15/2008] [Accepted: 10/20/2008] [Indexed: 11/30/2022]
|