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Boal AM, McGrady NR, Holden JM, Risner ML, Calkins DJ. Retinal ganglion cells adapt to ionic stress in experimental glaucoma. Front Neurosci 2023; 17:1142668. [PMID: 37051140 PMCID: PMC10083336 DOI: 10.3389/fnins.2023.1142668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/10/2023] [Indexed: 03/28/2023] Open
Abstract
IntroductionIdentification of early adaptive and maladaptive neuronal stress responses is an important step in developing targeted neuroprotective therapies for degenerative disease. In glaucoma, retinal ganglion cells (RGCs) and their axons undergo progressive degeneration resulting from stress driven by sensitivity to intraocular pressure (IOP). Despite therapies that can effectively manage IOP many patients progress to vision loss, necessitating development of neuronal-based therapies. Evidence from experimental models of glaucoma indicates that early in the disease RGCs experience altered excitability and are challenged with dysregulated potassium (K+) homeostasis. Previously we demonstrated that certain RGC types have distinct excitability profiles and thresholds for depolarization block, which are associated with sensitivity to extracellular K+.MethodsHere, we used our inducible mouse model of glaucoma to investigate how RGC sensitivity to K+ changes with exposure to elevated IOP.ResultsIn controls, conditions of increased K+ enhanced membrane depolarization, reduced action potential generation, and widened action potentials. Consistent with our previous work, 4 weeks of IOP elevation diminished RGC light-and current-evoked responses. Compared to controls, we found that IOP elevation reduced the effects of increased K+ on depolarization block threshold, with IOP-exposed cells maintaining greater excitability. Finally, IOP elevation did not alter axon initial segment dimensions, suggesting that structural plasticity alone cannot explain decreased K+ sensitivity.DiscussionThus, in response to prolonged IOP elevation RGCs undergo an adaptive process that reduces sensitivity to changes in K+ while diminishing excitability. These experiments give insight into the RGC response to IOP stress and lay the groundwork for mechanistic investigation into targets for neuroprotective therapy.
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Kv3 Channels Contribute to the Excitability of Subpopulations of Spinal Cord Neurons in Lamina VII. eNeuro 2022; 9:ENEURO.0510-21.2021. [PMID: 35058310 PMCID: PMC8868027 DOI: 10.1523/eneuro.0510-21.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 12/21/2021] [Indexed: 11/29/2022] Open
Abstract
Autonomic parasympathetic preganglionic neurons (PGNs) drive contraction of the bladder during micturition but remain quiescent during bladder filling. This quiescence is postulated to be because of recurrent inhibition of PGN by fast-firing adjoining interneurons. Here, we defined four distinct neuronal types within Lamina VII, where PGN are situated, by combining whole cell patch clamp recordings with k-means clustering of a range of electrophysiological parameters. Additional morphologic analysis separated these neuronal classes into parasympathetic preganglionic populations (PGN) and a fast-firing interneuronal population. Kv3 channels are voltage-gated potassium channels (Kv) that allow fast and precise firing of neurons. We found that blockade of Kv3 channels by tetraethylammonium (TEA) reduced neuronal firing frequency and isolated high-voltage-activated Kv currents in the fast-firing population but had no effect in PGN populations. Furthermore, Kv3 blockade potentiated the local and descending inhibitory inputs to PGN indicating that Kv3-expressing inhibitory neurons are synaptically connected to PGN. Taken together, our data reveal that Kv3 channels are crucial for fast and regulated neuronal output of a defined population that may be involved in intrinsic spinal bladder circuits that underpin recurrent inhibition of PGN.
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Laboissonniere LA, Goetz JJ, Martin GM, Bi R, Lund TJS, Ellson L, Lynch MR, Mooney B, Wickham H, Liu P, Schwartz GW, Trimarchi JM. Molecular signatures of retinal ganglion cells revealed through single cell profiling. Sci Rep 2019; 9:15778. [PMID: 31673015 PMCID: PMC6823391 DOI: 10.1038/s41598-019-52215-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 10/11/2019] [Indexed: 01/27/2023] Open
Abstract
Retinal ganglion cells can be classified into more than 40 distinct subtypes, whether by functional classification or transcriptomics. The examination of these subtypes in relation to their physiology, projection patterns, and circuitry would be greatly facilitated through the identification of specific molecular identifiers for the generation of transgenic mice. Advances in single cell transcriptomic profiling have enabled the identification of molecular signatures for cellular subtypes that are only rarely found. Therefore, we used single cell profiling combined with hierarchical clustering and correlate analyses to identify genes expressed in distinct populations of Parvalbumin-expressing cells and functionally classified RGCs. RGCs were manually isolated based either upon fluorescence or physiological distinction through cell-attached recordings. Microarray hybridization and RNA-Sequencing were employed for the characterization of transcriptomes and in situ hybridization was utilized to further characterize gene candidate expression. Gene candidates were identified based upon cluster correlation, as well as expression specificity within physiologically distinct classes of RGCs. Further, we identified Prph, Ctxn3, and Prkcq as potential candidates for ipRGC classification in the murine retina. The use of these genes, or one of the other newly identified subset markers, for the generation of a transgenic mouse would enable future studies of RGC-subtype specific function, wiring, and projection.
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Affiliation(s)
- Lauren A Laboissonniere
- Department of Molecular Genetics and Microbiology 2033 Mowry Road, University of Florida, Gainesville, FL, 32610, USA
| | - Jillian J Goetz
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine Northwestern University, Chicago, IL, 60611, USA
| | | | - Ran Bi
- Department of Statistics, 2117 Snedecor Hall, Iowa State University, Ames, IA, 50011, USA
| | - Terry J S Lund
- Department of Genetics, Development and Cell Biology 2437 Pammel Drive, 2114 Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Laura Ellson
- Department of Genetics, Development and Cell Biology 2437 Pammel Drive, 2114 Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Madison R Lynch
- Department of Genetics, Development and Cell Biology 2437 Pammel Drive, 2114 Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Bailey Mooney
- Department of Genetics, Development and Cell Biology 2437 Pammel Drive, 2114 Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Hannah Wickham
- Department of Genetics, Development and Cell Biology 2437 Pammel Drive, 2114 Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Peng Liu
- Department of Statistics, 2117 Snedecor Hall, Iowa State University, Ames, IA, 50011, USA
| | - Gregory W Schwartz
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine Northwestern University, Chicago, IL, 60611, USA
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Estes S, Artinian L, Rehder V. Modulation of growth cone filopodial length by carbon monoxide. Dev Neurobiol 2016; 77:677-690. [PMID: 27513310 DOI: 10.1002/dneu.22430] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/04/2016] [Accepted: 08/09/2016] [Indexed: 12/22/2022]
Abstract
Carbon monoxide (CO) is physiologically produced via heme degradation by heme oxygenase enzymes. Whereas CO has been identified as an important physiological signaling molecule, the roles it plays in neuronal development and regeneration are poorly understood. During these events, growth cones guide axons through a rich cellular environment to locate target cells and establish synaptic connections. Previously, we have shown that another gaseous signaling molecule, nitric oxide (NO), has potent effects on growth cone motility. With NO and CO sharing similar cellular targets, we wanted to determine whether CO affected growth cone motility as well. We assessed how CO affected growth cone filopodial length and determined the signaling pathway by which this effect was mediated. Using two well-characterized neurons from the freshwater snail, Helisoma trivolvis, it was found that the CO donor, carbon monoxide releasing molecule-2 (CORM-2), increased filopodial length. CO utilized a signaling pathway that involved the activation of soluble guanylyl cyclase, protein kinase G, and ryanodine receptors. While increases in filopodial length often occur from robust increases in intracellular calcium levels, the timing in which CO increased filopodial length corresponded with low basal calcium levels in growth cones. Taken together with findings of a heme oxygenase-like protein in the Helisoma nervous system, these results provide evidence for CO as a modulator of growth cone motility and implicate CO as a neuromodulatory signal during neuronal development and/or regeneration. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 677-690, 2017.
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Affiliation(s)
- Stephen Estes
- Biology Department, Georgia State University, Atlanta, Georgia, 30302
| | - Liana Artinian
- Biology Department, Georgia State University, Atlanta, Georgia, 30302
| | - Vincent Rehder
- Biology Department, Georgia State University, Atlanta, Georgia, 30302
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Estes S, Zhong LR, Artinian L, Tornieri K, Rehder V. The role of action potentials in determining neuron-type-specific responses to nitric oxide. Dev Neurobiol 2014; 75:435-51. [DOI: 10.1002/dneu.22233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 09/22/2014] [Indexed: 12/14/2022]
Affiliation(s)
- Stephen Estes
- Department of Biology; Georgia State University; Atlanta Georgia 30302
| | - Lei Ray Zhong
- Department of Biology; Georgia State University; Atlanta Georgia 30302
| | - Liana Artinian
- Department of Biology; Georgia State University; Atlanta Georgia 30302
| | - Karine Tornieri
- Department of Biology; Georgia State University; Atlanta Georgia 30302
| | - Vincent Rehder
- Department of Biology; Georgia State University; Atlanta Georgia 30302
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Zhong YS, Wang J, Liu WM, Zhu YH. Potassium ion channels in retinal ganglion cells (review). Mol Med Rep 2013; 8:311-9. [PMID: 23732984 DOI: 10.3892/mmr.2013.1508] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 05/22/2013] [Indexed: 11/06/2022] Open
Abstract
Retinal ganglion cells (RGCs) consolidate visual processing and constitute the last step prior to the transmission of signals to higher brain centers. RGC death is a major cause of visual impairment in optic neuropathies, including glaucoma, age‑related macular degeneration, diabetic retinopathy, uveoretinitis and vitreoretinopathy. Discharge patterns of RGCs are primarily determined by the presence of ion channels. As the most diverse group of ion channels, potassium (K+) channels play key roles in modulating the electrical properties of RGCs. Biochemical, molecular and pharmacological studies have identified a number of K+ channels in RGCs, including inwardly rectifying K+ (Kir), ATP‑sensitive K+ (KATP), tandem‑pore domain K+ (TASK), voltage‑gated K+ (Kv), ether‑à‑go‑go (Eag) and Ca2+‑activated K+ (KCa) channels. Kir channels are important in the maintenance of the resting membrane potential and controlling RGC excitability. KATP channels are involved in RGC survival and neuroprotection. TASK channels are hypothesized to contribute to the regulation of resting membrane potentials and firing patterns of RGCs. Kv channels are important regulators of cellular excitability, functioning to modulate the amplitude, duration and frequency of action potentials and subthreshold depolarizations, and are also important in RGC development and protection. Eag channels may contribute to dendritic repolarization during excitatory postsynaptic potentials and to the attenuation of the back propagation of action potentials. KCa channels have been observed to contribute to repetitive firing in RGCs. Considering these important roles of K+ channels in RGCs, the study of K+ channels may be beneficial in elucidating the pathophysiology of RGCs and exploring novel RGC protection strategies.
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Affiliation(s)
- Yi-Sheng Zhong
- Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, P.R. China
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Kuznetsov KI, Maslov VY, Fedulova SA, Veselovsky NS. Voltage-Operated Calcium Currents in Retinal Ganglion Cells of the Rat Eye. NEUROPHYSIOLOGY+ 2013. [DOI: 10.1007/s11062-013-9344-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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