1
|
Tran KKN, Wong VHY, Hoang A, Finkelstein DI, Bui BV, Nguyen CTO. Retinal alpha-synuclein accumulation correlates with retinal dysfunction and structural thinning in the A53T mouse model of Parkinson's disease. Front Neurosci 2023; 17:1146979. [PMID: 37214398 PMCID: PMC10196133 DOI: 10.3389/fnins.2023.1146979] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 04/17/2023] [Indexed: 05/24/2023] Open
Abstract
Abnormal alpha-synuclein (α-SYN) protein deposition has long been recognized as one of the pathological hallmarks of Parkinson's disease's (PD). This study considers the potential utility of PD retinal biomarkers by investigating retinal changes in a well characterized PD model of α-SYN overexpression and how these correspond to the presence of retinal α-SYN. Transgenic A53T homozygous (HOM) mice overexpressing human α-SYN and wildtype (WT) control littermates were assessed at 4, 6, and 14 months of age (male and female, n = 15-29 per group). In vivo retinal function (electroretinography, ERG) and structure (optical coherence tomography, OCT) were recorded, and retinal immunohistochemistry and western blot assays were performed to examine retinal α-SYN and tyrosine hydroxylase. Compared to WT controls, A53T mice exhibited reduced light-adapted (cone photoreceptor and bipolar cell amplitude, p < 0.0001) ERG responses and outer retinal thinning (outer plexiform layer, outer nuclear layer, p < 0.0001) which correlated with elevated levels of α-SYN. These retinal signatures provide a high throughput means to study α-SYN induced neurodegeneration and may be useful in vivo endpoints for PD drug discovery.
Collapse
Affiliation(s)
- Katie K. N. Tran
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Vickie H. Y. Wong
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Anh Hoang
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - David I. Finkelstein
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Christine T. O. Nguyen
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC, Australia
| |
Collapse
|
2
|
Lee PY, Zhao D, Wong VHY, Chrysostomou V, Crowston JG, Bui BV. The Effect of Aging on Retinal Function and Retinal Ganglion Cell Morphology Following Intraocular Pressure Elevation. Front Aging Neurosci 2022; 14:859265. [PMID: 35645783 PMCID: PMC9133539 DOI: 10.3389/fnagi.2022.859265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Aging and elevated intraocular pressure (IOP) are two major risk factors for glaucomatous optic neuropathy; a condition characterized by the selective, progressive injury, and subsequent loss of retinal ganglion cells (RGCs). We examined how age modified the capacity for RGCs to functionally recover following a reproducible IOP elevation (50 mmHg for 30 min). We found that RGC functional recovery (measured using electroretinography) was complete by 7 days in 3-month-old mice but was delayed in 12-month-old mice until 14 days. At the 7-day recovery endpoint when RGC function had recovered in young but not older eyes, we examined RGC structural responses to IOP-related stress by analyzing RGC dendritic morphology. ON-RGC cell volume was attenuated following IOP elevation in both young and older mice. We also found that following IOP elevation OFF-RGC dendritic morphology became less complex per cell volume in young mice, an effect that was not observed in older eyes. Our data suggest that adaptations in OFF-RGCs in young eyes were associated with better functional recovery 7 days after IOP elevation. Loss of RGC cellular adaptations may account for delayed functional recovery in older eyes.
Collapse
Affiliation(s)
- Pei Ying Lee
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Vickie H. Y. Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Vicki Chrysostomou
- Singapore Eye Research Institute, Singapore, Singapore,Duke-NUS Medical School, Singapore, Singapore
| | - Jonathan G. Crowston
- Singapore Eye Research Institute, Singapore, Singapore,Duke-NUS Medical School, Singapore, Singapore
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia,*Correspondence: Bang V. Bui,
| |
Collapse
|
3
|
Loo JH, Lee YS, Woon CY, Yong VHK, Tan B, Schmetterer L, Chong RS. Loss of Caveolin-1 Impairs Light Flicker-Induced Neurovascular Coupling at the Optic Nerve Head. Front Neurosci 2021; 15:764898. [PMID: 34819834 PMCID: PMC8606647 DOI: 10.3389/fnins.2021.764898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/18/2021] [Indexed: 11/13/2022] Open
Abstract
Glaucoma is a neurodegenerative disease, which results in characteristic visual field defects. Intraocular pressure (IOP) remains the main risk factor for this leading cause of blindness. Recent studies suggest that disturbances in neurovascular coupling (NVC) may be associated with glaucoma. The resultant imbalance between vascular perfusion and neuronal stimulation in the eye may precede retinal ganglion cell (RGC) loss and increase the susceptibility of the eye to raised IOP and glaucomatous degeneration. Caveolin-1 (Cav-1) is an integral scaffolding membrane protein found abundantly in retinal glial and vascular tissues, with possible involvement in regulating the neurovascular coupling response. Mutations in Cav-1 have been identified as a major genetic risk factor for glaucoma. Therefore, we aim to evaluate the effects of Cav-1 depletion on neurovascular coupling, retinal vessel characteristics, RGC density and the positive scotopic threshold response (pSTR) in Cav-1 knockout (KO) versus wild type C57/Bl6 mice (WT). Following light flicker stimulation of the retina, Cav-1 KO mice showed a smaller increase in perfusion at the optic nerve head and peripapillary arteries, suggesting defective neurovascular coupling. Evaluation of the superficial capillary plexus in Cav-1 KO mice also revealed significant differences in vascular morphology with higher vessel density, junction density and decreased average vessel length. Cav-1 KO mice exhibited higher IOP and lower pSTR amplitude. However, there was no significant difference in RGC density between Cav-1 KO and wild type mice. These findings highlight the role of Cav-1 in regulating neurovascular coupling and IOP and suggest that the loss of Cav-1 may predispose to vascular dysfunction and decreased RGC signaling in the absence of structural loss. Current treatment for glaucoma relies heavily on IOP-lowering drugs, however, there is an immense potential for new therapeutic strategies that increase Cav-1 expression or augment its downstream signaling in order to avert vascular dysfunction and glaucomatous change.
Collapse
Affiliation(s)
- Jing Hong Loo
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Ying Shi Lee
- Singapore Eye Research Institute, Singapore, Singapore
| | - Chang Yi Woon
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | | | - Bingyao Tan
- Singapore Eye Research Institute, Singapore, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore, Singapore
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore, Singapore.,Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland.,Department of Clinical Pharmacology, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Rachel S Chong
- Singapore Eye Research Institute, Singapore, Singapore.,Duke-National University of Singapore Graduate Medical School, Singapore, Singapore
| |
Collapse
|
4
|
Perche O, Lesne F, Patat A, Raab S, Twyman R, Ring RH, Briault S. Electroretinography and contrast sensitivity, complementary translational biomarkers of sensory deficits in the visual system of individuals with fragile X syndrome. J Neurodev Disord 2021; 13:45. [PMID: 34625026 PMCID: PMC8501595 DOI: 10.1186/s11689-021-09375-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/30/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Disturbances in sensory function are an important clinical feature of neurodevelopmental disorders such as fragile X syndrome (FXS). Evidence also directly connects sensory abnormalities with the clinical expression of behavioral impairments in individuals with FXS; thus, positioning sensory function as a potential clinical target for the development of new therapeutics. Using electroretinography (ERG) and contrast sensitivity (CS), we previously reported the presence of sensory deficits in the visual system of the Fmr1-/y genetic mouse model of FXS. The goals of the current study were two-folds: (1) to assess the feasibility of measuring ERG and CS as a biomarker of sensory deficits in individuals with FXS, and (2) to investigate whether the deficits revealed by ERG and CS in Fmr1-/y mice translate to humans with FXS. METHODS Both ERG and CS were measured in a cohort of male individuals with FXS (n = 20, 18-45 years) and age-matched healthy controls (n = 20, 18-45 years). Under light-adapted conditions, and using both single flash and flicker (repeated train of flashes) stimulation protocols, retinal function was recorded from individual subjects using a portable, handheld, full-field flash ERG device (RETeval®, LKC Technologies Inc., Gaithersburg, MD, USA). CS was assessed in each subject using the LEA SYMBOLS® low-contrast test (Good-Lite, Elgin, IL, USA). RESULTS Data recording was successfully completed for ERG and assessment of CS in most individuals from both cohorts demonstrating the feasibility of these methods for use in the FXS population. Similar to previously reported findings from the Fmr1-/y genetic mouse model, individuals with FXS were found to exhibit reduced b-wave and flicker amplitude in ERG and an impaired ability to discriminate contrasts compared to healthy controls. CONCLUSIONS This study demonstrates the feasibility of using ERG and CS for assessing visual deficits in FXS and establishes the translational validity of the Fmr1-/y mice phenotype to individuals with FXS. By including electrophysiological and functional readouts, the results of this study suggest the utility of both ERG and CS (ERG-CS) as complementary translational biomarkers for characterizing sensory abnormalities found in FXS, with potential applications to the clinical development of novel therapeutics that target sensory function abnormalities to treat core symptomatology in FXS. TRIAL REGISTRATION ID-RCB number 2019-A01015-52 registered on the 17 May 2019.
Collapse
Affiliation(s)
- Olivier Perche
- Genetic Department, Centre Hospitalier Régional d'Orléans, Orléans, France
- UMR7355, Centre National de la Recherche Scientifique (CNRS), Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
- Kaerus Bioscience Ltd., London, EC1Y 4YX, UK
| | | | - Alain Patat
- Kaerus Bioscience Ltd., London, EC1Y 4YX, UK
| | | | | | - Robert H Ring
- Kaerus Bioscience Ltd., London, EC1Y 4YX, UK
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Sylvain Briault
- Genetic Department, Centre Hospitalier Régional d'Orléans, Orléans, France.
- UMR7355, Centre National de la Recherche Scientifique (CNRS), Orléans, France.
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France.
- Kaerus Bioscience Ltd., London, EC1Y 4YX, UK.
| |
Collapse
|
5
|
Blades F, Wong VHY, Nguyen CTO, Bui BV, Kilpatrick TJ, Binder MD. Tyro3 Contributes to Retinal Ganglion Cell Function, Survival and Dendritic Density in the Mouse Retina. Front Neurosci 2020; 14:840. [PMID: 32922258 PMCID: PMC7457004 DOI: 10.3389/fnins.2020.00840] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/20/2020] [Indexed: 01/10/2023] Open
Abstract
Retinal ganglion cells (RGCs) are the only output neurons of the vertebrate retina, integrating signals from other retinal neurons and transmitting information to the visual centers of the brain. The death of RGCs is a common outcome in many optic neuropathies, such as glaucoma, demyelinating optic neuritis and ischemic optic neuropathy, resulting in visual defects and blindness. There are currently no therapies in clinical use which can prevent RGC death in optic neuropathies; therefore, the identification of new targets for supporting RGC survival is crucial in the development of novel treatments for eye diseases. In this study we identify that the receptor tyrosine kinase, Tyro3, is critical for normal neuronal function in the adult mouse retina. The loss of Tyro3 results in a reduction in photoreceptor and RGC function as measured using electroretinography. The reduction in RGC function was associated with a thinner retinal nerve fiber layer and fewer RGCs. In the central retina, independent of the loss of RGCs, Tyro3 deficiency resulted in a dramatic reduction in the number of RGC dendrites in the inner plexiform layer. Our results show that Tyro3 has a novel, previously unidentified role in retinal function, RGC survival and RGC morphology. The Tyro3 pathway could therefore provide an alternative, targetable pathway for RGC protective therapeutics.
Collapse
Affiliation(s)
- Farrah Blades
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Trevor J Kilpatrick
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Michele D Binder
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| |
Collapse
|
6
|
Zhao D, Wong VHY, Nguyen CTO, Jobling AI, Fletcher EL, Vingrys AJ, Bui BV. Reversibility of Retinal Ganglion Cell Dysfunction From Chronic IOP Elevation. Invest Ophthalmol Vis Sci 2020; 60:3878-3886. [PMID: 31529082 DOI: 10.1167/iovs.19-27113] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To test the hypothesis that the capacity for retinal ganglion cells to functionally recover from chronic IOP elevation is dependent on the duration of IOP elevation. Methods IOP elevation was induced in one eye in anesthetized (isoflurane) adult C57BL6/J mice using a circumlimbal suture. Sutures were left in place for 8 and 16 weeks (n = 30 and 28). In two other groups the suture was cut after 8 and 12 weeks (n = 30 and 28), and ganglion cell function (electroretinography) and retinal structure (optical coherence tomography) were assessed 4 weeks later. Ganglion cell density was quantified by counting RBPMS (RNA-binding protein with multiple splicing)-stained cells. Results With IOP elevation (∼10 mm Hg above baseline), ganglion cell function declined to 75% ± 8% at 8 weeks and 59% ± 4% at 16 weeks relative to contralateral control eyes. The retinal nerve fiber layer was thinner at 8 (84% ± 4%) and 16 weeks (83% ± 3%), without a significant difference in total retinal thickness. Ganglion cell function recovered with IOP normalization (suture removal) at week 8 (97% ± 7%), but not at week 12 (73% ± 6%). Ganglion cell loss was found in all groups (-8% to -13%). Conclusions In the mouse circumlimbal suture model, 12 weeks of IOP elevation resulted in irreversible ganglion cell dysfunction, whereas retinal dysfunction was fully reversible after 8 weeks of IOP elevation.
Collapse
Affiliation(s)
- Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
7
|
van Koeverden AK, He Z, Nguyen CTO, Vingrys AJ, Bui BV. Systemic hypertension is not protective against chronic intraocular pressure elevation in a rodent model. Sci Rep 2018; 8:7107. [PMID: 29739991 PMCID: PMC5940769 DOI: 10.1038/s41598-018-25264-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 04/16/2018] [Indexed: 02/07/2023] Open
Abstract
High intraocular pressure is the most well documented glaucoma risk factor; however many patients develop and/or show progression of glaucoma in its absence. It is now thought that in some instances, ocular perfusion pressure (blood pressure – intraocular pressure) may be as important as intraocular pressure alone. Thus, systemic hypertension would be protective against glaucoma. Epidemiological studies, however, are inconclusive. One theory of why hypertension may not protect against elevated intraocular pressure in spite of increasing ocular perfusion pressure is that with time, morphological changes to the vasculature and autoregulatory failure outweigh the benefits of improved perfusion pressure, ultimately leading to poor retinal and optic nerve head blood supply. In this study we showed the presence of increased wall:lumen ratio and wall area of the ophthalmic artery in rats with chronic hypertension in addition to failure of retinal autoregulation in response to acute modification of ocular perfusion pressure. Subsequently we found that in spite of dramatically increasing ocular perfusion pressure, chronic systemic hypertension failed to protect retinal structure and function from a rodent model of glaucoma.
Collapse
Affiliation(s)
- Anna K van Koeverden
- Department of Optometry and Vision Sciences, the University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, the University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, the University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, the University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, the University of Melbourne, Parkville, 3010, Victoria, Australia.
| |
Collapse
|
8
|
Lee JY, Oh SJ. Functional Analysis and Immunochemical Analyses of Ca 2+ Homeostasis-Related Proteins Expression of Glaucoma-Induced Retinal Degeneration in Rats. Exp Neurobiol 2018. [PMID: 29535566 PMCID: PMC5840458 DOI: 10.5607/en.2018.27.1.16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The retinal degeneration resulting from elevated intraocular pressure was evaluated through functional and morphological analyses, for better understanding of the pathophysiology of glaucoma. Ocular hypertension was induced via unilateral episcleral venous cauterization in rats. Experimental time was set at 1 and 3 days, and 1, 2, 4, and 8 weeks post-operation. Retinal function was analyzed using electroretinography. For morphological analysis, retinal tissues were processed for immunochemistry by using antibodies against the calcium-sensing receptor and calcium-binding proteins. Apoptosis was analyzed using the TUNEL method and electron microscopy. Amplitudes of a- and b-wave in scotopic and photopic responses were found to be reduced in all glaucomatous retinas. Photopic negative response for ganglion cell function significantly reduced from 1-day and more significantly reduced in 2-week glaucoma. Calcium-sensing receptor immunoreactivity in ganglion cells remarkably reduced at 8 weeks; conversely, protein amounts increased significantly. Calcium-binding proteins immunoreactivity in amacrine cells clearly reduced at 8 weeks, despite of uneven changes in protein amounts. Apoptosis appeared in both photoreceptors and ganglion cells in 8-week glaucomatous retina. Apoptotic feature of photoreceptors was typical, whereas that of ganglion cells was necrotic in nature. These findings suggest that elevated intraocular pressure affects the sensitivity of photoreceptors and retinal ganglion cells, and leads to apoptotic death. The calcium-sensing receptor may be a useful detector for alteration of extracellular calcium levels surrounding the ganglion cells.
Collapse
Affiliation(s)
- Ji-Yeon Lee
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Su-Ja Oh
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| |
Collapse
|
9
|
Liu H, He Z, Nguyen CTO, Vingrys AJ, Bui BV. Reversal of functional loss in a rat model of chronic intraocular pressure elevation. Ophthalmic Physiol Opt 2016; 37:71-81. [DOI: 10.1111/opo.12331] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/17/2016] [Indexed: 02/04/2023]
Affiliation(s)
- Hsin‐Hua Liu
- Department of Optometry & Vision Sciences University of Melbourne Parkville Australia
| | - Zheng He
- Department of Optometry & Vision Sciences University of Melbourne Parkville Australia
| | | | - Algis J. Vingrys
- Department of Optometry & Vision Sciences University of Melbourne Parkville Australia
| | - Bang V. Bui
- Department of Optometry & Vision Sciences University of Melbourne Parkville Australia
| |
Collapse
|
10
|
Contreras L, Ramirez L, Du J, Hurley JB, Satrústegui J, de la Villa P. Deficient glucose and glutamine metabolism in Aralar/AGC1/Slc25a12 knockout mice contributes to altered visual function. Mol Vis 2016; 22:1198-1212. [PMID: 27746674 PMCID: PMC5063090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 10/10/2016] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To characterize the vision phenotype of mice lacking Aralar/AGC1/Slc25a12, the mitochondrial aspartate-glutamate carrier mutated in global cerebral hypomyelination (OMIM 612949). METHODS We tested overnight dark-adapted control and aralar-deficient mice for the standard full electroretinogram (ERG) response. The metabolic stress of dark-adaptation was reduced by 5 min illumination after which the ERG response was monitored in darkness. We used the electrical response to two identical saturating light flashes (paired-flash stimulation) to isolate the inner retina and photoreceptor responses. Retinal morphology was examined with hematoxylin and eosin staining, immunohistochemistry of antibodies against retinal cells, and 4',6-diamidino-2-phenylindole (DAPI) labeling. RESULTS Aralar plays a pivotal role in retina metabolism as aralar provides de novo synthesis pathway for glutamine, protects glutamate from oxidation, and is required for efficient glucose oxidative metabolism. Aralar-deficient mice are not blind as their retinas have light-evoked activity. However, we report an approximate 50% decrease in the ERG amplitude response in the light-evoked activity of dark-adapted retinas from aralar-deficient mice, in spite of normal retina histology. The defective response is partly reversed by exposure to a brief illumination period, which lowers the metabolic stress of dark-adaptation. The metabolic stress and ERG alteration takes place primarily in photoreceptors, but the response to two flashes applied in fast succession also revealed an alteration in synaptic transmission consistent with an imbalance of glutamate and an energy deficit in the inner retina neurons. CONCLUSIONS We propose that compromised glucose oxidation and altered glutamine and glutamate metabolism in the absence of aralar are responsible for the phenotype reported.
Collapse
Affiliation(s)
- Laura Contreras
- Centro de Biología Molecular Severo Ochoa CSIC-UAM, CI.B.E.R. de Enfermedades Raras, Instituto de Investigación Sanitaria Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Laura Ramirez
- Department of Systems Biology, University of Alcalá, Alcalá de Henares, Spain
| | - Jianhai Du
- Department of Biochemistry, University of Washington, Seattle, WA.,Department of Ophthalmology, University of Washington, Seattle, WA
| | - James B. Hurley
- Department of Biochemistry, University of Washington, Seattle, WA.,Department of Ophthalmology, University of Washington, Seattle, WA
| | - Jorgina Satrústegui
- Centro de Biología Molecular Severo Ochoa CSIC-UAM, CI.B.E.R. de Enfermedades Raras, Instituto de Investigación Sanitaria Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Pedro de la Villa
- Department of Systems Biology, University of Alcalá, Alcalá de Henares, Spain
| |
Collapse
|
11
|
Full-field electroretinogram in autism spectrum disorder. Doc Ophthalmol 2016; 132:83-99. [DOI: 10.1007/s10633-016-9529-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 02/02/2016] [Indexed: 11/25/2022]
|
12
|
Ragauskas S, Leinonen H, Puranen J, Rönkkö S, Nymark S, Gurevicius K, Lipponen A, Kontkanen O, Puoliväli J, Tanila H, Kalesnykas G. Early retinal function deficit without prominent morphological changes in the R6/2 mouse model of Huntington's disease. PLoS One 2014; 9:e113317. [PMID: 25469887 PMCID: PMC4254453 DOI: 10.1371/journal.pone.0113317] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 10/24/2014] [Indexed: 11/30/2022] Open
Abstract
Huntington’s disease (HD) is an inherited neurodegenerative disorder that primarily affects the medium-size GABAergic neurons of striatum. The R6/2 mouse line is one of the most widely used animal models of HD. Previously the hallmarks of HD-related pathology have been detected in photoreceptors and interneurons of R6/2 mouse retina. Here we aimed to explore the survival of retinal ganglion cells (RGCs) and functional integrity of distinct retinal cell populations in R6/2 mice. The pattern electroretinography (PERG) signal was lost at the age of 8 weeks in R6/2 mice in contrast to the situation in wild-type (WT) littermates. This defect may be attributable to a major reduction in photopic ERG responses in R6/2 mice which was more evident in b- than a-wave amplitudes. At the age of 4 weeks R6/2 mice had predominantly the soluble form of mutant huntingtin protein (mHtt) in the RGC layer cells, whereas the aggregated form of mHtt was found in the majority of those cells from the 12-week-old R6/2 mice and onwards. Retinal astrocytes did not contain mHtt deposits. The total numbers of RGC layer cells, retinal astrocytes as well as optic nerve axons did not differ between 18-week-old R6/2 mice and their WT controls. Our data indicate that mHtt deposition does not cause RGC degeneration or retinal astrocyte loss in R6/2 mice even at a late stage of HD-related pathology. However, due to functional deficits in the rod- and cone-pathways, the R6/2 mice suffer progressive deficits in visual capabilities starting as early as 4 weeks; at 8 weeks there is severe impairment. This should be taken into account in any behavioral testing conducted in R6/2 mice.
Collapse
Affiliation(s)
- Symantas Ragauskas
- Department of Ophthalmology, Institute of Clinical Medicine, School of Medicine, University of Eastern Finland, Kuopio, Finland
- Vilnius Gediminas Technical University, Department of Biochemistry, Vilnius, Lithuania
- State Research Institute for Innovative Medicine, Vilnius, Lithuania
- Experimentica Ltd., Kuopio, Finland
| | - Henri Leinonen
- Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Jooseppi Puranen
- Department of Ophthalmology, Institute of Clinical Medicine, School of Medicine, University of Eastern Finland, Kuopio, Finland
- Experimentica Ltd., Kuopio, Finland
| | - Seppo Rönkkö
- Department of Ophthalmology, Institute of Clinical Medicine, School of Medicine, University of Eastern Finland, Kuopio, Finland
| | - Soile Nymark
- Department of Electronics and Communications Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Kestutis Gurevicius
- Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Arto Lipponen
- Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | | | | | - Heikki Tanila
- Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Giedrius Kalesnykas
- Department of Ophthalmology, Institute of Clinical Medicine, School of Medicine, University of Eastern Finland, Kuopio, Finland
- Experimentica Ltd., Kuopio, Finland
- * E-mail:
| |
Collapse
|