Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice
Interphotoreceptor retinoid-binding protein (IRBP) is an abundant glycoprotein in the subretinal space bound by the photoreceptor (PR) outer segments and the processes of the retinal pigmented epithelium (RPE). IRBP binds retinoids, including 11-cis-retinal and all-trans-retinol. In this study, visu...
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| Format: | Article |
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MDPI AG
2023-06-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/13/10655 |
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| author | Marci L. DeRamus Jessica V. Jasien Jess M. Eppstein Pravallika Koala Timothy W. Kraft |
| author_facet | Marci L. DeRamus Jessica V. Jasien Jess M. Eppstein Pravallika Koala Timothy W. Kraft |
| author_sort | Marci L. DeRamus |
| collection | DOAJ |
| description | Interphotoreceptor retinoid-binding protein (IRBP) is an abundant glycoprotein in the subretinal space bound by the photoreceptor (PR) outer segments and the processes of the retinal pigmented epithelium (RPE). IRBP binds retinoids, including 11-cis-retinal and all-trans-retinol. In this study, visual function for demanding visual tasks was assessed in IRBP knock-out (KO) mice. Surprisingly, IRBP KO mice showed no differences in scotopic critical flicker frequency (CFF) compared to wildtype (WT). However, they did have lower photopic CFF than WT. IRBP KO mice had reduced scotopic and photopic acuity and contrast sensitivity compared to WT. IRBP KO mice had a significant reduction in outer nuclear layer (ONL) thickness, PR outer and inner segment, and full retinal thickness (FRT) compared to WT. There were fewer cones in IRBP KO mice. Overall, these results confirm substantial loss of rods and significant loss of cones within 30 days. Absence of IRBP resulted in cone circuit damage, reducing photopic flicker, contrast sensitivity, and spatial frequency sensitivity. The c-wave was reduced and accelerated in response to bright steps of light. This result also suggests altered retinal pigment epithelium activity. There appears to be a compensatory mechanism such as higher synaptic gain between PRs and bipolar cells since the loss of the b-wave did not linearly follow the loss of rods, or the a-wave. Scotopic CFF is normal despite thinning of ONL and reduced scotopic electroretinogram (ERG) in IRBP KO mice, suggesting either a redundancy or plasticity in circuits detecting (encoding) scotopic flicker at threshold even with substantial rod loss. |
| first_indexed | 2024-03-11T01:39:58Z |
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| id | doaj.art-57a00a55b2a548439320d6b92bbd28b7 |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-11T01:39:58Z |
| publishDate | 2023-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-57a00a55b2a548439320d6b92bbd28b72023-11-18T16:41:33ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-06-0124131065510.3390/ijms241310655Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out MiceMarci L. DeRamus0Jessica V. Jasien1Jess M. Eppstein2Pravallika Koala3Timothy W. Kraft4Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USADepartment of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USADepartment of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USADepartment of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USADepartment of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USAInterphotoreceptor retinoid-binding protein (IRBP) is an abundant glycoprotein in the subretinal space bound by the photoreceptor (PR) outer segments and the processes of the retinal pigmented epithelium (RPE). IRBP binds retinoids, including 11-cis-retinal and all-trans-retinol. In this study, visual function for demanding visual tasks was assessed in IRBP knock-out (KO) mice. Surprisingly, IRBP KO mice showed no differences in scotopic critical flicker frequency (CFF) compared to wildtype (WT). However, they did have lower photopic CFF than WT. IRBP KO mice had reduced scotopic and photopic acuity and contrast sensitivity compared to WT. IRBP KO mice had a significant reduction in outer nuclear layer (ONL) thickness, PR outer and inner segment, and full retinal thickness (FRT) compared to WT. There were fewer cones in IRBP KO mice. Overall, these results confirm substantial loss of rods and significant loss of cones within 30 days. Absence of IRBP resulted in cone circuit damage, reducing photopic flicker, contrast sensitivity, and spatial frequency sensitivity. The c-wave was reduced and accelerated in response to bright steps of light. This result also suggests altered retinal pigment epithelium activity. There appears to be a compensatory mechanism such as higher synaptic gain between PRs and bipolar cells since the loss of the b-wave did not linearly follow the loss of rods, or the a-wave. Scotopic CFF is normal despite thinning of ONL and reduced scotopic electroretinogram (ERG) in IRBP KO mice, suggesting either a redundancy or plasticity in circuits detecting (encoding) scotopic flicker at threshold even with substantial rod loss.https://www.mdpi.com/1422-0067/24/13/10655IRBPretinaRPEERGOKRflicker |
| spellingShingle | Marci L. DeRamus Jessica V. Jasien Jess M. Eppstein Pravallika Koala Timothy W. Kraft Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice International Journal of Molecular Sciences IRBP retina RPE ERG OKR flicker |
| title | Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice |
| title_full | Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice |
| title_fullStr | Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice |
| title_full_unstemmed | Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice |
| title_short | Retinal Responses to Visual Stimuli in Interphotoreceptor Retinoid Binding-Protein Knock-Out Mice |
| title_sort | retinal responses to visual stimuli in interphotoreceptor retinoid binding protein knock out mice |
| topic | IRBP retina RPE ERG OKR flicker |
| url | https://www.mdpi.com/1422-0067/24/13/10655 |
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