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https://www.readbyqxmd.com/read/28223508/c-terminal-phosphorylation-regulates-the-kinetics-of-a-subset-of-melanopsin-mediated-behaviors-in-mice
#1
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...
February 21, 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
#2
Jens Hannibal, Anders Tolstrup Christensen, 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...
February 3, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28153865/mechanisms-creating-transient-and-sustained-photoresponses-in-mammalian-retinal-ganglion-cells
#3
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)...
February 2, 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
#4
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
#5
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
#6
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
#7
Bushra Yasin, Elkana Kohn, Maximilian Peters, Rachel Zaguri, Shirley Weiss, Krystina Schopf, Ben Katz, Armin Huber, Baruch Minke
The intrinsically photosensitive 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...
January 24, 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
#8
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
#9
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
https://www.readbyqxmd.com/read/28061512/assessment-of-rod-cone-and-intrinsically-photosensitive-retinal-ganglion-cell-contributions-to-the-canine-chromatic-pupillary-response
#10
Connie Y Yeh, Kristin L Koehl, Christine D Harman, Simone Iwabe, José M Guzman, Simon M Petersen-Jones, Randy H Kardon, András M Komáromy
Purpose: The purpose of this study was to evaluate a chromatic pupillometry protocol for specific functional assessment of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) in dogs. Methods: Chromatic pupillometry was tested and compared in 37 dogs in different stages of primary loss of rod, cone, and combined rod/cone and optic nerve function, and in 5 wild-type (WT) dogs. Eyes were stimulated with 1-s flashes of dim (1 cd/m2) and bright (400 cd/m2) blue light (for scotopic conditions) or bright red (400 cd/m2) light with 25-cd/m2 blue background (for photopic conditions)...
January 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28031289/attenuated-pupillary-light-responses-and-downregulation-of-opsin-expression-parallel-decline-in-circadian-disruption-in-two-different-mouse-models-of-huntington-s-disease
#11
Koliane Ouk, Steven Hughes, Carina A Pothecary, Stuart N Peirson, A Jennifer Morton
Circadian deficits in Huntington's disease (HD) are recapitulated in both fragment (R6/2) and full-length (Q175) mouse models of HD. Circadian rhythms are regulated by the suprachiasmatic nuclei (SCN) in the hypothalamus, which are primarily entrained by light detected by the retina. The SCN receives input from intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin, but also receive input from rods and cones. In turn, ipRGCs mediate a range of non-image forming responses to light including circadian entrainment and the pupillary light response (PLR)...
December 27, 2016: Human Molecular Genetics
https://www.readbyqxmd.com/read/28003454/modulation-of-recognition-memory-performance-by-light-requires-both-melanopsin-and-classical-photoreceptors
#12
Shu K E Tam, Sibah Hasan, Steven Hughes, Mark W Hankins, Russell G Foster, David M Bannerman, Stuart N Peirson
Acute light exposure exerts various effects on physiology and behaviour. Although the effects of light on brain network activity in humans are well demonstrated, the effects of light on cognitive performance are inconclusive, with the size, as well as direction, of the effect depending on the nature of the task. Similarly, in nocturnal rodents, bright light can either facilitate or disrupt performance depending on the type of task employed. Crucially, it is unclear whether the effects of light on behavioural performance are mediated via the classical image-forming rods and cones or the melanopsin-expressing photosensitive retinal ganglion cells...
December 28, 2016: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/27997691/survey-of-retinal-ganglion-cell-morphology-in-marmoset
#13
Rania A Masri, Kumiko A Percival, Amane Koizumi, Paul R Martin, Ulrike Grünert
In primate retina, the midget, parasol, and small bistratified cell populations form the large majority of ganglion cells. In addition, there is a variety of low-density wide-field ganglion cell types, which are less well characterized. Here we studied retinal ganglion cells in the common marmoset, Callithrix jacchus, using particle-mediated gene-transfer. Ganglion cells were transfected with an expression plasmid for the postsynaptic density 95-green fluorescent protein. The retinas were processed with established immunohistochemical markers for bipolar and/or amacrine cells in order to determine ganglion cell dendritic stratification...
December 20, 2016: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/27992553/intrinsically-photosensitive-retinal-ganglion-cells-iprgcs-are-necessary-for-light-entrainment-of-peripheral-clocks
#14
Paulo Kofuji, Ludovic S Mure, Logan J Massman, Nicole Purrier, Satchidananda Panda, William C Engeland
Light is a powerful entrainer of circadian clocks in almost all eukaryotic organisms promoting synchronization of internal circadian rhythms with external environmental light-dark (LD) cycles. In mammals, the circadian system is organized in a hierarchical manner, in which a central pacemaker in the suprachiasmatic nucleus (SCN) synchronizes oscillators in peripheral tissues. Recent evidence demonstrates that photoentrainment of the SCN proceeds via signaling from a subpopulation of retinal ganglion cells (RGCs) which are melanopsin-expressing and intrinsically photosensitive (ipRGCs)...
2016: PloS One
https://www.readbyqxmd.com/read/27930778/melanopsin-containing-or-non-melanopsin-containing-retinal-ganglion-cells-response-to-acute-ocular-hypertension-with-or-without-brain-derived-neurotrophic-factor-neuroprotection
#15
Giuseppe Rovere, Francisco M Nadal-Nicolás, Jiawei Wang, Jose M Bernal-Garro, Nuria García-Carrillo, Maria Paz Villegas-Pérez, Marta Agudo-Barriuso, Manuel Vidal-Sanz
Purpose: To analyze the responses of different retinal ganglion cell (RGC) types to acute ocular hypertension (AOH) and intravitreal administration of brain-derived neurotrophic factor (BDNF). Methods: In adult albino rats, the anterior chamber of the left eye was cannulated with a needle connected to a saline container elevated 1½ meters above the eye for 75 minutes. Rats received 12 hours before a 5 μl intravitreal injection containing 5 μg BDNF in 1% albumin PBS or vehicle and were analyzed 3, 7, 14, or 45 days later...
December 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27914990/presence-of-melanopsin-in-human-crystalline-lens-epithelial-cells-and-its-role-in-melatonin-synthesis
#16
Hanan Awad Alkozi, Xiaoyu Wang, Maria J Perez de Lara, Jesus Pintor
Melanopsin is a non-image forming photoreceptor known to be present in the retina and it is considered to have light regulated tasks among other functions. In the present work, melanopsin presence in human lens epithelial cells as well as in human lens tissue is described for the first time. Moreover, studying the concentration of melatonin and its synthesising enzyme AANAT proved a clear link between melanopsin activation and the suppression of melatonin synthesis. Melanopsin sensitivity to specific wavelength (465-480 nm, blue) was confirmed after making temporal studies incubating lens epithelial cells under light, red, green, blue and total darkness for 2, 4, 8, 12 h and analysing the concentration of both melatonin and its synthesising enzyme AANAT, discovering that melatonin levels after submitting cells to total darkness are significantly higher to ones submitted to white or specifically blue light (***p < 0...
November 30, 2016: Experimental Eye Research
https://www.readbyqxmd.com/read/27899883/commentary-melanopsin-regulates-both-sleep-promoting-and-arousal-promoting-responses-to-light
#17
COMMENT
Christian Cajochen, Sarah L Chellappa
No abstract text is available yet for this article.
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27893096/chemogenetic-activation-of-iprgcs-drives-changes-in-dark-adapted-scotopic-electroretinogram
#18
Nina Milosavljevic, Annette E Allen, Jasmina Cehajic-Kapetanovic, Robert J Lucas
Purpose: The purpose of this study was to investigate the impact of activating melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) on dark-adapted (scotopic) electroretinograms (ERG). Methods: We used mice (Opn4Cre/+) expressing cre recombinase in melanopsin-expressing cells for a targeted gene delivery of a chemogenetic Gq-coupled receptor, hM3Dq, to ipRGCs. Intraperitoneal injection of clozapine N-oxide (CNO) at 5 mg/kg was used for acute activation of hM3Dq and thus excitation of ipRGCs in darkness...
November 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27824104/degeneration-and-energy-shortage-in-the-suprachiasmatic-nucleus-underlies-the-circadian-rhythm-disturbance-in-apoe-mice-implications-for-alzheimer-s-disease
#19
Lan Zhou, Qian Gao, Meng Nie, Jing-Li Gu, Wei Hao, Lin Wang, Ji-Min Cao
Alzheimer's disease (AD) patients suffer sleep disorders and circadian rhythm disturbances (CRDs). The underlying mechanisms are incompletely understood, and treatments are lacking. In this study, we characterized the locomotor activity, clock gene expression, morphological degeneration and energy metabolism of suprachiasmatic nucleus (SCN), together with retinal light sensing, in ApoE(-/-) mice, a model for AD. Compared with the control C57BL/6J mice, ApoE(-/-) mice exhibited disordered circadian locomotor activity under dim light and constant darkness, with impaired re-entrainment to phase change schedules...
November 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27821359/pupillary-response-abnormalities-in-depressive-disorders
#20
Scott A Laurenzo, Randy Kardon, Johannes Ledolter, Pieter Poolman, Ashley M Schumacher, James B Potash, Jan M Full, Olivia Rice, Anna Ketcham, Cole Starkey, Jess G Fiedorowicz
Depressive disorders lack objective physiological measurements to characterize the affected population and facilitate study of relevant mechanisms. The melanopsin-mediated light signaling pathway may contribute to seasonal variation and can be measured non-invasively by pupillometry. We prospectively studied changes in melanopsin-mediated pupillary constriction in 19 participants with major depressive disorder (MDD) and 10 control across the summer and winter solstices. The melanopsin-mediated response, as measured by the pupil's sustained constriction six s after a high intensity blue light stimulus, was marginally attenuated in those with MDD relative to controls (p=0...
December 30, 2016: Psychiatry Research
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