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Yuan M, Jin S, Tan G, Song S, Liu Y, Wang H, Shen Y. A Non-canonical Excitatory PV RGC-PV SC Visual Pathway for Mediating the Looming-evoked Innate Defensive Response. Neurosci Bull 2024; 40:310-324. [PMID: 37302108 PMCID: PMC10912393 DOI: 10.1007/s12264-023-01076-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/04/2023] [Indexed: 06/13/2023] Open
Abstract
Parvalbumin-positive retinal ganglion cells (PV+ RGCs) are an essential subset of RGCs found in various species. However, their role in transmitting visual information remains unclear. Here, we characterized PV+ RGCs in the retina and explored the functions of the PV+ RGC-mediated visual pathway. By applying multiple viral tracing strategies, we investigated the downstream of PV+ RGCs across the whole brain. Interestingly, we found that the PV+ RGCs provided direct monosynaptic input to PV+ excitatory neurons in the superficial layers of the superior colliculus (SC). Ablation or suppression of SC-projecting PV+ RGCs abolished or severely impaired the flight response to looming visual stimuli in mice without affecting visual acuity. Furthermore, using transcriptome expression profiling of individual cells and immunofluorescence colocalization for RGCs, we found that PV+ RGCs are predominant glutamatergic neurons. Thus, our findings indicate the critical role of PV+ RGCs in an innate defensive response and suggest a non-canonical subcortical visual pathway from excitatory PV+ RGCs to PV+ SC neurons that regulates looming visual stimuli. These results provide a potential target for intervening and treating diseases related to this circuit, such as schizophrenia and autism.
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Affiliation(s)
- Man Yuan
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, 430060, China
| | - Sen Jin
- The Brain Cognition and Brain Disease Institute, Shenzhen Key Laboratory of Viral Vectors for Biomedicine, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences (CAS), Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, National Medical Products Administration Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal Products, Shenzhen Key Laboratory of Quality Control Technology for Virus-Based Therapeutics, Guangdong Provincial Medical Products Administration, Shenzhen, 518055, China
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, CAS, Wuhan, 430071, China
| | - Gao Tan
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, 430060, China
| | - Siyuan Song
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine, Houston, 77030, USA
| | - Yizong Liu
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, 430060, China
| | - Huadong Wang
- The Brain Cognition and Brain Disease Institute, Shenzhen Key Laboratory of Viral Vectors for Biomedicine, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences (CAS), Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, National Medical Products Administration Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal Products, Shenzhen Key Laboratory of Quality Control Technology for Virus-Based Therapeutics, Guangdong Provincial Medical Products Administration, Shenzhen, 518055, China
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, CAS, Wuhan, 430071, China
| | - Yin Shen
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, 430060, China.
- Frontier Science Center of Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, 430071, China.
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Pan F, Massey SC. Dye coupling of horizontal cells in the primate retina. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1173706. [PMID: 38983052 PMCID: PMC11182241 DOI: 10.3389/fopht.2023.1173706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 10/03/2023] [Indexed: 07/11/2024]
Abstract
In the monkey retina, there are two distinct types of axon-bearing horizontal cells, known as H1 and H2 horizontal cells (HCs). In this study, cell bodies were prelabled using 4',6-diamidino-2-phenylindole (DAPI), and both H1 and H2 horizontal cells were filled with Neurobiotin™ to reveal their coupling, cellular details, and photoreceptor contacts. The confocal analysis of H1 and H2 HCs was used to assess the colocalization of terminal dendrites with glutamate receptors at cone pedicles. After filling H1 somas, a large coupled mosaic of H1 cells was labeled. The dendritic terminals of H1 cells contacted red/green cone pedicles, with the occasional sparse contact with blue cone pedicles observed. The H2 cells were also dye-coupled. They had larger dendritic fields and lower densities. The dendritic terminals of H2 cells preferentially contacted blue cone pedicles, but additional contacts with nearly all cones within the dendritic field were still observed. The red/green cones constitute 99% of the input to H1 HCs, whereas H2 HCs receive a more balanced input, which is composed of 58% red/green cones and 42% blue cones. These observations confirm those made in earlier studies on primate horizontal cells by Dacey and Goodchild in 1996. Both H1 and H2 HCs were axon-bearing. H1 axon terminals (H1 ATs) were independently coupled and contacted rod spherules exclusively. In contrast, the H2 axon terminals contacted cones, with some preference for blue cone pedicles, as reported by Chan and Grünert in 1998. The primate retina contains three independently coupled HC networks in the outer plexiform layer (OPL), identified as H1 and H2 somatic dendrites, and H1 ATs. At each cone pedicle, the colocalization of both H1 and H2 dendritic tips with GluA4 subunits close to the cone synaptic ribbons indicates that glutamate signaling from the cones to H1 and H2 horizontal cells is mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors.
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Affiliation(s)
- Feng Pan
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
- Centre for Eye and Vision Research (CEVR), Hong Kong, Hong Kong SAR, China
- Research Centre for SHARP Vision (RCSV), The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
| | - Stephen C. Massey
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, TX, United States
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3
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Jo A, Deniz S, Xu J, Duvoisin RM, DeVries SH, Zhu Y. A sign-inverted receptive field of inhibitory interneurons provides a pathway for ON-OFF interactions in the retina. Nat Commun 2023; 14:5937. [PMID: 37741839 PMCID: PMC10517963 DOI: 10.1038/s41467-023-41638-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 09/11/2023] [Indexed: 09/25/2023] Open
Abstract
A fundamental organizing plan of the retina is that visual information is divided into ON and OFF streams that are processed in separate layers. This functional dichotomy originates in the ON and OFF bipolar cells, which then make excitatory glutamatergic synapses onto amacrine and ganglion cells in the inner plexiform layer. We have identified an amacrine cell (AC), the sign-inverting (SI) AC, that challenges this fundamental plan. The glycinergic, ON-stratifying SI-AC has OFF light responses. In opposition to the classical wiring diagrams, it receives inhibitory inputs from glutamatergic ON bipolar cells at mGluR8 synapses, and excitatory inputs from an OFF wide-field AC at electrical synapses. This "inhibitory ON center - excitatory OFF surround" receptive-field of the SI-AC allows it to use monostratified dendrites to conduct crossover inhibition and push-pull activation to enhance light detection by ACs and RGCs in the dark and feature discrimination in the light.
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Affiliation(s)
- Andrew Jo
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Sercan Deniz
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Jian Xu
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Robert M Duvoisin
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Steven H DeVries
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
| | - Yongling Zhu
- Departments of Ophthalmology and Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
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Urbán P, Pöstyéni E, Czuni L, Herczeg R, Fekete C, Gábriel R, Kovács-Valasek A. miRNA Profiling of Developing Rat Retina in the First Three Postnatal Weeks. Cell Mol Neurobiol 2023:10.1007/s10571-023-01347-3. [PMID: 37084144 DOI: 10.1007/s10571-023-01347-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 04/04/2023] [Indexed: 04/22/2023]
Abstract
The morphogenesis of the mammalian retina depends on the precise control of gene expression during development. Small non-coding RNAs, including microRNAs play profound roles in various physiological and pathological processes via gene expression regulation. A systematic analysis of the expression profile of small non-coding RNAs in developing Wistar rat retinas (postnatally day 5 (P5), P7, P10, P15 and P21) was executed using IonTorrent PGM next-generation sequencing technique to reveal the crucial players in the early postnatal retinogenesis. Our analysis reveals extensive regulatory potential of microRNAs during retinal development. We found a group of microRNAs that show constant high abundance (miR-19, miR-101; miR-181, miR-183, miR-124 and let-7) during the development process. Others are present only in the early stages (miR-20a, miR-206, miR-133, miR-466, miR-1247, miR-3582), or at later stages (miR-29, miR-96, miR-125, miR-344 or miR-664). Further miRNAs were detected which are differentially expressed in time. Finally, pathway enrichment analysis has revealed 850 predicted target genes that mainly participate in lipid-, amino acid- and glycan metabolisms in the examined time-period (P5-P21). P5-P7 transition revealed the importance of miRNAs in glutamatergic synapse and gap junction pathways. Significantly downregulated miRNAs rno-miR-30c1 and 2, rno-miR-205 and rno-miR-503 were detected to target Prkx (ENSRNOG00000003696), Adcy6 (ENSRNOG00000011587), Gnai3 (ENSRNOG00000019465) and Gja1 (ENSRNOG00000000805) genes. The dataset described here will be a valuable resource for clarifying new regulatory mechanisms for retinal development and will greatly contribute to our understanding of the divergence and function of microRNAs.
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Affiliation(s)
- Péter Urbán
- János Szentágothai Research Centre, University of Pécs, Pecs, Hungary
- Department of General and Environmental Microbiology, University of Pécs, Pecs, Hungary
| | - Etelka Pöstyéni
- Experimental Zoology and Neurobiology, University of Pécs, Pecs, Hungary
| | - Lilla Czuni
- János Szentágothai Research Centre, University of Pécs, Pecs, Hungary
| | - Róbert Herczeg
- János Szentágothai Research Centre, University of Pécs, Pecs, Hungary
| | - Csaba Fekete
- Department of General and Environmental Microbiology, University of Pécs, Pecs, Hungary
| | - Róbert Gábriel
- János Szentágothai Research Centre, University of Pécs, Pecs, Hungary
- Experimental Zoology and Neurobiology, University of Pécs, Pecs, Hungary
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Kwon KM, Pak JH, Jeon CJ. Immunocytochemical localization of the AMPA glutamate receptor subtype GluR2/3 in the squid optic lobe. Acta Histochem 2022; 124:151941. [PMID: 35963117 DOI: 10.1016/j.acthis.2022.151941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/03/2022] [Accepted: 08/03/2022] [Indexed: 11/17/2022]
Abstract
As a major excitatory neurotransmitter in the cephalopod visual system, glutamate signaling is facilitated by ionotropic receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR). In cephalopods with large and well-developed brains, the optic lobes (OL) mainly process visual inputs and are involved in learning and memory. Although the presence of AMPAR in squid OL has been reported, the organization of specific AMPAR-containing neurons remains unknown. This study aimed to investigate the immunocytochemical localization of the AMPA glutamate receptor subtype 2/3-immunoreactive (GluR2/3-IR) neurons in the OL of Pacific flying squid (Tordarodes pacificus). Morphologically diverse GluR2/3-IR neurons were predominantly located in the tangential zone of the medulla. Medium-to-large GluR2/3-IR neurons were also detected. The distribution patterns and cell morphologies of calcium-binding protein (CBP)-IR neurons, specifically calbindin-D28K (CB)-, calretinin (CR)-, and parvalbumin (PV)-IR neurons, were similar to those of GluR2/3-IR neurons. However, two-color immunofluorescence revealed that GluR2/3-IR neurons did not colocalize with the CBP-IR neurons. Furthermore, the specific localizations and diverse types of GluR2/3-IR neurons that do not express CB, CR, or PV in squid OL were determined. These findings further contribute to the existing data on glutamatergic visual systems and provide new insights for understanding the visual processing mechanisms in cephalopods.
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Affiliation(s)
- Kyung-Min Kwon
- Department of Biology, School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, College of Natural Sciences, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea; Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jae-Hong Pak
- Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Chang-Jin Jeon
- Department of Biology, School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, College of Natural Sciences, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea; Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea.
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6
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Fonseca MI, Nouck-A-Nwal A, Ambrosio L, Altschwager P, Hansen RM, Fulton AB, Akula JD. The relation of the multifocal electroretinographic response to macular layer volume. Doc Ophthalmol 2022; 145:1-10. [PMID: 35536490 DOI: 10.1007/s10633-022-09873-z] [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: 11/18/2021] [Accepted: 04/18/2022] [Indexed: 11/03/2022]
Abstract
PURPOSE To determine the association of the multifocal electroretinographic (mfERG) response amplitude with the volumes of the inner, postreceptor, and photoreceptor retinal layers in the region stimulated by each mfERG element. METHODS Sixteen healthy, young adult control subjects were studied. Each of the 103 hexagonal elements of the standard, scaled mfERG were aligned, where possible, with patches of retina imaged using optical coherence tomography. Stimuli falling on the fovea and on the optic nerve head were excluded. Linear mixed-effects modeling was then used to derive estimated coefficients (voltage/volume) for the mfERG response throughout the full 80 ms standard epoch. The resulting predicted response amplitudes originating in each layer were then compared to pharmacologically "dissected" mfERGs obtained from other studies in monkey eyes. RESULTS Across the duration of the response, the amplitude of the modeled contribution from (1) the inner retina was small-to-modest, (2) the postreceptor retina was larger and contained two prominent peaks, and (3) the photoreceptor response was the largest and most closely paralleled the overall (i.e., intact) response, including late-appearing oscillations. The significance of each layer's contribution was greatest when the absolute amplitude of that layer's response was largest. The contribution of the inner retina was maximally significant in the interval between the prominent troughs and peaks of the intact response. The contributions of the postreceptor and photoreceptor responses were maximally significant at the prominent troughs and peaks of the intact response. CONCLUSIONS The results of the model were in good overall agreement with previous interpretations of the cellular contributions to the mfERG. There was also fair agreement with pharmacologically dissected monkey mfERG responses. Thus, the estimations of the contributions of the retinal layers to the mfERG so produced appeared plausible.
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Affiliation(s)
- Mariana I Fonseca
- Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Ave, Fegan 4, Boston, MA, 02115, USA.,Behavioral Neuroscience, Northeastern University, Boston, MA, USA
| | - Alexandra Nouck-A-Nwal
- Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Ave, Fegan 4, Boston, MA, 02115, USA.,Behavioral Neuroscience, Northeastern University, Boston, MA, USA
| | - Lucia Ambrosio
- Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Ave, Fegan 4, Boston, MA, 02115, USA.,Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.,Department of Neuroscience, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy.,Department of Public Health, University of Naples Federico II, Napels, Italy
| | - Pablo Altschwager
- Department of Ophthalmology, Pontifical Catholic University of Chile, Santiago, Chile
| | - Ronald M Hansen
- Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Ave, Fegan 4, Boston, MA, 02115, USA.,Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Anne B Fulton
- Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Ave, Fegan 4, Boston, MA, 02115, USA.,Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - James D Akula
- Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Ave, Fegan 4, Boston, MA, 02115, USA. .,Department of Ophthalmology, Harvard Medical School, Boston, MA, USA. .,Department of Psychology, Northeastern University, Boston, MA, USA.
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7
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Abstract
Our sense of sight relies on photoreceptors, which transduce photons into the nervous system's electrochemical interpretation of the visual world. These precious photoreceptors can be disrupted by disease, injury, and aging. Once photoreceptors start to die, but before blindness occurs, the remaining retinal circuitry can withstand, mask, or exacerbate the photoreceptor deficit and potentially be receptive to newfound therapies for vision restoration. To maximize the retina's receptivity to therapy, one must understand the conditions that influence the state of the remaining retina. In this review, we provide an overview of the retina's structure and function in health and disease. We analyze a collection of observations on photoreceptor disruption and generate a predictive model to identify parameters that influence the retina's response. Finally, we speculate on whether the retina, with its remarkable capacity to function over light levels spanning nine orders of magnitude, uses these same adaptational mechanisms to withstand and perhaps mask photoreceptor loss.
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Affiliation(s)
- Joo Yeun Lee
- Department of Ophthalmology, University of California, San Francisco, California 94143, USA; , , ,
| | - Rachel A Care
- Department of Ophthalmology, University of California, San Francisco, California 94143, USA; , , ,
| | - Luca Della Santina
- Department of Ophthalmology, University of California, San Francisco, California 94143, USA; , , ,
- Bakar Computational Health Sciences Institute, University of California, San Francisco, California 94143, USA
| | - Felice A Dunn
- Department of Ophthalmology, University of California, San Francisco, California 94143, USA; , , ,
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9
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Westbrook AM. A review of the neurophysiology of the turtle retina: Horizontal and bipolar cells. Clin Exp Optom 2021. [DOI: 10.1111/j.1444-0938.1994.tb03001.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Akula JD, Ambrosio L, Howard FI, Hansen RM, Fulton AB. Extracting the ON and OFF contributions to the full-field photopic flash electroretinogram using summed growth curves. Exp Eye Res 2019; 189:107827. [PMID: 31600486 DOI: 10.1016/j.exer.2019.107827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/27/2019] [Accepted: 10/02/2019] [Indexed: 10/25/2022]
Abstract
Under cone-mediated (photopic) conditions, an "instantaneous" flash of light, including both stimulus onset and offset, will simultaneously activate both "ON" and "OFF" bipolar cells, which either depolarize (ON) or hyperpolarize (OFF) in response and, respectively, produce positive-going and negative-going deflections in the electroretinogram (ERG). The stimulus-response (SR) relationship of the photopic ON response demonstrates logistic growth, like that manifested in the rod-mediated (scotopic) b-wave, which is driven by a single class of depolarizing bipolar cell. However, the photopic b-wave SR function is importantly shaped by OFF responses, leading to a "photopic hill." Furthermore, both on and off stimuli elicit activity in both ON and OFF bipolar cells. This has made it difficult to produce meaningful parameters for ready interpretation of the photopic b-wave SR relationship. Therefore, we evaluated whether the sum of sigmoidal SR functions, as descriptors of the depolarizing and hyperpolarizing components of the photopic flash ERG, could be used to elucidate and quantitate the mechanisms that produce the photopic hill. We used a novel fitting routine to optimize a sum of simple sigmoidal curves to SR data in five groups of subjects: Healthy adult, 10-week-old infant, congenital stationary night blindness (CSNB), X-linked juvenile retinoschisis (XJR), and preterm-born, both without and with a history of retinopathy of prematurity (ROP). Differences in ON and OFF amplitude, sensitivity, and implicit time among the groups were then compared using parameters extracted from these fits. We found that our modeling procedure enabled plausible derivations of ON and OFF pathway contributions to the ERG, and that the parameters produced appeared to have physiological relevance. In adult subjects, the ON and OFF amplitudes were similar in magnitude with respectively longer and shorter implicit times. Infant, CSNB, and XJR subjects showed significant ON pathway deficits. History of preterm-birth, without or with a diagnosis of ROP, did not much affect cone responses.
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Affiliation(s)
- James D Akula
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Ophthalmology, Harvard Medical School, Boston, MA, United States.
| | - Lucia Ambrosio
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Ophthalmology, Harvard Medical School, Boston, MA, United States
| | - Fiona I Howard
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Psychology, Northeastern University, Boston, MA, United States
| | - Ronald M Hansen
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Ophthalmology, Harvard Medical School, Boston, MA, United States
| | - Anne B Fulton
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Ophthalmology, Harvard Medical School, Boston, MA, United States
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11
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Samani NN, Proudlock FA, Siram V, Suraweera C, Hutchinson C, Nelson CP, Al-Uzri M, Gottlob I. Retinal Layer Abnormalities as Biomarkers of Schizophrenia. Schizophr Bull 2018; 44:876-885. [PMID: 29272501 PMCID: PMC6007436 DOI: 10.1093/schbul/sbx130] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Schizophrenia is associated with several brain deficits, as well as visual processing deficits, but clinically useful biomarkers are elusive. We hypothesized that retinal layer changes, noninvasively visualized using spectral-domain optical coherence tomography (SD-OCT), may represent a possible "window" to these abnormalities. METHODS A Leica EnvisuTM SD-OCT device was used to obtain high-resolution central foveal B-scans in both eyes of 35 patients with schizophrenia and 50 demographically matched controls. Manual retinal layer segmentation was performed to acquire individual and combined layer thickness measurements in 3 macular regions. Contrast sensitivity was measured at 3 spatial frequencies in a subgroup of each cohort. Differences were compared using adjusted linear models and significantly different layer measures in patients underwent Spearman Rank correlations with contrast sensitivity, quantified symptoms severity, disease duration, and antipsychotic medication dose. RESULTS Total retinal and photoreceptor complex thickness was reduced in all regions in patients (P < .0001). Segmentation revealed consistent thinning of the outer nuclear layer (P < .001) and inner segment layer (P < .05), as well as a pattern of parafoveal ganglion cell changes. Low spatial frequency contrast sensitivity was reduced in patients (P = .002) and correlated with temporal parafoveal ganglion cell complex thinning (R = .48, P = .01). Negative symptom severity was inversely correlated with foveal photoreceptor complex thickness (R = -.54, P = .001) and outer nuclear layer thickness (R = -.47, P = .005). CONCLUSIONS Our novel findings demonstrate considerable retinal layer abnormalities in schizophrenia that are related to clinical features and visual function. With time, SD-OCT could provide easily-measurable biomarkers to facilitate clinical assessment and further our understanding of the disease.
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Affiliation(s)
| | - Frank A Proudlock
- Ulverscroft Eye Unit, University of Leicester, Leicester, UK,Department of Neuroscience, Psychology and Behaviour, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, UK
| | - Vasantha Siram
- Leicestershire Partnership NHS Trust, Bradgate Unit, Glenfield Hospital, Leicester, UK
| | - Chathurie Suraweera
- Leicestershire Partnership NHS Trust, Bradgate Unit, Glenfield Hospital, Leicester, UK
| | - Claire Hutchinson
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, UK
| | - Christopher P Nelson
- NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, UK
| | - Mohammed Al-Uzri
- Leicestershire Partnership NHS Trust, Bradgate Unit, Glenfield Hospital, Leicester, UK,Adult Social and Epidemiological Psychiatry and Disability Research Group, Department of Health Sciences, University of Leicester, Leicester General Hospital, Leicester, UK
| | - Irene Gottlob
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, UK,To whom correspondence should be addressed; Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, PO Box 65, Leicester LE2 7LX, UK; tel: +44-116-252-3268, e-mail:
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12
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Lee JS, Kim HG, Jeon CJ. Identification of synaptic pattern of NMDA receptor subunits upon direction-selective retinal ganglion cells in developing and adult mouse retina. Acta Histochem 2017; 119:495-507. [PMID: 28545760 DOI: 10.1016/j.acthis.2017.05.002] [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: 08/21/2016] [Revised: 04/30/2017] [Accepted: 05/05/2017] [Indexed: 11/25/2022]
Abstract
Direction selectivity of the retina is a unique mechanism and critical function of eyes for surviving. Direction-selective retinal ganglion cells (DS RGCs) strongly respond to preferred directional stimuli, but rarely respond to the opposite or null directional stimuli. These DS RGCs are sensitive to glutamate, which is secreted from bipolar cells. Using immunocytochemistry, we studied with the distributions of N-methyl-d-aspartate (NMDA) receptor subunits on the dendrites of DS RGCs in the developing and adult mouse retina. DS RGCs were injected with Lucifer yellow for identification of dendritic morphology. The triple-labeled images of dendrites, kinesin II, and NMDA receptor subunits were visualized using confocal microscopy and were reconstructed from high-resolution confocal images. Although our results revealed that the synaptic pattern of NMDA receptor subunits on dendrites of DS RGCs was not asymmetric in developing and adult mouse retina, they showed the anatomical connectivity of NMDA glutamatergic synapses onto DS RGCs and the developmental formation of the direction selectivity in the mouse retina. Through the comprehensive interpretation of the direction-selective neural circuit, this study, therefore, implies that the direction selectivity may be generated by the asymmetry of the excitatory glutamatergic inputs and the inhibitory inputs onto DS RGCs.
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13
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Pannicke T, Ivo Chao T, Reisenhofer M, Francke M, Reichenbach A. Comparative electrophysiology of retinal Müller glial cells-A survey on vertebrate species. Glia 2016; 65:533-568. [PMID: 27767232 DOI: 10.1002/glia.23082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/15/2016] [Accepted: 09/28/2016] [Indexed: 12/13/2022]
Abstract
Müller cells are the dominant macroglial cells in the retina of all vertebrates. They fulfill a variety of functions important for retinal physiology, among them spatial buffering of K+ ions and uptake of glutamate and other neurotransmitters. To this end, Müller cells express inwardly rectifying K+ channels and electrogenic glutamate transporters. Moreover, a lot of voltage- and ligand-gated ion channels, aquaporin water channels, and electrogenic transporters are expressed in Müller cells, some of them in a species-specific manner. For example, voltage-dependent Na+ channels are found exclusively in some but not all mammalian species. Whereas a lot of data exist from amphibians and mammals, the results from other vertebrates are sparse. It is the aim of this review to present a survey on Müller cell electrophysiology covering all classes of vertebrates. The focus is on functional studies, mainly performed using the whole-cell patch-clamp technique. However, data about the expression of membrane channels and transporters from immunohistochemistry are also included. Possible functional roles of membrane channels and transporters are discussed. Obviously, electrophysiological properties involved in the main functions of Müller cells developed early in vertebrate evolution. GLIA 2017;65:533-568.
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Affiliation(s)
- Thomas Pannicke
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
| | - T Ivo Chao
- Institute of Anatomy and Cell Biology, Medical School Göttingen, Germany
| | - Miriam Reisenhofer
- Department of Chemistry, University of Zürich, Switzerland
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Mike Francke
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
- Sächsischer Inkubator für klinische Translation (SIKT), Universität Leipzig, Germany
| | - Andreas Reichenbach
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
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Binda NS, Carayon CPP, Agostini RM, Pinheiro ACDN, Cordeiro MN, Silva MAR, Silva JF, Pereira EMR, da Silva Junior CA, de Castro Junior CJ, Guimarães ALS, Gomez MV. PhTx3-4, a Spider Toxin Calcium Channel Blocker, Reduces NMDA-Induced Injury of the Retina. Toxins (Basel) 2016; 8:toxins8030070. [PMID: 26978403 PMCID: PMC4810215 DOI: 10.3390/toxins8030070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 01/26/2016] [Accepted: 03/01/2016] [Indexed: 11/16/2022] Open
Abstract
The in vivo neuroprotective effect of PhTx3-4, a spider toxin N-P/Q calcium channel blocker, was studied in a rat model of NMDA-induced injury of the retina. NMDA (N-Methyl-d-Aspartate)-induced retinal injury in rats reduced the b-wave amplitude by 62% ± 3.6%, indicating the severity of the insult. PhTx3-4 treatment increased the amplitude of the b-wave, which was almost equivalent to the control retinas that were not submitted to injury. The PhTx3-4 functional protection of the retinas recorded on the ERG also was observed in the neuroprotection of retinal cells. NMDA-induced injury reduced live cells in the retina layers and the highest reduction, 84%, was in the ganglion cell layer. Notably, PhTx3-4 treatment caused a remarkable reduction of dead cells in the retina layers, and the highest neuroprotective effect was in the ganglion cells layer. NMDA-induced cytotoxicity of the retina increased the release of glutamate, reactive oxygen species (ROS) production and oxidative stress. PhTx3-4 treatment reduced glutamate release, ROS production and oxidative stress measured by malondialdehyde. Thus, we presented for the first time evidence of in vivo neuroprotection from NMDA-induced retinal injury by PhTx3-4 (-ctenitoxin-Pn3a), a spider toxin that blocks N-P/Q calcium channels.
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Affiliation(s)
- Nancy Scardua Binda
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Charles Porto Petruceli Carayon
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Rafael Mourão Agostini
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Ana Cristina do Nascimento Pinheiro
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Marta Nascimento Cordeiro
- Ezequiel Dias Foundation (FUNED), Laboratory of Biochemistry, Rua Conde Pereira Carneiro 80, Belo Horizonte, Minas Gerais 30510-010, Brazil.
| | - Marco Aurélio Romano Silva
- Faculty of Medicine, Minas Gerais Federal University, Neuroscience Laboratory, Av. Alfredo Balena 190, Belo Horizonte, Minas Gerais 30130-100, Brazil.
| | - Juliana Figueira Silva
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Elizete Maria Rita Pereira
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Claudio Antonio da Silva Junior
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Célio José de Castro Junior
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
| | - Andre Luiz Sena Guimarães
- Department of Dentistry, Montes Claros State University, University Hospital, Health Laboratory Research, Montes Claros, Montes Claros, Minas Gerais 39401-001, Brazil.
| | - Marcus Vinicius Gomez
- Institute of Education and Research Santa Casa Belo Horizonte-Laboratory of Toxins, Rua Domingos Vieira 590, Belo Horizonte, Minas Gerais 30150-240, Brazil.
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Kalloniatis M, Nivison-Smith L, Chua J, Acosta ML, Fletcher EL. Using the rd1 mouse to understand functional and anatomical retinal remodelling and treatment implications in retinitis pigmentosa: A review. Exp Eye Res 2015; 150:106-21. [PMID: 26521764 DOI: 10.1016/j.exer.2015.10.019] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 12/31/2022]
Abstract
Retinitis Pigmentosa (RP) reflects a range of inherited retinal disorders which involve photoreceptor degeneration and retinal pigmented epithelium dysfunction. Despite the multitude of genetic mutations being associated with the RP phenotype, the clinical and functional manifestations of the disease remain the same: nyctalopia, visual field constriction (tunnel vision), photopsias and pigment proliferation. In this review, we describe the typical clinical phenotype of human RP and review the anatomical and functional remodelling which occurs in RP determined from studies in the rd/rd (rd1) mouse. We also review studies that report a slowing down or show an acceleration of retinal degeneration and finally we provide insights on the impact retinal remodelling may have in vision restoration strategies.
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Affiliation(s)
- M Kalloniatis
- Centre for Eye Health, University of New South Wales, Kensington, NSW, Australia; School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia; School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand; Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia.
| | - L Nivison-Smith
- Centre for Eye Health, University of New South Wales, Kensington, NSW, Australia; School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia
| | - J Chua
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - M L Acosta
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - E L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
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Park YH, Mueller BH, McGrady NR, Ma HY, Yorio T. AMPA receptor desensitization is the determinant of AMPA receptor mediated excitotoxicity in purified retinal ganglion cells. Exp Eye Res 2015; 132:136-50. [PMID: 25643624 DOI: 10.1016/j.exer.2015.01.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 12/08/2014] [Accepted: 01/29/2015] [Indexed: 01/15/2023]
Abstract
The ionotropic glutamate receptors (iGLuR) have been hypothesized to play a role in neuronal pathogenesis by mediating excitotoxic death. Previous studies on iGluR in the retina have focused on two broad classes of receptors: NMDA and non-NMDA receptors including the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor (AMPAR) and kainate receptor. In this study, we examined the role of receptor desensitization on the specific excitotoxic effects of AMPAR activation on primary retinal ganglion cells (RGCs). Purified rat RGCs were isolated from postnatal day 4-7 Sprague-Dawley rats. Calcium imaging was used to identify the functionality of the AMPARs and selectivity of the s-AMPA agonist. Phosphorylated CREB and ERK1/2 expression were performed following s-AMPA treatment. s-AMPA excitotoxicity was determined by JC-1 mitochondrial membrane depolarization assay, caspase 3/7 luciferase activity assay, immunoblot analysis for α-fodrin, and Live (calcein AM)/Dead (ethidium homodimer-1) assay. RGC cultures of 98% purity, lacking Iba1 and GFAP expression were used for the present studies. Isolated prenatal RGCs expressed calcium permeable AMPAR and s-AMPA (100 μM) treatment of cultured RGCs significantly increased phosphorylation of CREB but not that of ERK1/2. A prolonged (6 h) AMPAR activation in purified RGCs using s-AMPA (100 μM) did not depolarize the RGC mitochondrial membrane potential. In addition, treatment of cultured RGCs with s-AMPA, both in the presence and absence of trophic factors (BDNF and CNTF), did not increase caspase 3/7 activities or the cleavage of α-fodrin (neuronal apoptosis marker), as compared to untreated controls. Lastly, a significant increase in cell survival of RGCs was observed after s-AMPA treatment as compared to control untreated RGCs. However, preventing the desensitization of AMPAR with the treatment with either kainic acid (100 μM) or the combination of s-AMPA and cyclothiazide (50 μM) significantly reduced cell survivability. Activation of the AMPAR in RGCs does not appear to activate a signaling cascade to apoptosis, suggesting that RGCs in vitro are not susceptible to AMPA excitotoxicity as previously hypothesized. Conversely, preventing AMPAR desensitization through differential agonist activation caused AMPAR mediated excitotoxicity. Activation of the AMPAR in increasing CREB phosphorylation was dependent on the presence of calcium, which may help explain this action in increasing RGC survival.
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Affiliation(s)
- Yong H Park
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA.
| | - Brett H Mueller
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Nolan R McGrady
- Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Hai-Ying Ma
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Thomas Yorio
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA.
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17
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Chen T, Gionfriddo JR, Tai PY, Novakowski AN, Alyahya K, Madl JE. Oxidative stress increases in retinas of dogs in acute glaucoma but not in chronic glaucoma. Vet Ophthalmol 2014; 18:261-70. [PMID: 24814303 DOI: 10.1111/vop.12177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To test the hypothesis that oxidative stress occurs early in the pathogenesis of glaucoma in dogs. ANIMALS Sections from eight control retinas and 25 retinas from dogs with primary glaucoma. METHODS For retinas embedded in paraffin, sections were immunohistochemically stained for malondialdehyde (MDA) and 3-nitrotyrosine (NT). For retinas embedded in plastic, serial 0.5-μm sections were immunogold-stained for total glutathione, taurine, and glutamate. RESULTS Increased immunostaining for MDA and NT, markers of oxidative stress, occurred in retinal ganglion cells (RGCs) and other neurons in acute glaucoma, but not in chronic glaucoma. In minimally damaged regions, immunostaining for the antioxidant glutathione was decreased in RGCs, neurons of the inner nuclear layer (INL), and Müller cell processes. The loss of glutathione immunostaining in RGCs occurred without a decrease in glutamate immunostaining. Neurons with nuclear damage in the INL had low levels of glutathione, taurine, and glutamate. In severely damaged regions, immunostaining for glutathione was increased in the remaining retinal tissue. CONCLUSIONS Immunohistochemical staining revealed an increase in markers of oxidative stress and loss of glutathione in neurons with minimal damage during acute glaucoma. Oxidative changes were no longer present in chronic glaucomatous retinas, suggesting transient oxidative stress occurs early in glaucoma. The loss of glutathione in minimally damaged regions occurred without a significant redistribution of glutamate, suggesting oxidative stress may occur before glutamate redistribution. Alteration in markers of oxidative stress occurs early in canine glaucoma, suggesting oxidative stress may contribute to subsequent glutamate redistribution and other damaging processes.
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Affiliation(s)
- Thomas Chen
- Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado
| | - Juliet R Gionfriddo
- Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado
| | - Pei-Yi Tai
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Anna N Novakowski
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Khaleel Alyahya
- College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - James E Madl
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
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18
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Poly (ADP-ribose) polymerase mediates diabetes-induced retinal neuropathy. Mediators Inflamm 2013; 2013:510451. [PMID: 24347828 PMCID: PMC3857786 DOI: 10.1155/2013/510451] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 10/30/2013] [Accepted: 11/03/2013] [Indexed: 12/15/2022] Open
Abstract
Retinal neuropathy is an early event in the development of diabetic retinopathy. One of the potential enzymes that are activated by oxidative stress in the diabetic retina is poly (ADP-ribose) polymerase (PARP). We investigated the effect of the PARP inhibitor 1,5-isoquinolinediol on the expression of the neurodegeneration mediators and markers in the retinas of diabetic rats. After two weeks of streptozotocin-induced diabetes, rats were treated with 1,5-isoquinolinediol (3 mg/kg/day). After 4 weeks of diabetes, the retinas were harvested and the levels of reactive oxygen species (ROS) were determined fluorometrically and the expressions of PARP, phosporylated-ERK1/2, BDNF, synaptophysin, glutamine synthetase (GS), and caspase-3 were determined by Western blot analysis. Retinal levels of ROS, PARP-1/2, phosphorylated ERK1/2, and cleaved caspase-3 were significantly increased, whereas the expressions of BDNF synaptophysin and GS were significantly decreased in the retinas of diabetic rats, compared to nondiabetic rats. Administration of 1,5-isoquinolinediol did not affect the metabolic status of the diabetic rats, but it significantly attenuated diabetes-induced upregulation of PARP, ROS, ERK1/2 phosphorylation, and cleaved caspase-3 and downregulation of BDNF, synaptophysin, and GS. These findings suggest a beneficial effect of the PARP inhibitor in increasing neurotrophic support and ameliorating early retinal neuropathy induced by diabetes.
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Sivakumar V, Foulds WS, Luu CD, Ling EA, Kaur C. Hypoxia-induced retinal ganglion cell damage through activation of AMPA receptors and the neuroprotective effects of DNQX. Exp Eye Res 2013; 109:83-97. [PMID: 23375774 DOI: 10.1016/j.exer.2013.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 01/04/2013] [Accepted: 01/06/2013] [Indexed: 11/19/2022]
Abstract
Hypoxia-induced glutamate accumulation in neural tissues results in damage to neurons through excitotoxic mechanisms via activation of glutamate receptors (GluRs). Here we examine whether hypoxia in the developing retina would cause activation of the ionotropic α-amino-3-hydroxy-5-methylisoxazole-4-propioate (AMPA) GluRs and increase in Ca(2+) influx into retinal ganglion cells (RGCs) that might ultimately lead to their death. Neonatal Wistar rats were subjected to hypoxia for 2h and then sacrificed at various time points after the exposure together with normal age matched control rats. Primary cultures of RGCs were also prepared and subjected to hypoxia. Expression of AMPA glutamate receptor (GluR) 1-4 was examined in the retina. Additionally, expression of GluRs, intracellular Ca(2+) influx, reactive oxygen species (ROS) generation and cell death were investigated in cultured RGCs. GluR1-4 mRNA and protein expression showed a significant increase (P < 0.01) over control values after the hypoxic exposure both in vivo and in vitro. Cells expressing GluR1-4 in the retina were identified as RGCs by double immunofluorescence labeling with Thy1.1. Increased intracellular Ca(2+) in cultured RGCs following hypoxic exposure was reduced (P < 0.01) by 10 μM AMPA antagonist 6, 7-dinitroquinoxaline-2,3-dione (DNQX). Our results suggest that following a hypoxic insult, an increased amount of glutamate accumulates in the neonatal retina. This would then activate AMPA receptors which may damage RGCs through increased Ca(2+) accumulation and ROS generation. The involvement of AMPA receptors in damaging the RGCs is evidenced by suppression of intracellular Ca(2+) influx by DNQX which also decreased ROS generation and cell death by 50%.
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Affiliation(s)
- V Sivakumar
- Department of Anatomy, Yong Loo Lin School of Medicine, Blk MD10, 4 Medical Drive, National University of Singapore, Singapore 117597, Singapore
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Vitreous mediators in retinal hypoxic diseases. Mediators Inflamm 2013; 2013:935301. [PMID: 23365490 PMCID: PMC3556845 DOI: 10.1155/2013/935301] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 10/19/2012] [Accepted: 12/01/2012] [Indexed: 12/31/2022] Open
Abstract
The causes of retinal hypoxia are many and varied. Under hypoxic conditions, a variety of soluble factors are secreted into the vitreous cavity including growth factors, cytokines, and chemokines. Cytokines, which usually serve as signals between neighboring cells, are involved in essentially every important biological process, including cell proliferation, inflammation, immunity, migration, fibrosis, tissue repair, and angiogenesis. Cytokines and chemokines are multifunctional mediators that can direct the recruitment of leukocytes to sites of inflammation, promote the process, enhance immune responses, and promote stem cell survival, development, and homeostasis. The modern particle-based flow cytometric analysis is more direct, stable and sensitive than the colorimetric readout of the conventional ELISA but, similar to ELISA, is influenced by vitreous hemorrhage, disruption of the blood-retina barrier, and high serum levels of a specific protein. Finding patterns in the expression of inflammatory cytokines specific to a particular disease can substantially contribute to the understanding of its basic mechanism and to the development of a targeted therapy.
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21
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Rejdak R, Junemann A, Grieb P, Thaler S, Schuettauf F, Chorągiewicz T, Zarnowski T, Turski WA, Zrenner E. Kynurenic acid and kynurenine aminotransferases in retinal aging and neurodegeneration. Pharmacol Rep 2012; 63:1324-34. [PMID: 22358081 DOI: 10.1016/s1734-1140(11)70697-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 06/24/2011] [Indexed: 10/25/2022]
Abstract
The kynurenine aminotransferases (KATs) KAT I and KAT II are pivotal to the synthesis of kynurenic acid (KYNA), the only known endogenous glutamate receptor antagonist and neuroprotectant. KAT I and II have been found in avian, rodent, and human retina. Expression of KAT I in Müller cell endfeet and KAT II in retinal ganglion cells has been documented. Developmental changes in KAT expression and KYNA concentration in the avian and rodent retina have also been found. Studies of retinal neurodegeneration have shown alterations in KYNA synthesis in the retina in response to retinal ganglion cell loss. In DBA/2J mice, a model of ocular hypertension, an age-dependent decrease of retinal KYNA and KATs was found. In the corpora amylacea in the human retina intensive KAT I and II immunoreactivity was demonstrated. In summary, these findings point to the potential involvement of KYNA in the mechanisms of retinal aging and neurodegeneration.
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Affiliation(s)
- Robert Rejdak
- Centre for Ophthalmology, University of Tübingen, Roentgenweg 11, D-72076 Tübingen, Germany.
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22
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Phoneutria spider toxins block ischemia-induced glutamate release and neuronal death of cell layers of the retina. Retina 2011; 31:1392-9. [PMID: 21394062 DOI: 10.1097/iae.0b013e318205b249] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PURPOSE To investigate the effect of calcium channel blockers, spider toxins, on cell viability and the glutamate content of ischemic retinal slices. METHODS Rat retinal slices were subjected to ischemia via exposure to oxygen-deprived low-glucose medium for 45 minutes. Slices were either treated or not treated with the toxins PhTx3, Tx3-3, and Tx3-4. After oxygen-deprived low-glucose insult, glutamate content and cell viability were assessed in the slices by confocal and optical microscopy. RESULTS In the retinal ischemic slices that were treated with PhTx3, Tx3-3, and Tx3-4, confocal imaging showed a decrease in cell death of 79.5 ± 3.1%, 75.5 ± 5.8%, and 61 ± 3.8%, respectively. Neuroprotective effects were also observed 15, 30, 60, and 90 minutes after the onset of the retinal ischemic injury. As a result of the ischemia, glutamate increased from 6.2 ± 1.0 nMol/mg protein to 13.2 ± 1.0 nMol/mg protein and was inhibited by PhTx3, Tx3-3, and Tx3-4 to 8.6 ± 0.7, 8.8 ± 0.9, and 7.4 ± 0.8 nMol/mg protein, respectively. Histologic analysis of the live cells in the outer, inner, and ganglion cell layers of the ischemic slices showed a considerable reduction in cell death by the toxin treatment. CONCLUSION Spider toxins reduced glutamate content and cell death of retinal ischemic slices.
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A precise temporal dissection of monosodium glutamate-induced apoptotic events in newborn rat retina in vivo. Neurochem Res 2011; 36:1464-74. [PMID: 21512746 DOI: 10.1007/s11064-011-0472-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2011] [Indexed: 01/11/2023]
Abstract
Although L-glutamate is the main excitatory neurotransmitter in the retina, excess glutamate level triggers severe neuronal damages. Therefore, monosodium glutamate has been used to probe neurodegenerative mechanisms but precise toxicity schedule is not available in vivo. We report, for the first time, a temporal analysis of apoptotic processes induced by subcutaneously applied monosodium glutamate. We investigated the glutamate triggered subcellular processes over a time scale of 48 h in neonatal retina. We employed immunoblots to measure the level of activated apoptotic factors and immunocytochemistry to reveal the dying cells. Upregulation of active caspase-9 started at 3 h and peaked at 6 h post-injection. Activations of caspase-3, caspase-6 and caspase-7 consistent with their late-phase roles increased at 6 h post-injection. The apoptotic processes were terminated by 24 h post-injection. Caspase 12 and calpain-2 seemed unaffected by subcutaneous monosodium glutamate administration. Uniquely, we found that the ubiquitous calpain-1 is not expressed in newborn rat retina.
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Sherry DM, Ulshafer RJ. Neurotransmitter-specific identification and characterization of neurons in the all-cone retina of Anolis carolinensis II: Glutamate and aspartate. Vis Neurosci 2009; 9:313-23. [PMID: 1356423 DOI: 10.1017/s0952523800010725] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractImmunocytochemical and autoradiographic methods were used to identify neurons in the pure cone retina of the lizard (Anolis carolinensis) that are likely to employ glutamate (GLU) or aspartate (ASP) as a neurotransmitter.GLU immunocytochemistry demonstrated high levels of endogenous GLU in all cone types and numerous bipolar cells. Moderate GLU levels were found in horizontal and ganglion cells. Müller cells and most amacrine cells had very low GLU levels. GLU immunoreactivity (GLU-IR) in the cones was present from the inner segment to the synaptic pedicle. A large spherical cell type with moderate GLU-IR was identified in the proximal inner plexiform layer (IPL). These cells also contain ASP and have been tentatively identified as amacrine cells. Uptake of [3H]-L-GLU labeled all retinal layers. All cone types and Müller cells sequestered [3H]-D-ASP, a substrate specific for the GLU transporter.Anti-ASP labeling was observed in cones, horizontal cells, amacrine cells, and cells in the ganglion cell layer. ASP immunoreactivity (ASP-IR) in the cones was confined to the inner segment. One ASP-containing pyriform amacrine cell subtype ramifying in IPL sublamina b was identified.Analysis of GLU-IR, ASP-IR, and GABA-IR on serial sections indicated that there were two distinct populations of horizontal cells in the Anolis retina: one containing GABA-IR, GLU-IR, and ASP-IR; and another type containing only GLU-IR and ASP-IR. Light GLU-IR was frequently found in GABA-containing amacrine cells but ASP-IR was not.The distinct distributions of GLU and ASP may indicate distinctly different roles for these amino acids. GLU, not ASP, is probably the major neurotransmitter in the cone-biploar-ganglion cell pathway of the Anolis retina. Both GLU and ASP are present in horizontal cells and specific subpopulations of amacrine cells, but it is unclear if GLU or ASP have a neurotransmitter role in these cells.
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Affiliation(s)
- D M Sherry
- Department of Neuroscience, University of Florida, Gainesville
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Linn DM, Massey SC. GABA inhibits ACh release from the rabbit retina: A direct effect or feedback to bipolar cells? Vis Neurosci 2009; 8:97-106. [PMID: 1348426 DOI: 10.1017/s0952523800009263] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThe cholinergic amacrine cells of the rabbit retina may be labeled with [3H]-Ch and the activity of the cholinergic population monitored by following the release of [3H]-ACh. We have tested the effect of muscimol, a potent GABAA agonist, on (1) the light-evoked release of ACh, presumably mediated via bipolar cells, which are known to have a direct input to the cholinergic amacrine cells and (2) ACh release produced by exogenous glutamate analogs that probably have a direct effect on cholinergic amacrine cells. Muscimol blocked the light-evoked release of ACh with an IC50 of 1.0 μM. In contrast, ACh release produced by nonsaturating doses of kainate or NMDA was not reduced even by 100 μM muscimol. Thus, we have been unable to demonstrate a direct effect of GABA on the cholinergic amacrine cells.GABA antagonists, such as picrotoxin, caused a large increase in the base release and potentiated the light-evoked release of ACh. Both these effects were abolished by DNQX, a kainate antagonist that blocks the input to cholinergic amacine cells from bipolar cells. DNQX blocked the effects of picrotoxin even when controls showed that the mechanism of ACh release was still functional. Together, these results imply that the dominant site for the GABA-mediated inhibition of ACh release is on the bipolar cell input to the cholinergic amacrine cells. This is consistent with previous anatomical and physiological evidence that bipolar cells receive negative feedback from GABA amacrine cells.
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Affiliation(s)
- D M Linn
- Sensory Sciences Center, Graduate School of Biomedical Sciences, University of Texas Health Science Center, Houston 77030
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Osborne NN. Recent clinical findings with memantine should not mean that the idea of neuroprotection in glaucoma is abandoned. Acta Ophthalmol 2009; 87:450-4. [PMID: 19141144 DOI: 10.1111/j.1755-3768.2008.01459.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Loss of vision in primary open-angle glaucoma (glaucoma) is caused by retinal ganglion cells dying at a seemingly steady and variable rate in different patients. Present treatments for all glaucoma patients are inadequate and a goal to rectify this is to discover appropriate drugs or chemicals (neuroprotectants) that can be taken orally to slow down retinal ganglion cell death and have negligible side-effects. It was therefore of great disappointment to learn earlier this year that the one clinical trial conducted to test the efficacy of memantine as a neuroprotectant for glaucoma was unsuccessful. In this article, I consider the mechanisms by which retinal ganglion cells may die in glaucoma and suggest that memantine may have benefited patients taking it but to a level that was difficult to detect with present methodologies. Ganglion cells are induced to die by different triggers in glaucoma, suggesting that neuroprotectants with multiple modes of actions are likely to reveal clearer results than was found for memantine. Therefore, the idea of neuroprotection in glaucoma must not be abandoned.
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Affiliation(s)
- Neville N Osborne
- Nuffield Laboratory of Ophthalmology, John Radcliffe Hospital, Oxford University, Headley Way, Oxford, UK.
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Rousseaux CG. A Review of Glutamate Receptors I: Current Understanding of Their Biology. J Toxicol Pathol 2008. [DOI: 10.1293/tox.21.25] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Colin G. Rousseaux
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of Ottawa
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Rousseaux CG. A Review of Glutamate Receptors II: Pathophysiology and Pathology. J Toxicol Pathol 2008. [DOI: 10.1293/tox.21.133] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Colin G. Rousseaux
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of Ottawa
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Puller C, Haverkamp S, Grünert U. OFF midget bipolar cells in the retina of the marmoset, Callithrix jacchus, express AMPA receptors. J Comp Neurol 2007; 502:442-54. [PMID: 17366611 DOI: 10.1002/cne.21315] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent studies suggested that different types of OFF bipolar cells express specific types of ionotropic (AMPA or kainate) glutamate receptors (GluRs) at their contacts with cone pedicles. However, the question of which GluR type is expressed by which type of OFF bipolar cell in primate retina is still open. In this study, the expression of AMPA and kainate receptor subunits at the dendritic tips of flat (OFF) midget bipolar (FMB) cells was analyzed in the retina of the common marmoset, Callithrix jacchus. We used preembedding electron microscopy and double immunofluorescence with subunit-specific antibodies. The FMB cells were labeled with antibodies against the carbohydrate epitope CD15. Cone pedicles were identified with peanut agglutinin. Immunoreactivity for the GluR1 subunit and for CD15 is preferentially located at triad-associated flat contacts. Furthermore, the large majority of GluR1 immunoreactive puncta is localized at the dendritic tips of FMB cells. These results suggest that FMB cells express the AMPA receptor subunit GluR1. In contrast, the kainate receptor subunit GluR5 is not colocalized with the dendritic tips of FMB cells or with the GluR1 subunit. Immunoreactive puncta for the GluR1 subunit are found at all M/L-cone pedicles but are only rarely associated with S-cone pedicles. This is consistent with our recent findings in marmoset retina that FMB cells do not contact S-cone pedicles. The presence of GluR5 clusters at S-cone pedicles indicates that in primate retinas OFF bipolar cells expressing kainate receptor subunits receive some S-cone input.
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Affiliation(s)
- Christian Puller
- Department of Neuroanatomy, Max-Planck-Institute for Brain Research, D-60528 Frankfurt/Main, Germany
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Kwon OJ, Kim MS, Kim TJ, Jeon CJ. Identification of synaptic pattern of kainate glutamate receptor subtypes on direction-selective retinal ganglion cells. Neurosci Res 2007; 58:255-64. [PMID: 17466402 DOI: 10.1016/j.neures.2007.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/19/2007] [Accepted: 03/20/2007] [Indexed: 11/24/2022]
Abstract
In this article we investigate the distributions of kainate glutamate receptor subtypes GluR5-7 and KA1, 2 on the dendritic arbors of direction-selective (DS) retinal ganglion cells (RGCs) of the rabbit retina to search for anisotropies, which might contribute to a directional preference of DS RGCs. The distribution of the kainate receptor subunits on the DS RGCs was determined using antibody immunocytochemistry. DS RGCs were injected with Lucifer yellow and the cells were identified by their characteristic morphology. The double-labeled images of dendrites and receptors were visualized using confocal microscopy and were reconstructed from high-resolution confocal images. We found no evidence of asymmetry in any of the kainate receptor subunits examined on the dendritic arbors of both On and Off layers of DS RGCs. Our results indicate that direction selectivity appears to lie in the neuronal circuitry afferent to the ganglion cell.
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Affiliation(s)
- Oh-Ju Kwon
- Neuroscience Lab, Department of Biology, College of Natural Sciences, Kyungpook National University, 1370 Sankyuk-dong, Daegu 702-701, South Korea
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31
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Opere CA, Zheng WD, Zhao M, Lee JS, Kulkarni KH, Ohia SE. Inhibition of potassium- and ischemia-evoked [3H] D-aspartate release from isolated bovine retina by cannabinoids. Curr Eye Res 2006; 31:645-53. [PMID: 16877273 DOI: 10.1080/02713680600762747] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We investigated the effect of cannabinoids on potassium chloride (K+)- and ischemia-induced [3H]D-aspartate release from isolated bovine retinae. The superfusion method was employed for studies of [3H]-neurotransmitter release. Cannabinoid receptor CB1 agonists, but not the CB2 agonist JWH 015, inhibited K+ -induced [3H]D-aspartate release from bovine retinae with the following rank order of activity: anandamide > ACEA > methanandamide > WIN 55,212-2. In the ischemic model, the rank order of activity was as follows: methanandamide > ACEA > WIN 55,212-2. The CB1 receptor antagonist AM 251 blocked inhibitory responses produced by cannabinoids in both experimental conditions. In conclusion, cannabinoids inhibit evoked [3H]D-aspartate release from isolated bovine retinae via an effect on CB1 receptors.
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Affiliation(s)
- Catherine A Opere
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University Medical Center, Omaha, Nebrasaka 68178, USA.
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Chang B, Heckenlively JR, Bayley PR, Brecha NC, Davisson MT, Hawes NL, Hirano AA, Hurd RE, Ikeda A, Johnson BA, McCall MA, Morgans CW, Nusinowitz S, Peachey NS, Rice DS, Vessey KA, Gregg RG. The nob2 mouse, a null mutation in Cacna1f: anatomical and functional abnormalities in the outer retina and their consequences on ganglion cell visual responses. Vis Neurosci 2006; 23:11-24. [PMID: 16597347 PMCID: PMC2831086 DOI: 10.1017/s095252380623102x] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 11/09/2005] [Indexed: 11/06/2022]
Abstract
Glutamate release from photoreceptor terminals is controlled by voltage-dependent calcium channels (VDCCs). In humans, mutations in the Cacna1f gene, encoding the alpha1F subunit of VDCCs, underlie the incomplete form of X-linked congenital stationary night blindness (CSNB2). These mutations impair synaptic transmission from rod and cone photoreceptors to bipolar cells. Here, we report anatomical and functional characterizations of the retina in the nob2 (no b-wave 2) mouse, a naturally occurring mutant caused by a null mutation in Cacna1f. Not surprisingly, the b-waves of both the light- and dark-adapted electroretinogram are abnormal in nob2 mice. The outer plexiform layer (OPL) is disorganized, with extension of ectopic neurites through the outer nuclear layer that originate from rod bipolar and horizontal cells, but not from hyperpolarizing bipolar cells. These ectopic neurites continue to express mGluR6, which is frequently associated with profiles that label with the presynaptic marker Ribeye, indicating potential points of ectopic synapse formation. However, the morphology of the presynaptic Ribeye-positive profiles is abnormal. While cone pedicles are present their morphology also appears compromised. Characterizations of visual responses in retinal ganglion cells in vivo, under photopic conditions, demonstrate that ON-center cells have a reduced dynamic range, although their basic center-surround organization is retained; no alteration in the responses of OFF-center cells was evident. These results indicate that nob2 mice are a valuable model in which to explore the pathophysiological mechanisms associated with Cacna1f mutations causing CSNB2, and the subsequent effects on visual information processing. Further, the nob2 mouse represents a model system in which to define the signals that guide synapse formation and/or maintenance in the OPL.
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Affiliation(s)
- Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine, USA
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Dmitriev AV, Mangel SC. Electrical Feedback in the Cone Pedicle: A Computational Analysis. J Neurophysiol 2006; 95:1419-27. [PMID: 16319220 DOI: 10.1152/jn.00098.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
One of the fundamental principles of neuroscience is that direct electrical interactions between neurons are not possible without specialized electrical contacts, gap junctions, because the transmembrane resistance of neurons is typically much higher than the resistance of the adjacent extracellular space. However it has been proposed that in the retina direct electrical interactions between cones and second-order neurons occur due to the specific morphology of the cone synaptic terminal. This electrical mechanism could potentially explain the phenomenon of “negative feedback” from horizontal cells to cones and the recent finding that the tips of horizontal cell dendrites contain hemichannels has rekindled interest in the idea. We quantitatively evaluated the possibility that hemichannels and/or glutamate channels mediate electrical feedback from horizontal cells to cones. The calculations show that it is unlikely that an electrical mechanism plays a significant functional role because 1) the necessity of preserving adequate cone-to-horizontal-cell synaptic transmission limits the extracellular space resistance and the horizontal-cell dendritic transmembrane resistances to values at which the effectiveness of electrical feedback is very low and its electrical effect on the cone presynaptic membrane is negligible, 2) electrical feedback is most effective in the dark and weaker during light adaptation, which contradicts the experimental data, and 3) electrical negative feedback is associated with much stronger electrical positive feedback from horizontal cells to cones, a phenomenon that has never been reported. Therefore it is likely that negative feedback from horizontal cells to cones is chemical in nature.
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Affiliation(s)
- Andrey V Dmitriev
- Dept. of Neuroscience, The Ohio State University College of Medicine, 333 W. 10th Ave., Columbus, OH 43210, USA.
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Famiglietti EV. Synaptic organization of complex ganglion cells in rabbit retina: type and arrangement of inputs to directionally selective and local-edge-detector cells. J Comp Neurol 2005; 484:357-91. [PMID: 15770656 DOI: 10.1002/cne.20433] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The type and topographic distribution of synaptic inputs to a directionally selective (DS) rabbit retinal ganglion cell (GC) were examined and were compared with those received by two other complex GC types. The percentage of cone bipolar cell (BC) input, presumably an index of sustained responses and simple receptive field properties, is much higher than expected for complex GCs in reference to previous reports in other species: approximately 20% for the type 1 bistratified ON-OFF DS GC and for a multistratified GC, and approximately 40% for the small-tufted local-edge-detector GC. Consistent with a previous study (Famiglietti [1991] J. Comp. Neurol. 309:40-70), no ultrastructural evidence is found for inhibitory synapses from starburst amacrine cells to the ON-OFF DS GC. The density of inputs to the ON-OFF DS GC is high and rather evenly distributed over the dendritic tree. Clustering of inputs brings excitatory and inhibitory inputs into proximity, but the strict on-path condition of more proximal inhibitory inputs, favoring shunting inhibition, is not satisfied. Prominent BC input and its regional variation suggest that BCs play key roles in DS neural circuitry, both pre- and postsynaptic to the ON-OFF DS GC, according to a bilayer model (Famiglietti [1993] Invest. Ophthalmol. Vis. Sci. 34:S985). Asymmetry of inhibitory amacrine cell input may signify a region on the preferred side of the receptive field, the inhibition-free zone (Barlow and Levick [1965] J. Physiol. (Lond.) 178:477-504), supporting a role for postsynaptic integration in the DS mechanism. Prominent BC input to the local-edge-detector, often without accompanying amacrine cell input, indicates presynaptic integration in forming its trigger feature.
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Affiliation(s)
- Edward V Famiglietti
- Department of Ophthalmology, Rhode Island Hospital, Providence, Rhode Island 02903, USA.
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Kim IB, Park MR, Kang TH, Kim HJ, Lee EJ, Ahn MD, Chun MH. Synaptic connections of cone bipolar cells that express the neurokinin 1 receptor in the rabbit retina. Cell Tissue Res 2005; 321:1-8. [PMID: 15902497 DOI: 10.1007/s00441-005-1122-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2004] [Accepted: 03/18/2005] [Indexed: 12/31/2022]
Abstract
We have investigated and further characterized, in the rabbit retina, the synaptic connectivity of the ON-type cone bipolar cells that are immunoreactive for an antibody against the neurokinin-1 receptor (NK1R). NK1R-immunoreactive bipolar cell axons terminate in stratum 4 of the inner plexiform layer. The axons of NK1R-positive bipolar cells receive synaptic inputs from amacrine cells through conventional synapses and from putative AII amacrine cells via gap junctions. The major outputs from NK1R-positive bipolar cells make contacts with amacrine cell processes. The most frequent postsynaptic dyads comprise two amacrine cell processes. Double-labeling experiments with antibodies against NK1R and either calretinin or glycine have demonstrated that NK1R-immunoreactive bipolar cells form gap junctions with AII amacrine cells. Thus, NK1R-positive cone bipolar cells, together with calbindin-positive cone bipolar cells, may play an important role in transferring rod signals to the ON-type ganglion cells of the cone pathway in the rabbit retina.
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Affiliation(s)
- In-Beom Kim
- Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seoul, 137-701, South Korea
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Pignataro L, Sitaramayya A, Finnemann SC, Sarthy VP. Nonsynaptic localization of the excitatory amino acid transporter 4 in photoreceptors. Mol Cell Neurosci 2005; 28:440-51. [PMID: 15737735 DOI: 10.1016/j.mcn.2004.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 10/01/2004] [Accepted: 10/06/2004] [Indexed: 11/27/2022] Open
Abstract
Excitatory amino acid transporters (EAATs) are involved in regulating extracellular glutamate levels at synaptic regions in the CNS. EAAT1, 2, 3, and 5 have been found in the mammalian retina, but the presence of EAAT4 has remained controversial. Recently, we found a high level of EAAT4 mRNA in the human retina, and this observation lead us to examine whether EAAT4 was expressed in the mammalian retina. Immunoblotting studies showed the presence of EAAT4-immunoreactive proteins in human and mouse retinas, corresponding to EAAT4 monomers and dimers. Immunohistochemistry revealed that EAAT4 was localized in rod and cone photoreceptor outer segments in the human retina, and in the outer and inner segments of mouse and ground squirrel retinas. In no case was EAAT4 found in the outer plexiform layer or in any other layer in the retina. EAAT4 expression by photoreceptors was confirmed by immunoblotting a purified rod outer segment preparation, which showed the presence of a 50-kDa EAAT4-immunoreactive protein. In addition, the EAAT4-associated protein, GTRAP41, was found in the human, mouse, and squirrel retinas as well as in the rod outer segment preparation. Further immunocytochemical and co-immunoprecipitation experiments demonstrated that GTRAP41 was colocalized and interacted in vivo with EAAT4. Importantly, glutamate uptake and drug inhibition experiments showed that an EAAT4-like glutamate uptake system is present in the rod outer segments. Finally, we examined whether glutamate signaling mediated by EAAT4 can modulate rod outer segment phagocytosis by the retinal pigment epithelium. Results of the present study show that EAAT4 is present in the outer segments, a nonsynaptic region of photoreceptors, where it might provide a feedback mechanism for sensing extracellular glutamate or serve as an outer barrier to prevent glutamate from escaping from the retina.
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Affiliation(s)
- Leonardo Pignataro
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Kalloniatis M, Sun D, Foster L, Haverkamp S, Wässle H. Localization of NMDA receptor subunits and mapping NMDA drive within the mammalian retina. Vis Neurosci 2005; 21:587-97. [PMID: 15595182 DOI: 10.1017/s0952523804214080] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Glutamate is a major neurotransmitter in the retina and other parts of the central nervous system, exerting its influence through ionotropic and metabotropic receptors. One ionotropic receptor, the N-methyl-D-aspartate(NMDA) receptor, is central to neural shaping, but also plays a major role during neuronal development and in disease processes. We studied the distribution pattern of different subunits of the NMDA receptor within the rat retina including quantifying the pattern of labelling for all the NRI splice variants, the NR2A and NR2B subunits. The labelling pattern for the subunits was confined predominantly in the outer two-thirds of the inner plexiform layer. We also wanted to probe NMDA receptor function using an organic cation, agmatine (AGB); a marker for cation channel activity. Although there was an NMDA concentration-dependent increase in AGB labelling of amacrine cells and ganglion cells, we found no evidence of functional NMDA receptors on horizontal cells in the peripheral rabbit retina, nor in the visual streak where the type A horizontal cell was identified by GABA labelling. Basal AGB labelling within depolarizing bipolar cells was also noted. This basal bipolar cell AGB labelling was not modulated by NMDA and was completely abolished by the use of L-2-amino-4-phosphono-butyric acid,which is known to hyperpolarize retinal depolarizing bipolar cells. AGB is therefore not only useful as a probe of ligand-gated drive, but can also identify neurons that have constitutively open cationic channels. In combination,the NMDA receptor subunit distribution pattern and the AGB gating experiments strongly suggests that this ionotropic glutamate receptor is functional in the cone-driven pathway of the inner retina.
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Affiliation(s)
- Michael Kalloniatis
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand.
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Chapter 1 Morphology and physiology of the retina. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s1567-4231(09)70198-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Szabó A, Varga V, Toimela T, Hiitelä K, Tähti H, Oja SS, Süveges I, Salminen L. Laser treatment of cultured retinal pigment epithelial cells-evaluation of the cellular damage in vitro. J Ocul Pharmacol Ther 2004; 20:246-55. [PMID: 15279729 DOI: 10.1089/1080768041223594] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Evaluation of the effects of laser photocoagulation on cultured primary retinal pigment epithelial cells. METHODS Cells were treated by a diode laser (678 nm) with 800 and 1600 mW for 0.186 second. Cell toxicity was tested by the WST-1 assay, and the uptakes of glutamate and gamma-aminobutyric acid (GABA) were measured. RESULTS Laser photocoagulation (1600 mW) caused cell damage and the mitochondrial enzyme activity evaluated by a WST-1 test significantly decreased by 20%-30%. Laser treatment caused a dose-dependent decrease in glutamate uptake but increased GABA uptake. CONCLUSIONS Laser treatment and the laser-induced increase in temperature influence transport processes in retinal pigment epithelial cells and may cause cell damage in the posterior part of the retina.
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Affiliation(s)
- Antal Szabó
- Brain Research Center, University of Tampere, Medical School, Finland.
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Linden R, Martins RAP, Silveira MS. Control of programmed cell death by neurotransmitters and neuropeptides in the developing mammalian retina. Prog Retin Eye Res 2004; 24:457-91. [PMID: 15845345 DOI: 10.1016/j.preteyeres.2004.10.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
It has long been known that a barrage of signals from neighboring and connecting cells, as well as components of the extracellular matrix, control cell survival. Given the extensive repertoire of retinal neurotransmitters, neuromodulators and neurotrophic factors, and the exhuberant interconnectivity of retinal interneurons, it is likely that various classes of released neuroactive substances may be involved in the control of sensitivity to retinal cell death. The aim of this article is to review evidence that neurotransmitters and neuropeptides control the sensitivity to programmed cell death in the developing retina. Whereas the best understood mechanism of execution of cell death is that of caspase-mediated apoptosis, current evidence shows that not only there are many parallel pathways to apoptotic cell death, but non-apoptotic programs of execution of cell death are also available, and may be triggered either in isolation or combined with apoptosis. The experimental data show that many upstream signaling pathways can modulate cell death, including those dependent on the second messengers cAMP-PKA, calcium and nitric oxide. Evidence for anterograde neurotrophic control is provided by a variety of models of the central nervous system, and the data reviewed here indicate that an early function of certain neurotransmitters, such as glutamate and dopamine, as well as neuropeptides such as pituitary adenylyl cyclase-activating polypeptide and vasoactive intestinal peptide is the trophic support of cell populations in the developing retina. This may have implications both regarding the mechanisms of retinal organogenesis, as well as pathological conditions leading to retinal dystrophies and to dysfunctional cellular behavior.
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Affiliation(s)
- Rafael Linden
- Centro de Ciencias da Saude, Instituto de Biofísica da UFRJ, Cidade Universitária, bloco G, Rio de Janeiro 21949-900, Brazil.
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Kao YH, Lassová L, Bar-Yehuda T, Edwards RH, Sterling P, Vardi N. Evidence that certain retinal bipolar cells use both glutamate and GABA. J Comp Neurol 2004; 478:207-18. [PMID: 15368537 DOI: 10.1002/cne.20221] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Retinal bipolar neurons release the excitatory transmitter, glutamate. However, certain bipolar cells contain GABA, raising the question whether a neuron might release both transmitters and, if so, what function might the inhibitory transmitter play in a particular circuit? Here we identify a subset of cone bipolar cells in cat retina that contain glutamate, plus its vesicular transporter (VGLUT1), and GABA, plus its synthetic enzyme (GAD(65)) and its vesicular transporter (VGAT). These cells are negative for a marker of ON bipolar cells and restrict their axons to the OFF strata of the inner synaptic layer. They do not colocalize with the neurokinin 3 receptor that stains a type (or two) of OFF bipolar cells. By "targeted injection," we identified two types of OFF bipolar cell with the machinery to make and package both transmitters. One of these types costratifies with a dopamine plexus.
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Affiliation(s)
- Yen-Hong Kao
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6058, USA
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Rauen T, Wiessner M, Sullivan R, Lee A, Pow DV. A new GLT1 splice variant: cloning and immunolocalization of GLT1c in the mammalian retina and brain. Neurochem Int 2004; 45:1095-106. [PMID: 15337309 DOI: 10.1016/j.neuint.2004.04.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 03/10/2004] [Accepted: 04/27/2004] [Indexed: 01/18/2023]
Abstract
We have identified a novel carboxyl-terminal splice-variant of the glutamate transporter GLT1, which we denote as GLT1c. Within the rat brain only low levels of protein and message were detected, protein expression being restricted to end feet of astrocytes apposed to blood vessels or some astrocytes adjacent to the ventricles. Conversely, within the retina, this variant was selectively and heavily expressed in the synaptic terminals of both rod- and cone-photoreceptors in both humans and rats. Double-immunolabelling with antibodies to the carboxyl region of GLT1b/GLT1v, which is strongly expressed in apical dendrites of bipolar cells and in cone photoreceptors revealed that in the rat GLT1c was co-localised with GLT1b/GLT1v in cone photoreceptors but not with GLT1b/GLT1v in bipolar cells. GLT1c expression was developmentally regulated, only appearing at around postnatal day 7 in the rat retina, when photoreceptors first exhibit a dark current. Since the glutamate transporter EAAT5 is also expressed in terminals of rod photoreceptor terminals these data indicate that rod photoreceptors express two glutamate transporters with distinct properties. Similarly, cone photoreceptors express two glutamate transporters. We suggest that differential usage of these transporters by rod and cone photoreceptors may influence the kinetics of glutamate transmission by these neurons.
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Affiliation(s)
- Thomas Rauen
- Institut für Biochemie, Westfälische-Wilhelms-Universitat Münster, Wilhelm-Klemm-Street 2, D-48149 Münster, Germany.
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Barabás P, Kovács I, Kardos J, Schousboe A. Exogenous glutamate and taurine exert differential actions on light-induced release of two endogenous amino acids in isolated rat retina. J Neurosci Res 2003; 73:731-6. [PMID: 12929141 DOI: 10.1002/jnr.10697] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A dark-adapted isolated rat retina, preloaded with [(14)C]glutamate ([(14)C]Glu) and [(3)H]taurine ([(3)H]Tau), was superfused with artificial cerebrospinal fluid (ACSF) in the absence and presence of Glu (1 mM) or Tau (1 mM), as well as the Glu uptake inhibitors dihydrokainic acid (DHK, 0.04 mM) and trans-L-pyrrolidine-2,4-dicarboxylate (t-PDC, 0.004 mM). After 10 min of light stimulation, the extracellular level of [(14)C]Glu and [(3)H]Tau was reduced to 82 +/- 2% and 65 +/- 4% of the control, respectively. Basal release was enhanced when Tau and t-PDC were applied together, although none of the compounds had any effect when applied individually. Glu and DHK had no effect. The decrease of [(14)C]Glu efflux evoked by light stimuli was enhanced by t-PDC and Tau, either added separately or together, whereas Glu and DHK were without effect. In contrast, [(3)H]Tau efflux variations induced by light stimuli were reduced markedly by both Tau and Glu. These findings suggest distinctly different roles of Tau and Glu in light-induced responses in mammalian retina, including a possible role for Tau in light adaptation processes.
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Affiliation(s)
- Péter Barabás
- Department of Neurochemistry, Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest, Hungary
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Kamphuis W, Dijk F, O'Brien BJ. Gene expression of AMPA-type glutamate receptor subunits in rod-type ON bipolar cells of rat retina. Eur J Neurosci 2003; 18:1085-92. [PMID: 12956708 DOI: 10.1046/j.1460-9568.2003.02841.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The retinal rod bipolar cell type is involved in the sign-inverting depolarizing ON-type response to light. This response is mediated by the metabotropic glutamate receptor type 6 (mGluR6) expressed on the rod bipolar dendrites. In a previous immunocytochemical study, an unexpected colocalization was reported [W. Kamphuis et al. (2003) J. Comp. Neurol., 455, 172-186] of mGluR6 with the ionotropic AMPA-type glutamate receptor subunit GluR2 in rod bipolar cells of rat retina. The aim of the present study was to investigate whether expression of both genes could be found at the single-cell level. Two approaches were followed. (i). Retinal cells were isolated by enzymatic and mechanical treatment. Single cells with a bipolar morphology were harvested, subjected to multiplex PCR with protein kinase C (PKC)-, mGluR6- and GluR1-4-specific primers, followed by a real-time quantitative PCR assay. Of 23 studied cells, 74% expressed PKC and 87% expressed mGluR6. Using the presence of both transcripts as the criterion for a rod bipolar cell signature (n = 15), 73% of these cells expressed GluR2, with a minor contribution of GluR1 (20%), GluR3 (7%), and GluR4 (20%). Quantification of the transcript levels demonstrated that mGluR6 and GluR2 genes are expressed at similar levels in rod ON-type bipolar cells. (ii). Rod bipolar cells were identified in retinal sections by immunolabelling with a protein kinase C antibody and isolated using laser pressure catapulting (LPC). Quantitative PCR was employed to assess gene expression levels of reference genes, PKCalpha, mGluR6 and the GluR subunits. However, in samples from PKCalpha-immunopositive somata no significant enrichment of PKCalpha transcript levels was observed when compared with control samples from immunonegative somata. We conclude that this approach lacks sufficient spatial specificity. In conclusion, the results show coexpression of mGluR6 and GluR2 in rod bipolar cells; this is in good agreement with the results of previous immunocytochemical studies. The functional implications of AMPA-type glutamate receptors for ON-type rod bipolar-mediated signal transduction remains to be elucidated.
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Affiliation(s)
- Willem Kamphuis
- Graduate School for the Neurosciences Amsterdam, the Netherlands.
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Kamphuis W, Klooster J, Dijk F. Expression of AMPA-type glutamate receptor subunit (GluR2) in ON-bipolar neurons in the rat retina. J Comp Neurol 2003; 455:172-86. [PMID: 12454983 DOI: 10.1002/cne.10469] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The role of glutamate receptors (GluR) in the signal pathways of the retina is widely recognized. Photoreceptors make synaptic contact with functionally different classes of bipolar cells. The OFF-type bipolar cells mediate light offset-evoked responses and use ionotropic alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA)- or kainate-type GluRs, whereas bipolars involved in the ON-pathway use the metabotropic GluR6. This dichotomy predicts a defined expression pattern of AMPA-type GluRs and mGluR6 in bipolar cell classes. This hypothesis was tested by performing immunocytochemical double labeling studies combining GluR-specific antibodies with markers specific for the diverse bipolar cell populations in the rat retina. AMPA-type receptors are composed of combinations of four types of subunits, GluR1-4. GluR1 is expressed by a few somata in the outer part of the inner nuclear layer (INL). Sparse colocalization with any of the bipolar markers used could be established. In contrast, GluR2 is expressed by many of the somata in the outer zone of the INL. At the transcript level, in situ hybridizations demonstrated abundant GluR2 expression over the complete width of the INL. In contrast to our expectations, approximately 70% of the somata labeled by the rod ON-bipolar markers protein kinase C (PKC) or Goalpha, colocalized with GluR2. Approximately 90% of the OFF-type bipolar cells, identified as recoverin-positive, showed GluR2 immunoreactivity. At least 40% of the somata that were mGluR6-immunoreactive, a both rod and cone ON-type bipolar marker, were GluR2-immunopositive. Ultrastructurally, examples were observed of GluR2 localization in bipolar processes with labeling outside the actual compartment associated with the synaptic complex of the rod terminal. No specific antibody was available against GluR3, but 74% of the PKC-positive cells were GluR2/3-positive. GluR4 did not show a somatic localization making double labeling impossible. On the basis of these results, we conclude that ionotropic GluRs are expressed by rod ON-type bipolar cells (PKC- or Goalpha-immunoreactive), and by cone ON- and OFF-type bipolars based on a colocalization with nearly all of the present recoverin-positive somata. Our observations show that the functional dichotomy in ON- and OFF-type bipolars is not reflected in a matching expression pattern of ionotropic and metabotropic GluRs. This finding raises the intriguing possibility that the AMPA-type GluRs are, in an as yet unclear manner, involved in the ON signaling pathways of rods and cones.
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Affiliation(s)
- Willem Kamphuis
- Graduate School for the Neurosciences Amsterdam, Netherlands Ophthalmic Research Institute-KNAW, Glaucoma Research Group, 1105 BA Amsterdam, The Netherlands.
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Shankaranarayana Rao BS, Raju TR. Enhanced metabolic activity coincides with survival and differentiation of cultured rat retinal ganglion cells exposed to glutamate. Neuroscience 2002; 113:547-53. [PMID: 12150775 DOI: 10.1016/s0306-4522(02)00200-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neurotransmitters are prominent candidates for trans-cellular signals that influence the development of the CNS. The present study has examined the effect of glutamate on survival, differentiation and metabolic activity of cultured rat retinal ganglion cells at 3 days in vitro. Retinal cultures from neonatal Wistar rats were treated with glutamate for 48 h. The metabolic activity was markedly increased in the retinal ganglion cells exposed to 20 microM glutamate. This was accompanied by an enhanced survival of these neurons. The number of differentiated retinal ganglion cells as determined by microtubule-associated protein-2 labeling was significantly increased following exposure to low but not higher doses of glutamate. The effect of glutamate on the metabolic activity and differentiation was blocked by tetrodotoxin. The results of the present study shows that glutamate has a significant effect on survival, differentiation and metabolic activity. An increase in the metabolic activity indicates an enhancement in the electrical activity. Thus, our results are consistent with the hypothesis that glutamate is critically involved in the regulation of electrical activity in developing rat retinal ganglion cells.
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Blanco R, Germain F, Velasco A, Villa PDL. Down-regulation of glutamate-induced conductances of retinal horizontal cells after ganglion cell axotomy. Exp Eye Res 2002; 75:209-16. [PMID: 12137766 DOI: 10.1006/exer.2002.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
After a complete optic nerve section (ONS), retinal neurons may display retrograde transneuronal modifications in synaptic structure and function related to the retinal disconnection from the brain. The molecular and physiological basis of these changes is not yet fully understood. Immunoreactivity for calbindin was used to specifically immunolabel the horizontal cells (HC) in order to study any morphologic changes in the outer plexiform layer (OPL) after axotomy-induced degeneration of retinal ganglion cells (RGC) in the rabbit retina. Glutamate-gated conductance expressed by HC enzymatically dissociated from the rabbit retina were studied at 12 and 21 days after ONS by using the whole-cell voltage-clamp technique. The amplitudes of glutamate-induced currents on HC were significantly reduced 3 weeks after axotomy. However, no morphologic changes within the OPL were detected coincident with the progressive loss of glutamatergic responses; similarly, HC dissociated from the axotomized retinal tissue did not differ in morphology or appearance from control retinas. The main finding in this study is that the HC experiment a retrograde transneuronal down-regulation of their ionotropic glutamate-induced conductance following axotomy-induced degeneration of RGC.
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Affiliation(s)
- RomAn Blanco
- Department of Physiology, School of Medicine, University of Alcala, Madrid, Spain
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Gábriel R, Wilhelm M. Structure and function of photoreceptor and second-order cell mosaics in the retina of Xenopus. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 210:77-120. [PMID: 11580209 DOI: 10.1016/s0074-7696(01)10004-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The structure, physiology, synaptology, and neurochemistry of photoreceptors and second-order (horizontal and bipolar) cells of Xenopus laevis retina is reviewed. Rods represent 53% of the photoreceptors; the majority (97%) are green light-sensitive. Cones belong to large long-wavelength-sensitive (86%), large short-wavelength-sensitive (10%), and miniature ultraviolet wavelength-sensitive (4%) groups. Photoreceptors release glutamate tonically in darkness, hyperpolarize upon light stimulation and their transmitter release decreases. Photoreceptors form ribbon synapses with second-order cells where postsynaptic elements are organized into triads. Their overall adaptational status is regulated by ambient light conditions and set by the extracellular dopamine concentration. The activity of photoreceptors is under circadian control and is independent of the central body clock. Bipolar cell density is about 6000 cells/mm2 They receive mixed inputs from rods and cones. Some bipolar cell types violate the rule of ON-OFF segregation, giving off terminal branches in both sublayers of the inner plexiform layer. The majority of them contain glutamate, a small fraction is GABA-positive and accumulates serotonin. Luminosity-type horizontal cells are more frequent (approximately 1,000 cells/mm2) than chromaticity cells (approximately 450 cells/mm2). The dendritic field size of the latter type was threefold bigger than that of the former. Luminosity cells contact all photoreceptor types, whereas chromatic cells receive their inputs from the short-wavelength-sensitive cones and rods. Luminosity cells are involved in generating depolarizing responses in chromatic horizontal cells by red light stimulation which form multiple synapses with blue-light-sensitive cones. Calculations indicate that convergence ratios in Xenopus are similar to those in central retinal regions of mammals, predicting comparable spatial resolution.
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Affiliation(s)
- R Gábriel
- Department of General Zoology and Neurobiology, University of Pécs, Hungary
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Reye P, Sullivan R, Fletcher EL, Pow DV. Distribution of two splice variants of the glutamate transporter GLT1 in the retinas of humans, monkeys, rabbits, rats, cats, and chickens. J Comp Neurol 2002; 445:1-12. [PMID: 11891650 DOI: 10.1002/cne.10095] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Antibodies have been generated against two carboxyl-terminal splice variants of the glutamate transporter GLT1, namely, the originally described version of GLT1 and GLT1-B, and labelling has been examined in multiple species, including chickens and humans. Although strong specific labelling was observed in each species, divergent patterns of expression were noted. Moreover, each antibody was sensitive to the phosphorylation state of the appropriate protein, because chemical removal of phosphates using alkaline phosphatase revealed a broader range of labelled elements in most cases. In general, GLT1-B was present in cone photoreceptors and in rod and cone bipolar cells in the retinas of rabbits, rats, and cats. In the cone-dominated retinas of chickens and in marmosets, GLT1-B was associated only with cone photoreceptors, whereas, in macaque and human retinas, GLT1-B was associated with bipolar cells and terminals of photoreceptors. In some species, such as cats, GLT-B was also present in horizontal cells. By contrast, GLT1 distribution varied. GLT1 was associated with amacrine cells in chickens, rats, cats, and rabbits and with bipolar cells in marmosets and macaques. In the rat retina, rod photoreceptor terminals also contained GLT1, but this was evident only in enzymatically dephosphorylated tissues. We conclude that the two variants of GLT1 are present in all species examined but are differentially distributed in a species-specific manner. Moreover, each cell type generally expresses only one splice variant of GLT1.
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Affiliation(s)
- Peter Reye
- Department of Physiology and Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane 4072, Queensland, Australia
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