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https://www.readbyqxmd.com/read/28420980/loss-of-melanopsin-expressing-ganglion-cell-subtypes-and-dendritic-degeneration-in-the-aging-human-retina
#1
Gema Esquiva, Pedro Lax, Juan J Pérez-Santonja, José M García-Fernández, Nicolás Cuenca
In mammals, melanopsin-expressing retinal ganglion cells (mRGCs) are, among other things, involved in several non-image-forming visual functions, including light entrainment of circadian rhythms. Considering the profound impact of aging on visual function and ophthalmic diseases, here we evaluate changes in mRGCs throughout the life span in humans. In 24 post-mortem retinas from anonymous human donors aged 10-81 years, we assessed the distribution, number and morphology of mRGCs by immunostaining vertical retinal sections and whole-mount retinas with antibodies against melanopsin...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/28414048/light-and-the-laboratory-mouse
#2
Stuart N Peirson, Laurence A Brown, Carina A Pothecary, Lindsay A Benson, Angus S Fisk
Light exerts widespread effects on physiology and behaviour. As well as the widely-appreciated role of light in vision, light also plays a critical role in many non-visual responses, including regulating circadian rhythms, sleep, pupil constriction, heart rate, hormone release and learning and memory. In mammals, responses to light are all mediated via retinal photoreceptors, including the classical rods and cones involved in vision as well as the recently identified melanopsin-expressing photoreceptive retinal ganglion cells (pRGCs)...
April 13, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28412540/melanopsin-expressing-retinal-ganglion-cells-are-resistant-to-cell-injury-but-not-always
#3
Birgitte Georg, Anna Ghelli, Carla Giordano, Fred N Ross-Cisneros, Alfredo A Sadun, Valerio Carelli, Jens Hannibal, Chiara La Morgia
Melanopsin retinal ganglion cells (mRGCs) are intrinsically photosensitive RGCs deputed to non-image forming functions of the eye such as synchronization of circadian rhythms to light-dark cycle. These cells are characterized by unique electrophysiological, anatomical and biochemical properties and are usually more resistant than conventional retinal ganglion cells to different insults, such as axotomy and different paradigms of stress. We also demonstrated that these cells are relatively spared compared to conventional RGCs in mitochondrial optic neuropathies, i...
April 12, 2017: Mitochondrion
https://www.readbyqxmd.com/read/28399269/loss-of-melanopsin-expressing-retinal-ganglion-cells-in-patients-with-diabetic-retinopathy
#4
Elisabeth Anne Obara, Jens Hannibal, Steffen Heegaard, Jan Fahrenkrug
Purpose: Photo-entrainment of the circadian clock is mediated by melanopsin-expressing retinal ganglion cells (mRGCs) located in the retina. Patients suffering from diabetic retinopathy (DR) show impairment of light regulated circadian activity such as sleep disorders, altered blood pressure, and abnormal melatonin secretion. The aim of this study was to assess the impact of DR on the expression of mRGCs in the human retina. Methods: The expression of mRGCs and RGCs was determined in eye sections containing retinal tissue from patients with DR (n = 6) and respective age-matched controls (n = 8) using immunohistochemistry by costaining with antibodies against RNA binding protein with multiple splicing (RBPMS), which identified RGCs and melanopsin which identified the mRGCs...
April 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28395083/pathological-confirmation-of-optic-neuropathy-in-familial-dysautonomia
#5
Carlos E Mendoza-Santiesteban, Jose-Alberto Palma, Thomas R Hedges, Nora V Laver, Nada Farhat, Lucy Norcliffe-Kaufmann, Horacio Kaufmann
Clinical data suggest that optic neuropathy and retinal ganglion cell loss are the main cause of visual decline in patients with familial dysautonomia, but this has not previously been confirmed by pathological analyses. We studied retinas and optic nerves in 6 eyes from 3 affected patients obtained at autopsy. Analyses included routine neurohistology and immunohistochemistry for neurofilaments, cytochrome c oxidase (COX), and melanopsin-containing ganglion cells. We observed profound axon loss in the temporal portions of optic nerves with relative preservation in the nasal portions; this correlated with clinical and optical coherence tomography findings in 1 patient...
March 1, 2017: Journal of Neuropathology and Experimental Neurology
https://www.readbyqxmd.com/read/28339754/expression-of-deep-brain-photoreceptors-in-the-pekin-drake-a-possible-role-in-the-maintenance-of-testicular-function
#6
R Haas, E Alenciks, S Meddle, G S Fraley
Several putative deep brain photoreceptors (DBPs) have been identified, such as melanopsin, opsin 5, and vertebrate ancient opsin. The aim of this study was to elucidate the role of DBPs in gonadal regulation in the Pekin drake. As previously reported, we observed opsin-like immunoreactivity (-ir) in the lateral septum (LS), melanopsin-ir in the premammillary nucleus (PMM), and opsin 5-ir in the periventricular organ. To determine the sensitivity of the DBPs to specific wavelengths of light, drakes were given an acute exposure to red, blue, or white light...
February 23, 2017: Poultry Science
https://www.readbyqxmd.com/read/28332564/pupillary-responses-in-non-proliferative-diabetic-retinopathy
#7
Jason C Park, Yi-Fan Chen, Norman P Blair, Felix Y Chau, Jennifer I Lim, Yannek I Leiderman, Mahnaz Shahidi, J Jason McAnany
The goal of this study was to determine the extent of rod-, cone-, and melanopsin-mediated pupillary light reflex (PLR) abnormalities in diabetic patients who have non-proliferative diabetic retinopathy (NPDR). Fifty diabetic subjects who have different stages of NPDR and 25 age-equivalent, non-diabetic controls participated. PLRs were measured in response to full-field, brief-flash stimuli under conditions that target the rod, cone, and intrinsically-photosensitive (melanopsin) retinal ganglion cell pathways...
March 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28271634/choroideremia-melanopsin-mediated-postillumination-pupil-relaxation-is-abnormally-slow
#8
Shakoor Ba-Ali, Søren Kirchhoff Christensen, Birgit Sander, Thomas Rosenberg, Michael Larsen, Henrik Lund-Andersen
PURPOSE: To investigate the rod-cone and melanopsin pupillary light response (PLR) pathways in choroideremia. METHODS: Eight patients with choroideremia and 18 healthy age-matched controls underwent chromatic pupillometry by applying blue (463 nm) and red light (643 nm) at 100 lux intensity to the right eye while recording pupil diameters. Absolute baseline pupil size (mm), normalized maximal pupil constriction and the early and late postillumination pupillary dilation, from 0 to 10 seconds and 10 to 30 seconds after the end of illumination, respectively, were determined...
March 8, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/28266650/pupillary-responses-to-short-wavelength-light-are-preserved-in-aging
#9
A V Rukmini, Dan Milea, Tin Aung, Joshua J Gooley
With aging, less blue light reaches the retina due to gradual yellowing of the lens. This could result in reduced activation of blue light-sensitive melanopsin-containing retinal ganglion cells, which mediate non-visual light responses (e.g., the pupillary light reflex, melatonin suppression, and circadian resetting). Herein, we tested the hypothesis that older individuals show greater impairment of pupillary responses to blue light relative to red light. Dose-response curves for pupillary constriction to 469-nm blue light and 631-nm red light were compared between young normal adults aged 21-30 years (n = 60) and older adults aged ≥50 years (normal, n = 54; mild cataract, n = 107; severe cataract, n = 18)...
March 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28264100/the-relation-between-light-induced-lacrimation-and-the-melanopsin-driven-postillumination-pupil-response
#10
Shaobo Lei, Herbert C Goltz, Xingqiao Chen, Marija Zivcevska, Agnes M F Wong
Purpose: To investigate the chromatic characteristics and intensity-response function of light-induced reflex lacrimation and its correlation with the melanopsin-driven postillumination pupil response (PIPR). Methods: Eleven visually normal participants completed the experiment. Lacrimation was measured in one eye by placing a calibrated filter paper strip in the conjunctival sac over a 1 minute-interval (Schirmer's test) during which participants received either no light stimulation (baseline trial) or one flash of blue or red light stimuli presented binocularly with a Ganzfeld stimulator, while the pupil response was recorded simultaneously from the fellow eye by using an eye tracker...
March 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28251921/clinical-implications-of-the-melanopsin-based-non-image-forming-visual-system
#11
REVIEW
Alexander Ksendzovsky, I Jonathan Pomeraniec, Kareem A Zaghloul, J Javier Provencio, Ignacio Provencio
Since the discovery of the non-image-forming visual system, tremendous research efforts have been dedicated to understanding its mechanisms and functional roles. Original functions associated with the melanopsin system include the photoentrainment of circadian sleep-wake cycles and the pupillary light reflex. Recent findings, however, suggest a much broader involvement of this system in an array of physiologic responses to light. This newfound insight into the underlying function of the non-image-forming system has revealed the many connections to human pathology and attendant disease states, including seasonal affective disorder, migraine, glaucoma, inherited mitochondrial optic neuropathy, and sleep dysregulation of aging...
March 28, 2017: Neurology
https://www.readbyqxmd.com/read/28223508/c-terminal-phosphorylation-regulates-the-kinetics-of-a-subset-of-melanopsin-mediated-behaviors-in-mice
#12
Preethi Somasundaram, Glenn R Wyrick, Diego Carlos Fernandez, Alireza Ghahari, Cindy M Pinhal, Melissa Simmonds Richardson, Alan C Rupp, Lihong Cui, Zhijian Wu, R Lane Brown, Tudor Constantin Badea, Samer Hattar, Phyllis R Robinson
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and mediate several non-image-forming visual functions, including circadian photoentrainment and the pupillary light reflex (PLR). ipRGCs act as autonomous photoreceptors via the intrinsic melanopsin-based phototransduction pathway and as a relay for rod/cone input via synaptically driven responses. Under low light intensities, where only synaptically driven rod/cone input activates ipRGCs, the duration of the ipRGC response will be determined by the termination kinetics of the rod/cone circuits...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28160289/melanopsin-expressing-human-retinal-ganglion-cells-subtypes-distribution-and-intraretinal-connectivity
#13
Jens Hannibal, Anders Tolstrup Christiansen, Steffen Heegaard, Jan Fahrenkrug, Jens Folke Kiilgaard
Intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin belong to a heterogenic population of RGCs which regulate the circadian clock, masking behavior, melatonin suppression, the pupillary light reflex, and sleep/wake cycles. The different functions seem to be associated to different subtypes of melanopsin cells. In rodents, subtype classification has associated subtypes to function. In primate and human retina such classification has so far, not been applied. In the present study using antibodies against N- and C-terminal parts of human melanopsin, confocal microscopy and 3D reconstruction of melanopsin immunoreactive (-ir) RGCs, we applied the criteria used in mouse on human melanopsin-ir RGCs...
June 1, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28153865/mechanisms-creating-transient-and-sustained-photoresponses-in-mammalian-retinal-ganglion-cells
#14
Xiwu Zhao, Aaron N Reifler, Melanie M Schroeder, Elizabeth R Jaeckel, Andrew P Chervenak, Kwoon Y Wong
Retinal neurons use sustained and transient light responses to encode visual stimuli of different frequency ranges, but the underlying mechanisms remain poorly understood. In particular, although earlier studies in retinal ganglion cells (RGCs) proposed seven potential mechanisms, all seven have since been disputed, and it remains unknown whether different RGC types use different mechanisms or how many mechanisms are used by each type. Here, we conduct a comprehensive survey in mice and rats of 12 candidate mechanisms that could conceivably produce tonic rod/cone-driven ON responses in intrinsically photosensitive RGCs (ipRGCs) and transient ON responses in three types of direction-selective RGCs (TRHR+, Hoxd10+ ON, and Hoxd10+ ON-OFF cells)...
March 6, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28143576/enhancement-of-autonomic-and-psychomotor-arousal-by-exposures-to-blue-wavelength-light-importance-of-both-absolute-and-relative-contents-of-melanopic-component
#15
Emi Yuda, Hiroki Ogasawara, Yutaka Yoshida, Junichiro Hayano
BACKGROUND: Blue light containing rich melanopsin-stimulating (melanopic) component has been reported to enhance arousal level, but it is unclear whether the determinant of the effects is the absolute or relative content of melanopic component. We compared the autonomic and psychomotor arousal effects of melanopic-enriched blue light of organic light-emitting diode (OLED) with those of OLED lights with lesser absolute amount of melanopic component (green light) and with greater absolute but lesser relative content (white light)...
January 31, 2017: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/28135360/retinal-architecture-and-melanopsin-mediated-pupillary-response-characteristics-a-putative-pathophysiologic-signature-for-the-retino-hypothalamic-tract-in-multiple-sclerosis
#16
Ethan Meltzer, Peter V Sguigna, Adnan Subei, Shin Beh, Eric Kildebeck, Darrel Conger, Amy Conger, Marlen Lucero, Benjamin S Frohman, Ashley N Frohman, Shiv Saidha, Steven Galetta, Peter A Calabresi, Robert Rennaker, Teresa C Frohman, Randy H Kardon, Laura J Balcer, Elliot M Frohman
Importance: A neurophysiologic signature of the melanopsin-mediated persistent constriction phase of the pupillary light reflex may represent a surrogate biomarker for the integrity of the retinohypothalamic tract, with potential utility for investigating alterations in homeostatic mechanisms associated with brain disorders and implications for identifying new treatments. Objective: To characterize abnormalities of retinal architecture in patients with multiple sclerosis (MS) and corresponding alterations in the melanopsin-mediated sustained pupillary constriction response...
January 30, 2017: JAMA Neurology
https://www.readbyqxmd.com/read/28135345/melanopsin-effects-on-pupil-responses-is-the-eye-the-window-to-the-weary-soul
#17
Owen B White, Fiona Costello
No abstract text is available yet for this article.
January 30, 2017: JAMA Neurology
https://www.readbyqxmd.com/read/28119450/ectopic-expression-of-mouse-melanopsin-in-drosophila-photoreceptors-reveals-fast-response-kinetics-and-persistent-dark-excitation
#18
Bushra Yasin, Elkana Kohn, Maximilian Peters, Rachel Zaguri, Shirley Weiss, Krystina Schopf, Ben Katz, Armin Huber, Baruch Minke
The intrinsically photosensitive M1 retinal ganglion cells (ipRGC) initiate non-image-forming light-dependent activities and express the melanopsin (OPN4) photopigment. Several features of ipRGC photosensitivity are characteristic of fly photoreceptors. However, the light response kinetics of ipRGC is much slower due to unknown reasons. Here we used transgenic Drosophila, in which the mouse OPN4 replaced the native Rh1 photopigment of Drosophila R1-6 photoreceptors, resulting in deformed rhabdomeric structure...
March 3, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28103478/modulation-of-fast-narrowband-oscillations-in-the-mouse-retina-and-dlgn-according-to-background-light-intensity
#19
Riccardo Storchi, Robert A Bedford, Franck P Martial, Annette E Allen, Jonathan Wynne, Marcelo A Montemurro, Rasmus S Petersen, Robert J Lucas
Background light intensity (irradiance) substantially impacts the visual code in the early visual system at synaptic and single-neuron levels, but its influence on population activity is largely unexplored. We show that fast narrowband oscillations, an important feature of population activity, systematically increase in amplitude as a function of irradiance in both anesthetized and awake, freely moving mice and at the level of the retina and dorsal lateral geniculate nucleus (dLGN). Narrowband coherence increases with irradiance across large areas of the dLGN, but especially for neighboring units...
January 18, 2017: Neuron
https://www.readbyqxmd.com/read/28097654/melanopsin-expressing-ganglion-cells-in-human-retina-morphology-distribution-and-synaptic-connections
#20
Subha Nasir-Ahmad, Sammy C S Lee, Paul R Martin, Ulrike Grünert
Melanopsin-expressing retinal ganglion cells are intrinsically photosensitive cells that are involved in non-image forming visual processes such as the pupillary light reflex and circadian entrainment but also contribute to visual perception. Here we used immunohistochemistry to study the morphology, density, distribution and synaptic connectivity of melanopsin-expressing ganglion cells in four post mortem human donor retinas. Two types of melanopsin-expressing ganglion cells were distinguished based on their dendritic stratification near either the outer or the inner border of the inner plexiform layer...
January 18, 2017: Journal of Comparative Neurology
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