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Felder-Schmittbuhl MP, Hicks D, Ribelayga CP, Tosini G. Melatonin in the mammalian retina: Synthesis, mechanisms of action and neuroprotection. J Pineal Res 2024; 76:e12951. [PMID: 38572848 DOI: 10.1111/jpi.12951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/09/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024]
Abstract
Melatonin is an important player in the regulation of many physiological functions within the body and in the retina. Melatonin synthesis in the retina primarily occurs during the night and its levels are low during the day. Retinal melatonin is primarily synthesized by the photoreceptors, but whether the synthesis occurs in the rods and/or cones is still unclear. Melatonin exerts its influence by binding to G protein-coupled receptors named melatonin receptor type 1 (MT1) and type 2 (MT2). MT1 and MT2 receptors activate a wide variety of signaling pathways and both receptors are present in the vertebrate photoreceptors where they may form MT1/MT2 heteromers (MT1/2h). Studies in rodents have shown that melatonin signaling plays an important role in the regulation of retinal dopamine levels, rod/cone coupling as well as the photopic and scotopic electroretinogram. In addition, melatonin may play an important role in protecting photoreceptors from oxidative stress and can protect photoreceptors from apoptosis. Critically, melatonin signaling is involved in the modulation of photoreceptor viability during aging and other studies have implicated melatonin in the pathogenesis of age-related macular degeneration. Hence melatonin may represent a useful tool in the fight to protect photoreceptors-and other retinal cells-against degeneration due to aging or diseases.
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Affiliation(s)
- Marie Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Université de Strasbourg, Strasbourg, France
| | - David Hicks
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Christophe P Ribelayga
- Department of Vision Sciences, College of Optometry, University of Houston, Houston, Texas, USA
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, USA
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Ye Z, Wei Y, Zhang G, Ge L, Wu C, Ren Y, Wang J, Xu X, Yang J, Wang T. Circadian rhythm regulation in the sea cucumber Apostichopus japonicus: Insights into clock gene expression, photoperiod susceptibility, and neurohormone signaling. Comp Biochem Physiol B Biochem Mol Biol 2024; 270:110930. [PMID: 38065309 DOI: 10.1016/j.cbpb.2023.110930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/03/2023] [Accepted: 12/03/2023] [Indexed: 01/10/2024]
Abstract
Sea cucumber Apostichopus japonicus displays the typical circadian rhythms. This present study investigated the molecular regulation of clock genes, as well as monoamines and melatonin, in multiple tissues of A. japonicus, responding to the photoperiod. In order to determine their pivotal role in circadian rhythms, the crucial clock genes, namely AjClock, AjArnt1, AjCry1, and AjTimeless, were identified and a comprehensive analysis of their expressions across various tissues in adult A. japonicus was conducted, revealing the potential existence of central and peripheral oscillators. Results demonstrated that the tissues of polian vesicle and nerve ring exhibited significant clock gene expression associated with the orchestration of circadian regulation, and that environmental light fluctuations exerted influence on the expression of these clock genes. However, a number of genes, such as AjArnt1 and AjCry1, maintained their circadian rhythmicity even under continuous light conditions. Moreover, we further investigated the circadian patterns of melatonin (MT), serotonin (5-HT), and dopamine (DA) secretion in A. japonicus, data that underscored the tissue-specific regulatory differences and the inherent adaptability to dynamic light environments. Collectively, these findings will provide the molecular mechanisms controlling the circadian rhythm in echinoderms and the candidate tissues playing the role of central oscillators in sea cucumbers.
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Affiliation(s)
- Zhiqing Ye
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Ying Wei
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Guangbo Zhang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Lifei Ge
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Chenqian Wu
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Yucheng Ren
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Jixiu Wang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Xiuwen Xu
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Jingwen Yang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China
| | - Tianming Wang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China.
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Joylin S, Mutalik S, Kalaivani M, Shenoy RP, Ghosh M, Nishitha, Kumar EOAM, Theruveethi N. Influence of different LED wavelengths on retinal melatonin levels - A rodent study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166665. [PMID: 37652369 DOI: 10.1016/j.scitotenv.2023.166665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/22/2023] [Accepted: 08/27/2023] [Indexed: 09/02/2023]
Abstract
BACKGROUND Retinal melatonin is crucial for neuroprotection. Exposure to light-emitting diodes (LEDs) affects retinal neurons, possibly influencing retinal melatonin levels. Hence, we aimed to quantify the retinal melatonin level with different LED wavelengths. METHOD A total of 24 Sprague Dawley (SD) male rats were divided into four groups (n = 6 in each group) as normal controls (NC), blue light (BL), white light (WL), and yellow light (YL). The rats in the experimental groups were exposed to different wavelengths of LEDs for 28 days (12:12 h light-dark cycle) with uniform illumination of 450-500 lx. Following exposure, the rats were subjected to behavioral tests such as passive avoidance and elevated plus maze tests. Following the behavior tests, the rats were sacrificed, eyes were enucleated, and retinal tissue was stored at -80 °C. The homogenized retina was used for reactive oxygen species (ROS) and melatonin quantification using an enzyme-linked immunosorbent assay (ELISA) kit. RESULTS Passive avoidance test revealed a significant difference across the groups (p < 0.0004). The BL exposure group demonstrated increased latency to enter the dark compartment (DC) and impaired motor memory. The elevated plus maze test revealed a significant difference across all the groups (p < 0.012), where the time spent in the closed arm was greater in the BL exposure group. Comparison of ROS levels revealed a significant difference across the groups (p < 0.0001), with increased nitric oxide concentrations in the experimental groups. Melatonin levels were significantly decreased in the light exposure groups (p < 0.0001) compared to the NC group. CONCLUSION Cumulative exposure to different LED wavelengths resulted in increased anxiety with impaired motor activity. This was also complemented by the addition of oxidative stress leading to decreased melatonin levels in the retina, which might trigger retinal neuronal damage.
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Affiliation(s)
- Stelyna Joylin
- Department of Optometry, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India
| | - Srinivas Mutalik
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, India
| | - Manokaran Kalaivani
- Department of Biochemistry, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, India
| | - Revathi P Shenoy
- Department of Medical Laboratory Technology, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India
| | - Mousumi Ghosh
- Department of Optometry, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India
| | - Nishitha
- Department of Optometry, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India
| | - Elizebeth Olive Akansha Manoj Kumar
- Department of Optometry, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India; College of Optometry, University of Houston, Houston, TX, USA
| | - Nagarajan Theruveethi
- Department of Optometry, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India.
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Ribelayga CP, O’Brien J. When microscopy and electrophysiology meet connectomics-Steve Massey's contribution to unraveling the structure and function of the rod/cone gap junction. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1305131. [PMID: 38983007 PMCID: PMC11182179 DOI: 10.3389/fopht.2023.1305131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 10/31/2023] [Indexed: 07/11/2024]
Abstract
Electrical synapses, formed of gap junctions, are ubiquitous components of the central nervous system (CNS) that shape neuronal circuit connectivity and dynamics. In the retina, electrical synapses can create a circuit, control the signal-to-noise ratio in individual neurons, and support the coordinated neuronal firing of ganglion cells, hence, regulating signal processing at the network, single-cell, and dendritic level. We, the authors, and Steve Massey have had a long interest in gap junctions in retinal circuits, in general, and in the network of photoreceptors, in particular. Our combined efforts, based on a wide array of techniques of molecular biology, microscopy, and electrophysiology, have provided fundamental insights into the molecular structure and properties of the rod/cone gap junction. Yet, a full understanding of how rod/cone coupling controls circuit dynamics necessitates knowing its operating range. It is well established that rod/cone coupling can be greatly reduced or eliminated by bright-light adaptation or pharmacological treatment; however, the upper end of its dynamic range has long remained elusive. This held true until Steve Massey's recent interest for connectomics led to the development of a new strategy to assess this issue. The effort proved effective in establishing, with precision, the connectivity rules between rods and cones and estimating the theoretical upper limit of rod/cone electrical coupling. Comparing electrophysiological measurements and morphological data indicates that under pharmacological manipulation, rod/cone coupling can reach the theoretical maximum of its operating range, implying that, under these conditions, all the gap junction channels present at the junctions are open. As such, channel open probability is likely the main determinant of rod/cone coupling that can change momentarily in a time-of-day- and light-dependent manner. In this article we briefly review our current knowledge of the molecular structure of the rod/cone gap junction and of the mechanisms behind its modulation, and we highlight the recent work led by Steve Massey. Steve's contribution has been critical toward asserting the modulation depth of rod/cone coupling as well as elevating the rod/cone gap junction as one of the most suitable models to examine the role of electrical synapses and their plasticity in neural processing.
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Affiliation(s)
- Christophe P. Ribelayga
- Department of Vision Sciences, University of Houston College of Optometry, Houston, TX, United States
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Kovács-Öller T, Szarka G, Hoffmann G, Péntek L, Valentin G, Ross L, Völgyi B. Extrinsic and Intrinsic Factors Determine Expression Levels of Gap Junction-Forming Connexins in the Mammalian Retina. Biomolecules 2023; 13:1119. [PMID: 37509155 PMCID: PMC10377540 DOI: 10.3390/biom13071119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
Gap junctions (GJs) are not static bridges; instead, GJs as well as the molecular building block connexin (Cx) proteins undergo major expression changes in the degenerating retinal tissue. Various progressive diseases, including retinitis pigmentosa, glaucoma, age-related retinal degeneration, etc., affect neurons of the retina and thus their neuronal connections endure irreversible changes as well. Although Cx expression changes might be the hallmarks of tissue deterioration, GJs are not static bridges and as such they undergo adaptive changes even in healthy tissue to respond to the ever-changing environment. It is, therefore, imperative to determine these latter adaptive changes in GJ functionality as well as in their morphology and Cx makeup to identify and distinguish them from alterations following tissue deterioration. In this review, we summarize GJ alterations that take place in healthy retinal tissue and occur on three different time scales: throughout the entire lifespan, during daily changes and as a result of quick changes of light adaptation.
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Affiliation(s)
- Tamás Kovács-Öller
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Gergely Szarka
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Gyula Hoffmann
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Loretta Péntek
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
| | - Gréta Valentin
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
| | - Liliana Ross
- Faculty of Science, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Béla Völgyi
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
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Bhoi JD, Goel M, Ribelayga CP, Mangel SC. Circadian clock organization in the retina: From clock components to rod and cone pathways and visual function. Prog Retin Eye Res 2023; 94:101119. [PMID: 36503722 PMCID: PMC10164718 DOI: 10.1016/j.preteyeres.2022.101119] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 12/13/2022]
Abstract
Circadian (24-h) clocks are cell-autonomous biological oscillators that orchestrate many aspects of our physiology on a daily basis. Numerous circadian rhythms in mammalian and non-mammalian retinas have been observed and the presence of an endogenous circadian clock has been demonstrated. However, how the clock and associated rhythms assemble into pathways that support and control retina function remains largely unknown. Our goal here is to review the current status of our knowledge and evaluate recent advances. We describe many previously-observed retinal rhythms, including circadian rhythms of morphology, biochemistry, physiology, and gene expression. We evaluate evidence concerning the location and molecular machinery of the retinal circadian clock, as well as consider findings that suggest the presence of multiple clocks. Our primary focus though is to describe in depth circadian rhythms in the light responses of retinal neurons with an emphasis on clock control of rod and cone pathways. We examine evidence that specific biochemical mechanisms produce these daily light response changes. We also discuss evidence for the presence of multiple circadian retinal pathways involving rhythms in neurotransmitter activity, transmitter receptors, metabolism, and pH. We focus on distinct actions of two dopamine receptor systems in the outer retina, a dopamine D4 receptor system that mediates circadian control of rod/cone gap junction coupling and a dopamine D1 receptor system that mediates non-circadian, light/dark adaptive regulation of gap junction coupling between horizontal cells. Finally, we evaluate the role of circadian rhythmicity in retinal degeneration and suggest future directions for the field of retinal circadian biology.
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Affiliation(s)
- Jacob D Bhoi
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA
| | - Manvi Goel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA.
| | - Stuart C Mangel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA.
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Tan ML, Xie CT, Tu X, Li YW, Chen QL, Shen YJ, Liu ZH. Short daylight photoperiod alleviated alarm substance-stimulated fear response of zebrafish. Gen Comp Endocrinol 2023; 338:114274. [PMID: 36940834 DOI: 10.1016/j.ygcen.2023.114274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/11/2023] [Accepted: 03/17/2023] [Indexed: 03/23/2023]
Abstract
Photoperiod has been well-documented to be involved in regulating many activities of animals. However, whether photoperiod takes part in mood control, such as fear response in fish and the underlying mode(s) of action remain unclear. In this study, adult zebrafish males and females (Danio rerio) were exposed to different photoperiods, Blank (12 h light: 12 h dark), Control (12 h light: 12 h dark), Short daylight (SD, 6 h light: 18 h dark) and Long daylight (LD, 18 h light: 6 h dark) for 28 days. After exposure, fear response of the fish was investigated using a novel tank diving test. After alarm substance administration, the onset to higher half, total duration in lower half and duration of freezing in SD-fish were significantly decreased, suggesting that short daylight photoperiod is capable of alleviating fear response in zebrafish. In contrast, comparing with the Control, LD didn't show significant effect on fear response of the fish. Further investigation revealed that SD increased the levels of melatonin (MT), serotonin (5-HT) and dopamine (DA) in the brain while decreased the plasma level of cortisol comparing to the Control. Moreover, the expressions of genes in MT, 5-HT and DA pathways and HPI axis were also altered consistently. Our data indicated that short daylight photoperiod might alleviate fear response of zebrafish probably through interfering with MT/5-HT/DA pathways and HPI axis.
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Affiliation(s)
- Mei-Ling Tan
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Cheng-Ting Xie
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Xin Tu
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Ying-Wen Li
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Qi-Liang Chen
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Yan-Jun Shen
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China
| | - Zhi-Hao Liu
- Chongqing Key Laboratory of Animal Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, China.
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Diurnal changes in the efficiency of information transmission at a sensory synapse. Nat Commun 2022; 13:2613. [PMID: 35551183 PMCID: PMC9098879 DOI: 10.1038/s41467-022-30202-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 04/21/2022] [Indexed: 11/29/2022] Open
Abstract
Neuromodulators adapt sensory circuits to changes in the external world or the animal’s internal state and synapses are key control sites for such plasticity. Less clear is how neuromodulation alters the amount of information transmitted through the circuit. We investigated this question in the context of the diurnal regulation of visual processing in the retina of zebrafish, focusing on ribbon synapses of bipolar cells. We demonstrate that contrast-sensitivity peaks in the afternoon accompanied by a four-fold increase in the average Shannon information transmitted from an active zone. This increase reflects higher synaptic gain, lower spontaneous “noise” and reduced variability of evoked responses. Simultaneously, an increase in the probability of multivesicular events with larger information content increases the efficiency of transmission (bits per vesicle) by factors of 1.5-2.7. This study demonstrates the multiplicity of mechanisms by which a neuromodulator can adjust the synaptic transfer of sensory information. Neuromodulators can adjust how sensory signals are processed. In this study, the authors demonstrate how time of day affects the way information is transmitted in the zebrafish retina.
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Gurlevik U, Kara H, Yasar E. Effect of methylphenidate as a dopaminergic agent on myopia: Pilot study. Int J Clin Pract 2021; 75:e14665. [PMID: 34324770 DOI: 10.1111/ijcp.14665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/05/2021] [Accepted: 07/26/2021] [Indexed: 12/18/2022] Open
Abstract
Background Methylphenidate (MPH) hydrochloride is used as a first-line treatment for attention deficit hyperactivity disorder (ADHD). However, there is concern that this treatment may be associated with increased risk of refractive disorder. The aim of this study was to investigate the effect of MPH therapy on myopic shifts in refraction in children diagnosed with ADHD. Methods This study, children with ADHD and meeting inclusion criteria were examined before the initiation of MPH treatment and 3, 6 and 12 months after the initiation of treatment. Twenty age-gender-matched participants who applied to the outpatient ophthalmology clinic with various complaints were included in the study as a control group. Cycloplegic refraction examination and detailed eye measurements were performed at each visit. Results Nineteen patients were included in this study and the group consisted of 11 (57.9%) females and 8 (42.1%) males. The mean age of patients was 11.3 ± 2. (range: 8-18) years. During 12 months of use of MPH, the spherical equivalent changed from -0.36 ± 1.08 to -0.39 ± 1.05, and this difference was not statistically significant (P = .187). Axial length ranged from 22.92 ± 0.66. There was a change to 22.93 ± 0.62, and this difference was not statistically significant (P = .076). In the control group, the spherical equivalent changed from -0.43 ± 0.62 to -0.56 ± 0.84, and this difference was statistically significant. (P = .012) There was a change in the axial length from 22.97 ± 0.78 to 22.99 ± 0.62, and this difference was statistically significant (P = .015). Conclusions No significant changes spherical equivalent and axial length were detected during 12-month MPH use, but the increased spherical equivalent and axial length in the control group in the similar age group may indicate that MPH may reduce myopic shifts in refraction progression through dopamine, similar to in vivo studies. What's known Myopia is spreading rapidly in technologically advanced societies. There is strong evidence that myopia develops as the axial length of the eye increases as a result of spending more time indoors and working in close distances in parallel with the increase in education level. Animal studies have shown that decreased dopamine release plays an important role in the development of myopia. What's new The effect of dopamine in slowing or stopping myopia in experimental studies has also been demonstrated in human studies. No significant change in spherical equivalent and axial length was observed in methylphenidate users compared with control patients of similar age group. A significant increase in spherical equivalent and axial length was detected in the control group. This pilot study will shed light on future studies on the safe use of dopamine in the treatment of myopic shifts.
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Affiliation(s)
- Ugur Gurlevik
- Department of Ophthalmology, Aksaray University Faculty of Medicine, Aksaray Education and Research Hospital, Aksaray, Turkey
| | - Halil Kara
- Department of Child and Adolescent Psychiatry, Aksaray University Faculty of Medicine, Aksaray Education and Research Hospital, Aksaray, Turkey
| | - Erdogan Yasar
- Department of Ophthalmology, Aksaray University Faculty of Medicine, Aksaray Education and Research Hospital, Aksaray, Turkey
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Cao J, Mangel SC. Interactions of cone cannabinoid CB1 and dopamine D4 receptors increase day/night difference in rod-cone gap junction coupling in goldfish retina. J Physiol 2021; 599:4085-4100. [PMID: 34252195 DOI: 10.1113/jp281308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 06/30/2021] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS Although cone and rod photoreceptor cells in the retina have a type of cannabinoid receptor called a CB1 receptor, little is known about how cannabinoids, the active component in marijuana, affect retinal function. Studies have shown that a circadian (24-h) clock in the retina uses dopamine receptors, which are also on photoreceptors, to regulate gap junctions (a type of cell-to-cell communication) between rods and cones, so that they are functional (open) at night but closed in the day. We show that CB1 receptors have opposite effects on rod-cone gap junctions in day and night, decreasing communication in the day when dopamine receptors are active and increasing communication when dopamine receptors are inactive. CB1 and dopamine receptors thus work together to enhance the day/night difference in rod-cone gap junction communication. The increased rod-cone communication at night due to cannabinoid CB1 receptors may help improve night vision. ABSTRACT Cannabinoid CB1 receptors and dopamine D4 receptors in the brain form receptor complexes that interact but the physiological function of these interactions in intact tissue remains unclear. In vertebrate retina, rods and cones, which are connected by gap junctions, express both CB1 and D4 receptors. Because the retinal circadian clock uses cone D4 receptors to decrease rod-cone gap junction coupling in the day and to increase it at night, we studied whether an interaction between cone CB1 and D4 receptors increases the day/night difference in rod-cone coupling compared to D4 receptors acting alone. Using electrical recording and injections of Neurobiotin tracer into individual cones in intact goldfish retinas, we found that SR141716A (a CB1 receptor antagonist) application alone in the day increased both the extent of rod-cone tracer coupling and rod input to cones, which reaches cones via open gap junctions. Conversely, SR141716A application alone at night or SR141716A application in the day following 30-min spiperone (a D4 receptor antagonist) application decreased both rod-cone tracer coupling and rod input to cones. These results show that endogenous activation of cone CB1 receptors decreases rod-cone coupling in the day when D4 receptors are activated but increases it at night when D4 receptors are not activated. Therefore, the D4 receptor-dependent day/night switch in the effects of CB1 receptor activation results in an enhancement of the day/night difference in rod-cone coupling. This synergistic interaction increases detection of very dim large objects at night and fine spatial details in the day.
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Affiliation(s)
- Jiexin Cao
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, Ohio State University, Columbus, OH, USA.,Department of Neuroscience, Ohio State University College of Medicine, Columbus, OH, USA
| | - Stuart C Mangel
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, Ohio State University, Columbus, OH, USA.,Department of Neuroscience, Ohio State University College of Medicine, Columbus, OH, USA
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Goel M, Mangel SC. Dopamine-Mediated Circadian and Light/Dark-Adaptive Modulation of Chemical and Electrical Synapses in the Outer Retina. Front Cell Neurosci 2021; 15:647541. [PMID: 34025356 PMCID: PMC8131545 DOI: 10.3389/fncel.2021.647541] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 04/06/2021] [Indexed: 12/17/2022] Open
Abstract
The vertebrate retina, like most other brain regions, undergoes relatively slow alterations in neural signaling in response to gradual changes in physiological conditions (e.g., activity changes to rest), or in response to gradual changes in environmental conditions (e.g., day changes into night). As occurs elsewhere in the brain, the modulatory processes that mediate slow adaptation in the retina are driven by extrinsic signals (e.g., changes in ambient light level) and/or by intrinsic signals such as those of the circadian (24-h) clock in the retina. This review article describes and discusses the extrinsic and intrinsic modulatory processes that enable neural circuits in the retina to optimize their visual performance throughout day and night as the ambient light level changes by ~10 billion-fold. In the first synaptic layer of the retina, cone photoreceptor cells form gap junctions with rods and signal cone-bipolar and horizontal cells (HCs). Distinct extrinsic and intrinsic modulatory processes in this synaptic layer are mediated by long-range feedback of the neuromodulator dopamine. Dopamine is released by dopaminergic cells, interneurons whose cell bodies are located in the second synaptic layer of the retina. Distinct actions of dopamine modulate chemical and electrical synapses in day and night. The retinal circadian clock increases dopamine release in the day compared to night, activating high-affinity dopamine D4 receptors on cones. This clock effect controls electrical synapses between rods and cones so that rod-cone electrical coupling is minimal in the day and robust at night. The increase in rod-cone coupling at night improves the signal-to-noise ratio and the reliability of very dim multi-photon light responses, thereby enhancing detection of large dim objects on moonless nights.Conversely, maintained (30 min) bright illumination in the day compared to maintained darkness releases sufficient dopamine to activate low-affinity dopamine D1 receptors on cone-bipolar cell dendrites. This non-circadian light/dark adaptive process regulates the function of GABAA receptors on ON-cone-bipolar cell dendrites so that the receptive field (RF) surround of the cells is strong following maintained bright illumination but minimal following maintained darkness. The increase in surround strength in the day following maintained bright illumination enhances the detection of edges and fine spatial details.
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Affiliation(s)
- Manvi Goel
- Department of Neuroscience, Ohio State University College of Medicine, Columbus, OH, United States
| | - Stuart C Mangel
- Department of Neuroscience, Ohio State University College of Medicine, Columbus, OH, United States
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12
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Abstract
SIGNIFICANCE Investigation of the mechanism and the role of melanopsin in lens-induced myopia is necessary to find out potential targets in the prevention of myopia development. PURPOSE We aimed to study the effect and mechanism of retinal melanopsin on lens-induced myopia in guinea pigs, as well as the interactions between melanopsin and other myopic regulation neurotransmitters such as dopamine and melatonin, and to explore the possible role of melanopsin in the prevention of myopia development. METHODS Twenty-day-old tricolor guinea pigs were randomly divided into four groups: control group, defocus group, defocus + AA92593 group, and defocus + dimethyl sulfoxide (DMSO) group. The defocus eyes wore -6.00 D lens. In the defocus + AA92593 group, the vitreous cavities were injected with melanopsin antagonist AA92593. In the defocus + DMSO group, the vitreous cavities were injected with 5% DMSO as the administration control. The expression of retinal melanopsin protein was measured with immunofluorescence staining and Western blot. The content of dopamine and melatonin in the retina was determined by the high-performance liquid chromatography electrochemical method. RESULTS Compared with the defocus group, intravitreal injection of AA92593 resulted in increased axial length of the defocus eyes (defocus, 8.05 ± 0.09 mm; defocus + AA92593, 8.15 ± 0.11 mm; P = .008), lower refractive degree (defocus, -1.98 ± 0.82 D; defocus + AA92593, -2.59 ± 0.97 D; P = .05), decreased relative expression of retinal melanopsin protein (defocus, 0.67 ± 0.11; defocus + AA92593, 0.20 ± 0.06; P < .0001), and increased melatonin content in the defocus eyes (defocus, 0.38 ± 0.09 ng/mg; defocus + AA92593, 0.55 ± 0.13 ng/mg; P = .01), but it had no obvious effect on dopamine content (defocus, 0.64 ± 0.18 ng/mg; defocus + AA9259, 0.61 ± 0.17 ng/mg; P > .99). The melatonin content of retina in the defocus + AA92593 group was correlated with refractive error (Pearson correlation coefficient = -0.68, P = .006) and eye axis length (Pearson correlation coefficient = 0.74, P = .02). CONCLUSIONS Retinal melanopsin has inhibitory effect on lens-induced myopia development in guinea pigs, and such effect may be related to retinal melatonin.
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13
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Ostrin LA. Ocular and systemic melatonin and the influence of light exposure. Clin Exp Optom 2021; 102:99-108. [DOI: 10.1111/cxo.12824] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 07/09/2018] [Accepted: 07/09/2018] [Indexed: 12/15/2022] Open
Affiliation(s)
- Lisa A Ostrin
- University of Houston College of Optometry, Houston, Texas, USA,
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14
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Széll N, Fehér T, Maróti Z, Kalmár T, Latinovics D, Nagy I, Orosz ZZ, Janáky M, Facskó A, Sohajda Z. Myopia-26, the female-limited form of early-onset high myopia, occurring in a European family. Orphanet J Rare Dis 2021; 16:45. [PMID: 33482870 PMCID: PMC7825233 DOI: 10.1186/s13023-021-01673-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 01/05/2021] [Indexed: 11/30/2022] Open
Abstract
Background Female-limited early-onset high myopia, also called Myopia-26 is a rare monogenic disorder characterized by severe short sightedness starting in early childhood and progressing to blindness potentially by the middle ages. Despite the X-linked locus of the mutated ARR3 gene, the disease paradoxically affects females only, with males being asymptomatic carriers. Previously, this disease has only been observed in Asian families and has not gone through detailed investigation concerning collateral symptoms or pathogenesis. Results We found a large Hungarian family displaying female-limited early-onset high myopia. Whole exome sequencing of two individuals identified a novel nonsense mutation (c.214C>T, p.Arg72*) in the ARR3 gene. We carried out basic ophthalmological testing for 18 family members, as well as detailed ophthalmological examination (intraocular pressure, axial length, fundus appearance, optical coherence tomography, visual field- testing) as well as colour vision- and electrophysiology tests (standard and multifocal electroretinography, pattern electroretinography and visual evoked potentials) for eight individuals. Ophthalmological examinations did not reveal any signs of cone dystrophy as opposed to animal models. Electrophysiology and colour vision tests similarly did not evidence a general cone system alteration, rather a central macular dysfunction affecting both the inner and outer (postreceptoral and receptoral) retinal structures in all patients with ARR3 mutation. Conclusions This is the first description of a Caucasian family displaying Myopia-26. We present two hypotheses that could potentially explain the pathomechanism of this disease.
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Affiliation(s)
- Noémi Széll
- Kenézy Gyula University Hospital, Debrecen Medical University, Debrecen, Hungary.,Doctoral School of Clinical Medicine, University of Szeged, Szeged, Hungary
| | - Tamás Fehér
- Institute of Biochemistry, Biological Research Centre, Szeged, Hungary.
| | - Zoltán Maróti
- Genetic Diagnostic Laboratory, University of Szeged, Szeged, Hungary
| | - Tibor Kalmár
- Genetic Diagnostic Laboratory, University of Szeged, Szeged, Hungary
| | | | - István Nagy
- Institute of Biochemistry, Biological Research Centre, Szeged, Hungary.,Seqomics Biotechnology Ltd, Mórahalom, Hungary
| | - Zsuzsanna Z Orosz
- Department of Ophthalmology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Márta Janáky
- Department of Ophthalmology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Andrea Facskó
- Department of Ophthalmology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Sohajda
- Kenézy Gyula University Hospital, Debrecen Medical University, Debrecen, Hungary. .,Department of Ophthalmology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
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15
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Cao J, Ribelayga CP, Mangel SC. A Circadian Clock in the Retina Regulates Rod-Cone Gap Junction Coupling and Neuronal Light Responses via Activation of Adenosine A 2A Receptors. Front Cell Neurosci 2021; 14:605067. [PMID: 33510619 PMCID: PMC7835330 DOI: 10.3389/fncel.2020.605067] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 12/15/2020] [Indexed: 12/26/2022] Open
Abstract
Adenosine, a major neuromodulator in the central nervous system (CNS), is involved in a variety of regulatory functions such as the sleep/wake cycle. Because exogenous adenosine displays dark- and night-mimicking effects in the vertebrate retina, we tested the hypothesis that a circadian (24 h) clock in the retina uses adenosine to control neuronal light responses and information processing. Using a variety of techniques in the intact goldfish retina including measurements of adenosine overflow and content, tracer labeling, and electrical recording of the light responses of cone photoreceptor cells and cone horizontal cells (cHCs), which are post-synaptic to cones, we demonstrate that a circadian clock in the retina itself-but not activation of melatonin or dopamine receptors-controls extracellular and intracellular adenosine levels so that they are highest during the subjective night. Moreover, the results show that the clock increases extracellular adenosine at night by enhancing adenosine content so that inward adenosine transport ceases. Also, we report that circadian clock control of endogenous cone adenosine A2A receptor activation increases rod-cone gap junction coupling and rod input to cones and cHCs at night. These results demonstrate that adenosine and A2A receptor activity are controlled by a circadian clock in the retina, and are used by the clock to modulate rod-cone electrical synapses and the sensitivity of cones and cHCs to very dim light stimuli. Moreover, the adenosine system represents a separate circadian-controlled pathway in the retina that is independent of the melatonin/dopamine pathway but which nevertheless acts in concert to enhance the day/night difference in rod-cone coupling.
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Affiliation(s)
- Jiexin Cao
- Department of Neuroscience, The Ohio State University College of Medicine, Columbus, OH, United States
| | - Christophe P Ribelayga
- Department of Neuroscience, The Ohio State University College of Medicine, Columbus, OH, United States
| | - Stuart C Mangel
- Department of Neuroscience, The Ohio State University College of Medicine, Columbus, OH, United States
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16
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Korshunov KS, Blakemore LJ, Trombley PQ. Illuminating and Sniffing Out the Neuromodulatory Roles of Dopamine in the Retina and Olfactory Bulb. Front Cell Neurosci 2020; 14:275. [PMID: 33110404 PMCID: PMC7488387 DOI: 10.3389/fncel.2020.00275] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/04/2020] [Indexed: 01/28/2023] Open
Abstract
In the central nervous system, dopamine is well-known as the neuromodulator that is involved with regulating reward, addiction, motivation, and fine motor control. Yet, decades of findings are revealing another crucial function of dopamine: modulating sensory systems. Dopamine is endogenous to subsets of neurons in the retina and olfactory bulb (OB), where it sharpens sensory processing of visual and olfactory information. For example, dopamine modulation allows the neural circuity in the retina to transition from processing dim light to daylight and the neural circuity in the OB to regulate odor discrimination and detection. Dopamine accomplishes these tasks through numerous, complex mechanisms in both neural structures. In this review, we provide an overview of the established and emerging research on these mechanisms and describe similarities and differences in dopamine expression and modulation of synaptic transmission in the retinas and OBs of various vertebrate organisms. This includes discussion of dopamine neurons’ morphologies, potential identities, and biophysical properties along with their contributions to circadian rhythms and stimulus-driven synthesis, activation, and release of dopamine. As dysregulation of some of these mechanisms may occur in patients with Parkinson’s disease, these symptoms are also discussed. The exploration and comparison of these two separate dopamine populations shows just how remarkably similar the retina and OB are, even though they are functionally distinct. It also shows that the modulatory properties of dopamine neurons are just as important to vision and olfaction as they are to motor coordination and neuropsychiatric/neurodegenerative conditions, thus, we hope this review encourages further research to elucidate these mechanisms.
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Affiliation(s)
- Kirill S Korshunov
- Department of Biological Science, Florida State University, Tallahassee, FL, United States.,Program in Neuroscience, Florida State University, Tallahassee, FL, United States
| | - Laura J Blakemore
- Department of Biological Science, Florida State University, Tallahassee, FL, United States.,Program in Neuroscience, Florida State University, Tallahassee, FL, United States
| | - Paul Q Trombley
- Department of Biological Science, Florida State University, Tallahassee, FL, United States.,Program in Neuroscience, Florida State University, Tallahassee, FL, United States
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17
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Ko GYP. Circadian regulation in the retina: From molecules to network. Eur J Neurosci 2020; 51:194-216. [PMID: 30270466 PMCID: PMC6441387 DOI: 10.1111/ejn.14185] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022]
Abstract
The mammalian retina is the most unique tissue among those that display robust circadian/diurnal oscillations. The retina is not only a light sensing tissue that relays light information to the brain, it has its own circadian "system" independent from any influence from other circadian oscillators. While all retinal cells and retinal pigment epithelium (RPE) possess circadian oscillators, these oscillators integrate by means of neural synapses, electrical coupling (gap junctions), and released neurochemicals (such as dopamine, melatonin, adenosine, and ATP), so the whole retina functions as an integrated circadian system. Dysregulation of retinal clocks not only causes retinal or ocular diseases, it also impacts the circadian rhythm of the whole body, as the light information transmitted from the retina entrains the brain clock that governs the body circadian rhythms. In this review, how circadian oscillations in various retinal cells are integrated, and how retinal diseases affect daily rhythms.
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Affiliation(s)
- Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas
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18
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Sheng W, Jin M, Pan G, Weng S, Sik A, Han L, Liu K. Cellular localization of melatonin receptor Mel1b in pigeon retina. Neuropeptides 2019; 78:101974. [PMID: 31645269 DOI: 10.1016/j.npep.2019.101974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/10/2019] [Accepted: 09/22/2019] [Indexed: 12/15/2022]
Abstract
Melatonin, an important neuromodulator involved in circadian rhythms, modulates a series of physiological processes via activating its specific receptors, namely Mel1a (MT1), Mel1b (MT2) and Mel1c receptors. In this work, the localization of Mel1b receptor was studied in pigeon retina using double immunohistochemistry staining and confocal scanning microscopy. Our results showed that Mel1b receptor widely existed in the outer segment of photoreceptors and in the somata of dopaminergic amacrine cells, cholinergic amacrine cells, glycinergic AII amacrine cells, conventional ganglion cells and intrinsically photosensitive retinal ganglion cells, while horizontal cells, bipolar cells and Müller glial cells seemed to lack immunoreactivity of Mel1b receptor. That multiple types of retinal cells expressing Mel1b receptor suggests melatonin may directly modulate the activities of retina via activating Mel1b receptor.
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Affiliation(s)
- Wenlong Sheng
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China.
| | - Meng Jin
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Ge Pan
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Shijun Weng
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Attila Sik
- Institute of Transdisciplinary Discoveries, University of Pecs, Pecs, Hungary; Institute of Physiology, Medical School, University of Pecs, Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Pecs, Hungary; Medical School, University of Birmingham, Birmingham, UK
| | - Liwen Han
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Kechun Liu
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China.
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19
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Shakhmantsir I, Dooley SJ, Kishore S, Chen D, Pierce E, Bennett J, Sehgal A. RNA Splicing Factor Mutations That Cause Retinitis Pigmentosa Result in Circadian Dysregulation. J Biol Rhythms 2019; 35:72-83. [PMID: 31726916 DOI: 10.1177/0748730419887876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Circadian clocks regulate multiple physiological processes in the eye, but their requirement for retinal health remains unclear. We previously showed that Drosophila homologs of spliceosome proteins implicated in human retinitis pigmentosa (RP), the most common genetically inherited cause of blindness, have a role in the brain circadian clock. In this study, we report circadian phenotypes in murine models of RP. We found that mice carrying a homozygous H2309P mutation in Pre-mRNA splicing factor 8 (Prpf8) display a lengthened period of the circadian wheel-running activity rhythm. We show also that the daily cycling of circadian gene expression is dampened in the retina of Prpf8-H2309P mice. Surprisingly, molecular rhythms are intact in the eye cup, which includes the retinal pigment epithelium (RPE), even though the RPE is thought to be the primary tissue affected in this form of RP. Downregulation of Prp31, another RNA splicing factor implicated in RP, leads to period lengthening in a human cell culture model. The period of circadian bioluminescence in primary fibroblasts of human RP patients is not significantly altered. Together, these studies link a prominent retinal disorder to circadian deficits, which could contribute to disease pathology.
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Affiliation(s)
- Iryna Shakhmantsir
- Chronobiology and Sleep institute (CSI) and Howard Hughes Medical Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Graduate Program in Cell and Molecular Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Scott J Dooley
- Graduate Program in Cell and Molecular Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Center for Advanced Retinal and Ocular Therapeutics, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Siddharth Kishore
- Graduate Program in Cell and Molecular Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Dechun Chen
- Chronobiology and Sleep institute (CSI) and Howard Hughes Medical Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Eric Pierce
- Ocular Genomics Institute, Mass Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Jean Bennett
- Center for Advanced Retinal and Ocular Therapeutics, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Amita Sehgal
- Chronobiology and Sleep institute (CSI) and Howard Hughes Medical Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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20
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Daily variation of D2 dopamine receptor transcription in the brain of the Japanese eel Anguilla japonica and its regulation with dopamine and melatonin. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110581. [PMID: 31634572 DOI: 10.1016/j.cbpa.2019.110581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/31/2019] [Accepted: 09/17/2019] [Indexed: 11/22/2022]
Abstract
Dopamine plays a crucial role in controlling reproduction in eels, and its action is mediated through D2-type dopamine receptors. D2A and D2B receptors in the Japanese eel Anguilla japonica were cloned and characterized in the present study. Attention (daily expression patterns in the brain and endogenous regulation) was paid to D2B receptor because it is considered to play a crucial role in eel reproduction. The cDNAs of D2A and D2B receptors had open reading frames comprising 456 and 454 amino acid residues, respectively, which were phylogenetically clustered with those of other teleost species. Both receptors were highly expressed in the brain. D2B receptor transcript levels exhibited high day/low night variation in the midbrain and pituitary, suggesting that its transcription in these tissues is regulated in a daily manner, possibly under influence of melatonin. Intraperitoneal injection of dopamine downregulated D2B receptor transcription significantly in the midbrain and moderately in the pituitary within 1 h, but upregulated its transcription in the forebrain. Co-injection of dopamine with its antagonist (domperidone) reversed the effect of dopamine in the pituitary and forebrain, but not in the midbrain, suggesting that the effect of dopamine on D2B receptor transcription differs among brain regions. The same treatment with melatonin resulted in decreased D2B receptor transcription in the midbrain. These findings indicate that dopamine and melatonin have key roles in the daily variation in D2B receptor transcription in the brain of Japanese eel, and that they are related to a daily base secretion of hormones in the hypothalamic-pituitary-gonadal axis in this species.
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21
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Ribelayga C, Mangel SC. Circadian clock regulation of cone to horizontal cell synaptic transfer in the goldfish retina. PLoS One 2019; 14:e0218818. [PMID: 31461464 PMCID: PMC6713326 DOI: 10.1371/journal.pone.0218818] [Citation(s) in RCA: 5] [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: 01/28/2019] [Accepted: 06/10/2019] [Indexed: 11/19/2022] Open
Abstract
Although it is well established that the vertebrate retina contains endogenous circadian clocks that regulate retinal physiology and function during day and night, the processes that the clocks affect and the means by which the clocks control these processes remain unresolved. We previously demonstrated that a circadian clock in the goldfish retina regulates rod-cone electrical coupling so that coupling is weak during the day and robust at night. The increase in rod-cone coupling at night introduces rod signals into cones so that the light responses of both cones and cone horizontal cells, which are post-synaptic to cones, become dominated by rod input. By comparing the light responses of cones, cone horizontal cells and rod horizontal cells, which are post-synaptic to rods, under dark-adapted conditions during day and night, we determined whether the daily changes in the strength of rod-cone coupling could account entirely for rhythmic changes in the light response properties of cones and cone horizontal cells. We report that although some aspects of the day/night changes in cone and cone horizontal cell light responses, such as response threshold and spectral tuning, are consistent with modulation of rod-cone coupling, other properties cannot be solely explained by this phenomenon. Specifically, we found that at night compared to the day the time course of spectrally-isolated cone photoresponses was slower, cone-to-cone horizontal cell synaptic transfer was highly non-linear and of lower gain, and the delay in cone-to-cone horizontal cell synaptic transmission was longer. However, under bright light-adapted conditions in both day and night, cone-to-cone horizontal cell synaptic transfer was linear and of high gain, and no additional delay was observed at the cone-to-cone horizontal cell synapse. These findings suggest that in addition to controlling rod-cone coupling, retinal clocks shape the light responses of cone horizontal cells by modulating cone-to-cone horizontal cell synaptic transmission.
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Affiliation(s)
- Christophe Ribelayga
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- MD Anderson/UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Stuart C. Mangel
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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22
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Sakai K, Yamamoto Y, Ikeuchi T. Vertebrates originally possess four functional subtypes of G protein-coupled melatonin receptor. Sci Rep 2019; 9:9465. [PMID: 31263128 PMCID: PMC6602942 DOI: 10.1038/s41598-019-45925-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 06/18/2019] [Indexed: 01/28/2023] Open
Abstract
Melatonin receptors (MTNRs) belonging to the G protein-coupled receptor family are considered to consist of three subtypes in vertebrates: MTNR1a, MTNR1b and MTNR1c. Additionally, MTNR1a-like genes have been identified in teleostean species as a fish-specific subtype of MTNR1a. However, similar molecules to this MTNR1a-like gene can be found in some reptiles upon searching the DNA database. We hypothesized that a vertebrate can essentially have four functional subtypes of MTNR as ohnologs. Thus, in the present study we examined the molecular phylogeny, expression patterns and pharmacological profile(s) using the teleost medaka (Oryzias latipes). The four conserved subtypes of MTNR (MTNR1a, MTNR1b, MTNR1c and MTNR1a-like) in vertebrates were classified based on synteny and phylogenetic analysis. The fourth MTNR, termed MTNR1a-like, could be classified as MTNR1d. It was observed by using RT-qPCR that expression patterns differed amongst these subtypes. Moreover, mtnr1a, mtnr1c and mtnr1a-like/mtnr1d expression was elevated during short days compared to long days in diencephalons. All the subtypes were activated by melatonin and transduced signals into the Gi pathway, to perform a cAMP-responsive reporter gene assay. It was shown that MTNR originally consisted of four subtypes: MTNR1a, MTNR1b, MTNR1c and MTNR1d. These subtypes were functional, at least in fish, although some organisms, including mammals, have lost one or two subtypes.
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Affiliation(s)
- Kotowa Sakai
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga, 526-0829, Japan
| | - Yuya Yamamoto
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga, 526-0829, Japan
| | - Toshitaka Ikeuchi
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga, 526-0829, Japan.
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23
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Felder-Schmittbuhl MP, Buhr ED, Dkhissi-Benyahya O, Hicks D, Peirson SN, Ribelayga CP, Sandu C, Spessert R, Tosini G. Ocular Clocks: Adapting Mechanisms for Eye Functions and Health. Invest Ophthalmol Vis Sci 2019; 59:4856-4870. [PMID: 30347082 PMCID: PMC6181243 DOI: 10.1167/iovs.18-24957] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vision is a highly rhythmic function adapted to the extensive changes in light intensity occurring over the 24-hour day. This adaptation relies on rhythms in cellular and molecular processes, which are orchestrated by a network of circadian clocks located within the retina and in the eye, synchronized to the day/night cycle and which, together, fine-tune detection and processing of light information over the 24-hour period and ensure retinal homeostasis. Systematic or high throughput studies revealed a series of genes rhythmically expressed in the retina, pointing at specific functions or pathways under circadian control. Conversely, knockout studies demonstrated that the circadian clock regulates retinal processing of light information. In addition, recent data revealed that it also plays a role in development as well as in aging of the retina. Regarding synchronization by the light/dark cycle, the retina displays the unique property of bringing together light sensitivity, clock machinery, and a wide range of rhythmic outputs. Melatonin and dopamine play a particular role in this system, being both outputs and inputs for clocks. The retinal cellular complexity suggests that mechanisms of regulation by light are diverse and intricate. In the context of the whole eye, the retina looks like a major determinant of phase resetting for other tissues such as the retinal pigmented epithelium or cornea. Understanding the pathways linking the cell-specific molecular machineries to their cognate outputs will be one of the major challenges for the future.
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Affiliation(s)
- Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Ethan D Buhr
- Department of Ophthalmology, University of Washington Medical School, Seattle, Washington, United States
| | - Ouria Dkhissi-Benyahya
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - David Hicks
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, United States
| | - Cristina Sandu
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
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24
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Mogavero F, Jager A, Glennon JC. Clock genes, ADHD and aggression. Neurosci Biobehav Rev 2018; 91:51-68. [DOI: 10.1016/j.neubiorev.2016.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 10/31/2016] [Accepted: 11/03/2016] [Indexed: 12/25/2022]
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25
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Kopperud KL, Grace MS. Circadian Rhythms of Retinomotor Movement in a Marine Megapredator, the Atlantic Tarpon, Megalops atlanticus. Int J Mol Sci 2017; 18:E2068. [PMID: 28956858 PMCID: PMC5666750 DOI: 10.3390/ijms18102068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 11/16/2022] Open
Abstract
Many ecologically and economically important marine fish species worldwide spend portions of their lives in coastal regions that are increasingly inundated by artificial light at night. However, while extensive research illustrates the harmful effects of inappropriate light exposure on biological timing in humans, rodents and birds, comparable studies on marine fish are virtually nonexistent. This study aimed to assess the effects of light on biological clock function in the marine fish retina using the Atlantic tarpon (Megalops atlanticus) as a model. Using anti-opsin immunofluorescence, we observed robust rhythms of photoreceptor outer segment position (retinomotor movement) over the course of the daily light-dark cycle: cone outer segments were contracted toward the inner retina and rods were elongated during the day; the opposite occurred at night. Phase shifting the daily light-dark cycle caused a corresponding shift of retinomotor movement timing, and cone retinomotor movement persisted in constant darkness, indicating control by a circadian clock. Constant light abolished retinomotor movements of both photoreceptor types. Thus, abnormally-timed light exposure may disrupt normal M. atlanticus clock function and harm vision, which in turn may affect prey capture and predator avoidance. These results should help inform efforts to mitigate the effects of coastal light pollution on organisms in marine ecosystems.
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Affiliation(s)
- Kristin L Kopperud
- College of Science, Florida Institute of Technology, 150 West University Blvd, Melbourne, FL 32901, USA.
| | - Michael S Grace
- College of Science, Florida Institute of Technology, 150 West University Blvd, Melbourne, FL 32901, USA.
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26
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Isorna E, de Pedro N, Valenciano AI, Alonso-Gómez ÁL, Delgado MJ. Interplay between the endocrine and circadian systems in fishes. J Endocrinol 2017; 232:R141-R159. [PMID: 27999088 DOI: 10.1530/joe-16-0330] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 12/20/2016] [Indexed: 12/11/2022]
Abstract
The circadian system is responsible for the temporal organisation of physiological functions which, in part, involves daily cycles of hormonal activity. In this review, we analyse the interplay between the circadian and endocrine systems in fishes. We first describe the current model of fish circadian system organisation and the basis of the molecular clockwork that enables different tissues to act as internal pacemakers. This system consists of a net of central and peripherally located oscillators and can be synchronised by the light-darkness and feeding-fasting cycles. We then focus on two central neuroendocrine transducers (melatonin and orexin) and three peripheral hormones (leptin, ghrelin and cortisol), which are involved in the synchronisation of the circadian system in mammals and/or energy status signalling. We review the role of each of these as overt rhythms (i.e. outputs of the circadian system) and, for the first time, as key internal temporal messengers that act as inputs for other endogenous oscillators. Based on acute changes in clock gene expression, we describe the currently accepted model of endogenous oscillator entrainment by the light-darkness cycle and propose a new model for non-photic (endocrine) entrainment, highlighting the importance of the bidirectional cross-talking between the endocrine and circadian systems in fishes. The flexibility of the fish circadian system combined with the absence of a master clock makes these vertebrates a very attractive model for studying communication among oscillators to drive functionally coordinated outputs.
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Affiliation(s)
- Esther Isorna
- Departamento de Fisiología (Fisiología Animal II)Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Nuria de Pedro
- Departamento de Fisiología (Fisiología Animal II)Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana I Valenciano
- Departamento de Fisiología (Fisiología Animal II)Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Ángel L Alonso-Gómez
- Departamento de Fisiología (Fisiología Animal II)Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - María J Delgado
- Departamento de Fisiología (Fisiología Animal II)Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
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Ward AH, Siegwart JT, Frost MR, Norton TT. Intravitreally-administered dopamine D2-like (and D4), but not D1-like, receptor agonists reduce form-deprivation myopia in tree shrews. Vis Neurosci 2017; 34:E003. [PMID: 28304244 PMCID: PMC5567805 DOI: 10.1017/s0952523816000195] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We examined the effect of intravitreal injections of D1-like and D2-like dopamine receptor agonists and antagonists and D4 receptor drugs on form-deprivation myopia (FDM) in tree shrews, mammals closely related to primates. In eleven groups (n = 7 per group), we measured the amount of FDM produced by monocular form deprivation (FD) over an 11-day treatment period. The untreated fellow eye served as a control. Animals also received daily 5 µL intravitreal injections in the FD eye. The reference group received 0.85% NaCl vehicle. Four groups received a higher, or lower, dose of a D1-like receptor agonist (SKF38393) or antagonist (SCH23390). Four groups received a higher, or lower, dose of a D2-like receptor agonist (quinpirole) or antagonist (spiperone). Two groups received the D4 receptor agonist (PD168077) or antagonist (PD168568). Refractions were measured daily; axial component dimensions were measured on day 1 (before treatment) and day 12. We found that in groups receiving the D1-like receptor agonist or antagonist, the development of FDM and altered ocular component dimensions did not differ from the NaCl group. Groups receiving the D2-like receptor agonist or antagonist at the higher dose developed significantly less FDM and had shorter vitreous chambers than the NaCl group. The D4 receptor agonist, but not the antagonist, was nearly as effective as the D2-like agonist in reducing FDM. Thus, using intravitreally-administered agents, we did not find evidence supporting a role for the D1-like receptor pathway in reducing FDM in tree shrews. The reduction of FDM by the dopamine D2-like agonist supported a role for the D2-like receptor pathway in the control of FDM. The reduction of FDM by the D4 receptor agonist, but not the D4 antagonist, suggests an important role for activation of the dopamine D4 receptor in the control of axial elongation and refractive development.
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Affiliation(s)
- Alexander H. Ward
- Genetics, Genomics and Bioinformatics Theme, University of Alabama at Birmingham, Birmingham, AL 35294
| | - John T. Siegwart
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Michael R. Frost
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Thomas T. Norton
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294
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Kunst S, Wolloscheck T, Kelleher DK, Wolfrum U, Sargsyan SA, Iuvone PM, Baba K, Tosini G, Spessert R. Pgc-1α and Nr4a1 Are Target Genes of Circadian Melatonin and Dopamine Release in Murine Retina. Invest Ophthalmol Vis Sci 2016; 56:6084-94. [PMID: 26393668 DOI: 10.1167/iovs.15-17503] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
PURPOSE The neurohormones melatonin and dopamine mediate clock-dependent/circadian regulation of inner retinal neurons and photoreceptor cells and in this way promote their functional adaptation to time of day and their survival. To fulfill this function they act on melatonin receptor type 1 (MT1 receptors) and dopamine D4 receptors (D4 receptors), respectively. The aim of the present study was to screen transcriptional regulators important for retinal physiology and/or pathology (Dbp, Egr-1, Fos, Nr1d1, Nr2e3, Nr4a1, Pgc-1α, Rorβ) for circadian regulation and dependence on melatonin signaling/MT1 receptors or dopamine signaling/D4 receptors. METHODS This was done by gene profiling using quantitative polymerase chain reaction in mice deficient in MT1 or D4 receptors. RESULTS The data obtained determined Pgc-1α and Nr4a1 as transcriptional targets of circadian melatonin and dopamine signaling, respectively. CONCLUSIONS The results suggest that Pgc-1α and Nr4a1 represent candidate genes for linking circadian neurohormone release with functional adaptation and healthiness of retina and photoreceptor cells.
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Affiliation(s)
- Stefanie Kunst
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany 2Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Tanja Wolloscheck
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Debra K Kelleher
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Uwe Wolfrum
- Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - S Anna Sargsyan
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - P Michael Iuvone
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Kenkichi Baba
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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29
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Pack W, Hill DD, Wong KY. Melatonin modulates M4-type ganglion-cell photoreceptors. Neuroscience 2015; 303:178-88. [PMID: 26141846 PMCID: PMC4532552 DOI: 10.1016/j.neuroscience.2015.06.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/30/2015] [Accepted: 06/23/2015] [Indexed: 11/21/2022]
Abstract
In the retina, melatonin is secreted at night by rod/cone photoreceptors and serves as a dark-adaptive signal. Melatonin receptors have been found in many retinal neurons including melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), suggesting it could modulate the physiology of these inner retinal photoreceptors. Here, we investigated whether melatonin modulates the alpha-like M4-type ipRGCs, which are believed to mediate image-forming vision as well as non-image-forming photoresponses. Applying melatonin during daytime (when endogenous melatonin secretion is low) caused whole-cell-recorded M4 cells' rod/cone-driven depolarizing photoresponses to become broader and larger, whereas the associated elevation in spike rate was reduced. Melanopsin-based light responses were not affected significantly. Nighttime application of the melatonin receptor antagonist luzindole also altered M4 cells' rod/cone-driven light responses but in the opposite ways: the duration and amplitude of the graded depolarization were reduced, whereas the accompanying spiking increase was enhanced. These luzindole-induced changes confirmed that M4 cells are modulated by endogenous melatonin. Melatonin could induce the above effects by acting directly on M4 cells because immunohistochemistry detected MT1 receptors in these cells, although it could also act presynaptically. Interestingly, the daytime and nighttime recordings showed significant differences in resting membrane potential, spontaneous spike rate and rod/cone-driven light responses, suggesting that M4 cells are under circadian control. This is the first report of a circadian variation in ipRGCs' resting properties and synaptic input, and of melatoninergic modulation of ipRGCs.
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Affiliation(s)
- W Pack
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States
| | - D D Hill
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States
| | - K Y Wong
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States; Department of Molecular, Cellular & Developmental Biology, University of Michigan, Ann Arbor, MI 48105, United States.
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30
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Connaughton VP, Wetzell B, Arneson LS, DeLucia V, L. Riley A. Elevated dopamine concentration in light-adapted zebrafish retinas is correlated with increased dopamine synthesis and metabolism. J Neurochem 2015. [DOI: 10.1111/jnc.13264] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Bradley Wetzell
- Department of Psychology; American University; Washington District of Columbia USA
| | - Lynne S. Arneson
- Department of Biology; American University; Washington District of Columbia USA
| | - Vittoria DeLucia
- Department of Biology; American University; Washington District of Columbia USA
| | - Anthony L. Riley
- Department of Psychology; American University; Washington District of Columbia USA
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31
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Zheng C, Deng QQ, Liu LL, Wang MY, Zhang G, Sheng WL, Weng SJ, Yang XL, Zhong YM. Orexin-A differentially modulates AMPA-preferring responses of ganglion cells and amacrine cells in rat retina. Neuropharmacology 2015; 93:80-93. [PMID: 25656479 DOI: 10.1016/j.neuropharm.2015.01.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/22/2014] [Accepted: 01/20/2015] [Indexed: 01/18/2023]
Abstract
By activating their receptors (OX1R and OX2R) orexin-A/B regulate wake/sleeping states, feeding behaviors, but the function of these peptides in the retina remains unknown. Using patch-clamp recordings and calcium imaging in rat isolated retinal cells, we demonstrated that orexin-A suppressed α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)-preferring receptor-mediated currents (AMPA-preferring currents) in ganglion cells (GCs) through OX1R, but potentiated those in amacrine cells (ACs) through OX2R. Consistently, in rat retinal slices orexin-A suppressed light-evoked AMPA-preferring receptor-mediated excitatory postsynaptic currents in GCs, but potentiated those in ACs. Intracellular dialysis of GDP-β-S or preincubation with the Gi/o inhibitor pertussis toxin (PTX) abolished both the effects. Either cAMP/the protein kinase A (PKA) inhibitor Rp-cAMP or cGMP/the PKG blocker KT5823 failed to alter the orexin-A effects. Whilst both of them involved activation of protein kinase C (PKC), the effects on GCs and ACs were respectively eliminated by the phosphatidylinositol (PI)-phospholipase C (PLC) inhibitor and phosphatidylcholine (PC)-PLC inhibitor. Moreover, in GCs orexin-A increased [Ca(2+)]i and the orexin-A effect was blocked by intracellular Ca(2+)-free solution and by inositol 1,4,5-trisphosphate (IP3) receptor antagonists. In contrast, orexin-A did not change [Ca(2+)]i in ACs and the orexin-A effect remained in intracellular or extracellular Ca(2+)-free solution. We conclude that a distinct Gi/o/PI-PLC/IP3/Ca(2+)-dependent PKC signaling pathway, following the activation of OX1R, is likely responsible for the orexin-A effect on GCs, whereas a Gi/o/PC-PLC/Ca(2+)-independent PKC signaling pathway, following the activation of OX2R, mediates the orexin-A effect on ACs. These two actions of orexin-A, while working in concert, provide a characteristic way for modulating information processing in the inner retina.
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Affiliation(s)
- Chao Zheng
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China; Cell Electrophysiology Laboratory, Wannan Medical College, 22 West Wenchang Road, Wuhu, Anhui 241002, China
| | - Qin-Qin Deng
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Lei-Lei Liu
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Meng-Ya Wang
- Cell Electrophysiology Laboratory, Wannan Medical College, 22 West Wenchang Road, Wuhu, Anhui 241002, China
| | - Gong Zhang
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Wen-Long Sheng
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Shi-Jun Weng
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Xiong-Li Yang
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
| | - Yong-Mei Zhong
- Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
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Zhang Z, Li H, Liu X, O’Brien J, Ribelayga CP. Circadian clock control of connexin36 phosphorylation in retinal photoreceptors of the CBA/CaJ mouse strain. Vis Neurosci 2015; 32:E009. [PMID: 26241696 PMCID: PMC4760741 DOI: 10.1017/s0952523815000061] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The gap-junction-forming protein connexin36 (Cx36) represents the anatomical substrate of photoreceptor electrical coupling in mammals. The strength of coupling is directly correlated to the phosphorylation of Cx36 at two regulatory sites: Ser110 and Ser293. Our previous work demonstrated that the extent of biotinylated tracer coupling between photoreceptor cells, which provides an index of the extent of electrical coupling, depends on the mouse strain. In the C57Bl/6J strain, light or dopamine reduces tracer coupling and Cx36 phosphorylation in photoreceptors. Conversely, darkness or a dopaminergic antagonist increases tracer coupling and Cx36 phosphorylation, regardless of the daytime. In the CBA/CaJ strain, photoreceptor tracer coupling is not only regulated by light and dopamine, but also by a circadian clock, a type of oscillator with a period close to 24 h and intrinsic to the retina, so that under prolonged dark-adapted conditions tracer coupling is broader at night compared to daytime. In the current study, we examined whether the modulation of photoreceptor coupling by a circadian clock in the CBA/CaJ mouse photoreceptors reflected a change in Cx36 protein expression and/or phosphorylation. We found no significant change in Cx36 expression or in the number of Cx36 gap junction among the conditions examined. However, we found that Cx36 phosphorylation is higher under dark-adapted conditions at night than in the daytime, and is the lowest under prolonged illumination at any time of the day/night cycle. Our observations are consistent with the view that the circadian clock regulation of photoreceptor electrical coupling is mouse strain-dependent and highlights the critical position of Cx36 phosphorylation in the control of photoreceptor coupling.
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Affiliation(s)
- Zhijing Zhang
- Richard S. Ruiz Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Medical School, Houston, TX
| | - Hongyan Li
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Medical School, Houston, TX
| | - Xiaoqin Liu
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Medical School, Houston, TX
| | - John O’Brien
- Richard S. Ruiz Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Medical School, Houston, TX
- Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX
- Program in Neuroscience, Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, TX
- Neuroscience Research Center, The University of Texas Health Science Center at Houston, Houston, TX
| | - Christophe P. Ribelayga
- Richard S. Ruiz Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Medical School, Houston, TX
- Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX
- Program in Neuroscience, Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, TX
- Neuroscience Research Center, The University of Texas Health Science Center at Houston, Houston, TX
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Cazaméa-Catalan D, Besseau L, Falcón J, Magnanou E. The timing of Timezyme diversification in vertebrates. PLoS One 2014; 9:e112380. [PMID: 25486407 PMCID: PMC4259306 DOI: 10.1371/journal.pone.0112380] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 10/15/2014] [Indexed: 01/23/2023] Open
Abstract
All biological functions in vertebrates are synchronized with daily and seasonal changes in the environment by the time keeping hormone melatonin. Its nocturnal surge is primarily due to the rhythmic activity of the arylalkylamine N-acetyl transferase AANAT, which thus became the focus of many investigations regarding its evolution and function. Various vertebrate isoforms have been reported from cartilaginous fish to mammals but their origin has not been clearly established. Using phylogeny and synteny, we took advantage of the increasing number of available genomes in order to test whether the various rounds of vertebrate whole genome duplications were responsible for the diversification of AANAT. We highlight a gene secondary loss of the AANAT2 in the Sarcopterygii, revealing for the first time that the AAANAT1/2 duplication occurred before the divergence between Actinopterygii (bony fish) and Sarcopterygii (tetrapods, lobe-finned fish, and lungfish). We hypothesize the teleost-specific whole genome duplication (WDG) generated the appearance of the AANAT1a/1b and the AANAT2/2′paralogs, the 2′ isoform being rapidly lost in the teleost common ancestor (ray-finned fish). We also demonstrate the secondary loss of the AANAT1a in a Paracantopterygii (Atlantic cod) and of the 1b in some Ostariophysi (zebrafish and cave fish). Salmonids present an even more diverse set of AANATs that may be due to their specific WGD followed by secondary losses. We propose that vertebrate AANAT diversity resulted from 3 rounds of WGD followed by previously uncharacterized secondary losses. Extant isoforms show subfunctionalized localizations, enzyme activities and affinities that have increased with time since their emergence.
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Affiliation(s)
- Damien Cazaméa-Catalan
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
- CNRS, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
| | - Laurence Besseau
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
- CNRS, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
| | - Jack Falcón
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
- CNRS, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
| | - Elodie Magnanou
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
- CNRS, UMR 7232, BIOM Biologie Intégrative des Organismes Marins, Observatoire Océanologique, Banyuls/Mer, France
- * E-mail:
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34
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Popova E. Role of dopamine in distal retina. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2014; 200:333-58. [PMID: 24728309 DOI: 10.1007/s00359-014-0906-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/24/2014] [Accepted: 03/25/2014] [Indexed: 01/11/2023]
Abstract
Dopamine is the most abundant catecholamine in the vertebrate retina. Despite the description of retinal dopaminergic cells three decades ago, many aspects of their function in the retina remain unclear. There is no consensus among the authors about the stimulus conditions for dopamine release (darkness, steady or flickering light) as well as about its action upon the various types of retinal cells. Many contradictory results exist concerning the dopamine effect on the gross electrical activity of the retina [reflected in electroretinogram (ERG)] and the receptors involved in its action. This review summarized current knowledge about the types of the dopaminergic neurons and receptors in the retina as well as the effects of dopamine receptor agonists and antagonists on the light responses of photoreceptors, horizontal and bipolar cells in both nonmammalian and mammalian retina. Special focus of interest concerns their effects upon the diffuse ERG as a useful tool for assessment of the overall function of the distal retina. An attempt is made to reveal some differences between the dopamine actions upon the activity of the ON versus OFF channel in the distal retina. The author has included her own results demonstrating such differences.
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Affiliation(s)
- E Popova
- Department of Physiology, Medical Faculty, Medical University, 1431, Sofia, Bulgaria,
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35
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McMahon DG, Iuvone PM, Tosini G. Circadian organization of the mammalian retina: from gene regulation to physiology and diseases. Prog Retin Eye Res 2013; 39:58-76. [PMID: 24333669 DOI: 10.1016/j.preteyeres.2013.12.001] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 11/27/2013] [Accepted: 12/01/2013] [Indexed: 01/27/2023]
Abstract
The retinal circadian system represents a unique structure. It contains a complete circadian system and thus the retina represents an ideal model to study fundamental questions of how neural circadian systems are organized and what signaling pathways are used to maintain synchrony of the different structures in the system. In addition, several studies have shown that multiple sites within the retina are capable of generating circadian oscillations. The strength of circadian clock gene expression and the emphasis of rhythmic expression are divergent across vertebrate retinas, with photoreceptors as the primary locus of rhythm generation in amphibians, while in mammals clock activity is most robust in the inner nuclear layer. Melatonin and dopamine serve as signaling molecules to entrain circadian rhythms in the retina and also in other ocular structures. Recent studies have also suggested GABA as an important component of the system that regulates retinal circadian rhythms. These transmitter-driven influences on clock molecules apparently reinforce the autonomous transcription-translation cycling of clock genes. The molecular organization of the retinal clock is similar to what has been reported for the SCN although inter-neural communication among retinal neurons that form the circadian network is apparently weaker than those present in the SCN, and it is more sensitive to genetic disruption than the central brain clock. The melatonin-dopamine system is the signaling pathway that allows the retinal circadian clock to reconfigure retinal circuits to enhance light-adapted cone-mediated visual function during the day and dark-adapted rod-mediated visual signaling at night. Additionally, the retinal circadian clock also controls circadian rhythms in disk shedding and phagocytosis, and possibly intraocular pressure. Emerging experimental data also indicate that circadian clock is also implicated in the pathogenesis of eye disease and compelling experimental data indicate that dysfunction of the retinal circadian system negatively impacts the retina and possibly the cornea and the lens.
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Affiliation(s)
- Douglas G McMahon
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - P Michael Iuvone
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, USA; Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, 30310 GA, USA.
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Hwang CK, Chaurasia SS, Jackson CR, Chan GCK, Storm DR, Iuvone PM. Circadian rhythm of contrast sensitivity is regulated by a dopamine-neuronal PAS-domain protein 2-adenylyl cyclase 1 signaling pathway in retinal ganglion cells. J Neurosci 2013; 33:14989-97. [PMID: 24048828 PMCID: PMC3776053 DOI: 10.1523/jneurosci.2039-13.2013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/16/2013] [Accepted: 08/06/2013] [Indexed: 12/25/2022] Open
Abstract
Spatial variation in light intensity, called spatial contrast, comprises much of the visual information perceived by mammals, and the relative ability to detect contrast is referred to as contrast sensitivity (Purves et al., 2012). Recently, retinal dopamine D4 receptors (D4Rs) have been implicated in modulating contrast sensitivity (Jackson et al., 2012); however, the cellular and molecular mechanisms have not been elucidated. Our study demonstrates a circadian rhythm of contrast sensitivity that peaks during the daytime, and that its regulation involves interactions of D4Rs, the clock gene Npas2, and the clock-controlled gene adenylyl cyclase 1 (Adcy1) in a subset of retinal ganglion cells (RGCs). Targeted disruption of the gene encoding D4Rs reduces the amplitude of the contrast sensitivity rhythm by reducing daytime sensitivity and abolishes the rhythmic expression of Npas2 and Adcy1 mRNA in the ganglion cell layer (GCL) of the retina. Npas2(-/-) and Adcy1(-/-) mice show strikingly similar reductions in the contrast sensitivity rhythm to that in mice lacking D4Rs. Moreover, Adcy1 transcript rhythms were abolished in the GCL of Npas2(-/-) mice. Luciferase reporter assays demonstrated that the Adcy1 promoter is selectively activated by neuronal PAS-domain protein 2 (NPAS2)/BMAL1. Our results indicate that the contrast sensitivity rhythm is modulated by D4Rs via a signaling pathway that involves NPAS2-mediated circadian regulation of Adcy1. Hence, we have identified a circadian clock mechanism in a subset of RGCs that modulates an important aspect of retinal physiology and visual processing.
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Affiliation(s)
- Christopher K. Hwang
- Departments of Ophthalmology and Pharmacology, and
- Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Shyam S. Chaurasia
- Departments of Ophthalmology and Pharmacology, and
- Translational Clinical Research Laboratory, Singapore Eye Research Institute, Singapore
- Signature Research Program in Neuroscience and Behavioral Disorder, and
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 169712
| | - Chad R. Jackson
- Departments of Ophthalmology and Pharmacology, and
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, and
| | - Guy C.-K. Chan
- Department of Pharmacology, University of Washington, Seattle, Washington 98195
| | - Daniel R. Storm
- Department of Pharmacology, University of Washington, Seattle, Washington 98195
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Newkirk GS, Hoon M, Wong RO, Detwiler PB. Inhibitory inputs tune the light response properties of dopaminergic amacrine cells in mouse retina. J Neurophysiol 2013; 110:536-52. [PMID: 23636722 DOI: 10.1152/jn.00118.2013] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dopamine (DA) is a neuromodulator that in the retina adjusts the circuitry for visual processing in dim and bright light conditions. It is synthesized and released from retinal interneurons called dopaminergic amacrine cells (DACs), whose basic physiology is not yet been fully characterized. To investigate their cellular and input properties as well as light responses, DACs were targeted for whole cell recording in isolated retina using two-photon fluorescence microscopy in a mouse line where the dopamine receptor 2 promoter drives green fluorescent protein (GFP) expression. Differences in membrane properties gave rise to cell-to-cell variation in the pattern of resting spontaneous spike activity ranging from silent to rhythmic to periodic burst discharge. All recorded DACs were light sensitive and generated responses that varied with intensity. The threshold response to light onset was a hyperpolarizing potential change initiated by rod photoreceptors that was blocked by strychnine, indicating a glycinergic amacrine input onto DACs at light onset. With increasing light intensity, the ON response acquired an excitatory component that grew to dominate the response to the strongest stimuli. Responses to bright light (photopic) stimuli also included an inhibitory OFF response mediated by GABAergic amacrine cells driven by the cone OFF pathway. DACs expressed GABA (GABA(A)α1 and GABA(A)α3) and glycine (α2) receptor clusters on soma, axon, and dendrites consistent with the light response being shaped by dual inhibitory inputs that may serve to tune spike discharge for optimal DA release.
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Affiliation(s)
- G S Newkirk
- Department of Physiology & Biophysics and Program in Neurobiology & Behavior, University of Washington, Seattle, WA, USA
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38
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Li H, Zhang Z, Blackburn MR, Wang SW, Ribelayga CP, O'Brien J. Adenosine and dopamine receptors coregulate photoreceptor coupling via gap junction phosphorylation in mouse retina. J Neurosci 2013; 33:3135-50. [PMID: 23407968 PMCID: PMC3711184 DOI: 10.1523/jneurosci.2807-12.2013] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 12/20/2012] [Accepted: 12/24/2012] [Indexed: 11/21/2022] Open
Abstract
Gap junctions in retinal photoreceptors suppress voltage noise and facilitate input of rod signals into the cone pathway during mesopic vision. These synapses are highly plastic and regulated by light and circadian clocks. Recent studies have revealed an important role for connexin36 (Cx36) phosphorylation by protein kinase A (PKA) in regulating cell-cell coupling. Dopamine is a light-adaptive signal in the retina, causing uncoupling of photoreceptors via D4 receptors (D4R), which inhibit adenylyl cyclase (AC) and reduce PKA activity. We hypothesized that adenosine, with its extracellular levels increasing in darkness, may serve as a dark signal to coregulate photoreceptor coupling through modulation of gap junction phosphorylation. Both D4R and A2a receptor (A2aR) mRNAs were present in photoreceptors, inner nuclear layer neurons, and ganglion cells in C57BL/6 mouse retina, and showed cyclic expression with partially overlapping rhythms. Pharmacologically activating A2aR or inhibiting D4R in light-adapted daytime retina increased photoreceptor coupling. Cx36 among photoreceptor terminals, representing predominantly rod-cone gap junctions but possibly including some rod-rod and cone-cone gap junctions, was phosphorylated in a PKA-dependent manner by the same treatments. Conversely, inhibiting A2aR or activating D4R in daytime dark-adapted retina decreased Cx36 phosphorylation with similar PKA dependence. A2a-deficient mouse retina showed defective regulation of photoreceptor gap junction phosphorylation, fairly regular dopamine release, and moderately downregulated expression of D4R and AC type 1 mRNA. We conclude that adenosine and dopamine coregulate photoreceptor coupling through opposite action on the PKA pathway and Cx36 phosphorylation. In addition, loss of the A2aR hampered D4R gene expression and function.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Chromatography, High Pressure Liquid
- Connexins/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Dark Adaptation/physiology
- Gap Junctions/metabolism
- Gap Junctions/physiology
- Gene Expression/physiology
- Image Processing, Computer-Assisted
- Immunohistochemistry
- In Situ Hybridization
- In Vitro Techniques
- Mice
- Mice, Inbred C57BL
- Phosphorylation
- Real-Time Polymerase Chain Reaction
- Receptors, Adenosine A2/genetics
- Receptors, Adenosine A2/physiology
- Receptors, Dopamine/genetics
- Receptors, Dopamine/physiology
- Receptors, Dopamine D4/biosynthesis
- Receptors, Dopamine D4/genetics
- Receptors, Purinergic P1/genetics
- Receptors, Purinergic P1/physiology
- Retinal Cone Photoreceptor Cells/physiology
- Retinal Rod Photoreceptor Cells/physiology
- Gap Junction delta-2 Protein
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Affiliation(s)
- Hongyan Li
- Richard S. Ruiz, MD, Department of Ophthalmology and Visual Science, The University of Texas Medical School and
| | - Zhijing Zhang
- Richard S. Ruiz, MD, Department of Ophthalmology and Visual Science, The University of Texas Medical School and
| | - Michael R. Blackburn
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School, Houston, Texas 77030; and
- Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Steven W. Wang
- Richard S. Ruiz, MD, Department of Ophthalmology and Visual Science, The University of Texas Medical School and
- Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Christophe P. Ribelayga
- Richard S. Ruiz, MD, Department of Ophthalmology and Visual Science, The University of Texas Medical School and
- Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - John O'Brien
- Richard S. Ruiz, MD, Department of Ophthalmology and Visual Science, The University of Texas Medical School and
- Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas 77030
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Das P, Pradhan D, Maiti B. Circadian rhythms of gonadal and extra-gonadal hormonal and glycemic profiles during the breeding phase of the ovarian cycle of Indian estuarine grey mullets,Mugil cephalusL. BIOL RHYTHM RES 2013. [DOI: 10.1080/09291016.2011.632609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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40
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Huang H, Wang Z, Weng SJ, Sun XH, Yang XL. Neuromodulatory role of melatonin in retinal information processing. Prog Retin Eye Res 2013; 32:64-87. [PMID: 22986412 DOI: 10.1016/j.preteyeres.2012.07.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 12/15/2022]
Affiliation(s)
- Hai Huang
- Institute of Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, PR China
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41
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Role of melatonin and its receptors in the vertebrate retina. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 300:211-42. [PMID: 23273863 DOI: 10.1016/b978-0-12-405210-9.00006-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Melatonin is a chemical signal of darkness that is produced by retinal photoreceptors and pinealocytes. In the retina, melatonin diffuses from the photoreceptors to bind to specific receptors on a variety of inner retinal neurons to modify their activity. Potential target cells for melatonin in the inner retina are amacrine cells, bipolar cells, horizontal cells, and ganglion cells. Melatonin inhibits the release of dopamine from amacrine cells and increases the light sensitivity of horizontal cells. Melatonin receptor subtypes show differential, cell-specific patterns of expression that are likely to underlie differential functional modulation of specific retinal pathways. Melatonin potentiates rod signals to ON-type bipolar cells, via activation of the melatonin MT2 (Mel1b) receptor, suggesting that melatonin modulates the function of specific retinal circuits based on the differential distribution of its receptors. The selective and differential expression of melatonin receptor subtypes in cone circuits suggest a conserved function for melatonin in enhancing transmission from rods to second-order neurons and thus promote dark adaptation.
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42
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Tosini G, Baba K, Hwang CK, Iuvone PM. Melatonin: an underappreciated player in retinal physiology and pathophysiology. Exp Eye Res 2012; 103:82-9. [PMID: 22960156 DOI: 10.1016/j.exer.2012.08.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 12/14/2022]
Abstract
In the vertebrate retina, melatonin is synthesized by the photoreceptors with high levels of melatonin at night and lower levels during the day. Melatonin exerts its influence by interacting with a family of G-protein-coupled receptors that are negatively coupled with adenylyl cyclase. Melatonin receptors belonging to the subtypes MT(1) and MT(2) have been identified in the mammalian retina. MT(1) and MT(2) receptors are found in all layers of the neural retina and in the retinal pigmented epithelium. Melatonin in the eye is believed to be involved in the modulation of many important retinal functions; it can modulate the electroretinogram (ERG), and administration of exogenous melatonin increases light-induced photoreceptor degeneration. Melatonin may also have protective effects on retinal pigment epithelial cells, photoreceptors and ganglion cells. A series of studies have implicated melatonin in the pathogenesis of age-related macular degeneration, and melatonin administration may represent a useful approach to prevent and treat glaucoma. Melatonin is used by millions of people around the world to retard aging, improve sleep performance, mitigate jet lag symptoms, and treat depression. Administration of exogenous melatonin at night may also be beneficial for ocular health, but additional investigation is needed to establish its potential.
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Affiliation(s)
- Gianluca Tosini
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA.
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43
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Hamilton WR, Trickler WJ, Robinson BL, Paule MG, Ali SF. Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on retinal dopaminergic system in mice. Neurosci Lett 2012; 515:107-10. [PMID: 22414866 DOI: 10.1016/j.neulet.2012.02.085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 10/28/2022]
Abstract
The neurotoxins methamphetamine (METH) and MPTP are well-known for their effects on the nigrostriatal dopaminergic system and use in modeling neurodegenerative disorders such as Parkinson's disease. It is not well-known though, how METH or MPTP affects the visual system and specifically the retinal dopaminergic system. This study was designed to examine acute effects of multiple doses of METH and MPTP on the retinal dopaminergic system. Mice were exposed to either low- (LD) 10 mg/kg total dose or high-dose (HD) 30 mg/kg total dose, of METH or MPTP and the retinal catecholaminergic system was analyzed by HPLC. METH produced no significant changes in dopamine (DA), its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) or DA usage in the retina. LD-MPTP produced no change in DA level, but significantly decreased DOPAC and HVA. LD-MPTP also significantly decreased DA usage as measured by the DOPAC/DA and HVA/DA ratios. HD-MPTP significantly decreased DA, DOPAC and HVA, but did not affect DA usage. Taken together these results suggest that inhibition of the DA metabolizing enzymes monoamine oxidase A (MAO) or catechol-O-methyl transferase (COMT) may take place at lower doses of MPTP treatment; conversely, higher doses of MPTP may cause decreases in DA, DOPAC and HVA through another mechanism.
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Affiliation(s)
- W Ryan Hamilton
- Neurochemistry Laboratory, Division of Neurotoxicology, National Center for Toxicological Research/USFDA, Jefferson, AR 72079, USA
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Servili A, Herrera-Pérez P, Kah O, Muñoz-Cueto JA. The retina is a target for GnRH-3 system in the European sea bass, Dicentrarchus labrax. Gen Comp Endocrinol 2012; 175:398-406. [PMID: 22138555 DOI: 10.1016/j.ygcen.2011.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 10/21/2011] [Accepted: 11/11/2011] [Indexed: 12/11/2022]
Abstract
The European sea bass expresses three GnRH (Gonadotrophin Releasing Hormone) forms that exert pleiotropic actions via several classes of receptors. The GnRH-1 form is responsible for the endogenous regulation of gonadotrophin release by the pituitary gland but the role of GnRH-2 and GnRH-3 remains unclear in fish. In a previous study performed in sea bass, we have provided evidence of direct links between the GnRH-2 cells and the pineal organ and demonstrated a functional role for GnRH-2 in the modulation of the secretory activity of this photoreceptive organ. In this study, we have investigated the possible relationship between the GnRH-3 system and the retina in the same species. Thus, using a biotinylated dextran-amine tract-tracing method, we reveal the presence of retinopetal cells in the terminal nerve of sea bass, a region that also contains GnRH-3-immunopositive cells. Moreover, GnRH-3-immunoreactive fibers were observed at the boundary between the inner nuclear and the inner plexiform layers, and also within the ganglion cell layer. These results strongly suggest that the GnRH-3 neurons located in the terminal nerve area represent the source of GnRH-3 innervation in the retina of this species. In order to clarify whether the retina is a target for GnRH, the expression pattern of GnRH receptors (dlGnRHR) was also analyzed by RT-PCR and in situ hybridization. RT-PCR revealed the retinal expression of dlGnRHR-II-2b, -1a, -1b and -1c, while in situ hybridization only showed positive signals for the receptors dlGnRHR-II-2b and -1a. Finally, double-immunohistochemistry showed that GnRH-3 projections reaching the sea bass retina end in close proximity to tyrosine hydroxylase (dopaminergic) cells, which also expressed the dlGnRHR-II-2b receptor subtype. Taken together, these results suggest an important role for GnRH-3 in the modulation of dopaminergic cell activities and retinal functions in sea bass.
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Affiliation(s)
- Arianna Servili
- Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR), E-11510 Puerto Real, Spain
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45
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RGS2 and RGS4 modulate melatonin-induced potentiation of glycine currents in rat retinal ganglion cells. Brain Res 2011; 1411:1-8. [DOI: 10.1016/j.brainres.2011.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 04/08/2011] [Accepted: 07/05/2011] [Indexed: 11/18/2022]
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46
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Yammouni R, Bozzano A, Douglas RH. A latitudinal cline in the efficacy of endogenous signals: evidence derived from retinal cone contraction in fish. ACTA ACUST UNITED AC 2011; 214:501-8. [PMID: 21228209 DOI: 10.1242/jeb.048538] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Like many physiological systems synchronised to the light:dark cycle, retinomotor movements in 'lower' vertebrates are controlled by both the ambient illumination and input from endogenous circadian oscillators. In the present study, we examine the relative influence of these two signals in various species of teleost fish with different latitudes of origin. We find equatorial species show very strong endogenous control. The cones of the glowlight tetra, for example, continue to go through undiminished cycles of contraction and relaxation that mirror the previous light:dark cycle for at least two weeks in continual darkness. To quantify the relative effectiveness of the ambient light compared with endogenous signals in causing cone contraction, the degree to which seven teleost species responded to light during the dark phase of their light:dark cycle was examined. In this situation the retina receives conflicting instructions; while the light is acting directly to cause light adaptation, any endogenous signal tends to keep the retinal elements dark adapted. The further from the equator a species originated, the more its cones contracted in response to such illumination, suggesting animals from higher latitudes make little use of endogenous oscillators and rely more on ambient illumination to control behaviours. Equatorial species, however, rely on internal pacemakers to a much greater degree and are relatively insensitive to exogenous light signals. Because these data are consistent with published observations in systems as diverse as melatonin synthesis in Arctic reindeer and the behaviour of regional populations of Drosophila, latitudinal clines in the efficacy of circadian oscillators may be a common feature among animals.
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Affiliation(s)
- Robert Yammouni
- Henry Wellcome Laboratory for Vision Sciences, Department of Optometry and Visual Science, City University London, Northampton Square, London, EC1V 0HB, UK
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47
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Yang XF, Miao Y, Ping Y, Wu HJ, Yang XL, Wang Z. Melatonin inhibits tetraethylammonium-sensitive potassium channels of rod ON type bipolar cells via MT2 receptors in rat retina. Neuroscience 2010; 173:19-29. [PMID: 21094224 DOI: 10.1016/j.neuroscience.2010.11.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 10/29/2010] [Accepted: 11/13/2010] [Indexed: 11/16/2022]
Abstract
By challenging specific receptors, melatonin synthesized and released by photoreceptors regulates various physiological functions in the vertebrate retina. Here, we studied modulatory effects of melatonin on K+ currents of rod-dominant ON type bipolar cells (Rod-ON-BCs) in rat retinal slices by patch-clamp techniques. Double immunofluorescence experiments conducted in isolated cell and retinal section preparations showed that the melatonin MT₂ receptor was expressed in somata, dendrites and axon terminals of rat Rod-ON-BCs. Electrophysiologically, application of melatonin selectively inhibited the tetraethylammonium (TEA)-sensitive K+ current component, but did not show any effect on the 4-aminopyridine (4-AP)-sensitive component. Consistent with the immunocytochemical result, the melatonin effect was blocked by co-application of 4-phenyl-2-propionamidotetralin (4-P-PDOT), a specific MT₂ receptor antagonist. Neither protein kinase A (PKA) nor protein kinase G (PKG) seemed to be involved because both the PKA inhibitor Rp-cAMP and the PKG inhibitor KT5823 did not block the melatonin-induced suppression of the K+ currents. In contrast, application of the phospholipase C (PLC) inhibitor U73122 or the protein kinase C (PKC) inhibitor bisindolylmaleimide IV (Bis IV) eliminated the melatonin effect, and when the Ca²+ chelator BAPTA-containing pipette was used, melatonin failed to inhibit the K+ currents. These results suggest that suppression of the TEA-sensitive K+ current component via activation of MT₂ receptors expressed on rat Rod-ON-BCs may be mediated by a Ca²+-dependent PLC/inositol 1,4,5-trisphosphate (IP₃/PKC signaling pathway.
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Affiliation(s)
- X-F Yang
- Institutes of Brain Science, Institute of Neurobiology and State Key Laboratory of Medical Neurobiology, Fudan University, 138 Yixueyuan Road, Shanghai 200032, PR China
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48
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Zhao WJ, Zhang M, Miao Y, Yang XL, Wang Z. Melatonin potentiates glycine currents through a PLC/PKC signalling pathway in rat retinal ganglion cells. J Physiol 2010; 588:2605-19. [PMID: 20519319 PMCID: PMC2916991 DOI: 10.1113/jphysiol.2010.187641] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 05/24/2010] [Indexed: 12/15/2022] Open
Abstract
In vertebrate retina, melatonin regulates various physiological functions. In this work we investigated the mechanisms underlying melatonin-induced potentiation of glycine currents in rat retinal ganglion cells (RGCs). Immunofluorescence double labelling showed that rat RGCs were solely immunoreactive to melatonin MT(2) receptors. Melatonin potentiated glycine currents of RGCs, which was reversed by the MT(2) receptor antagonist 4-P-PDOT. The melatonin effect was blocked by intracellular dialysis of GDP-beta-S. Either preincubation with pertussis toxin or application of the phosphatidylcholine (PC)-specific phospholipase C (PLC) inhibitor D609, but not the phosphatidylinositol (PI)-PLC inhibitor U73122, blocked the melatonin effect. The protein kinase C (PKC) activator PMA potentiated the glycine currents and in the presence of PMA melatonin failed to cause further potentiation of the currents, whereas application of the PKC inhibitor bisindolylmaleimide IV abolished the melatonin-induced potentiation. The melatonin effect persisted when [Ca(2+)](i) was chelated by BAPTA, and melatonin induced no increase in [Ca(2+)](i). Neither cAMP-PKA nor cGMP-PKG signalling pathways seemed to be involved because 8-Br-cAMP or 8-Br-cGMP failed to cause potentiation of the glycine currents and both the PKA inhibitor H-89 and the PKG inhibitor KT5823 did not block the melatonin-induced potentiation. In consequence, a distinct PC-PLC/PKC signalling pathway, following the activation of G(i/o)-coupled MT(2) receptors, is most likely responsible for the melatonin-induced potentiation of glycine currents of rat RGCs. Furthermore, in rat retinal slices melatonin potentiated light-evoked glycine receptor-mediated inhibitory postsynaptic currents in RGCs. These results suggest that melatonin, being at higher levels at night, may help animals to detect positive or negative contrast in night vision by modulating inhibitory signals largely mediated by glycinergic amacrine cells in the inner retina.
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Affiliation(s)
- Wen-Jie Zhao
- Institutes of Brain Science and Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
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49
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Ribelayga C, Mangel SC. Identification of a circadian clock-controlled neural pathway in the rabbit retina. PLoS One 2010; 5:e11020. [PMID: 20548772 PMCID: PMC2883549 DOI: 10.1371/journal.pone.0011020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Accepted: 04/09/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Although the circadian clock in the mammalian retina regulates many physiological processes in the retina, it is not known whether and how the clock controls the neuronal pathways involved in visual processing. METHODOLOGY/PRINCIPAL FINDINGS By recording the light responses of rabbit axonless (A-type) horizontal cells under dark-adapted conditions in both the day and night, we found that rod input to these cells was substantially increased at night under control conditions and following selective blockade of dopamine D(2), but not D(1), receptors during the day, so that the horizontal cells responded to very dim light at night but not in the day. Using neurobiotin tracer labeling, we also found that the extent of tracer coupling between rabbit rods and cones was more extensive during the night, compared to the day, and more extensive in the day following D(2) receptor blockade. Because A-type horizontal cells make synaptic contact exclusively with cones, these observations indicate that the circadian clock in the mammalian retina substantially increases rod input to A-type horizontal cells at night by enhancing rod-cone coupling. Moreover, the clock-induced increase in D(2) receptor activation during the day decreases rod-cone coupling so that rod input to A-type horizontal cells is minimal. CONCLUSIONS/SIGNIFICANCE Considered together, these results identify the rod-cone gap junction as a key site in mammals through which the retinal clock, using dopamine activation of D(2) receptors, controls signal flow in the day and night from rods into the cone system.
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Affiliation(s)
- Christophe Ribelayga
- Department of Neuroscience, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Stuart C. Mangel
- Department of Neuroscience, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
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Physiology and pharmacology of melatonin in relation to biological rhythms. Pharmacol Rep 2009; 61:383-410. [PMID: 19605939 DOI: 10.1016/s1734-1140(09)70081-7] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 05/01/2009] [Indexed: 01/01/2023]
Abstract
Melatonin is an evolutionarily conserved molecule that serves a time-keeping function in various species. In vertebrates, melatonin is produced predominantly by the pineal gland with a marked circadian rhythm that is governed by the central circadian pacemaker (biological clock) in the suprachiasmatic nuclei of the hypothalamus. High levels of melatonin are normally found at night, and low levels are seen during daylight hours. As a consequence, melatonin has been called the "darkness hormone". This review surveys the current state of knowledge regarding the regulation of melatonin synthesis, receptor expression, and function. In particular, it addresses the physiological, pathological, and therapeutic aspects of melatonin in humans, with an emphasis on biological rhythms.
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