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Moore-Dotson JM, Eggers ED. Reductions in Calcium Signaling Limit Inhibition to Diabetic Retinal Rod Bipolar Cells. Invest Ophthalmol Vis Sci 2020; 60:4063-4073. [PMID: 31560762 PMCID: PMC6779064 DOI: 10.1167/iovs.19-27137] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Purpose The balance of neuronal excitation and inhibition is important for proper retinal signaling. A previous report showed that diabetes selectively reduces light-evoked inhibition to the retinal dim light rod pathway, changing this balance. Here, changes in mechanisms of retinal inhibitory synaptic transmission after 6 weeks of diabetes are investigated. Methods Diabetes was induced in C57BL/6J mice by three intraperitoneal injections of streptozotocin (STZ, 75 mg/kg), and confirmed by blood glucose levels more than 200 mg/dL. After 6 weeks, whole-cell voltage-clamp recordings of electrically evoked inhibitory postsynaptic currents from rod bipolar cells and light-evoked excitatory postsynaptic currents from A17-amacrine cells were made in dark-adapted retinal slices. Results Diabetes shortened the timecourse of directly activated lateral GABAergic inhibitory amacrine cell inputs to rod bipolar cells. The timing of GABA release onto rod bipolar cells depends on a prolonged amacrine cell calcium signal that is reduced by slow calcium buffering. Therefore, the effects of calcium buffering with EGTA-acetoxymethyl ester (AM) on diabetic GABAergic signaling were tested. EGTA-AM reduced GABAergic signaling in diabetic retinas more strongly, suggesting that diabetic amacrine cells have reduced calcium signals. Additionally, the timing of release from reciprocal inhibitory inputs to diabetic rod bipolar cells was reduced, but the activation of the A17 amacrine cells responsible for this inhibition was not changed. Conclusions These results suggest that reduced light-evoked inhibitory input to rod bipolar cells is due to reduced and shortened calcium signals in presynaptic GABAergic amacrine cells. A reduction in calcium signaling may be a common mechanism limiting inhibition in the retina.
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Affiliation(s)
- Johnnie M Moore-Dotson
- Departments of Physiology and Biomedical Engineering, University of Arizona, Tucson, Arizona, United States
| | - Erika D Eggers
- Departments of Physiology and Biomedical Engineering, University of Arizona, Tucson, Arizona, United States
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Van Hook MJ, Nawy S, Thoreson WB. Voltage- and calcium-gated ion channels of neurons in the vertebrate retina. Prog Retin Eye Res 2019; 72:100760. [PMID: 31078724 PMCID: PMC6739185 DOI: 10.1016/j.preteyeres.2019.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 02/06/2023]
Abstract
In this review, we summarize studies investigating the types and distribution of voltage- and calcium-gated ion channels in the different classes of retinal neurons: rods, cones, horizontal cells, bipolar cells, amacrine cells, interplexiform cells, and ganglion cells. We discuss differences among cell subtypes within these major cell classes, as well as differences among species, and consider how different ion channels shape the responses of different neurons. For example, even though second-order bipolar and horizontal cells do not typically generate fast sodium-dependent action potentials, many of these cells nevertheless possess fast sodium currents that can enhance their kinetic response capabilities. Ca2+ channel activity can also shape response kinetics as well as regulating synaptic release. The L-type Ca2+ channel subtype, CaV1.4, expressed in photoreceptor cells exhibits specific properties matching the particular needs of these cells such as limited inactivation which allows sustained channel activity and maintained synaptic release in darkness. The particular properties of K+ and Cl- channels in different retinal neurons shape resting membrane potentials, response kinetics and spiking behavior. A remaining challenge is to characterize the specific distributions of ion channels in the more than 100 individual cell types that have been identified in the retina and to describe how these particular ion channels sculpt neuronal responses to assist in the processing of visual information by the retina.
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Affiliation(s)
- Matthew J Van Hook
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Scott Nawy
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA.
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3
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Functional Roles of Complexin 3 and Complexin 4 at Mouse Photoreceptor Ribbon Synapses. J Neurosci 2017; 36:6651-67. [PMID: 27335398 DOI: 10.1523/jneurosci.4335-15.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 05/10/2016] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Complexins (Cplxs) are SNARE complex regulators controlling the speed and Ca(2+) sensitivity of SNARE-mediated synaptic vesicle fusion. We have shown previously that photoreceptor ribbon synapses in mouse retina are equipped with Cplx3 and Cplx4 and that lack of both Cplxs perturbs photoreceptor ribbon synaptic function; however, Cplx3/4 function in photoreceptor synaptic transmission remained elusive. To investigate Cplx3/4 function in photoreceptor ribbon synapses, voltage-clamp recordings from postsynaptic horizontal cells were performed in horizontal slice preparations of Cplx3/4 wild-type (WT) and Cplx3/4 double knock-out (DKO) mice. We measured tonic activity in light and dark, current responses to changes in luminous intensity, and electrically evoked postsynaptic responses. Cplx3/4 decreased the frequency of tonic events and shifted their amplitude distribution to smaller values. Light responses were sustained in the presence of Cplx3/4, but transient in their absence. Finally, Cplx3/4 increased synaptic vesicle release evoked by electrical stimulation. Using electron microscopy, we quantified the number of synaptic vesicles at presynaptic ribbons after light or dark adaptation. In Cplx3/4 WT photoreceptors, the number of synaptic vesicles associated with the ribbon base close to the release site was significantly lower in light than in dark. This is in contrast to Cplx3/4 DKO photoreceptors, in which the number of ribbon-associated synaptic vesicles remained unchanged regardless of the adaptational state. Our results indicate a suppressing and a facilitating action of Cplx3/4 on Ca(2+)-dependent tonic and evoked neurotransmitter release, respectively, and a regulatory role in the adaptation-dependent availability of synaptic vesicles for release at photoreceptor ribbon synapses. SIGNIFICANCE STATEMENT Synaptic vesicle fusion at active zones of chemical synapses is executed by SNARE complexes. Complexins (Cplxs) are SNARE complex regulators and photoreceptor ribbon synapses are equipped with Cplx3 and Cplx4. The absence of both Cplxs perturbs ribbon synaptic function. Because we lack information on Cplx function in photoreceptor synaptic transmission, we investigated Cplx function using voltage-clamp recordings from postsynaptic horizontal cells of Cplx3/4 wild-type and Cplx3/4 double knock-out mice and quantified synaptic vesicle number at the ribbon after light and dark adaptation using electron microscopy. The findings reveal a suppressing action of Cplx3/4 on tonic neurotransmitter release, a facilitating action on evoked release, and a regulatory role of Cplx3/4 in the adaptation-dependent availability of synaptic vesicles at mouse photoreceptor ribbon synapses.
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Krishnamoorthy V, Weick M, Gollisch T. Sensitivity to image recurrence across eye-movement-like image transitions through local serial inhibition in the retina. eLife 2017; 6. [PMID: 28230526 PMCID: PMC5338922 DOI: 10.7554/elife.22431] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 02/20/2017] [Indexed: 01/28/2023] Open
Abstract
Standard models of stimulus encoding in the retina postulate that image presentations activate neurons according to the increase of preferred contrast inside the receptive field. During natural vision, however, images do not arrive in isolation, but follow each other rapidly, separated by sudden gaze shifts. We here report that, contrary to standard models, specific ganglion cells in mouse retina are suppressed after a rapid image transition by changes in visual patterns across the transition, but respond with a distinct spike burst when the same pattern reappears. This sensitivity to image recurrence depends on opposing effects of glycinergic and GABAergic inhibition and can be explained by a circuit of local serial inhibition. Rapid image transitions thus trigger a mode of operation that differs from the processing of simpler stimuli and allows the retina to tag particular image parts or to detect transition types that lead to recurring stimulus patterns. DOI:http://dx.doi.org/10.7554/eLife.22431.001
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Affiliation(s)
- Vidhyasankar Krishnamoorthy
- Department of Ophthalmology, University Medical Center Göttingen, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany.,Visual Coding Group, Max Planck Institute of Neurobiology, Martinsried, Germany
| | - Michael Weick
- Department of Ophthalmology, University Medical Center Göttingen, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany
| | - Tim Gollisch
- Department of Ophthalmology, University Medical Center Göttingen, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany.,Visual Coding Group, Max Planck Institute of Neurobiology, Martinsried, Germany
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Lauritzen JS, Sigulinsky CL, Anderson JR, Kalloniatis M, Nelson NT, Emrich DP, Rapp C, McCarthy N, Kerzner E, Meyer M, Jones BW, Marc RE. Rod-cone crossover connectome of mammalian bipolar cells. J Comp Neurol 2016; 527:87-116. [PMID: 27447117 PMCID: PMC5823792 DOI: 10.1002/cne.24084] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 06/08/2016] [Accepted: 06/30/2016] [Indexed: 11/11/2022]
Abstract
The basis of cross-suppression between rod and cone channels has long been an enigma. Using rabbit retinal connectome RC1, we show that all cone bipolar cell (BC) classes inhibit rod BCs via amacrine cell (AC) motifs (C1-6); that all cone BC classes are themselves inhibited by AC motifs (R1-5, R25) driven by rod BCs. A sparse symmetric AC motif (CR) is presynaptic and postsynaptic to both rod and cone BCs. ON cone BCs of all classes drive inhibition of rod BCs via motif C1 wide-field GABAergic ACs (γACs) and motif C2 narrow field glycinergic ON ACs (GACs). Each rod BC receives ≈10 crossover AC synapses and each ON cone BC can target ≈10 or more rod BCs via separate AC processes. OFF cone BCs mediate monosynaptic inhibition of rod BCs via motif C3 driven by OFF γACs and GACs and disynaptic inhibition via motifs C4 and C5 driven by OFF wide-field γACs and narrow-field GACs, respectively. Motifs C4 and C5 form halos of 60-100 inhibitory synapses on proximal dendrites of AI γACs. Rod BCs inhibit surrounding arrays of cone BCs through AII GAC networks that access ON and OFF cone BC patches via motifs R1, R2, R4, R5 and a unique ON AC motif R3 that collects rod BC inputs and targets ON cone BCs. Crossover synapses for motifs C1, C4, C5, and R3 are 3-4× larger than typical feedback synapses, which may be a signature for synaptic winner-take-all switches. J. Comp. Neurol. 527:87-116, 2019. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.
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Affiliation(s)
| | - Crystal L Sigulinsky
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - James R Anderson
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Michael Kalloniatis
- Department of Optometry and Vision Science and Centre for Eye Health, University of New South Wales, Sydney, Australia
| | - Noah T Nelson
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Daniel P Emrich
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Christopher Rapp
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Nicholas McCarthy
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Ethan Kerzner
- Scientific Computing and Imaging Institute, University of Utah School of Computing, Salt Lake City Utah, USA
| | - Miriah Meyer
- Scientific Computing and Imaging Institute, University of Utah School of Computing, Salt Lake City Utah, USA
| | - Bryan W Jones
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Robert E Marc
- Department of Ophthalmology, John A. Moran Vision Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
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Moore-Dotson JM, Beckman JJ, Mazade RE, Hoon M, Bernstein AS, Romero-Aleshire MJ, Brooks HL, Eggers ED. Early Retinal Neuronal Dysfunction in Diabetic Mice: Reduced Light-Evoked Inhibition Increases Rod Pathway Signaling. Invest Ophthalmol Vis Sci 2016; 57:1418-30. [PMID: 27028063 PMCID: PMC4819579 DOI: 10.1167/iovs.15-17999] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Purpose Recent studies suggest that the neural retinal response to light is compromised in diabetes. Electroretinogram studies suggest that the dim light retinal rod pathway is especially susceptible to diabetic damage. The purpose of this study was to determine whether diabetes alters rod pathway signaling. Methods Diabetes was induced in C57BL/6J mice by three intraperitoneal injections of streptozotocin (STZ; 75 mg/kg), and confirmed by blood glucose levels > 200 mg/dL. Six weeks after the first injection, whole-cell voltage clamp recordings of spontaneous and light-evoked inhibitory postsynaptic currents from rod bipolar cells were made in dark-adapted retinal slices. Light-evoked excitatory currents from rod bipolar and AII amacrine cells, and spontaneous excitatory currents from AII amacrine cells were also measured. Receptor inputs were pharmacologically isolated. Immunohistochemistry was performed on whole mounted retinas. Results Rod bipolar cells had reduced light-evoked inhibitory input from amacrine cells but no change in excitatory input from rod photoreceptors. Reduced light-evoked inhibition, mediated by both GABAA and GABAC receptors, increased rod bipolar cell output onto AII amacrine cells. Spontaneous release of GABA onto rod bipolar cells was increased, which may limit GABA availability for light-evoked release. These physiological changes occurred in the absence of retinal cell loss or changes in GABAA receptor expression levels. Conclusions Our results indicate that early diabetes causes deficits in the rod pathway leading to decreased light-evoked rod bipolar cell inhibition and increased rod pathway output that provide a basis for the development of early diabetic visual deficits.
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Affiliation(s)
| | - Jamie J Beckman
- Graduate Interdisciplinary Program in Physiological Sciences, University of Arizona, Tucson, Arizona, United States
| | - Reece E Mazade
- Graduate Interdisciplinary Program in Physiological Sciences, University of Arizona, Tucson, Arizona, United States
| | - Mrinalini Hoon
- Department of Biological Structure, University of Washington, Seattle, Washington, United States
| | - Adam S Bernstein
- Department of Physiology, University of Arizona, Tucson, Arizona, United States
| | | | - Heddwen L Brooks
- Department of Physiology, University of Arizona, Tucson, Arizona, United States
| | - Erika D Eggers
- Department of Physiology, University of Arizona, Tucson, Arizona, United States 4Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, United States
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Mazade RE, Eggers ED. Light adaptation alters inner retinal inhibition to shape OFF retinal pathway signaling. J Neurophysiol 2016; 115:2761-78. [PMID: 26912599 DOI: 10.1152/jn.00948.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/20/2016] [Indexed: 12/18/2022] Open
Abstract
The retina adjusts its signaling gain over a wide range of light levels. A functional result of this is increased visual acuity at brighter luminance levels (light adaptation) due to shifts in the excitatory center-inhibitory surround receptive field parameters of ganglion cells that increases their sensitivity to smaller light stimuli. Recent work supports the idea that changes in ganglion cell spatial sensitivity with background luminance are due in part to inner retinal mechanisms, possibly including modulation of inhibition onto bipolar cells. To determine how the receptive fields of OFF cone bipolar cells may contribute to changes in ganglion cell resolution, the spatial extent and magnitude of inhibitory and excitatory inputs were measured from OFF bipolar cells under dark- and light-adapted conditions. There was no change in the OFF bipolar cell excitatory input with light adaptation; however, the spatial distributions of inhibitory inputs, including both glycinergic and GABAergic sources, became significantly narrower, smaller, and more transient. The magnitude and size of the OFF bipolar cell center-surround receptive fields as well as light-adapted changes in resting membrane potential were incorporated into a spatial model of OFF bipolar cell output to the downstream ganglion cells, which predicted an increase in signal output strength with light adaptation. We show a prominent role for inner retinal spatial signals in modulating the modeled strength of bipolar cell output to potentially play a role in ganglion cell visual sensitivity and acuity.
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Affiliation(s)
- Reece E Mazade
- Departments of Physiology and Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Erika D Eggers
- Departments of Physiology and Biomedical Engineering, University of Arizona, Tucson, Arizona
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Smith BJ, Côté PD, Tremblay F. Dopamine modulation of rod pathway signaling by suppression of GABACfeedback to rod-driven depolarizing bipolar cells. Eur J Neurosci 2015; 42:2258-70. [DOI: 10.1111/ejn.12993] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/09/2015] [Accepted: 06/11/2015] [Indexed: 01/17/2023]
Affiliation(s)
- Benjamin J. Smith
- Department of Biology; Life Science Centre; Dalhousie University; Halifax NS Canada
| | - Patrice D. Côté
- Department of Biology; Life Science Centre; Dalhousie University; Halifax NS Canada
- Department of Ophthalmology and Visual Sciences; Dalhousie University; Halifax NS Canada
| | - François Tremblay
- Department of Ophthalmology and Visual Sciences; Dalhousie University; Halifax NS Canada
- IWK Health Centre; Eye Care Team; 5850 University Ave; PO Box 9700 Halifax NS Canada, B3K 6R8
- Department of Physiology and Biophysics; Dalhousie University; Halifax NS Canada
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