1
|
Silva B, Gonçalves LM, São Braz B, Delgado E. Topical ocular delivery of nanoparticles with epoetin beta in Wistar Hannover rats. Sci Rep 2023; 13:1559. [PMID: 36707615 PMCID: PMC9883504 DOI: 10.1038/s41598-023-28845-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 01/25/2023] [Indexed: 01/29/2023] Open
Abstract
Topical instillation of drugs targeting the posterior ocular segment is an expanding area of research. Chitosan and hyaluronic acid have remarkable mucoadhesive properties and potentially enhance pre-corneal retention time after topical instillation. Bearing this in mind, we explored the possibility of delivering epoetin beta (EPOβ) to the posterior segment of the eye in a chitosan-hyaluronic acid (CS/HA-EPOβ) nanoparticulate system using the topical route of administration. Complete ophthalmological examinations, electroretinography and microhematocrit evaluations were performed in Wistar Hannover (WH) rats, before and after topical administration of nanoparticles. The right eye received CS/HA-EPOβ and the left eye received only empty nanocarriers (control). Animals were split into 6 groups and at designated timepoints, all animals from each group (n = 3) were euthanized and both eyes enucleated. Retinal morphology and EPOβ ocular distribution were assessed, respectively, through hematoxylin and eosin (HE) and immunofluorescence staining. After topical administration, no adverse ocular signs were noted and no significant changes either in microhematocrits nor in electroretinographies were detected. During the study, intraocular pressure (IOP) was always kept within physiological range bilaterally. No histological changes were detected in any of the ocular globes. Immunofluorescence enabled the identification of EPOβ in the retina 12 h after the administration, its presence still being detectable at day 21. In conclusion, CS/HA nanoparticles could efficiently deliver EPOβ to the retina of WH rats after topical instillation, being considered biologically safe. Topical administration of this nanoformulation could be a valuable tool for retinal neuroprotection, decreasing risks associated with more invasive routes of administration, being cost effective and also increasing long-term patients' compliance.
Collapse
Affiliation(s)
- Beatriz Silva
- CIISA-Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal.,Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477, Lisbon, Portugal.,Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisbon, Portugal
| | - Lídia M Gonçalves
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisbon, Portugal
| | - Berta São Braz
- CIISA-Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal. .,Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477, Lisbon, Portugal.
| | - Esmeralda Delgado
- CIISA-Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal.,Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477, Lisbon, Portugal
| |
Collapse
|
2
|
Pasmanter N, Petersen-Jones SM. Characterization of scotopic and mesopic rod signaling pathways in dogs using the On-Off electroretinogram. BMC Vet Res 2022; 18:422. [PMID: 36463174 PMCID: PMC9719241 DOI: 10.1186/s12917-022-03505-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 11/07/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND The On-Off, or long flash, full field electroretinogram (ERG) separates retinal responses to flash onset and offset. Depending on degree of dark-adaptation and stimulus strength the On and Off ERG can be shaped by rod and cone photoreceptors and postreceptoral cells, including ON and OFF bipolar cells. Interspecies differences have been shown, with predominantly positive Off-response in humans and other primates and a negative Off-response in rodents and dogs. However, the rod signaling pathways that contribute to these differential responses have not been characterized. In this study, we designed a long flash protocol in the dog that varied in background luminance and stimulus strength allowing for some rod components to be present to better characterize how rod pathways vary from scotopic to mesopic conditions. RESULTS With low background light the rod a-wave remains while the b-wave is significantly reduced resulting in a predominantly negative waveform in mesopic conditions. Through modeling and subtraction of the rod-driven response, we show that rod bipolar cells saturate with dimmer backgrounds than rod photoreceptors, resulting in rod hyperpolarization contributing to a large underlying negativity with mesopic backgrounds. CONCLUSIONS Reduction in rod bipolar cell responses in mesopic conditions prior to suppression of rod photoreceptor responses may reflect the changes in signaling pathway of rod-driven responses needed to extend the range of lighting conditions over which the retina functions.
Collapse
Affiliation(s)
- Nate Pasmanter
- grid.17088.360000 0001 2150 1785Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road, D208 East Lansing, MI USA
| | - Simon M. Petersen-Jones
- grid.17088.360000 0001 2150 1785Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road, D208 East Lansing, MI USA
| |
Collapse
|
3
|
Silva B, Gonçalves LM, Braz BS, Delgado E. Chitosan and Hyaluronic Acid Nanoparticles as Vehicles of Epoetin Beta for Subconjunctival Ocular Delivery. Mar Drugs 2022; 20:md20020151. [PMID: 35200680 PMCID: PMC8878220 DOI: 10.3390/md20020151] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/31/2022] [Accepted: 02/11/2022] [Indexed: 02/06/2023] Open
Abstract
Neuroprotection in glaucoma using epoetin beta (EPOβ) has yielded promising results. Our team has developed chitosan-hyaluronic acid nanoparticles (CS/HA) designed to carry EPOβ into the ocular globe, improving the drug’s mucoadhesion and retention time on the ocular surface to increase its bioavailability. In the present in vivo study, we explored the possibility of delivering EPOβ to the eye through subconjunctival administration of chitosan-hyaluronic acid-EPOβ (CS/HA-EPOβ) nanoparticles. Healthy Wistar Hannover rats (n = 21) were split into 7 groups and underwent complete ophthalmological examinations, including electroretinography and microhematocrit evaluations before and after the subconjunctival administrations. CS/HA-EPOβ nanoparticles were administered to the right eye (OD), and the contralateral eye (OS) served as control. At selected timepoints, animals from each group (n = 3) were euthanized, and both eyes were enucleated for histological evaluation (immunofluorescence and HE). No adverse ocular signs, no changes in the microhematocrits (≈45%), and no deviations in the electroretinographies in both photopic and scotopic exams were observed after the administrations (p < 0.05). Intraocular pressure remained in the physiological range during the assays (11–22 mmHg). EPOβ was detected in the retina by immunofluorescence 12 h after the subconjunctival administration and remained detectable until day 21. We concluded that CS/HA nanoparticles could efficiently deliver EPOβ into the retina, and this alternative was considered biologically safe. This nanoformulation could be a promising tool for treating retinopathies, namely optic nerve degeneration associated with glaucoma.
Collapse
Affiliation(s)
- Beatriz Silva
- CIISA—Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisbon, Portugal; (B.S.); (E.D.)
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisbon, Portugal
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, 1600-277 Lisbon, Portugal;
| | - Lídia M. Gonçalves
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, 1600-277 Lisbon, Portugal;
| | - Berta São Braz
- CIISA—Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisbon, Portugal; (B.S.); (E.D.)
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisbon, Portugal
- Correspondence: ; Tel.: +351-21-3602025
| | - Esmeralda Delgado
- CIISA—Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisbon, Portugal; (B.S.); (E.D.)
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisbon, Portugal
| |
Collapse
|
4
|
Gerberich BG, Hannon BG, Hejri A, Winger EJ, Schrader Echeverri E, Nichols LM, Gersch HG, MacLeod NA, Gupta S, Read AT, Ritch MD, Sridhar S, Toothman MG, Gershon GS, Schwaner SA, Sánchez-Rodríguez G, Goyal V, Toporek AM, Feola AJ, Grossniklaus HE, Pardue MT, Ethier CR, Prausnitz MR. Transpupillary collagen photocrosslinking for targeted modulation of ocular biomechanics. Biomaterials 2021; 271:120735. [PMID: 33721571 PMCID: PMC8044034 DOI: 10.1016/j.biomaterials.2021.120735] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 02/15/2021] [Accepted: 02/21/2021] [Indexed: 12/21/2022]
Abstract
The central vision-threatening event in glaucoma is dysfunction and loss of retinal ganglion cells (RGCs), thought to be promoted by local tissue deformations. Here, we sought to reduce tissue deformation near the optic nerve head by selectively stiffening the peripapillary sclera, i.e. the scleral region immediately adjacent to the optic nerve head. Previous scleral stiffening studies to treat glaucoma or myopia have used either pan-scleral stiffening (not regionally selective) or regionally selective stiffening with limited access to the posterior globe. We present a method for selectively stiffening the peripapillary sclera using a transpupillary annular light beam to activate methylene blue administered by retrobulbar injection. Unlike prior approaches to photocrosslinking in the eye, this approach avoids the damaging effects of ultraviolet light by employing red light. This targeted photocrosslinking approach successfully stiffened the peripapillary sclera at 6 weeks post-treatment, as measured by whole globe inflation testing. Specifically, strain was reduced by 47% when comparing treated vs. untreated sclera within the same eye (n = 7, p=0.0064) and by 54% when comparing the peripapillary sclera of treated vs. untreated eyes (n = 7, p<0.0001). Post-treatment characterization of RGCs (optic nerve axon counts/density, and grading), retinal function (electroretinography), and retinal histology revealed that photocrosslinking was associated with some ocular toxicity. We conclude that a transpupillary photocrosslinking approach enables selective scleral stiffening targeted to the peripapillary region that may be useful in future treatments of glaucoma.
Collapse
Affiliation(s)
- B G Gerberich
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - B G Hannon
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - A Hejri
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - E J Winger
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - E Schrader Echeverri
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - L M Nichols
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - H G Gersch
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - N A MacLeod
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - S Gupta
- Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - A T Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - M D Ritch
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - S Sridhar
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - M G Toothman
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - G S Gershon
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - S A Schwaner
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - G Sánchez-Rodríguez
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - V Goyal
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - A M Toporek
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - A J Feola
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA
| | - H E Grossniklaus
- Winship Cancer Institute of Emory University, Atlanta, GA, USA; Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA, USA
| | - M T Pardue
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA
| | - C R Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
| | - M R Prausnitz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
| |
Collapse
|
5
|
Abstract
1. The electroretinogram (e.r.g.) of the isolated rat retina has been investigated by recording potential differences developed between two micropipettes.2. In the uniformly illuminated receptor layer, voltage gradients at 90 degrees to the long axes of the receptors are negligible in comparison with the radial voltage gradients.3. When all transsynaptic neural activity has been abolished, the photoresponse recorded across the receptor layer is very different from the photoresponse recorded across the inner retinal layer.4. The photoresponse developed across the inner retinal layers, slow P III, develops slowly and the peak voltage is approximately proportional to log. flash energy.5. The photovoltage across the receptor layer rises rapidly to its peak, before a significant fraction of slow P III has developed.6. The faster photovoltage (receptor potential) increases with flash intensity according to the hyperbolic function characteristic of photo-receptors.7. The faster photovoltage can be split into two components. Between the tips of the outer limbs and the bases of the inner limbs, it has a simple wave form. In the region between the bases of the inner limbs and the receptor synapses, there is an additional peak (nose) to the photovoltage.8. In the scleral portion of the receptor layer, the photovoltage approximately equals the dark voltage. In the remaining, vitreal portion of the receptor layer the photovoltage exceeds the dark voltage.9. Photocurrent divergence has been measured and the results indicate that the source of photocurrent extends further vitreally than the base of the outer limb.10. The results suggest that the photoresponse generated in the outer limb is modified by an active process which occurs in portions of the rods which are nearer the synapse.
Collapse
Affiliation(s)
- G B Arden
- Department of Visual Science, Institute of Ophthalmology, Judd Street, London WC1H 9QS
| |
Collapse
|
6
|
Randazzo J, Zhang Z, Hoff M, Kawada H, Sachs A, Yuan Y, Haider N, Kador P. Orally active multi-functional antioxidants are neuroprotective in a rat model of light-induced retinal damage. PLoS One 2011; 6:e21926. [PMID: 21779355 PMCID: PMC3136485 DOI: 10.1371/journal.pone.0021926] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 06/09/2011] [Indexed: 11/19/2022] Open
Abstract
Background Progression of age-related macular degeneration has been linked to iron dysregulation and oxidative stress that induce apoptosis of neural retinal cells. Since both antioxidants and chelating agents have been reported to reduce the progression of retinal lesions associated with AMD in experimental animals, the present study evaluates the ability of multi-functional antioxidants containing functional groups that can independently chelate redox metals and quench free radicals to protect the retina against light-induced retinal degeneration, a rat model of dry atrophic AMD. Methods/Results Proof of concept studies were conducted to evaluate the ability of 4-(5-hydroxypyrimidin-2-yl)-N,N-dimethyl-3,5-dioxopiperazine-1-sulfonamide (compound 4) and 4-(5-hydroxy-4,6-dimethoxypyrimidin-2-yl)-N,N-dimethyl-3,5-dioxopiperazine-1-sulfonamide (compound 8) to reduce retinal damage in 2-week dark adapted Wistar rats exposed to 1000 lx of light for 3 hours. Assessment of the oxidative stress markers 4- hydroxynonenal and nitrotyrosine modified proteins and Thioredoxin by ELISA and Western blots indicated that these compounds reduced the oxidative insult caused by light exposure. The beneficial antioxidant effects of these compounds in providing significant functional and structural protection were confirmed by electroretinography and quantitative histology of the retina. Conclusions/Significance The present study suggests that multi-functional compounds may be effective candidates for preventive therapy of AMD.
Collapse
Affiliation(s)
- James Randazzo
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Zifeng Zhang
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Michael Hoff
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Hiroyoshi Kawada
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Andrew Sachs
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Yang Yuan
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Neena Haider
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Ophthalmology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Peter Kador
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Ophthalmology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
| |
Collapse
|
7
|
Chen W, Yu M, Wang Y, Peng Y, Li X, Lam DMK, Chen X, Liu X. Non-Mitogenic Human Acidic Fibroblast Growth Factor Reduces Retinal Degeneration Induced by Sodium Iodate. J Ocul Pharmacol Ther 2009; 25:315-20. [PMID: 19650706 DOI: 10.1089/jop.2009.0015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Weiwei Chen
- Department of Ophthalmology and Ophthalmic Laboratories, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Man Yu
- Department of Ophthalmology and Ophthalmic Laboratories, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Yun Wang
- School of Pharmaceutical Science, Wenzhou Medical College, Wenzhou, People’s Republic of China
| | - Youwei Peng
- Retinal Neurobiology Laboratory, Boys Town National Research Hospital-East, Omaha, Nebraska
| | - Xiaokun Li
- School of Pharmaceutical Science, Wenzhou Medical College, Wenzhou, People’s Republic of China
| | - Dominic Man-Kit Lam
- Department of Ophthalmology and Ophthalmic Laboratories, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Xiaoming Chen
- Department of Ophthalmology and Ophthalmic Laboratories, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Xuyang Liu
- Department of Ophthalmology and Ophthalmic Laboratories, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| |
Collapse
|
8
|
Wachtmeister L. Incremental thresholds of the oscillatory potentials of the human electroretinogram in response to coloured light. Acta Ophthalmol 2009; 52:378-89. [PMID: 4408232 DOI: 10.1111/j.1755-3768.1974.tb00391.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
9
|
Valjakka A. The reflection of retinal light response information onto the superior colliculus in the rat. Graefes Arch Clin Exp Ophthalmol 2008; 245:1199-210. [PMID: 17219107 DOI: 10.1007/s00417-006-0519-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2006] [Revised: 11/22/2006] [Accepted: 12/02/2006] [Indexed: 10/23/2022] Open
Abstract
BACKGROUND The functional principles of mediation of retina-encoded visual information through the optic nerve to the superior colliculus (SC) of the contralateral brain hemisphere were investigated in non-drugged and unrestrained albino rats by considering the following issues: (1) the type of information transmitted, (2) the response components of the retina and SC involved in encoding the transmitted information, and (3) the timing of related processes. METHODS The field potential responses for different intensities of flashes, under different background illuminations, were simultaneously recorded from the sclera area of the eye and the optic layer of the contralateral SC. RESULTS It was found that the b-wave crest of the retinal electroretinogram (ERG) and the peak-1 or peak-2 of the SC correlate by their amplitude, while the a-wave trough of the retinal ERG and the peak-1 of the SC correlate by their latency. The values of these mutually correlating response components were invariably determined by the given light response bias of the retina (photoreceptors), the change in the photon flux of the light stimulus and, obviously, the change in the wavelength of the light stimulus. The a-wave trough, peak-1, b-wave crest and peak-2 were invariably induced in this time-order. CONCLUSIONS The data suggest that the information properties of (a) intensity, (b) presentation time and, obviously, (c) colour of the light stimulus, such as are shed on the retina, and information about the light response bias of the retina are mediated correlatively and quantitatively to the cell network system of the SC through the optic nerve. These processes must happen during the a-to-b-wave phases of the ERG. The data indicate that the random-type variations in the activity of the related cellular systems may actually be harnessed in mediating the defined information properties of the visual stimulus from the retina to the SC of the brain through the optic nerve. This study shows a method of measuring the function of the optic nerve.
Collapse
Affiliation(s)
- Antti Valjakka
- Department of Pharmaceutics, University of Kuopio, P.O. Box 1627, Kuopio 70211, Finland.
| |
Collapse
|
10
|
Green DG, Kapousta-Bruneau NV. Evidence that L-AP5 and D,L-AP4 can preferentially block cone signals in the rat retina. Vis Neurosci 2007; 24:9-15. [PMID: 17430605 DOI: 10.1017/s0952523807230123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Accepted: 05/16/2006] [Indexed: 11/05/2022]
Abstract
Several lines of evidence suggest that, as concentrations of two agonists of group III metabotropic glutamate receptors are increased, cone contributions to the b-wave are blocked before rod contributions. Application of L-AP5 (L-2-amino-5-phosphonobutyric acid) at concentrations of 50 microM and D,L-AP4 (D,L-2-amino-4-phosphonobutyric acid) at concentrations 2 microM had a greater effect in reducing the amplitude of the rat ERG b-wave at high light intensities than at low light intensities. The amplitude reduction occurs at flash intensities that saturate rod photoreceptor responses. When steady backgrounds are used to saturate rod photoreceptors, the b-wave responses show increased long-wavelength sensitivity. Responses on a rod saturating background are blocked by adding L-AP5 or AP4 at the above concentrations to the perfusate. Further evidence for metabotrophic receptors being involved comes from the observation that even when ionotropic glutamate receptors are pharmacologically blocked with MK801 and DNQX, AP4 selectively blocks cone contributions to the b-wave. Thus we suggest that the type III metabotrophic receptors on depolarizing cone bipolar cells or cone synaptic terminals are affected by concentrations of L-AP5 and D,L-AP4 that have minimal effects on rod bipolar cells or rod synaptic terminals.
Collapse
Affiliation(s)
- Daniel G Green
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
| | | |
Collapse
|
11
|
Yu TY, Acosta ML, Ready S, Cheong YL, Kalloniatis M. Light exposure causes functional changes in the retina: increased photoreceptor cation channel permeability, photoreceptor apoptosis, and altered retinal metabolic function. J Neurochem 2007; 103:714-24. [PMID: 17623037 DOI: 10.1111/j.1471-4159.2007.04766.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Light exposure induces retinal photoreceptor degeneration and retinal remodeling in both the normal rat retina and in animal models of retinal degeneration. Although cation entry is one of the triggers leading to apoptosis, it is unclear if this event occurs in isolation, or whether a number of pathways lead to photoreceptor apoptosis following light exposure. Following light exposure, we investigated the characteristics of cation entry, apoptotic markers [using terminal deoxynucleotidyl transferase (EC 2.7.7.31) dUTP nick-end labeling (TUNEL) labeling] and metabolic properties of retina from Sprague-Dawley (SD) rats and a rat model of retinitis pigmentosa [proline-23-histidine (P23H) rat]. Assessment of cation channel permeability using agmatine (AGB) labeling showed that excessive cation gating accompanied the series of anomalies that occur prior to photoreceptor loss. Increased AGB labeling in photoreceptors was seen in parallel with the appearance of apoptotic photoreceptors detected by TUNEL labeling with only a smaller proportion of cells colocalizing both markers. However, SD and P23H retinal photoreceptors differed in the amounts and colocalization of AGB gating and TUNEL labeling as a function of light exposure. Finally, reduced retinal lactate dehydrogenase levels were found in SD and P23H rat retinas after a 24-h light exposure period. Short-term (2 h) exposure of the P23H rat retina caused an increase in lactate dehydrogenase activity suggesting increased metabolic demand. These results suggest that energy availability may be exacerbated during the early stages of light exposure in susceptible retinas. Also, the concomitant observation of increased ion gating and TUNEL labeling suggest the existence of at least two possible mechanisms in light-damaged retinas in both SD and the P23H rat retina.
Collapse
Affiliation(s)
- Tzu-Ying Yu
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | | | | | | | | |
Collapse
|
12
|
Thomas BB, Aramant RB, Sadda SR, Seiler MJ. Light response differences in the superior colliculus of albino and pigmented rats. Neurosci Lett 2005; 385:143-7. [PMID: 15950381 DOI: 10.1016/j.neulet.2005.05.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2005] [Revised: 05/12/2005] [Accepted: 05/14/2005] [Indexed: 11/23/2022]
Abstract
Multi-unit visual responses to light intensities ranging from -6.46 to 0.81 logcd/m2 were recorded from the surface of the superior colliculus of dark-adapted normal pigmented and normal albino rats. Light sensitivity was significantly higher in albinos. The response onset latency was inversely proportional to the stimulus intensity. The progression of the stimulus intensity versus response onset latency curve showed a considerable difference between pigmented and albino rats. At low light levels, longer response onset latencies were recorded in pigmented rats than in albinos. This can be attributed to the transmission of rod-driven responses. The differences observed in the light response characteristics of albino rats may be indicative of their visual abnormalities.
Collapse
Affiliation(s)
- Biju B Thomas
- Department of Ophthalmology, Doheny Retina Institute, Doheny Eye Institute, Keck School of Medicine, University of Southern California, DVRC 402, 1355 San Pablo St., Los Angeles, CA 90033, USA
| | | | | | | |
Collapse
|
13
|
Ren JQ, McCarthy WR, Zhang H, Adolph AR, Li L. Behavioral visual responses of wild-type and hypopigmented zebrafish. Vision Res 2002; 42:293-9. [PMID: 11809482 DOI: 10.1016/s0042-6989(01)00284-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Zebrafish possess three classes of chromatophores that include iridophores, melanophores, and xanthophores. Mutations that lack one or two classes of chromatophores have been isolated or genetically constructed. Using a behavioral assay based on visually mediated escape responses, we measured the visual response of fully and partially pigmented zebrafish. In zebrafish that lack iridophores (roy mutants), the behavioral visual responses were similar to those of wild-type animals except at low contrast stimulation. In the absence of melanophores (albino mutants) or both melanophores and iridophores (ruby mutants), the behavioral visual responses were normal under moderate illumination but reduced when tested under dim or bright conditions or under low contrast stimulation. Together, the data suggest that screening pigments in the retina play a role in the regulation of behavioral visual responses and are necessary for avoiding "scatter" under bright light conditions.
Collapse
Affiliation(s)
- Jason Q Ren
- Department of Physiology, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536, USA
| | | | | | | | | |
Collapse
|
14
|
Saszik S, Bilotta J. Constant dark-rearing effects on visual adaptation of the zebrafish ERG. Int J Dev Neurosci 2001; 19:611-9. [PMID: 11705665 DOI: 10.1016/s0736-5748(01)00051-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Anatomical and electrophysiological studies have shown that zebrafish retinal neurons develop in a sequential manner. Several studies have examined the impact of restricted rearing environments on zebrafish visual development, but the results have been mixed. The purpose of this study was to examine the development of light adaptation properties of the zebrafish electroretinogram (ERG), and examine the effects of constant dark rearing on retinal development. Subjects were zebrafish, Danio rerio, reared under normal lighting conditions and zebrafish reared in constant dark from fertilization to 6 days postfertilization (dpf). Increment threshold functions were obtained from a- and b-wave ERG responses from normally reared subjects at different ages and from animals exposed to early constant dark rearing. Dark-reared subjects were tested immediately following constant dark exposure (6-9 dpf) and after exposure to normal cyclic lighting (11-13 dpf). Adult zebrafish were significantly more sensitive at lower background illuminations than were larvae zebrafish. Also, constant dark rearing had a differential effect on the a- and b-wave response measures. Constant dark rearing raised b-wave threshold uniformly across background illuminations, while only producing higher a-wave thresholds at low levels of illumination. These results are consistent with findings in studies on zebrafish retinal development, and may help explain some of the discrepancies across studies examining the effects of restricted rearing.
Collapse
Affiliation(s)
- S Saszik
- Department of Psychology and Biotechnology Center, Western Kentucky University, 1 Big Red Way, Bowling Green, KY 42101, USA
| | | |
Collapse
|
15
|
Nixon PJ, Bui BV, Armitage JA, Vingrys AJ. The contribution of cone responses to rat electroretinograms. Clin Exp Ophthalmol 2001; 29:193-6. [PMID: 11446467 DOI: 10.1046/j.1442-9071.2001.00402.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The contribution of rods and cones to the scotopic electroretinogram (ERG) of small animals is unclear, with a recent report suggesting that the mouse has no cone a-wave. The present study considered the contribution of cones to the ERG of the rat. Dark-adapted Long Evans rats (n = 4) had ERG signals collected following a single flash, which stimulated rods and cones (mixed response), or a twin-fash paradigm (short interstimulus interval, 1 s), which isolated cone responses. Rod signals were derived by digital subtraction of the cone signal from the mixed rod/cone ERG. The rat a-wave was found to be dominated by rod responses but cone responses contributed substantially (45%) to post-receptoral waveforms (b-wave) at higher light levels.
Collapse
Affiliation(s)
- P J Nixon
- Department of Optometry and Vision Sciences, University of Melbourne, Victoria, Australia
| | | | | | | |
Collapse
|
16
|
Abstract
The eyecup preparation has traditionally been used to study retinal physiology in lower vertebrates and in some mammals. The procedures for preparing eyecups of the rat and mouse have not been described, however. We now describe methods for preparing and maintaining viable eyecups for these two species. Eyecups were everted over a plastic dome and held in place between the two halves of a superfusion chamber. Fluid exchange in the chamber was rapid, with near total exchange occurring in 9 s. Eyecup viability was tested by monitoring light-evoked retinal responses as the preparation aged. In both rat and mouse, the amplitude of the electroretinogram (ERG) b-wave decreased slowly, declining to 1/2 maximal amplitude in approximately 70 min. Light-evoked spike activity of neurons in the ganglion cell layer remained stable for approximately 3 h and attenuated responses were recorded for an additional 1-2 h. Eyecups were able to dark adapt. Retinal sensitivity, tested by monitoring b-wave amplitude, recovered following exposure to an adapting light.
Collapse
Affiliation(s)
- E A Newman
- Department of Neuroscience, University of Minnesota, Minneapolis 55455, USA.
| | | |
Collapse
|
17
|
Nelson DE, Takahashi JS. Integration and saturation within the circadian photic entrainment pathway of hamsters. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R1351-61. [PMID: 10564207 DOI: 10.1152/ajpregu.1999.277.5.r1351] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sensitivity of the visual pathway that subserves circadian entrainment was measured in hamsters after prior stimulation and using trains of multiple pulses. Immediately after subsaturating stimulation in the late subjective night, there was a significant decrease in responsiveness that persisted for at least 1 h. The reduced responsiveness was not due to light adaptation (shifting of the stimulus-response curve) but rather to response saturation, which appeared to reduce the sensitivity to subsequent stimulation and limit the maximum response of the pacemaker. The system, therefore, integrates the total number of photons delivered in two light stimuli separated in time by up to 1 h. The responsiveness was also measured using stimulus trains containing 10-1,000 individual pulses of equal irradiance and equal total photons. Results suggest that this pathway is responsive to the total photons delivered in all of the stimuli and is not responsive to light onsets or offsets associated with individual stimuli. These data outline several fundamental characteristics of phase shifting for the circadian photic entrainment pathway in hamsters. Knowledge of these characteristics is important for designing and interpreting results of future studies to dissect the cellular and molecular nature of the mammalian circadian clock and for understanding how visual information affects the cellular clock during entrainment.
Collapse
Affiliation(s)
- D E Nelson
- Department of Biology, University of St. Thomas, St. Paul, Minnesota 55105, USA.
| | | |
Collapse
|
18
|
Goto Y, Tobimatsu S, Shigematsu J, Akazawa K, Kato M. Properties of rat cone-mediated electroretinograms during light adaptation. Curr Eye Res 1999; 19:248-53. [PMID: 10487963 DOI: 10.1076/ceyr.19.3.248.5313] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Our aim was to better understand how to isolate the cone-mediated response in rats. Therefore, we studied the difference of ERGs in the course of light adaptation between 2 and 20 Hz stimulus frequencies. METHODS A total of 90 rats divided into 18 different groups were used following overnight dark adaptation. ERGs were recorded against 3 different adapting field luminances (1.15, 1. 50 or 1.75 log cd/m(2)) with a combination of 3 stimulus flash intensities (0.86, 1.30 or 2.03 log cd sec/m( 2)). The responses were obtained at 2 minute intervals for 25 minutes of light adaptation. RESULTS The response of the rat cone ERG was large despite the small number of cones. The mean amplitude increased systematically from the dark-adapted value requiring more than 15 minutes to reach an asymptote at 2 Hz stimulation, but only 10 minutes at 20 Hz stimulation. The 2 Hz adaptation curves had biphasic pattern compared to the monophasic 20 Hz curve. This second increase in the amplitude at 2 Hz appeared at around 7-8 minutes as a function of adaptation time. This tendency was most evident when using a low adapting field luminance with a high flash intensity. CONCLUSIONS Our results suggest that the rods intrude much more during light adaptation at 2 Hz stimulation in rodents than in humans. Therefore, 20 Hz flicker stimulation can better isolate more the cone-mediated function than 2 Hz stimulation during the course of light adaptation in rats. Furthermore, the functional characteristics of the cone in rats may be different from that in humans.
Collapse
Affiliation(s)
- Y Goto
- Kyushu University Neurological Institute Department of Clinical Neurophysiology Fukuoka, Japan.
| | | | | | | | | |
Collapse
|
19
|
Shaw NA. The effects of electroconvulsive shock on retinal activity. Physiol Behav 1999; 67:153-9. [PMID: 10463642 DOI: 10.1016/s0031-9384(99)00045-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two experiments are reported examining the effects of electroconvulsive shock (ECS) on the electroretinogram (ERG) and the retinal oscillatory potentials (OPs) in the albino rat. Immediately after the induction of generalised seizure activity, both the ERG and the OPs were always preserved basically intact, despite minor alterations to their waveforms. In Experiment 1, it was found that small changes in amplitude of the ERG were recorded following ECS, but these were most likely artifactual. The only other notable finding was a temporary decrease in latency of the b-wave of the ERG. In Experiment 2, a slight overall attenuation in the amplitude of the OPs was observed. This was associated with a paradoxical decrease in the latencies of all three OP subcomponents similar to that found for the ERG b-wave. It is concluded that ECS does not interfere to any marked extent with either the transduction of the visual signal or its processing within the various retinal layers. This implies that the blockade of the afferent volley that occurs following ECS must be confined to the optic pathway or to the occipital cortex itself.
Collapse
Affiliation(s)
- N A Shaw
- Department of Physiology, School of Medicine, University of Auckland, New Zealand
| |
Collapse
|
20
|
Euler T, Wässle H. Immunocytochemical identification of cone bipolar cells in the rat retina. J Comp Neurol 1995; 361:461-78. [PMID: 8550893 DOI: 10.1002/cne.903610310] [Citation(s) in RCA: 270] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We studied the morphology of bipolar cells in fixed vertical tissue sections of the rat retina by injecting the cells with Lucifer Yellow and neurobiotin. In addition to the rod bipolar cell, nine different putative cone bipolar cell types were distinguished according to the position of their somata in the inner nuclear layer and the branching pattern and stratification level of their axon terminals in the inner plexiform layer. Some of these bipolar cell populations were labeled immunocytochemically in vertical and horizontal sections using antibodies against the calcium-binding protein recoverin, the glutamate transporter GLT-1, the alpha isoform of the protein kinase C, and the Purkinje cell marker L7. These immunocytochemically labeled cell types were characterized in terms of cell density and distribution. We found that rod bipolar cells and GLT-1-positive cone bipolar cells occur at higher densities in a small region located in the upper central retina. This area probably corresponds to the central area, which is the region of highest ganglion cell density. A second peak of rod bipolar cell density in the lower temporal periphery matches the retinal area of binocular overlap. The population densities of the immunocytochemically characterized bipolar cells indicate that at least 50% of all bipolar cells are cone bipolar cells. The variety and total number of cone bipolar cells is surprising because the retina of the rat contains 99% rods. Our findings suggest that cone bipolar cells may play a more important role in the visual system of the rat than previously thought.
Collapse
Affiliation(s)
- T Euler
- Max-Planck-Institut für Hirnforschung, Frankfurt, Germany
| | | |
Collapse
|
21
|
Abstract
The presence of two distinct cone types was demonstrated in the retina of the rat using two cone-specific monoclonal anti-visual pigment antibodies. Cones labelled by antibody COS-1 constituted the large majority (about 93%) of cones, and are most probably responsible for the green photopic sensitivity of the rat. About 7% of the cones were recognized by antibody OS-2, and are thought to be blue-sensitive elements. While OS-2 positive cones were evenly distributed throughout the retina, there were slight differences in the distribution of COS-1 positive cones. The cones made up about 0.85% of all photoreceptor cells. Although the OS-2 positive cones occur in a very low number (0.05% of all photoreceptors) and probably do not appreciably contribute to the photopic system of the rat, their presence in the rat strengthens the presumption that most mammalian species exhibit a dual cone system with a shortwave and a middle-to-longwave sensitivity.
Collapse
Affiliation(s)
- A Szél
- 2nd Department of Anatomy, Histology and Embryology, Semmelweis University of Medicine, Budapest, Hungary
| | | |
Collapse
|
22
|
Fox DA, Katz LM. Developmental lead exposure selectively alters the scotopic ERG component of dark and light adaptation and increases rod calcium content. Vision Res 1992; 32:249-55. [PMID: 1574840 DOI: 10.1016/0042-6989(92)90134-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Electrophysiological studies have established that lead exposure produces selective rod deficits. The present electroretinographic (ERG) and correlated calcium experiments examined whether low-level or moderate-level developmental lead exposure (peak blood lead of 19 and 59 micrograms/dl, respectively) altered dark adaptation and/or light adaptation. Developmental lead exposure produced long-term dose-response (1) decreases in the slope of the increment threshold function only at scotopic adapting backgrounds, (2) decreases only in the sensitivity of the rod phase of dark adaptation and (3) increases in the calcium content of rod outer segments which may partially mediate the ERG results. The relevance and applicability of these data to lead-exposed children have yet to be established.
Collapse
Affiliation(s)
- D A Fox
- College of Optometry, University of Houston, TX 77204-6052
| | | |
Collapse
|
23
|
Nelson DE, Takahashi JS. Sensitivity and integration in a visual pathway for circadian entrainment in the hamster (Mesocricetus auratus). J Physiol 1991; 439:115-45. [PMID: 1895235 PMCID: PMC1180102 DOI: 10.1113/jphysiol.1991.sp018660] [Citation(s) in RCA: 261] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. Light-induced phase shifts of the circadian rhythm of wheel-running activity were used to measure the photic sensitivity of a circadian pacemaker and the visual pathway that conveys light information to it in the golden hamster (Mesocricetus auratus). The sensitivity to stimulus irradiance and duration was assessed by measuring the magnitude of phase-shift responses to photic stimuli of different irradiance and duration. The visual sensitivity was also measured at three different phases of the circadian rhythm. 2. The stimulus-response curves measured at different circadian phases suggest that the maximum phase-shift is the only aspect of visual responsivity to change as a function of the circadian day. The half-saturation constants (sigma) for the stimulus-response curves are not significantly different over the three circadian phases tested. The photic sensitivity to irradiance (1/sigma) appears to remain constant over the circadian day. 3. The hamster circadian pacemaker and the photoreceptive system that subserves it are more sensitive to the irradiance of longer-duration stimuli than to irradiance of briefer stimuli. The system is maximally sensitive to the irradiance of stimuli of 300 s and longer in duration. A quantitative model is presented to explain the changes that occur in the stimulus-response curves as a function of photic stimulus duration. 4. The threshold for photic stimulation of the hamster circadian pacemaker is also quite high. The threshold irradiance (the minimum irradiance necessary to induce statistically significant responses) is approximately 10(11) photons cm-2 s-1 for optimal stimulus durations. This threshold is equivalent to a luminance at the cornea of 0.1 cd m-2. 5. We also measured the sensitivity of this visual pathway to the total number of photons in a stimulus. This system is maximally sensitive to photons in stimuli between 30 and 3600 s in duration. The maximum quantum efficiency of photic integration occurs in 300 s stimuli. 6. These results suggest that the visual pathways that convey light information to the mammalian circadian pacemaker possess several unique characteristics. These pathways are relatively insensitive to light irradiance and also integrate light inputs over relatively long durations. This visual system, therefore, possesses an optimal sensitivity of 'tuning' to total photons delivered in stimuli of several minutes in duration. Together these characteristics may make this visual system unresponsive to environmental 'noise' that would interfere with the entrainment of circadian rhythms to light-dark cycles.
Collapse
Affiliation(s)
- D E Nelson
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208
| | | |
Collapse
|
24
|
Abstract
It has long been an open question whether individual rod receptors in the mammalian retina show any light adaptation. The prevailing evidence so far has suggested that these cells, unlike those in lower vertebrates, adapt little if at all. The experiments on cat rods reported here, however, indicate that this is not really true. Since the cone system in the cat retina has a fairly high light threshold, the rods also need to adapt so that they do not saturate with light before the cones fully take over vision at higher light intensities. In similar experiments, adaptation was found in rods of other mammalian species, including primates.
Collapse
Affiliation(s)
- T Tamura
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | | | | |
Collapse
|
25
|
Abstract
In vitro studies have demonstrated that lead selectively and reversibly depresses the rod photoreceptor component of the electroretinogram (ERG). To determine if low-level lead exposure during early postnatal development produced long-term selective rod deficits, we examined rod and cone ERG functions and cyclic GMP and cyclic AMP metabolism in adult control and lead-exposed rats. A-wave and b-wave voltage-log intensity and latency-log intensity functions, generated from single-flash ERGs in fully dark-adapted rats, revealed that low-level lead exposure during early postnatal development caused a 23- and 18% decrease in maximum amplitude, a 1.0- and 0.5 log unit decrease in absolute sensitivity and a mean latency increase of 47- and 29%, respectively. Additional ERG experiments, using scotopically balanced stimuli and scotopic and photopic flicker fusion frequency functions, also demonstrated selective rod deficits. Cone ERGs, elicited by 30-Hz white flashes in the presence of a white background adapting light, were similar in control and lead-exposed rats. Lead exposure during early postnatal development caused cGMP levels in dark-adapted and light-adapted retinas to increase 40- and 25%, respectively, above controls whereas cyclic AMP levels remained unchanged. Light-activated cyclic GMP phosphodiesterase (cGMP-PDE) was inhibited 40% while guanylate cyclase activity was unchanged. The retinal lead concentration was 10(-6) M at the end of exposure (day 21) while at the time of ERG testing and biochemical analysis it was 10(-7) M. In vitro studies with adult control retinas incubated with 10(-9)-10(-4) M lead revealed a dose-response inhibition (10-40%) of cGMP-PDE between 10(-6)- and 10(-4) M lead and stimulation of guanylate cyclase (20-158%) only above 10(-4) M lead, indicating that cGMP-PDE is more sensitive to the direct effects of lead than the synthetic cGMP enzyme. These in vitro cyclic nucleotide metabolism results are similar to those we observed in vivo and both are consistent with the observed ERG changes. The selective rod-mediated amplitude, sensitivity and temporal deficits and the lack of effect on the cone ERGs clearly demonstrate that low-level lead exposure during early postnatal development causes a long-term selective disruption of rat rod photoreceptors. The relevance and applicability of these data to subclinical pediatric lead poisoning has yet to be established.
Collapse
Affiliation(s)
- D A Fox
- College of Optometry, University of Houston, TX 77004
| | | |
Collapse
|
26
|
Nussdorf JD, Powers MK. Spectral sensitivity of the electroretinogram b-wave in dark-adapted goldfish. Vis Neurosci 1988; 1:159-68. [PMID: 3154793 DOI: 10.1017/s0952523800001437] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The action spectrum of the ERG b-wave was measured under dark-adapted conditions in intact goldfish (Carassius auratus). It is substantially broader than the absorption spectrum of goldfish rod porphyropsin. Neither prolonged dark adaptation nor removal of possible efferent neural activity affected its shape. Moreover, a 682-nm background did not produce a selective loss of sensitivity to long wavelengths. The results imply that the spectral sensitivity of the b-wave in dark-adapted goldfish reflects the influence of at least two photoreceptor types which act as a single univariant mechanism near absolute threshold.
Collapse
Affiliation(s)
- J D Nussdorf
- Department of Psychology, Vanderbilt University, Nashville, TN 37240
| | | |
Collapse
|
27
|
Silveira LC, Heywood CA, Cowey A. Contrast sensitivity and visual acuity of the pigmented rat determined electrophysiologically. Vision Res 1987; 27:1719-31. [PMID: 3445463 DOI: 10.1016/0042-6989(87)90101-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The contrast sensitivity function of the rat was assessed by investigating the relationship between the amplitude of visually evoked cortical potentials (VECP) and the spatial frequency and contrast of grating stimuli. Pattern reversal VECPs were recorded in Area 17 in the region of representation of the central binocular visual field. Transient responses were obtained with a 1 Hz contrast reversal. The mean contralateral monocular CSF peaked around 0.1 c/deg, with a threshold sensitivity of 20-25, low frequency attenuation and a high frequency cut-off of 1.18 c/deg. The mean binocular CSF showed a cut-off of 1.20 c/deg, which matches several behavioural measurements of visual acuity. The greater binocular sensitivity in the low frequency range (0.04 c/deg) could be tentatively attributed to the greater influence of the population of large ganglion cells that reaches its maximal density in the ipsilateral projection.
Collapse
Affiliation(s)
- L C Silveira
- Department of Physiology, Federal University of Pará, Belém, Brazil
| | | | | |
Collapse
|
28
|
Sandberg MA, Pawlyk BS, Berson EL. Electroretinogram (ERG) sensitivity and phagosome frequency in the normal pigmented rat. Exp Eye Res 1986; 43:781-9. [PMID: 3803462 DOI: 10.1016/s0014-4835(86)80009-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Normal adult pigmented rats, born and raised in cyclic light for 25- to 27 days and then placed in darkness for up to 24 hr, showed an inverse relation between electroretinogram (ERG) sensitivity and phagosome frequency in the pigment epithelium over the course of a day. Linear regression revealed that a two-fold increase in the frequency of large phagosomes was associated with approximately a one-third decrease in ERG sensitivity. The observed 37-40% decline in ERG sensitivity 1.5 hr after expected light onset was significantly greater than what would be expected from the measured 11% shortening of rod outer segments at that time of day. Possible explanations for this disparity are considered.
Collapse
|
29
|
|
30
|
Abraham FA, Alpern M. Factors influencing threshold of the fundamental electrical response to sinusoidal excitation of human photoreceptors. J Physiol 1984; 357:151-72. [PMID: 6512688 PMCID: PMC1193252 DOI: 10.1113/jphysiol.1984.sp015494] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The amplitude and phase of the fundamental Fourier component of the electroretinogram (e.r.g.) in response to sinusoidally modulated light were studied in the range 7-50 Hz. Sensitivity was best at the lowest frequency. The threshold-frequency relationship divided into two parts. A weak steady background depressed sensitivity of the low, but increased sensitivity of the high, frequency component. At 8 Hz a small test spot was 0.7 log10 units more effective on the most sensitive part of the retina than on the optic disk. On the fovea, it was 0.1-0.2 log10 units less effective than on the disk. The fovea was 0.7 log10 units more sensitive to 25 Hz than the blind spot. Psychophysical and e.r.g. dark-adaptation curves were similar, but the former was 10(4) times more sensitive than the latter. Four sets of experiments examined the possibility that the Fourier component of the e.r.g. response at the modulation frequency of 8 Hz during the 'rod' phase of the e.r.g. dark-adaptation curve arose from excitation of rods alone. The only hint of a possible cone contribution was a very small but systematic increase in phase delay with increase in background wave number found while measuring the field sensitivity action spectrum. No suggestion was found that the fundamental Fourier component of threshold e.r.g. responses at the modulation frequency of 25 Hz was influenced by photons absorbed in rods.
Collapse
|
31
|
|
32
|
Brown CH, Green DG. Rod saturation in b-wave of the rat electroretinogram under two different anesthetics. Vision Res 1984; 24:87-90. [PMID: 6695511 DOI: 10.1016/0042-6989(84)90147-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
B-wave increment threshold experiments in the rat show that "rod saturation" occurs at different background levels with different anesthetics. Rod saturation builds up over the first 60 sec of light adaptation in pentobarbital anesthetized but not in urethane anesthetized animals. These and other findings suggest that "rod saturation" can occur when the rod photoreceptors themselves are not saturated.
Collapse
|
33
|
Abstract
Green, Dowling, Siegel and Ripps (1975) J. gen. Physiol. 65, 483-502 found that both receptors and post-receptoral elements regulate the process of light adaptation in skate retina. As a test of the generality of this conclusion, we repeated their experiments on the retina of the intact albino rat. Increment threshold and intensity-response functions of aspartate-isolated receptor potentials, ERG b-waves and single retinal ganglion cell axons were measured, and all were found to be similar to those described by Green et al. (1975). In particular, the adaptive properties of the b-wave and ganglion cells were similar to each other, but different from those of the receptor potential. We conclude that the retinal mechanisms of light adaptation are similar in rat and skate.
Collapse
|
34
|
|
35
|
Birch DG, Jacobs GH. Light-induced damage to photopic and scotopic mechanisms in the rat depends on rearing conditions. Exp Neurol 1980; 68:269-83. [PMID: 7363995 DOI: 10.1016/0014-4886(80)90085-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
36
|
Carter-Dawson LD, LaVail MM. Rods and cones in the mouse retina. I. Structural analysis using light and electron microscopy. J Comp Neurol 1979; 188:245-62. [PMID: 500858 DOI: 10.1002/cne.901880204] [Citation(s) in RCA: 511] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Rods and cones of the C57BL/6J mouse retina have been examined by light and electron microscopy to distinguish the structural features of the two photoreceptor types. By light microscopy, cone nuclei are conspicuously different from rod nuclei in 1-2 micrometer plastic sections. Cone nuclei have an irregularly shaped clump of heterochromatin that appears in single sections to be one to three clumps, whereas rod nuclei are more densely stained and have one large, central clump of heterochromatin. Cone nuclei make up approximately 3% of the photoreceptor nuclei in both the central and peripheral retina at all ages examined up to 267 days. Cone nuclei are confined to the outer half of the outer nuclear layer, and more than 50% of the cone nuclei lie adjacent to the outer limiting membrane. By electron microscopy, cones in the mouse retina meet virtually every morphological criterion of mammalian cones. The outer segments are conically shaped. Many, if not all of the outer segment discs are continuous with the outer plasma membrane, whereas almost all of the rod discs are not. Cone outer segments are only about half the length of the rod outer segments, and they are contacted by long, villous pigment epithelial cell processes. The cone inner segment diameter is greater than the outer segment diameter, and the accumulation of mitochondria present at the apical end of the inner segment forms a more conspicuous ellipsoid than in rods. The internal fiber or axon of the cone is larger in diameter than that of the rod, and it terminates in a large synaptic pedicle with multiple ribbon synapses, whereas the rod terminal is a smaller spherule with only a single ribbon synaptic complex.
Collapse
|
37
|
|
38
|
Jacobs GH, Tootell RB. Spectral components in the b-wave of the ground squirrel electroretinogram. Vision Res 1979; 19:1243-7. [PMID: 550585 DOI: 10.1016/0042-6989(79)90190-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
39
|
Abstract
1. Electroretinogram (e.r.g.) responses recorded from dark-reared rats with inherited retinal dystrophy (RCS) showed progressive decline in b-wave ampliture and prolongation of the time to the peak of the b-wave with age when compared with records obtained from dark-reared normal albino rats. 2. Dark-adaptation was followed in RCS and normal rats by recording the light intensity needed to evoke a criterion e.r.g. response at different time intervals after bleaching and 90% of the rhodopsin. 3. In normal rats, dark-adaptation was governed by two mechanisms. The first 25--35 min of recovery was determined by cones. The second branch, determined by the recovery of rods, lasted for about 3 hr and proceeded along an exponential time course with time constant of 41.4 +/- 2.4 min (S.E. of mean). 4. In RCS rats, the time course of the dark-adaptation after a 90% bleach depended on age. In 25--30 day old rats the recovery curve had at least three breaks separating three different mechanisms. Rats, 35--40 days old, exhibited double exponential recovery curves, while 45--70 day old rats recovered along a single exponential curve similar in time course to the cone branch of dark-adaptation found in normal rats. 5. Action spectra obtained from RCS rats at different time intervals of the recovery curve showed that in young rats, 25--30 days old, small e.r.g. responses recorded before bleaching and at the end of the recovery period were determined by rhodopsin while those recorded during the first part of the recovery from 90% bleach were determined by a combination of rods and cones. In RCS rats of advanced age (45--70 days old), rhodopsin was the major contributor to the e.r.g. responses recorded either before bleaching or at the end of the recovery period. 6. The gradual deterioration with age of the e.r.g. in RCS rats cannot be explained by either the decrease in quantum catch due to the decrease in rhodopsin content or by the linear relationship between log e.r.g. threshold and pigment concentration. 7. Using estimates of rhodopsin density within surviving rods obtained from retinal densitometry, it was shown that in RCS rats where more than 30% of normal levels of rhodopsin was located within the functioning rods, the log intensity needed for a criterion e.r.g. response measured at the end of the recovery period from a 90% bleach was linearly related to the fraction of 'functional' rhodopsin. 8. No simple relationship between log e.r.g. threshold and rhodopsin concentration could be found during the course of recovery in the dark from a strong bleaching exposure in RCS rats of all ages.
Collapse
|
40
|
|
41
|
Powers MK, Green DG. Single retinal ganglion cell responses in the dark-reared rat: grating acuity, contrast sensitivity, and defocusing. Vision Res 1978; 18:1533-9. [PMID: 726302 DOI: 10.1016/0042-6989(78)90008-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
42
|
Lanum J. The damaging effects of light on the retina. Empirical findings, theoretical and practical implications. Surv Ophthalmol 1978; 22:221-49. [PMID: 416513 DOI: 10.1016/0039-6257(78)90070-x] [Citation(s) in RCA: 208] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Light well below the intensity which causes thermal burns physiologically damages the retina. This damage is primarily localized in the receptors. The outer segments are most sensitive and slow recovery is possible if damage does not proceed to destruction of the inner segment. Many variables affect the extent and severity of light damage. Damage is correlated with continuity of source, light intensity, elevated body temperature, nocturnality, and albinism. Light damage has been considered only minimally in visual research with light preferences, reinforcement and discrimination, or in clinical settings. Based on the available evidence, it is suggested that retinal damage may be produced by such common light sources as room lighting, phototherapy techniques, ophthalmoscopes and fundus cameras. Further studies are recommended.
Collapse
|
43
|
|
44
|
|
45
|
Jacobs GH, Silverman MS. Electrophysiological evidence for rod and cone-based vision in the nocturnal flying squirrel. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1976. [DOI: 10.1007/bf00663431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
46
|
|
47
|
Ernst W, Kemp CM. Scotopic and photopic dark adaptation of the b wave isolated rat retina. Nature 1975; 258:170-1. [PMID: 1186899 DOI: 10.1038/258170a0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
48
|
Abstract
The receptive fields of 107 single cells in area 17 of the hooded rat were examined. About half the cells responded to stationary as well as moving stimuli and about half only to movement. A variety of receptive field types were observed. Some of the cells responding to stationary stimuli had circular receptive fields, some with and some without annuli, some had elongated receptive fields, some had irregular receptive fields. Of the cells that responded only to movement, some were orientation or direction specific and some were not. Only two cells were found that responded to stimulation of the ipsilateral eye. Columnar organization of the cortex was not observed.
Collapse
|
49
|
|
50
|
Hood D, Hock PA. Light adaptation of the receptors: increment threshold functions for the frog's rods and cones. Vision Res 1975; 15:545-53. [PMID: 1079658 DOI: 10.1016/0042-6989(75)90301-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|